I wonder how many of those developers are actually releasing though. For instance, I'm a registered developer (I paid my $100), but I did it solely for personal development.
That is, I'm an aerospace engineering grad student doing a lot of estimation and controls work, but mostly on the theory/simulation side -- as such I realized I really should have some experience working with actual hardware. Since my research doesn't provide that opportunity, and I had my phone, which has GPS, accelerometers and magnetometers handy, so I decided to see what I could do with it. Paying the dev fee was probably cheaper than buying custom-purpose hardware.
It's certainly been interesting, and I'm pretty far along in a program that one can attach to a telescope, align against known stars, and then determine where you're pointing afterwards -- but its entirely something I'm doing for me. When its finished (school, another project, and a girl have prevented me from working on it in a while), I'll probably push it on to the app store, sell it for a few bucks on the off chance I'll make the dev fee back, but really, if it makes the difference in me getting a job I want, then thats much more worthwhile to me.
Since anecdotes are evidence: I own a Kindle and I can only think of once (in a year and a half) where I've been stuck unable to read. When the battery lasts two weeks and it only takes a couple of hours to charge, its really hard to run out, even when you're really bad about leaving things charged like I am. My phone is much more of a pain when it comes to keeping it charged.
I haven't seen much on synthesized hydrocarbons, but if it can be done at a reasonable efficiency cost, it seems reasonable.
However, I'd say any analysis of biofuels based primarily on corn ethanol is questionable, even though I realize that its the most well developed one. The absurdity and of it, and the harm its done, is well document, and I don't deny it -- I'd say its largely attributable to the fact that no senator wants to rule out running for president, and the Iowa caucuses are pivotal for that.
However, I wonder if you don't give short shrift to the potential of algae-based fuels on non-arable lands. Sunlight is not a problem in a deserts, and from everything I know, salt water can be used, since the oceans are where the first algaes developed. This sounds ideal for deserts in California, Baja, and southern Arizona, as well as the Sahara.
Of course, the obvious answer is that this kind of research is relatively cheap, so fund it all and see what proves viable.
Show me an idea with reasonable designs (materials, layout, feasibility analysis, cost estimates) and I'll be interested.
I agree, our current technology is dangerous, primitive, expensive and cumbersome. It has one advantage though: it works. Unfortunately, I have yet to see an alternative that doesn't rely on some sort of unobtanium. Maybe a space elevator will work some day, but as yet, not even nanotubes are strong enough to handle the mass. If this technology actually pans out, then it makes things a little less dangerous and primitive, and I take that as a win.
Actually, the ability to cheaply fill fuel depots in orbit does a significant amount to reduce the problems associated with current launch technology. Consider Apollo. The massive Saturn V rocket was required because in addition to taking the CM, SM, and LM to orbit, it also had to take the fuel to get it from LEO to the moon -- fuel was the most significant fraction of the mass (2:1 or 3:1 if I remember correctly). Instead, if this had been available to move fuel to orbit on the cheap, you could have used a couple of Saturn IB rockets and rendezvoused in LEO with a freshly filled Earth departure stage. I wouldn't be surprised if it would have been able to cut the cost of Apollo in half. This could also allow a new moon mission architecture without the massive Ares V.
Remember, space missions are like exponential Russian nesting dolls. If you remove a layer (in my example, the EDS), you can reduce the initial launch mass drastically. This is why things like ISRU and various electric propulsion schemes are such hot topics, even though they don't help you get off the ground either.
I think algae-based biofuels are a good supplement to nuclear/hydro/wind/solar, not a replacement, just as gasoline is really a supplement to coal presently. That is, big power-generation stations are a majority of our energy use, but cars and trucks make up a significant portion as well, and pure EV's are going to have range issues for a long time.
