SpaceX's kerosene is a good decision for putting stuff into low earth orbit compared to hydrogen. When you go farther away than that, the hydrogen advantage kicks in. For Low Lunar Orbit and Mars transfer orbit, hydrogen is very useful.
The problem with going further away on hydrogen is that hydrogen is not generally considered a "storable" propellant; it's very hard to manage boiloff. Mild cryogenics like methane (SpaceX's plan) are easier. It allows you to use the same stage for transfer, entry, and launch burns.
Also, the Falcon heavy will need an extra stage to go much beyond geosynchronous orbit
Why? It's a 3-stager (or if you'd rather not count boosters as full stages, 2 1/2). Designed specifically with Mars missions in mind. 3 stages is a good number for kerolox missions to MTO if the stages have a low mass fraction (like SpaceX's do). You could even do it with 2, although it'd cut your payload.
The SLS solid boosters seem ready now.
They're not. You're confusing test firing with completion.
The big SLS first stage will probably be ready in 2 years.
In your dreams. The smallest variant isn't scheduled to fly for 1 1/2 years, and that's assuming that the schedule doesn't slip. That's Block 1, 70 tonnes. Block 1B (again, assuming no schedule slips) isn't scheduled until 2021 - and that's only 105 tonnes. There's three scheduled launches of Block 1B, the last in 2026. The latter being asteroid redirect, which, well, don't hold your breath;) There are no scheduled launches of Block 2 (130 tonnes).
You have this weird conception of how far along SLS is. They only even finished the test stand for the tank last month.
What, exactly, is the purpose of hanging in the clouds of Venus ?
What, exactly is the purpose of hanging out in the near-vacuum of Mars? What, exactly, is the purpose of life?
If you don't agree with the merits of the human race becoming a starfaring civilization centuries from now based on investments made today in getting the ball rolling today, I'm not going to debate that with you. But if you agree with that, then the whole point in expanding offworld is to develop into a multiplanetary species, where demand drives down launch costs and we learn, step by step, to make everything that we need in offworld environments and to become adept at the multi-month journeys between planets. At first, it's a sunk cost. With time, it's increasingly supported by trade. And after long periods of time, it brings the immense resources beyond our planet into our grasp.
If you want to talk about economics on Venus, here's a few for you.
* Power is immensely abundant. Many technologies that we employ are basically energy costs - to pick an example, isotope enrichment. So once the higher marginal capital cost for doing things on Venus becomes overtaken by the greater energy availability, Venus becomes the logical place to conduct such activities.
* Deuterium levels are ~240 times higher than on Earth. So depending on the level of enrichment you need and the means by which you return it, if you can return goods for somewhere in the "couple thousand to several tens of thousands of dollars per kilogram" range, it's profitable. Deuterium recovery can be rendered an inherent part of nighttime fuel cell power storage, since electrolysis has an excellent enrichment factor.
* Venus's lavas appear to be highly differentiated, and there's a great degree of chemical weathering and atmospheric processing, which can be another resource enrichment process. So concentrations of high value ores far greater than are found on Earth are not unrealistic. There are a couple dozen elements whose values are worth exporting at realistic launch costs several decades from now.
* Even simple rocks from offworld have great value (collectors, luxury goods, etc). It's not theoretical - people really do pay huge sums for offworld items. Their value will of course depend first the abundance of their export (if you export 100kg per year, you can sell for 10x more per kg than if you export 10000kg per year, which you can sell for 10x more per kg than if you export 1000000kg per year...). If you're selling in small quantities, the value could be in the millions of dollars per kilogram. Venus's surface atmosphere is dense enough that you can outright dredge loose rocks.
* The size of the market and sensitivity to export quantity also depends on their aesthetics (aka, moving more from the collectors market into the larger luxury goods market). This means minerals that are durable and aesthetically pleasing. What we've sampled so far of Venus's surface fits that bill - gabbro (sold as "black granite" - large crystalled, dark, hard rock, forms excellent slabs), anorthosite (rare on Earth, often associated with labradorite, which is an iridescent bluish-purple semiprecious to precious mineral), troctolite (rare, olivine (peridot)-rich relative of anorthosite and gabbro - looks like this when cut and polished), etc. It's one thing for your typical sheikh or dotcom millionaire to say "my yacht's countertop is made from the finest tuscan marble." It's another to say "my yacht's countertop is from freaking Venus." You're looking at a very large market in the 4 figure/kg range, a reasonable market in the 5 figure/kg range, and a small but decent market in the 6 figure/kg range.
* Venus's apparently high levels of repeated differentiation, in conditions very different from Earth, likely mean that some minerals, including gemstones, that are rare or no
Yes, wake me up when you've recreated Earth's vast diversity of industrial infrastructure on the moon.
Spacecraft are incredibly complex thing, and you're proposing to build them on a place where you're starting with absolutely nothing. And why? To save launch costs? Yes, launch costs are expensive relative to peoples' everyday experience, but they're only a (ever-diminishing) fraction of the cost of a whole mission.
If you're planning to wait until you can outright build entire spacecraft on the moon, you're planning on pushing Mars missions off by many generations. Even the concept that simple raw, bulk sheet metal of even comparable quality (and thus mass) to that available on Earth will be produced on the moon after two decades of high budget dedicated effort straddles the line between "crazy ambitious" and "crazy". Let alone being able to build it into something of relevance with sufficient reliability, and let alone being able to produce it at a rate that, after factoring in consumables that you have to ship from Earth to keep workers alive and all industrial processes running (consumable feedstocks, maintenance, etc) isn't vastly higher than on Earth.
There is absolutely nothing "cost saving" about operating on the moon; it is a huge money sink, and will continue to be so for generations. The same with Mars. You don't go there to save money, you go there as a very long-term investment in the future.
Well, they did produce that huge carbon fiber tank. Which appears to have failed during one of their pressure tanks. Really, building such a huge rocket out of composites is crazy ambitious (if not just crazy), but my hat goes off to them if they can succeed.
They've also made a mini-Raptor that they've started putting through tests. The fact that they've apparently managed those chamber pressures without corrosion problems so far is very impressive.
It occurred to me the other day that they have an interesting potential "halfway" route to ITS, which is that since they clearly plan to have different variants of the spaceship (cargo, crew, tanker), they could start off with the cargo variant and instead of a cargo fairing, have an interstage and use that to boost an elongated Falcon 9 (like the Falcon Heavy central core). So the spaceship would function as a first stage until it got its own booster so that it could function as a second stage. It'd be a perfect testbed for their new technologies (same construction style and engines as the booster, just smaller), while at the same time boosting SpaceX's launch capabilities into the super-heavy range. They'd want to use more atmosphere-optimized nozzles, but apart from that... it's already designed to handle much greater heat loads as well as full propulsive landings.
He's first going to have to learn how to launch that fast. That's one area where SpaceX hasn't had much success - getting its launch turnaround times down. Hopefully they will in the future. Also, since an explosion takes them out for half a year or more (regardless of turnaround times), they better up their reliability by an order of magnitude or more, since each increase in launch rate means more possible rockets that can fail. And of course they want the ITS booster to have a service life of 1000x launches, which means an immensely high reliability.