In my mind biofuels make a lot more sense than a hydrogen-based vehicle system, since they don't require a complete reworking of infrastructure, and it quite frankly seems a lot less pie-in-the-sky. These sound more like practical engineering problems, not fundamental issues (like how do you safely store hydrogen without $10K pressure tanks). Combine it with plug-in hybrids to minimize the need for the biofuels, and avoid localized pollution/smog, I think the combination of nuclear/renewables + biofuels seems like an ideal, sustainable energy strategy that doesn't require lifestyle sacrifices (the real political killer).
To be fair, you can in fact highlight phrases and earmark pages with the Kindle. In addition to storing them with the novel, if you plug it in to the computer, it appears as a flash drive and you can grab the file with your highlights, which could be convenient for some things.
Of course, the rest of your points are still reasonable.
If you're not heavily invested in the single use, then yes, you should buy a netbook. It is, in the end, a niche device, and will remain so until e-paper prices come down (at least).
But, if you are a heavy reader with some cash, it really is a great device to have (with the caveat of the well-documented DRM issues). I personally find its increased my amount of reading a lot, and its wonderful to be able to carry a couple of books and three weekly magazines in my bag in a single small device. A netbook wouldn't do the same job, since it wouldn't be as enjoyable to read off of (backlit LCD vs. e-paper), and because the lack of a single use makes it hard to lay in bed or sit in a recliner or couch for hours reading. The idea is to perform the single task well, by in many ways replicating the experience of a book (form factor, screen, how you hold it), so that the device disappears and you just notice what you're reading -- it works great for me since I don't have a psychological attachment to the feel and smell of paper.
Its very useful if you're interested in reading fiction and mostly-text magazines on a regular basis, and would like to carry a large library with you. Its not especially good for reference usage as the screen refresh rate is too slow, and the built-in web-browser is very limited -- only really much good for looking up things in wikipedia (which can be very nice, however).
Compared to other e-book readers -- its more constrained but more user-friendly. The built-in wireless makes it very easy to buy books without have to interact with a computer; however this comes at the constraint of being tied into the Amazon DRM system, for which the flaws are well documented. Unfortunately, since no DRM-free store with a good selection of modern literature exists, its likely if you're interested in an E-book you're going to be attached to some kind of DRM system.
I really enjoy mine and find it a pleasure to use, but as always: Buyer beware, particularly understand what the DRM implies, and whether you're willing to trade the convenience for the lack of true ownership.
"Publicly funded" means tax-supported in the US as well. Non-profits are usually referred to as 'non-profits' or '501c3' (after the tax code section). NASA is publicly funded here, the American Red Cross is non-profit.
Plus I'd say Merkel is more interesting because she's the first post-unification Chancellor from the East. That seems to be a more 'peaceful' thing since its indicative of a true unification.
I'd say that Ahmadinejad is in no way crazy. He puts on a tough-guy attitude towards the west because thats what his base supports. The Iranian mindset is that they are an old, proud nation (far older than us upstarts in America), and being subjugated and chastised by countries like the US and Europe grates -- for this reason the working classes really appreciate Ahmadinejad's aggressiveness as well as his populist policies. Really, the most irrational thing he's done lately is try to steal the recent election, since he was likely to win anyway, even if by an uncomfortably small margin. On the nuclear issue its questionable whether or not its mostly posturing, but most of that is under the control of the clerics, not the politicians. Additionally, posturing on the nuclear issue is popular domestically because, again, you have an old nation being told by new upstarts that 'no, you can't have these fancy bombs we have.'
On the effectiveness of US diplomatic posturing, I'd say that Obama's efforts at engagement were probably a major contributing factor to the recent unrest. Ahmadinejad's hard-line views were easier to justify to the young and educated when you had the worlds only superpower calling them part of the "Axis of Evil," but when you had the new guy saying "lets talk" and Ahmadinejad and his clerical keepers saying no, there was a powerful backlash. Some might argue that the Bush policies made it more likely as well, forcing the extremism of the theocracy to the surface to be exposed later by Obama (I believe there's a CSM Op-Ed to that effect). So... basically its all hard to say exactly.
Nope, Texas A&M. Its a good exciting target so I think a lot of schools do it for design projects, our particular project seems to have gotten some real traction though.
Of course, we'll see what these new numbers mean to us -- fortunately we've been selling our mission concept as a dress-rehearsal and science mission rather than an actual save-the-Earth doomsday avoidance mission.
Don't forget that if you're laying off everyone working on the project you're increasing unemployment and decreasing the amount those people are spending -- while I don't usually take that as a good argument for maintaining federal programs, maintaining useful programs that happen to maintain peoples employment seems like a decent idea, particularly for an administration that takes a fairly Keynesian view.
Of course, I'm a spacecraft engineer and not an economist so my view may be a little skewed.
This mission, a combined exploration/gravity-tractor mission, is one of the two main projects I've been doing in graduate school. So I guess its a little bit between the two (student/professional). Its definitely more in-depth than a senior design project, in that I've been working on it for 2-3 years. We're working with NASA Ames and some other groups, and have a strong potential path forward for eventual funding and building... so take it as it is.
I've been focusing on the tracking/radio-science portion of the problem, and my classwork has focused on dynamics and estimation, so... yeah, this particular article is probably the single thing I know the most about in the world... I wonder if that should worry me.
You'd probably have to apply a few km/s Delta-V (at least) to it in order to do that. All estimates show it entering the Earth's sphere of influence at about 5.87 km/s, which would be reasonable for putting it in orbit, if it were in the right place. Unfortunately, as it moves past the earth it gets sped up and moves on a hyperbolic orbit, it speeds up, so theres no real way to do it just by changing its position slightly (which could be done for ~$300M).
Basically, changing its position slightly in order to prevent an impact requires a very small amount of energy. For a 50 mN thrust for 1 year, 20 years ahead of time (which is enough to move it in 2036 by around 20 Earth radii), moves it about 500 meters and thus does about 25 Joules worth of work*. However, consider changing the velocity of something the size of Apophis (2.1e10 kg) from 5.8 km/s to say 3 km/s -- thats 2.5e17 Joules worth of work. Thats 800 MW over 10 years. I think there are probably better asteroids to capture in this case, and its certainly not an easy task by any definition.
*forgive me if the numbers are a bit off, but its the correct order of magnitude anyway
This kind of uncertainty is much easier to derive with fewer question marks than deriving the risk of catastrophic failure in a complex machine.
Basically what this implies is that taking new measurements, we have an improved estimate of the position of the asteroid at the current time, and the risk of impact is taken by projecting those into the future using well known and tested dynamic estimation methods. Current uncertainty is easily defined as a 6x6 covariance matrix (for the 6 state variables), and this matrix can be determined using a good least-squares estimation method and published measurement numbers.
In other words I give these numbers a lot more credence than risk numbers on the space shuttle. Theres a lot more science and lot fewer assumptions.
Also I would be careful comparing practices in the huge human-spaceflight program, centered at JSC and KSC with those of smaller planetery exploration programs from places like JPL and Ames. They have amazingly different cultures and practices -- NASA is in no way a monolithic entity.
All the models are run according the 'standard dynamic model' at JPL which includes gravity from the Sun, planets, large moons and large asteroids. Perturbations caused by objects outside the solar system are negligible compared to non-gravitational effects such as direct solar pressure and the Yarkovsky effect. These effects are impossible to model without knowledge of material composition, mass and structure, which you can't really get without going there.
However, the uncertainty caused by these non-gravitational effects is very small compared with the uncertainty caused by the fact that we just plain don't know quite where it is and how fast its going. In order to know where the asteroid will be in 2036 to within an Earth radius requires us to know where it is now to within about a meter -- the 2029 close approach in particular magnifies uncertainties incredibly (100x).
These state estimate uncertainties overwhelm any small errors in the dynamic model, and these new and improved probabilities come from refining the current state estimate. So yes, it is still valid to make these kind of predictions. You have to start early (10-20 years) to be able to stop it as well, so its important to keep an early eye on it.
Certainty is a funny word, but basically, the closer it gets the more confident you are in your prediction because small errors grow to large errors over time.