Anyway, SpaceX's big goal is to have their satellite service give them a nearly unlimited demand for launches in the coming decade, as well as a correspondingly huge income from global sales of satellite net / communications services - and to funnel those profits into ITS. Time will tell... but there's certainly no shortage of ambition.
That's the biggest concern I have. People tire of ongoing expenses. ISS seemed neat at first; now everyone hates it. Why would a moon base fare differently?
Long-term presences in space need to very quickly cut ties with earth, on order of greatest resource dependencies down to smallest resource dependencies. Aka, first things like oxygen, propellant, etc, then to industrial chemicals, of increasingly smaller quantities, with increasingly diversified manufacturing facilities, with very complex/low volume chemical feedstocks and manufacturing processes coming last. Cutting all ties is a process that would take centuries. But you can start with the low hanging fruit, bit by bit, and keep stockpiles of everything needed for maintenance that you can't produce locally.
Unfortunately, running counter to this is expansion. Because if you double the size of your operations, you also double your resource demands. So you need to improve resource independence at a faster rate than you grow.
Part of the problem with the moon is that it's just not a great place for ISRU. Volatiles are rare. We've never even sampled any moon that aren't depleted in volatiles, although there's some data to suggest that various volatiles might be scattered in permanently shaded areas (all of them, in the same place? That's a good question). Surface mineral diversity is limited - primarily light, non-volatile elements. Oxygen is at least widely abundant, but locked up tightly. And while the moon offers short transit times, it's surprisingly not that advantageous concerning delta-V. You can't aerocapture there, landing is fully powered (no parachute deceleration), and to get there you have to already be on such a high apogee orbit that it's not much more energy to go into a Mars transfer. Gravity is less and night is two days long. There are a couple "maybe" peaks of eternal light, but that doesn't mean that they're colocated with volatiles; the last I looked into it it looked like the closest suggested find of water was dozens of kilometers away from the nearest such peak, which would be quite the commute (and thus low throughput / high wear).
The moon is certainly the "cautious" option; emergency returns / resupplies are easy there, and communication fast. Its main value appears to be a testing ground for systems while minimizing risk. But it's not a very appealing place from a settlement perspective.
Of course, I prefer Venus to Mars, but that's neither here nor there;) I'd like to see a parallel program for both, as the same sort of booster and transfer stage can be used for both, so it's only habitat / ascent stage development costs that are doubled. And once you get past the differences in feedstock sources, production industrial processes converge (Venus advantaged by the higher power availability and easier ability to get rid of heat - excepting in the case of cryogenics, where Mars holds the advantage)
One, there would be howls of protest. Two, you're not taking that argument to its logical end. You should only send pygmy women by that logic.
Women do consume less resources (by a good margin on average) and take up less space, but if I recall correctly are more vulnerable to radiation-related disease. So it's a tossup depending on what factors are constraining your mission architecture.
Most designs are for many fibers in parallel. So in an impact you would lose one out of N.
Right. Because micrometeoroids/debris never strike edge on, and because only one fiber gets severed per impact, rather than the reality, which is that an impact is basically like a small explosion.
I have read the book, and it's an absurd degree of wishful thinking. Just ignoring the huge number of things that they just gloss over or omit outright, the materials technology they're talking about is about two orders of magnitude away from what we actually have, and might even be physically impossible. Measurements of individual carbon nanotubes (let alone bundles, let alone bulk fibres) don't approach the strengths being talked about there. Colossal carbon tube does better on an individual tube basis, but again, we're nowhere even close to the materials tech required. And for what? For a massive, very low throughput, tiny safety margin, most-failure-modes-unaccounted-for, low-power-efficiency means of access to space? Colour me unimpressed.
If you want something better, I recommend looking into Lofstrom loops (launch loops). Current materials tech, high efficiency, high throughput per unit mass, no orbit restrictions, and works even on tidally locked bodies.
Quite true. The materials technology required is about two orders of magnitude away from actual materials technology, for starters. And among the countless other problems with space elevators, they're not actually all that efficient. Laser power beaming over those distances works out to single-digit transfer efficiencies, and microwave power beaming even less (microwave power beaming to space can be efficient, but only if the receiving antenna is huge). And no, you can't regularly hang things or run power wires up a space elevator - the mass of the cable has to be vanishingly small.
Active-suspended structures, such as Lofstrom loops, are a much better choice. Power transfer efficiency can be greater than 50% and current materials technology should be sufficient. They can also be designed to shoot payloads into any orbit (unlike space elevators), and work independent of the properties of the body in question, as well as having far greater throughput per unit mass. There's really no reason to choose a space elevator over a Lofstrom loop.
It doesn't work like that. Radiative heating/cooling works via exchange of IR. You're not just giving it up; everything you're radiating at is proportionally radiating back at you. So you cool the most when you're radiatively exchanging with something that's very cold. Aka, you want to be radiatively exchanging with the cosmic microwave background, not with low-altitude clouds. That's the whole point of radiating at low absorption frequencies in the atmosphere: so that you're exchanging with space, not with atmospheric air.
1. That was just an old theory, and not a widely accepted one.
2. Given what we've just seen, it demonstrably isn't.
That doesn't mean that there aren't compounds formed at great pressure that can remain stable at moderate pressures and represent very dense energy sources - there surely are. Metastability is a very real thing. But apparently not in the case of metallic hydrogen at ~STP.
Assuming that this actually even was metallic hydrogen; even that is somewhat in dispute.
Indeed, on both counts. And in particular I like the word "rogue planet". Again you have an adjective imparting additional information about another object ("Rogue X"), "rogue" can be readily quantified ("Not in a stable orbit around any particular star or cluster of stars"), and it's a very evocative term. And rogue planets are absolutely expected according to our current models. They'll be incredibly difficult to find, but they're out there.
We're also coming to the realization that there's a lot of objects, potentially including large ones, that are only tenuously bound to our solar system. And it's likely that we readily exchange this mass with other nearby stars over cosmologic timescales; parts of our solar system (primarily distant ones) likely formed by other stars, and things that condensed during the formation of our star system are likely now orbiting other stars.
The short of it, Jupiter moves things around; it's very good at scattering other bodies, even large ones. First it dragged outer populations into the inner solar system, then scattered inner solar system material out, and then on its retreat pulled outer solar system material back in. It's actually a very big deal that it did that, as it brought ice into the inner solar system.
1. "Adjective nouns" need to have similarity to "noun" but aren't necessarily a subset. Gummy bears aren't a subset of bears either.
Gummy bears are not a scientific term. Besides, the IAU itself already uses the word dwarf in this manner. Dwarf stars, dwarf galaxies... but carved out an inexplicable exception for dwarf planets.