I would say, without significant funding you'd know for certain in the lead up to the 2029 close approach. During this event, the asteroid will pass within the geostationary satellite belt, and has the potential (1 in 250,000 now) to pass through a 'gravitational keyhole' that corresponds with a return impact trajectory. Note that the likelihood of impact in 2029 is zero (i.e. the 6-sigma boundaries of trajectory estimates are very far from the Earth).
Unfortunately, if you don't do something about it well before 2029, its unlikely you could do anything short of an Apollo-class-plus (Bruce Willis-class?) mission, in terms of funding, uncertainty, and national effort, to stop it. Put simply, its much easier to push the asteroid a kilometer (out of a keyhole) than it is to push it 3000 kilometers, but you have to do it earlier.
If you wanted to do very precise tracking to know if (and where) it was going to impact without waiting for the close approaches, you can do some of it with simply more observations with larger telescopes, and more ground-based radio ranging. However, you're going to get much better results (an order of magnitude) if you send a spacecraft out with a proper beacon. Two or three months in 2021 with this kind of tracking would give you 3-sigma (99%) reliability if it is to impact, and ascertain that it was not if it is not going to. A year of this tracking would tell you where exactly it was going to hit, within about 100km.
Of course, if you're already out there, its not too much more expensive to add the equipment to do a gravity tractor and move it away from a keyhole, since by 2022 it would be very difficult and very expensive to get a mitigation mission put together in time. A combined exploration and mitigation mission is estimated to cost about $350M, and in addition to improving knowledge about the unlikely but potentially imminent threat, would make it much easier to deal with future threats and contribute a lot to our understanding of near Earth asteroids in general. A pure exploration mission might be able to shave off $25M -- the only extra equipment is some Hall thrusters and a longer lifetime. I personally think there is political will for it at relatively low cost (Discovery-class mission), and scientific benefits beyond the mitigation of an admittedly small risk.
(Full Disclosure: Most of these numbers are pulled from a mission proposal I'm currently working on. The details aren't officially published yet, although they are being presented at a conference next week.)
If I'm designing a mission I'd be pretty happy to be able to cut my costs in half. Granted, it would be great to have a very cheap way to get to orbit, but as a practical engineer I'm much more impressed by a mostly functional prototype at the recommended scale with proper funding than I am by some theoretical work. While I have no reason to believe that laser propulsion will not work, it is at a TRL level of 2 from everything I can tell, while VASIMR is at TRL 6.
As someone looking at what I actually want to use to complete a mission, I'm much more interested in something that can cut my costs in half and is likely to be available within the next 10 years, than I am with something that has some paper concepts and a few basic lab experiments. I try not to be too much of a naysayer of new technology, but at the same time , comparing something entirely theoretical to something with significant amounts of development is absurd. Yes, if laser propulsion (or any other kind of new method to reach orbit) turns out to be a practical development it will be a much bigger deal, but in the meantime I find something that (almost) exists and reduces launch costs by half pretty valuable.
What this and other EP do is reduce the amount of fuel needed to get from LEO to where ever you're going. If you can reduce the mass fraction from say 2:1 to 1:2, you've cut your on-orbit mass in half, and thus can use a launch vehicle that's half the size.
While reducing the cost of the access to orbit is important, it doesn't mean that this is 'idiotic' and doesn't solve anything. I have issues with VASIMR (its always seemed very vapor-ish), but if its eventually capable of doing what it requires it will be a great tool for interplanetary missions. Something that can cut your launch costs in half isn't something to sneeze at.
In addition, it has one big advantage over, say, a space elevator. It is likely to eventually work in the next few decades(even if it is late and overbudget), and doesn't require materials that don't exist.
Space-based nuclear reactors aren't far fetched, but they are even more of vaporware than VASIMR as far as I'm concerned. I say this because it is at a lower TRL (Technology Readiness Level), and because there is less of a clear path forward for its development.
As you say, the reasons for this are largely political, but that doesn't mean that its not still an undeveloped technology with no clear path forward after JIMO got axed. VASIMR has prototypes and a proposed use, so its further along, but I still would like to see some flight-ready hardware that shows that it can really be as useful as its proponents claim before I get too excited about it. I've been hearing about it for 5 years, and I expect I'll keep hearing about it for a long time before it proves its utility.
None of this is to say it won't eventually be useful, but at present it doesn't seem like news worth mentioning to me.
I think my thought was more specifically "Oh God, not another VASIMR story."
I'll get excited when I see flight hardware, otherwise its just another slightly vaporish technology. The vapor is made particularly thin by its dependence on other development, specifically the very high power requirements that are likely to require advancements such as space-based nuclear reactors. From what I know, without this kind of power, it will be little more than an incremental improvement on current flight-proven EP methods.
My 2002 Nissan Altima gets 500 miles easily on a 20 gallon tank. But really, I'm pretty sure anything over 150 miles is overkill, since thats about the maximum you'd expect from a heavy day of local driving.
Long-distance road trips are always going to be the big "but" for any pure EV, until some real fast-charging technology appears. You can claim that most trips are going to fall within the 500 mile range, and its true that I can get from my college to my home town in about 450 miles, but that doesn't mean I don't go further on occasion. If you have multiple people driving on a cross country drive out west its not hard at all to imagine going 18 hours and 1200 miles without anything more -- in fact I plan on doing it in a couple of months.
You'll always have instances of going a bit further than a pure battery can handle -- without a fast loading energy reserve (biodiesel?) you can never achieve the freedom of travel a gas-powered car affords.
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I wonder how many of those developers are actually releasing though. For instance, I'm a registered developer (I paid my $100), but I did it solely for personal development.
That is, I'm an aerospace engineering grad student doing a lot of estimation and controls work, but mostly on the theory/simulation side -- as such I realized I really should have some experience working with actual hardware. Since my research doesn't provide that opportunity, and I had my phone, which has GPS, accelerometers and magnetometers handy, so I decided to see what I could do with it. Paying the dev fee was probably cheaper than buying custom-purpose hardware.
It's certainly been interesting, and I'm pretty far along in a program that one can attach to a telescope, align against known stars, and then determine where you're pointing afterwards -- but its entirely something I'm doing for me. When its finished (school, another project, and a girl have prevented me from working on it in a while), I'll probably push it on to the app store, sell it for a few bucks on the off chance I'll make the dev fee back, but really, if it makes the difference in me getting a job I want, then thats much more worthwhile to me.
Since anecdotes are evidence: I own a Kindle and I can only think of once (in a year and a half) where I've been stuck unable to read. When the battery lasts two weeks and it only takes a couple of hours to charge, its really hard to run out, even when you're really bad about leaving things charged like I am. My phone is much more of a pain when it comes to keeping it charged.
I haven't seen much on synthesized hydrocarbons, but if it can be done at a reasonable efficiency cost, it seems reasonable.
However, I'd say any analysis of biofuels based primarily on corn ethanol is questionable, even though I realize that its the most well developed one. The absurdity and of it, and the harm its done, is well document, and I don't deny it -- I'd say its largely attributable to the fact that no senator wants to rule out running for president, and the Iowa caucuses are pivotal for that.
However, I wonder if you don't give short shrift to the potential of algae-based fuels on non-arable lands. Sunlight is not a problem in a deserts, and from everything I know, salt water can be used, since the oceans are where the first algaes developed. This sounds ideal for deserts in California, Baja, and southern Arizona, as well as the Sahara.
Of course, the obvious answer is that this kind of research is relatively cheap, so fund it all and see what proves viable.
Show me an idea with reasonable designs (materials, layout, feasibility analysis, cost estimates) and I'll be interested.
I agree, our current technology is dangerous, primitive, expensive and cumbersome. It has one advantage though: it works. Unfortunately, I have yet to see an alternative that doesn't rely on some sort of unobtanium. Maybe a space elevator will work some day, but as yet, not even nanotubes are strong enough to handle the mass. If this technology actually pans out, then it makes things a little less dangerous and primitive, and I take that as a win.