I'd like to see a citation on this. I highly doubt that you can simulate the formation of a solar system where multiple Mars analogues can coexist in the same orbit
False equivalency. There's a difference between "two Mars sized planets existing in the same orbit" and "Mars' orbit having been cleared". And more to the point, the biggest problem with the concept of Mars clearing its orbit is that its orbit was already largely cleared when it formed. According to our best models, Jupiter reached all the way in to around where Mars' orbit is today, and had cleared almost everything to around 1 AU. Earth and Venus accreted from planetesimals between each other. Mars accreted from planetary embryos ejected to the space in-between Earth and Jupiter. Without Jupiter's migration, simulations produce an Earth-sized Mars and several planetary embryos in the asteroid belt on eccentric / high inclination orbits, something akin to the situation between Neptune and Pluto - except with the embryos nearly Mars-sized.
3. In a geological sense yes. But the current definition of planets is based on orbital mechanics, after which Earth is a lot closer to Jupiter than to Ceres/Pluto.
Huh? By what aspect of orbital mechanics? By semimajor axis and velocity, Earth is much closer to Ceres than Jupiter. Are you talking inclination and eccentricity? Then we should boot Mars in favour of low inclination / eccentricity asteroids.
4. Hydro-static equilibrium as a dividing line is way worse. There are roughly 100 TNOs where we don't really know whether they are elliptical.
Hydrostatic equilibrium can be very easily estimated based on mass, which can be approximately deduced within a range of feasible albedos and densities, and very accurately deduced if the body has a moon. By contrast, it's almost impossible to estimate neighborhood clearing to any distance beyond Neptune, or at all in the case of extrasolar planets. Which, to reiterate, the IAU definition says aren't planets, even though they have an extrasolar planet working group.
We'd have to visit each and every one of them with a probe just to put them in the proper category.
This is utter nonsense.
Meanwhile, it's completely clear which bodies qualify for the "clearing its orbit" rule.
No, it's not. We have virtually no clue what lies in the outer reach of our solar system. As we speak there's a search for a new planet that could be as big as an ice giant. It's a huge open question as to whether it would have cleared its neighborhood, and it will be very difficult to ascertain.
All currently qualifying planets have roughly 99% or more of the mass in their orbit in themselves. Ceres has 30%.
You seem to have some weird concept going on that "semimajor axis = orbit". Ceres has nothing of significance in its orbit. The asteroids are not all in the same orbit. They're certainly more likely to cross each others orbits, but that's not the same thing.
And again, since you apparently missed it: the reason that the inner solar system is largely cleared except for the asteroid belt (and the reason that the latter exists) is Jupiter. Mars did not clear its own neighborhood.
The IAU spend months in total hashing out this issue and three days talking in meetings before the vote
That's just the issue: that's not what happened. The IAU discussion was a disaster. Here's the timeline:
2005: The IAU appoints a committee to investigate the issue and generate a proposal. The committee investigated the issue for a year.
The IAU meeting is scheduled from 14-25 August 2006.
16 August: The committee recommends a definition based on hydrostatic equilibrium. No "cleared the neighborhood" nonsense. They publish their draft proposal.
18 August: The IAU division of planetary sciences (aka, the people who actually deal with planets) endorses the proposal.
Also 18 August: A subgroup of the IAU formed which opposed the proposal. An astronomer in the group (aka, someone who studies stars, not planets) - Julio Ángel Fernández - made up his own "cleared the neighborhood" definition. While most of the membership starts to trickle away over the next week, they remain determined to change the definition.
22 August: The original, hydrostatic equilibrium draft continued to be the basis for discussion. There were some tweaks made (some name changes and adjusting the double-planet definition), but it remained largely the same.
Late on 22 August: Fernández's group manages to get to just over half of the attendance at the (open) drafting meeting, leading to a very "heated" debate between the two sides.
22 to 24 August: The drafting group begins to meet and negotiate in secret. The last that the general attendance of the conference knew, they'll either end up with a vote on a purely hydrostatic definition, or (more likely) no vote at all due to the chaos. Attendence continues to dwindle, particularly among those who are okay with either a hydrostatic definition or none at all.
24 August: The current "cleared the neighborhood" definition is suddenly proposed and voted on on the same day. Only 10% of the conference attendance (4-5% of the IAU membership) is still present, mainly those who had been hanging on trying to get their definition through. They pass the new definition.
It's not generally laypeople who are upset about how it went down, it's IAU members. Many have complained bitterly about it to the press. The IAU's own committee of experts was ignored, in favour of a definition written in secret meetings and voted on by a small, very much nonrandom fraction of people, the vast majority of whom do not study planets.
If there's one thing I hate, it's people who pretend that anyone who opposes the IAU definition does so because they're ignorant morons overcome by some emotional attachment to Pluto, when in reality it's been planetary scientists themselves who have been the definition's harshest critics, because it's an internally self-inconsistent, linguistically flawed, false-premise-based definition that leads to all sorts of absurd results and contradicts terminology that was already in widespread use in the scientific literature.
Exactly. I think Stern's always been on the right side of this. The original paper that the Stern-Levison parameter comes from has a great system laid out, where you have a bunch of adjectives that you can apply to different bodies based on their varying physical (composition, size) and orbital parameters, and you can use any combination of them as needed. Which seems to me to be so obviously the right solution.
Saying pluto is a dwarf planet seems pretty good to me as it gives it a special place among planet like objects already.
If they had simply stopped there, that wouldn't have been a problem. The problem is that they didn't. They declared that dwarf planets aren't planets at all - which is nonsense. Mars has far more in common with Pluto than, say, Jupiter. If anything should have been separated out, it's the gas and ice giants from the rocky/icy planets.
Hydrostatic equilibrium is a very meaningful dividing line to split groupings on. If a body is in hydrostatic equilibrium, it's experienced dramatic geologic change in its history - differentiation, tectonics, internal heating, generally fluids (particularly liquid water), and on and on. It's the sort of place you go if you want to learn about planetary evolution or search for life. If a body is not in hydrostatic equilibrium, it's made of primordial materials, preserved largely intact. It's the sort of place you go to learn about the formation of our solar system and its building blocks.
It's rare that nature gives you such clear dividing lines, but when it comes to planets, it has. It's not perfect - you can (and do) have bodies that straddle the border and are only partially or slightly differentiated. But in general, nature has drawn an obvious line in the sand, and we should respect that.
if the object is really big and clear
Is Earth's orbit clear? No, we have a huge massive object co-orbiting with us. Is Neptune's orbit clear? No, it has Pluto in it. They try their hardest to pretend that the IAU actually chose a "gravitationally dominant" standard, but that's not what they actually put in the definition. The standard in the definition is "cleared the neighborhood".
And it's based on a false premise - that each planet cleared its own neighborhood. Which is just pseudoscience. All of our models show that Jupiter, and to a lesser extent Saturn, cleared most of the solar system, including the vast majority of the clearing around Mars, and a good fraction around Earth (lesser around Venus). Mars did not clear its own neighborhood. Nor is it gravitationally dominant in its neighborhood; the vast majority of asteroids are in orbital resonance with Jupiter and not Mars.
And I've heard some people try to sneak around this by saying "Okay, maybe it isn't gravitationally dominant / cleared its neighbood now, but it has enough of a Stern-Levison parameter that it would have been had Jupiter not existed". First off, that's changing the definition yet again (to "would have cleared its neighborhood if no other planets were there"). But beyond that, it's abuse of the Stern-Levison parameter. The Stern-Levison parameter is built around a body's ability to clear asteroids - bodies with the current size and orbital distribution of our asteroid belt. Not protoplanets. In the early solar system it was the ability to clear protoplanets that caused neighborhoods to be cleared. Jupiter got rid of some really massive things that were forming in and near the inner solar system. There's a reason why our planetary system has such an unusual size distribution: the inner planets start getting bigger, the stop getting bigger, then get small, then debris, then something huge. That "something huge" stripped the building blocks out of the inner solar system, preventing it from becoming dominated by super-Earths. Saturn appears to have been our savior - its (delayed) formation appears to have stopped Jupiter's inward migration.
And even just going with the Stern-Levison parameter - Neptune has a Pluto-sized body in its "neighborhood". Now, Pluto may be small compared to Neptune, but compared to Mars it wouldn't be - yet Mars has a much lower Stern-Levison parameter than Neptune. Again: the only reason Mars doesn't experience stuff like this is because Jupiter cleared its neighborhood for it.
Clearly given that people like Stern have regularly given interviews decrying the decision, and going so far as to call it "bullshit" (can you say that at NASA?), it's clearly not the storm in a teacup that you want to present it as.
What the proponents did was take a term widely used by planetary geologists and have it mean something completely different - akin to dentists suddenly declaring to doctors that the heart is no longer an organ and to stop referring to it as one. And contrary to your presentation of why they did it ("to make it easier to write journal articles") without fail every last supporter I've seen interviewed about their vote has given some variant of the following reason for why they voted the way they did: "I don't want my daughter having to memorize the names of hundreds of planets." Which is so blatantly unscientific it's embarrassing that such a thing would influence their decision at all on a scientific matter.
The IAU vote was narrow, at a conference only attended at all by a fraction of its membership, on the last day when a lot of the people opposed to the definition they passed had already left because it had looked up to that point like there was either not going to be a vote at all , or one on a hydrostatic equilibrium definition - all options that they were fine with. Only 10% of the people who attended were still around.
I have a lot of issues with the last vote, and that's just the start. Here's my full list:
1. Nomenclature: An "adjective-noun" should always be a subset of "noun". A "dwarf planet" should be no less seen as a type of planet than a "dwarf star" is seen as a type of star by the IAU.
2. Erroneous foundation: Current research agrees that most planets did not clear their own neighborhoods, and even that their neighborhoods may not always have been where they are. Jupiter, and Saturn to a lesser extent, have cleared most neighborhoods. Mars has 1/300th the Stern-Levison parameter as Neptune, and Neptune has multiple bodies a couple percent of Mars's mass (possibly even larger, we've only detected an estimated 1% of large KBOs) in its "neighborhood". Mars's neighborhood would in no way would be clear if Jupiter did not exist - even Earth's might not be. Should we demote the terrestrial planets as well?
Note that the Stern-Levison parameter does not go against this, as it's built around the ability of a planet to scatter a mass distribution similar to our current asteroid belt, not large protoplanets.
3. Comparative inconsistency: Earth is far more like Ceres and Pluto than it is like Jupiter, yet these very dissimilar groups - gas giants and terrestrial planets - are lumped together as "planets" while dwarfs are excluded.
4. Poor choice of dividing line: While defining objects inherently requires drawing lines between groups, the chosen line has been poorly selected. Achieving a rough hydrostatic equilibrium is a very meaningful dividing line - it means differentiation, mineralization processes, alteration of primordial materials, and so forth. It's also often associated with internal heat and, increasingly as we're realizing, a common association with subsurface fluids. In short, a body in a category of "not having achieved hydrostatic equilibrium" describes a body which one would study to learn about the origins of our solar system, while a body in a category of "having achieved hydrostatic equilibrium" describes a body one would study, for example, to learn more about tectonics, geochemistry, (potentially) biology, etc. By contrast, a dividing line of "clearing its neighborhood" - which doesn't even meet standard #2 - says little about the body itself.
5. Mutability: Under the IA definition, what an object is declared as can be altered without any of the properties of the object changing simply by its "neighborhood" changing in any of countless ways.
6. Situational inconsistency: (Related) An exact copy of Earth (what the vast majority of people would consider the prototype for what a planet s
They didn't die after a few minutes - they lasted for 1-2 hours. And they didn't cost a billion dollars, they were built on the cheap. The Soviets launched almost all of their Venus missions in pairs because they considered it likely that something would blow up or fail at some point along the way - not a rare situation, a number of their Venus missions never even left Earth orbit, and some didn't even get that far;). But of missions that actually got to Venus, they had great success, and even had one mission "rescued" by Venus (they designed it to parachute down, but the parachute broke - but the atmosphere slowed the fall so much that it survived the impact anyway).
For exploring Venus, if you're wanting PR, the Vega approach is the right one - aerobots, optionally paired with sondes. Aerial vehicles can fly for long periods of time studying the planet, and there's a number of exciting missions related to this being worked on (just waiting for funding). As for surface lifespans, they don't have to be limited. There's work on probes designed to "run hot" so that they don't need any (or only minimal) cooling, and there's also work on probes designed to lift off (bellows balloon) to a cooler layer of the atmosphere (to have any length of time to examine / process samples, cool down, etc) before re-descending any number of times. If you're only talking something with a ~2 hour lifespan on the surface and nothing else, you're talking something cheap, Discovery or at most New Frontiers class - not Flagship.
The main thing that's held everything back is that NASA almost never funds anything related to Venus. The last dedicated NASA mission to Venus (not counting flybies to other destinations that used Venus as a gravitational assist) was the Magellan probe, nearly three decades ago. And that came a decade after the previous NASA mission to Venus. Easiest planet to get to, and they almost never fund missions to study it. It's embarrassing.
There were a lot of contributing factors, but yes, this sadly was one. The Thiokol engineers were against launch, but they failed to make a sufficient case as to why exactly they felt the O-rings were unsafe (there actually was a Thiokol document showing that not only was O-ring failure high at low temperatures but that the second O-ring ceased to be redundant - but they didn't have the document available to them). The Shuttle program managers were getting mad at them for insisting on delays due to the low temperatures without being able to back it up (one of them said something along the lines of "My god, Thiokol - when do you want me to launch, April?") and eventually the Thiokol management dropped their objections (even though the engineers were still strongly against launch). The engineers all gathered round to watch the launch on TV, thinking it was going to explode on the pad. When it lifted off they all breathed a sigh of relief, only to have it dashed during the explosion.
Really, I have to give them credit where credit is due: by repeatedly pointing out errors (however trivial) out of the tens of thousands of news stories that are published every day, they've managed to get their supporters to the point where they'll trust a new story on www.siteiveneverheardofbefore.com/newishstuff/hillaryclintonpedophilering.html more than they will an actual newspaper. It's a real masterstroke in terms of controlling the narrative. "Anything negative you hear about me, it's fake, because there exist cases where newspapers have made errors, and we've selectively presented you only with those cases to create a narrative for you that newspapers are packed full of fakery." Not just newspapers - fact checkers, peer-reviewed articles, even official government statistics - all fake, because they've been presented with every case people can get their hands of of error, without the balancing context of the 10000x more that wasn't in error.