Actually, the ability to cheaply fill fuel depots in orbit does a significant amount to reduce the problems associated with current launch technology. Consider Apollo. The massive Saturn V rocket was required because in addition to taking the CM, SM, and LM to orbit, it also had to take the fuel to get it from LEO to the moon -- fuel was the most significant fraction of the mass (2:1 or 3:1 if I remember correctly). Instead, if this had been available to move fuel to orbit on the cheap, you could have used a couple of Saturn IB rockets and rendezvoused in LEO with a freshly filled Earth departure stage. I wouldn't be surprised if it would have been able to cut the cost of Apollo in half. This could also allow a new moon mission architecture without the massive Ares V.
Remember, space missions are like exponential Russian nesting dolls. If you remove a layer (in my example, the EDS), you can reduce the initial launch mass drastically. This is why things like ISRU and various electric propulsion schemes are such hot topics, even though they don't help you get off the ground either.
I think algae-based biofuels are a good supplement to nuclear/hydro/wind/solar, not a replacement, just as gasoline is really a supplement to coal presently. That is, big power-generation stations are a majority of our energy use, but cars and trucks make up a significant portion as well, and pure EV's are going to have range issues for a long time.
In my mind biofuels make a lot more sense than a hydrogen-based vehicle system, since they don't require a complete reworking of infrastructure, and it quite frankly seems a lot less pie-in-the-sky. These sound more like practical engineering problems, not fundamental issues (like how do you safely store hydrogen without $10K pressure tanks). Combine it with plug-in hybrids to minimize the need for the biofuels, and avoid localized pollution/smog, I think the combination of nuclear/renewables + biofuels seems like an ideal, sustainable energy strategy that doesn't require lifestyle sacrifices (the real political killer).
To be fair, you can in fact highlight phrases and earmark pages with the Kindle. In addition to storing them with the novel, if you plug it in to the computer, it appears as a flash drive and you can grab the file with your highlights, which could be convenient for some things.
Of course, the rest of your points are still reasonable.
If you're not heavily invested in the single use, then yes, you should buy a netbook. It is, in the end, a niche device, and will remain so until e-paper prices come down (at least).
But, if you are a heavy reader with some cash, it really is a great device to have (with the caveat of the well-documented DRM issues). I personally find its increased my amount of reading a lot, and its wonderful to be able to carry a couple of books and three weekly magazines in my bag in a single small device. A netbook wouldn't do the same job, since it wouldn't be as enjoyable to read off of (backlit LCD vs. e-paper), and because the lack of a single use makes it hard to lay in bed or sit in a recliner or couch for hours reading. The idea is to perform the single task well, by in many ways replicating the experience of a book (form factor, screen, how you hold it), so that the device disappears and you just notice what you're reading -- it works great for me since I don't have a psychological attachment to the feel and smell of paper.
Its very useful if you're interested in reading fiction and mostly-text magazines on a regular basis, and would like to carry a large library with you. Its not especially good for reference usage as the screen refresh rate is too slow, and the built-in web-browser is very limited -- only really much good for looking up things in wikipedia (which can be very nice, however).
Compared to other e-book readers -- its more constrained but more user-friendly. The built-in wireless makes it very easy to buy books without have to interact with a computer; however this comes at the constraint of being tied into the Amazon DRM system, for which the flaws are well documented. Unfortunately, since no DRM-free store with a good selection of modern literature exists, its likely if you're interested in an E-book you're going to be attached to some kind of DRM system.
I really enjoy mine and find it a pleasure to use, but as always: Buyer beware, particularly understand what the DRM implies, and whether you're willing to trade the convenience for the lack of true ownership.
"Publicly funded" means tax-supported in the US as well. Non-profits are usually referred to as 'non-profits' or '501c3' (after the tax code section). NASA is publicly funded here, the American Red Cross is non-profit.