In the words of XKCD: "Dear God, I would like to file a bug report".;)
It's the same thing that contributed to the Challenger explosion. They had a nice clean graph in front of them that plotted O-ring failures vs. temperature. There was no clear trend visible on the graph. The problem was that they omitted the successes, the cases where there were no O-ring failures. Here's what it looked like with that added in. All of the sudden there's a very clear trend of failure increasing at low temperatures - in fact, every low temperature launch had had O-ring failures, while very few high-temperature launches had. By being selective in what data you present (accidentally in that case, on purpose in the present case), you can get people to believe precisely the opposite of what is true.
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The problem with going further away on hydrogen is that hydrogen is not generally considered a "storable" propellant; it's very hard to manage boiloff. Mild cryogenics like methane (SpaceX's plan) are easier. It allows you to use the same stage for transfer, entry, and launch burns.
Why? It's a 3-stager (or if you'd rather not count boosters as full stages, 2 1/2). Designed specifically with Mars missions in mind. 3 stages is a good number for kerolox missions to MTO if the stages have a low mass fraction (like SpaceX's do). You could even do it with 2, although it'd cut your payload.
They're not. You're confusing test firing with completion.
In your dreams. The smallest variant isn't scheduled to fly for 1 1/2 years, and that's assuming that the schedule doesn't slip. That's Block 1, 70 tonnes. Block 1B (again, assuming no schedule slips) isn't scheduled until 2021 - and that's only 105 tonnes. There's three scheduled launches of Block 1B, the last in 2026. The latter being asteroid redirect, which, well, don't hold your breath ;) There are no scheduled launches of Block 2 (130 tonnes).
You have this weird conception of how far along SLS is. They only even finished the test stand for the tank last month.
What, exactly is the purpose of hanging out in the near-vacuum of Mars?
What, exactly, is the purpose of life?
If you don't agree with the merits of the human race becoming a starfaring civilization centuries from now based on investments made today in getting the ball rolling today, I'm not going to debate that with you. But if you agree with that, then the whole point in expanding offworld is to develop into a multiplanetary species, where demand drives down launch costs and we learn, step by step, to make everything that we need in offworld environments and to become adept at the multi-month journeys between planets. At first, it's a sunk cost. With time, it's increasingly supported by trade. And after long periods of time, it brings the immense resources beyond our planet into our grasp.
If you want to talk about economics on Venus, here's a few for you.
* Power is immensely abundant. Many technologies that we employ are basically energy costs - to pick an example, isotope enrichment. So once the higher marginal capital cost for doing things on Venus becomes overtaken by the greater energy availability, Venus becomes the logical place to conduct such activities.
* Deuterium levels are ~240 times higher than on Earth. So depending on the level of enrichment you need and the means by which you return it, if you can return goods for somewhere in the "couple thousand to several tens of thousands of dollars per kilogram" range, it's profitable. Deuterium recovery can be rendered an inherent part of nighttime fuel cell power storage, since electrolysis has an excellent enrichment factor.
* Venus's lavas appear to be highly differentiated, and there's a great degree of chemical weathering and atmospheric processing, which can be another resource enrichment process. So concentrations of high value ores far greater than are found on Earth are not unrealistic. There are a couple dozen elements whose values are worth exporting at realistic launch costs several decades from now.
* Even simple rocks from offworld have great value (collectors, luxury goods, etc). It's not theoretical - people really do pay huge sums for offworld items. Their value will of course depend first the abundance of their export (if you export 100kg per year, you can sell for 10x more per kg than if you export 10000kg per year, which you can sell for 10x more per kg than if you export 1000000kg per year...). If you're selling in small quantities, the value could be in the millions of dollars per kilogram. Venus's surface atmosphere is dense enough that you can outright dredge loose rocks.
* The size of the market and sensitivity to export quantity also depends on their aesthetics (aka, moving more from the collectors market into the larger luxury goods market). This means minerals that are durable and aesthetically pleasing. What we've sampled so far of Venus's surface fits that bill - gabbro (sold as "black granite" - large crystalled, dark, hard rock, forms excellent slabs), anorthosite (rare on Earth, often associated with labradorite, which is an iridescent bluish-purple semiprecious to precious mineral), troctolite (rare, olivine (peridot)-rich relative of anorthosite and gabbro - looks like this when cut and polished), etc. It's one thing for your typical sheikh or dotcom millionaire to say "my yacht's countertop is made from the finest tuscan marble." It's another to say "my yacht's countertop is from freaking Venus." You're looking at a very large market in the 4 figure/kg range, a reasonable market in the 5 figure/kg range, and a small but decent market in the 6 figure/kg range.
* Venus's apparently high levels of repeated differentiation, in conditions very different from Earth, likely mean that some minerals, including gemstones, that are rare or no
Yes, wake me up when you've recreated Earth's vast diversity of industrial infrastructure on the moon.
Spacecraft are incredibly complex thing, and you're proposing to build them on a place where you're starting with absolutely nothing. And why? To save launch costs? Yes, launch costs are expensive relative to peoples' everyday experience, but they're only a (ever-diminishing) fraction of the cost of a whole mission.
If you're planning to wait until you can outright build entire spacecraft on the moon, you're planning on pushing Mars missions off by many generations. Even the concept that simple raw, bulk sheet metal of even comparable quality (and thus mass) to that available on Earth will be produced on the moon after two decades of high budget dedicated effort straddles the line between "crazy ambitious" and "crazy". Let alone being able to build it into something of relevance with sufficient reliability, and let alone being able to produce it at a rate that, after factoring in consumables that you have to ship from Earth to keep workers alive and all industrial processes running (consumable feedstocks, maintenance, etc) isn't vastly higher than on Earth.
There is absolutely nothing "cost saving" about operating on the moon; it is a huge money sink, and will continue to be so for generations. The same with Mars. You don't go there to save money, you go there as a very long-term investment in the future.
Well, they did produce that huge carbon fiber tank. Which appears to have failed during one of their pressure tanks. Really, building such a huge rocket out of composites is crazy ambitious (if not just crazy), but my hat goes off to them if they can succeed.
They've also made a mini-Raptor that they've started putting through tests. The fact that they've apparently managed those chamber pressures without corrosion problems so far is very impressive.
It occurred to me the other day that they have an interesting potential "halfway" route to ITS, which is that since they clearly plan to have different variants of the spaceship (cargo, crew, tanker), they could start off with the cargo variant and instead of a cargo fairing, have an interstage and use that to boost an elongated Falcon 9 (like the Falcon Heavy central core). So the spaceship would function as a first stage until it got its own booster so that it could function as a second stage. It'd be a perfect testbed for their new technologies (same construction style and engines as the booster, just smaller), while at the same time boosting SpaceX's launch capabilities into the super-heavy range. They'd want to use more atmosphere-optimized nozzles, but apart from that... it's already designed to handle much greater heat loads as well as full propulsive landings.
He's first going to have to learn how to launch that fast. That's one area where SpaceX hasn't had much success - getting its launch turnaround times down. Hopefully they will in the future. Also, since an explosion takes them out for half a year or more (regardless of turnaround times), they better up their reliability by an order of magnitude or more, since each increase in launch rate means more possible rockets that can fail. And of course they want the ITS booster to have a service life of 1000x launches, which means an immensely high reliability.
Anyway, SpaceX's big goal is to have their satellite service give them a nearly unlimited demand for launches in the coming decade, as well as a correspondingly huge income from global sales of satellite net / communications services - and to funnel those profits into ITS. Time will tell... but there's certainly no shortage of ambition.
That's the biggest concern I have. People tire of ongoing expenses. ISS seemed neat at first; now everyone hates it. Why would a moon base fare differently?
Long-term presences in space need to very quickly cut ties with earth, on order of greatest resource dependencies down to smallest resource dependencies. Aka, first things like oxygen, propellant, etc, then to industrial chemicals, of increasingly smaller quantities, with increasingly diversified manufacturing facilities, with very complex/low volume chemical feedstocks and manufacturing processes coming last. Cutting all ties is a process that would take centuries. But you can start with the low hanging fruit, bit by bit, and keep stockpiles of everything needed for maintenance that you can't produce locally.
Unfortunately, running counter to this is expansion. Because if you double the size of your operations, you also double your resource demands. So you need to improve resource independence at a faster rate than you grow.
Part of the problem with the moon is that it's just not a great place for ISRU. Volatiles are rare. We've never even sampled any moon that aren't depleted in volatiles, although there's some data to suggest that various volatiles might be scattered in permanently shaded areas (all of them, in the same place? That's a good question). Surface mineral diversity is limited - primarily light, non-volatile elements. Oxygen is at least widely abundant, but locked up tightly. And while the moon offers short transit times, it's surprisingly not that advantageous concerning delta-V. You can't aerocapture there, landing is fully powered (no parachute deceleration), and to get there you have to already be on such a high apogee orbit that it's not much more energy to go into a Mars transfer. Gravity is less and night is two days long. There are a couple "maybe" peaks of eternal light, but that doesn't mean that they're colocated with volatiles; the last I looked into it it looked like the closest suggested find of water was dozens of kilometers away from the nearest such peak, which would be quite the commute (and thus low throughput / high wear).
The moon is certainly the "cautious" option; emergency returns / resupplies are easy there, and communication fast. Its main value appears to be a testing ground for systems while minimizing risk. But it's not a very appealing place from a settlement perspective.
Of course, I prefer Venus to Mars, but that's neither here nor there ;) I'd like to see a parallel program for both, as the same sort of booster and transfer stage can be used for both, so it's only habitat / ascent stage development costs that are doubled. And once you get past the differences in feedstock sources, production industrial processes converge (Venus advantaged by the higher power availability and easier ability to get rid of heat - excepting in the case of cryogenics, where Mars holds the advantage)
One, there would be howls of protest. Two, you're not taking that argument to its logical end. You should only send pygmy women by that logic.
Women do consume less resources (by a good margin on average) and take up less space, but if I recall correctly are more vulnerable to radiation-related disease. So it's a tossup depending on what factors are constraining your mission architecture.
Right. Because micrometeoroids/debris never strike edge on, and because only one fiber gets severed per impact, rather than the reality, which is that an impact is basically like a small explosion.
I have read the book, and it's an absurd degree of wishful thinking. Just ignoring the huge number of things that they just gloss over or omit outright, the materials technology they're talking about is about two orders of magnitude away from what we actually have, and might even be physically impossible. Measurements of individual carbon nanotubes (let alone bundles, let alone bulk fibres) don't approach the strengths being talked about there. Colossal carbon tube does better on an individual tube basis, but again, we're nowhere even close to the materials tech required. And for what? For a massive, very low throughput, tiny safety margin, most-failure-modes-unaccounted-for, low-power-efficiency means of access to space? Colour me unimpressed.
If you want something better, I recommend looking into Lofstrom loops (launch loops). Current materials tech, high efficiency, high throughput per unit mass, no orbit restrictions, and works even on tidally locked bodies.
Quite true. The materials technology required is about two orders of magnitude away from actual materials technology, for starters. And among the countless other problems with space elevators, they're not actually all that efficient. Laser power beaming over those distances works out to single-digit transfer efficiencies, and microwave power beaming even less (microwave power beaming to space can be efficient, but only if the receiving antenna is huge). And no, you can't regularly hang things or run power wires up a space elevator - the mass of the cable has to be vanishingly small.
Active-suspended structures, such as Lofstrom loops, are a much better choice. Power transfer efficiency can be greater than 50% and current materials technology should be sufficient. They can also be designed to shoot payloads into any orbit (unlike space elevators), and work independent of the properties of the body in question, as well as having far greater throughput per unit mass. There's really no reason to choose a space elevator over a Lofstrom loop.
Are you under the impression that Dragon doesn't have an RCS?
It doesn't work like that. Radiative heating/cooling works via exchange of IR. You're not just giving it up; everything you're radiating at is proportionally radiating back at you. So you cool the most when you're radiatively exchanging with something that's very cold. Aka, you want to be radiatively exchanging with the cosmic microwave background, not with low-altitude clouds. That's the whole point of radiating at low absorption frequencies in the atmosphere: so that you're exchanging with space, not with atmospheric air.
I can't even recognize snark anymore.
1. That was just an old theory, and not a widely accepted one.
2. Given what we've just seen, it demonstrably isn't.
That doesn't mean that there aren't compounds formed at great pressure that can remain stable at moderate pressures and represent very dense energy sources - there surely are. Metastability is a very real thing. But apparently not in the case of metallic hydrogen at ~STP.
Assuming that this actually even was metallic hydrogen; even that is somewhat in dispute.
Indeed, on both counts. And in particular I like the word "rogue planet". Again you have an adjective imparting additional information about another object ("Rogue X"), "rogue" can be readily quantified ("Not in a stable orbit around any particular star or cluster of stars"), and it's a very evocative term. And rogue planets are absolutely expected according to our current models. They'll be incredibly difficult to find, but they're out there.
We're also coming to the realization that there's a lot of objects, potentially including large ones, that are only tenuously bound to our solar system. And it's likely that we readily exchange this mass with other nearby stars over cosmologic timescales; parts of our solar system (primarily distant ones) likely formed by other stars, and things that condensed during the formation of our star system are likely now orbiting other stars.
The short of it, Jupiter moves things around; it's very good at scattering other bodies, even large ones. First it dragged outer populations into the inner solar system, then scattered inner solar system material out, and then on its retreat pulled outer solar system material back in. It's actually a very big deal that it did that, as it brought ice into the inner solar system.
Gummy bears are not a scientific term. Besides, the IAU itself already uses the word dwarf in this manner. Dwarf stars, dwarf galaxies... but carved out an inexplicable exception for dwarf planets.