Thought I'd try to clear it up.
Plus I'd say Merkel is more interesting because she's the first post-unification Chancellor from the East. That seems to be a more 'peaceful' thing since its indicative of a true unification.
I'd say that Ahmadinejad is in no way crazy. He puts on a tough-guy attitude towards the west because thats what his base supports. The Iranian mindset is that they are an old, proud nation (far older than us upstarts in America), and being subjugated and chastised by countries like the US and Europe grates -- for this reason the working classes really appreciate Ahmadinejad's aggressiveness as well as his populist policies. Really, the most irrational thing he's done lately is try to steal the recent election, since he was likely to win anyway, even if by an uncomfortably small margin. On the nuclear issue its questionable whether or not its mostly posturing, but most of that is under the control of the clerics, not the politicians. Additionally, posturing on the nuclear issue is popular domestically because, again, you have an old nation being told by new upstarts that 'no, you can't have these fancy bombs we have.'
On the effectiveness of US diplomatic posturing, I'd say that Obama's efforts at engagement were probably a major contributing factor to the recent unrest. Ahmadinejad's hard-line views were easier to justify to the young and educated when you had the worlds only superpower calling them part of the "Axis of Evil," but when you had the new guy saying "lets talk" and Ahmadinejad and his clerical keepers saying no, there was a powerful backlash. Some might argue that the Bush policies made it more likely as well, forcing the extremism of the theocracy to the surface to be exposed later by Obama (I believe there's a CSM Op-Ed to that effect). So... basically its all hard to say exactly.
Nope, Texas A&M. Its a good exciting target so I think a lot of schools do it for design projects, our particular project seems to have gotten some real traction though.
Of course, we'll see what these new numbers mean to us -- fortunately we've been selling our mission concept as a dress-rehearsal and science mission rather than an actual save-the-Earth doomsday avoidance mission.
Don't forget that if you're laying off everyone working on the project you're increasing unemployment and decreasing the amount those people are spending -- while I don't usually take that as a good argument for maintaining federal programs, maintaining useful programs that happen to maintain peoples employment seems like a decent idea, particularly for an administration that takes a fairly Keynesian view.
Of course, I'm a spacecraft engineer and not an economist so my view may be a little skewed.
Just a lowly graduate student who's been studying this particular problem for about a year.
This mission, a combined exploration/gravity-tractor mission, is one of the two main projects I've been doing in graduate school. So I guess its a little bit between the two (student/professional). Its definitely more in-depth than a senior design project, in that I've been working on it for 2-3 years. We're working with NASA Ames and some other groups, and have a strong potential path forward for eventual funding and building... so take it as it is.
I've been focusing on the tracking/radio-science portion of the problem, and my classwork has focused on dynamics and estimation, so... yeah, this particular article is probably the single thing I know the most about in the world... I wonder if that should worry me.
You'd probably have to apply a few km/s Delta-V (at least) to it in order to do that. All estimates show it entering the Earth's sphere of influence at about 5.87 km/s, which would be reasonable for putting it in orbit, if it were in the right place. Unfortunately, as it moves past the earth it gets sped up and moves on a hyperbolic orbit, it speeds up, so theres no real way to do it just by changing its position slightly (which could be done for ~$300M).
Basically, changing its position slightly in order to prevent an impact requires a very small amount of energy. For a 50 mN thrust for 1 year, 20 years ahead of time (which is enough to move it in 2036 by around 20 Earth radii), moves it about 500 meters and thus does about 25 Joules worth of work*. However, consider changing the velocity of something the size of Apophis (2.1e10 kg) from 5.8 km/s to say 3 km/s -- thats 2.5e17 Joules worth of work. Thats 800 MW over 10 years. I think there are probably better asteroids to capture in this case, and its certainly not an easy task by any definition.
*forgive me if the numbers are a bit off, but its the correct order of magnitude anyway
This kind of uncertainty is much easier to derive with fewer question marks than deriving the risk of catastrophic failure in a complex machine.