False equivalency. There's a difference between "two Mars sized planets existing in the same orbit" and "Mars' orbit having been cleared". And more to the point, the biggest problem with the concept of Mars clearing its orbit is that its orbit was already largely cleared when it formed. According to our best models, Jupiter reached all the way in to around where Mars' orbit is today, and had cleared almost everything to around 1 AU. Earth and Venus accreted from planetesimals between each other. Mars accreted from planetary embryos ejected to the space in-between Earth and Jupiter. Without Jupiter's migration, simulations produce an Earth-sized Mars and several planetary embryos in the asteroid belt on eccentric / high inclination orbits, something akin to the situation between Neptune and Pluto - except with the embryos nearly Mars-sized.
Huh? By what aspect of orbital mechanics? By semimajor axis and velocity, Earth is much closer to Ceres than Jupiter. Are you talking inclination and eccentricity? Then we should boot Mars in favour of low inclination / eccentricity asteroids.
Hydrostatic equilibrium can be very easily estimated based on mass, which can be approximately deduced within a range of feasible albedos and densities, and very accurately deduced if the body has a moon. By contrast, it's almost impossible to estimate neighborhood clearing to any distance beyond Neptune, or at all in the case of extrasolar planets. Which, to reiterate, the IAU definition says aren't planets, even though they have an extrasolar planet working group.
This is utter nonsense.
No, it's not. We have virtually no clue what lies in the outer reach of our solar system. As we speak there's a search for a new planet that could be as big as an ice giant. It's a huge open question as to whether it would have cleared its neighborhood, and it will be very difficult to ascertain.
You seem to have some weird concept going on that "semimajor axis = orbit". Ceres has nothing of significance in its orbit. The asteroids are not all in the same orbit. They're certainly more likely to cross each others orbits, but that's not the same thing.
And again, since you apparently missed it: the reason that the inner solar system is largely cleared except for the asteroid belt (and the reason that the latter exists) is Jupiter. Mars did not clear its own neighborhood.
That's just the issue: that's not what happened. The IAU discussion was a disaster. Here's the timeline:
2005: The IAU appoints a committee to investigate the issue and generate a proposal. The committee investigated the issue for a year.
The IAU meeting is scheduled from 14-25 August 2006.
16 August: The committee recommends a definition based on hydrostatic equilibrium. No "cleared the neighborhood" nonsense. They publish their draft proposal.
18 August: The IAU division of planetary sciences (aka, the people who actually deal with planets) endorses the proposal.
Also 18 August: A subgroup of the IAU formed which opposed the proposal. An astronomer in the group (aka, someone who studies stars, not planets) - Julio Ángel Fernández - made up his own "cleared the neighborhood" definition. While most of the membership starts to trickle away over the next week, they remain determined to change the definition.
22 August: The original, hydrostatic equilibrium draft continued to be the basis for discussion. There were some tweaks made (some name changes and adjusting the double-planet definition), but it remained largely the same.
Late on 22 August: Fernández's group manages to get to just over half of the attendance at the (open) drafting meeting, leading to a very "heated" debate between the two sides.
22 to 24 August: The drafting group begins to meet and negotiate in secret. The last that the general attendance of the conference knew, they'll either end up with a vote on a purely hydrostatic definition, or (more likely) no vote at all due to the chaos. Attendence continues to dwindle, particularly among those who are okay with either a hydrostatic definition or none at all.
24 August: The current "cleared the neighborhood" definition is suddenly proposed and voted on on the same day. Only 10% of the conference attendance (4-5% of the IAU membership) is still present, mainly those who had been hanging on trying to get their definition through. They pass the new definition.
It's not generally laypeople who are upset about how it went down, it's IAU members. Many have complained bitterly about it to the press. The IAU's own committee of experts was ignored, in favour of a definition written in secret meetings and voted on by a small, very much nonrandom fraction of people, the vast majority of whom do not study planets.
If there's one thing I hate, it's people who pretend that anyone who opposes the IAU definition does so because they're ignorant morons overcome by some emotional attachment to Pluto, when in reality it's been planetary scientists themselves who have been the definition's harshest critics, because it's an internally self-inconsistent, linguistically flawed, false-premise-based definition that leads to all sorts of absurd results and contradicts terminology that was already in widespread use in the scientific literature.
Exactly. I think Stern's always been on the right side of this. The original paper that the Stern-Levison parameter comes from has a great system laid out, where you have a bunch of adjectives that you can apply to different bodies based on their varying physical (composition, size) and orbital parameters, and you can use any combination of them as needed. Which seems to me to be so obviously the right solution.
If they had simply stopped there, that wouldn't have been a problem. The problem is that they didn't. They declared that dwarf planets aren't planets at all - which is nonsense. Mars has far more in common with Pluto than, say, Jupiter. If anything should have been separated out, it's the gas and ice giants from the rocky/icy planets.
Hydrostatic equilibrium is a very meaningful dividing line to split groupings on. If a body is in hydrostatic equilibrium, it's experienced dramatic geologic change in its history - differentiation, tectonics, internal heating, generally fluids (particularly liquid water), and on and on. It's the sort of place you go if you want to learn about planetary evolution or search for life. If a body is not in hydrostatic equilibrium, it's made of primordial materials, preserved largely intact. It's the sort of place you go to learn about the formation of our solar system and its building blocks.
It's rare that nature gives you such clear dividing lines, but when it comes to planets, it has. It's not perfect - you can (and do) have bodies that straddle the border and are only partially or slightly differentiated. But in general, nature has drawn an obvious line in the sand, and we should respect that.
Is Earth's orbit clear? No, we have a huge massive object co-orbiting with us. Is Neptune's orbit clear? No, it has Pluto in it. They try their hardest to pretend that the IAU actually chose a "gravitationally dominant" standard, but that's not what they actually put in the definition. The standard in the definition is "cleared the neighborhood".
And it's based on a false premise - that each planet cleared its own neighborhood. Which is just pseudoscience. All of our models show that Jupiter, and to a lesser extent Saturn, cleared most of the solar system, including the vast majority of the clearing around Mars, and a good fraction around Earth (lesser around Venus). Mars did not clear its own neighborhood. Nor is it gravitationally dominant in its neighborhood; the vast majority of asteroids are in orbital resonance with Jupiter and not Mars.
And I've heard some people try to sneak around this by saying "Okay, maybe it isn't gravitationally dominant / cleared its neighbood now, but it has enough of a Stern-Levison parameter that it would have been had Jupiter not existed". First off, that's changing the definition yet again (to "would have cleared its neighborhood if no other planets were there"). But beyond that, it's abuse of the Stern-Levison parameter. The Stern-Levison parameter is built around a body's ability to clear asteroids - bodies with the current size and orbital distribution of our asteroid belt. Not protoplanets. In the early solar system it was the ability to clear protoplanets that caused neighborhoods to be cleared. Jupiter got rid of some really massive things that were forming in and near the inner solar system. There's a reason why our planetary system has such an unusual size distribution: the inner planets start getting bigger, the stop getting bigger, then get small, then debris, then something huge. That "something huge" stripped the building blocks out of the inner solar system, preventing it from becoming dominated by super-Earths. Saturn appears to have been our savior - its (delayed) formation appears to have stopped Jupiter's inward migration.
And even just going with the Stern-Levison parameter - Neptune has a Pluto-sized body in its "neighborhood". Now, Pluto may be small compared to Neptune, but compared to Mars it wouldn't be - yet Mars has a much lower Stern-Levison parameter than Neptune. Again: the only reason Mars doesn't experience stuff like this is because Jupiter cleared its neighborhood for it.
Clearly given that people like Stern have regularly given interviews decrying the decision, and going so far as to call it "bullshit" (can you say that at NASA?), it's clearly not the storm in a teacup that you want to present it as.
What the proponents did was take a term widely used by planetary geologists and have it mean something completely different - akin to dentists suddenly declaring to doctors that the heart is no longer an organ and to stop referring to it as one. And contrary to your presentation of why they did it ("to make it easier to write journal articles") without fail every last supporter I've seen interviewed about their vote has given some variant of the following reason for why they voted the way they did: "I don't want my daughter having to memorize the names of hundreds of planets." Which is so blatantly unscientific it's embarrassing that such a thing would influence their decision at all on a scientific matter.
The IAU vote was narrow, at a conference only attended at all by a fraction of its membership, on the last day when a lot of the people opposed to the definition they passed had already left because it had looked up to that point like there was either not going to be a vote at all , or one on a hydrostatic equilibrium definition - all options that they were fine with. Only 10% of the people who attended were still around.
I have a lot of issues with the last vote, and that's just the start. Here's my full list:
1. Nomenclature: An "adjective-noun" should always be a subset of "noun". A "dwarf planet" should be no less seen as a type of planet than a "dwarf star" is seen as a type of star by the IAU.
2. Erroneous foundation: Current research agrees that most planets did not clear their own neighborhoods, and even that their neighborhoods may not always have been where they are. Jupiter, and Saturn to a lesser extent, have cleared most neighborhoods. Mars has 1/300th the Stern-Levison parameter as Neptune, and Neptune has multiple bodies a couple percent of Mars's mass (possibly even larger, we've only detected an estimated 1% of large KBOs) in its "neighborhood". Mars's neighborhood would in no way would be clear if Jupiter did not exist - even Earth's might not be. Should we demote the terrestrial planets as well?
Note that the Stern-Levison parameter does not go against this, as it's built around the ability of a planet to scatter a mass distribution similar to our current asteroid belt, not large protoplanets.
3. Comparative inconsistency: Earth is far more like Ceres and Pluto than it is like Jupiter, yet these very dissimilar groups - gas giants and terrestrial planets - are lumped together as "planets" while dwarfs are excluded.
4. Poor choice of dividing line: While defining objects inherently requires drawing lines between groups, the chosen line has been poorly selected. Achieving a rough hydrostatic equilibrium is a very meaningful dividing line - it means differentiation, mineralization processes, alteration of primordial materials, and so forth. It's also often associated with internal heat and, increasingly as we're realizing, a common association with subsurface fluids. In short, a body in a category of "not having achieved hydrostatic equilibrium" describes a body which one would study to learn about the origins of our solar system, while a body in a category of "having achieved hydrostatic equilibrium" describes a body one would study, for example, to learn more about tectonics, geochemistry, (potentially) biology, etc. By contrast, a dividing line of "clearing its neighborhood" - which doesn't even meet standard #2 - says little about the body itself.
5. Mutability: Under the IA definition, what an object is declared as can be altered without any of the properties of the object changing simply by its "neighborhood" changing in any of countless ways.
6. Situational inconsistency: (Related) An exact copy of Earth (what the vast majority of people would consider the prototype for what a planet s
No, in the middle cloud layer. But I think you should recheck the Venera photos, visibility is a lot more than one meter ;)
They didn't die after a few minutes - they lasted for 1-2 hours. And they didn't cost a billion dollars, they were built on the cheap. The Soviets launched almost all of their Venus missions in pairs because they considered it likely that something would blow up or fail at some point along the way - not a rare situation, a number of their Venus missions never even left Earth orbit, and some didn't even get that far ;). But of missions that actually got to Venus, they had great success, and even had one mission "rescued" by Venus (they designed it to parachute down, but the parachute broke - but the atmosphere slowed the fall so much that it survived the impact anyway).
For exploring Venus, if you're wanting PR, the Vega approach is the right one - aerobots, optionally paired with sondes. Aerial vehicles can fly for long periods of time studying the planet, and there's a number of exciting missions related to this being worked on (just waiting for funding). As for surface lifespans, they don't have to be limited. There's work on probes designed to "run hot" so that they don't need any (or only minimal) cooling, and there's also work on probes designed to lift off (bellows balloon) to a cooler layer of the atmosphere (to have any length of time to examine / process samples, cool down, etc) before re-descending any number of times. If you're only talking something with a ~2 hour lifespan on the surface and nothing else, you're talking something cheap, Discovery or at most New Frontiers class - not Flagship.
The main thing that's held everything back is that NASA almost never funds anything related to Venus. The last dedicated NASA mission to Venus (not counting flybies to other destinations that used Venus as a gravitational assist) was the Magellan probe, nearly three decades ago. And that came a decade after the previous NASA mission to Venus. Easiest planet to get to, and they almost never fund missions to study it. It's embarrassing.
There were a lot of contributing factors, but yes, this sadly was one. The Thiokol engineers were against launch, but they failed to make a sufficient case as to why exactly they felt the O-rings were unsafe (there actually was a Thiokol document showing that not only was O-ring failure high at low temperatures but that the second O-ring ceased to be redundant - but they didn't have the document available to them). The Shuttle program managers were getting mad at them for insisting on delays due to the low temperatures without being able to back it up (one of them said something along the lines of "My god, Thiokol - when do you want me to launch, April?") and eventually the Thiokol management dropped their objections (even though the engineers were still strongly against launch). The engineers all gathered round to watch the launch on TV, thinking it was going to explode on the pad. When it lifted off they all breathed a sigh of relief, only to have it dashed during the explosion.
Really, I have to give them credit where credit is due: by repeatedly pointing out errors (however trivial) out of the tens of thousands of news stories that are published every day, they've managed to get their supporters to the point where they'll trust a new story on www.siteiveneverheardofbefore.com/newishstuff/hillaryclintonpedophilering.html more than they will an actual newspaper. It's a real masterstroke in terms of controlling the narrative. "Anything negative you hear about me, it's fake, because there exist cases where newspapers have made errors, and we've selectively presented you only with those cases to create a narrative for you that newspapers are packed full of fakery." Not just newspapers - fact checkers, peer-reviewed articles, even official government statistics - all fake, because they've been presented with every case people can get their hands of of error, without the balancing context of the 10000x more that wasn't in error.
In the words of XKCD: "Dear God, I would like to file a bug report". ;)
It's the same thing that contributed to the Challenger explosion. They had a nice clean graph in front of them that plotted O-ring failures vs. temperature. There was no clear trend visible on the graph. The problem was that they omitted the successes, the cases where there were no O-ring failures. Here's what it looked like with that added in. All of the sudden there's a very clear trend of failure increasing at low temperatures - in fact, every low temperature launch had had O-ring failures, while very few high-temperature launches had. By being selective in what data you present (accidentally in that case, on purpose in the present case), you can get people to believe precisely the opposite of what is true.