Basically what this implies is that taking new measurements, we have an improved estimate of the position of the asteroid at the current time, and the risk of impact is taken by projecting those into the future using well known and tested dynamic estimation methods. Current uncertainty is easily defined as a 6x6 covariance matrix (for the 6 state variables), and this matrix can be determined using a good least-squares estimation method and published measurement numbers.
In other words I give these numbers a lot more credence than risk numbers on the space shuttle. Theres a lot more science and lot fewer assumptions.
Also I would be careful comparing practices in the huge human-spaceflight program, centered at JSC and KSC with those of smaller planetery exploration programs from places like JPL and Ames. They have amazingly different cultures and practices -- NASA is in no way a monolithic entity.
All the models are run according the 'standard dynamic model' at JPL which includes gravity from the Sun, planets, large moons and large asteroids. Perturbations caused by objects outside the solar system are negligible compared to non-gravitational effects such as direct solar pressure and the Yarkovsky effect. These effects are impossible to model without knowledge of material composition, mass and structure, which you can't really get without going there.
However, the uncertainty caused by these non-gravitational effects is very small compared with the uncertainty caused by the fact that we just plain don't know quite where it is and how fast its going. In order to know where the asteroid will be in 2036 to within an Earth radius requires us to know where it is now to within about a meter -- the 2029 close approach in particular magnifies uncertainties incredibly (100x).
These state estimate uncertainties overwhelm any small errors in the dynamic model, and these new and improved probabilities come from refining the current state estimate. So yes, it is still valid to make these kind of predictions. You have to start early (10-20 years) to be able to stop it as well, so its important to keep an early eye on it.
Certainty is a funny word, but basically, the closer it gets the more confident you are in your prediction because small errors grow to large errors over time.
I would say, without significant funding you'd know for certain in the lead up to the 2029 close approach. During this event, the asteroid will pass within the geostationary satellite belt, and has the potential (1 in 250,000 now) to pass through a 'gravitational keyhole' that corresponds with a return impact trajectory. Note that the likelihood of impact in 2029 is zero (i.e. the 6-sigma boundaries of trajectory estimates are very far from the Earth).
Unfortunately, if you don't do something about it well before 2029, its unlikely you could do anything short of an Apollo-class-plus (Bruce Willis-class?) mission, in terms of funding, uncertainty, and national effort, to stop it. Put simply, its much easier to push the asteroid a kilometer (out of a keyhole) than it is to push it 3000 kilometers, but you have to do it earlier.
If you wanted to do very precise tracking to know if (and where) it was going to impact without waiting for the close approaches, you can do some of it with simply more observations with larger telescopes, and more ground-based radio ranging. However, you're going to get much better results (an order of magnitude) if you send a spacecraft out with a proper beacon. Two or three months in 2021 with this kind of tracking would give you 3-sigma (99%) reliability if it is to impact, and ascertain that it was not if it is not going to. A year of this tracking would tell you where exactly it was going to hit, within about 100km.
Of course, if you're already out there, its not too much more expensive to add the equipment to do a gravity tractor and move it away from a keyhole, since by 2022 it would be very difficult and very expensive to get a mitigation mission put together in time. A combined exploration and mitigation mission is estimated to cost about $350M, and in addition to improving knowledge about the unlikely but potentially imminent threat, would make it much easier to deal with future threats and contribute a lot to our understanding of near Earth asteroids in general. A pure exploration mission might be able to shave off $25M -- the only extra equipment is some Hall thrusters and a longer lifetime. I personally think there is political will for it at relatively low cost (Discovery-class mission), and scientific benefits beyond the mitigation of an admittedly small risk.
(Full Disclosure: Most of these numbers are pulled from a mission proposal I'm currently working on. The details aren't officially published yet, although they are being presented at a conference next week.)
If I'm designing a mission I'd be pretty happy to be able to cut my costs in half. Granted, it would be great to have a very cheap way to get to orbit, but as a practical engineer I'm much more impressed by a mostly functional prototype at the recommended scale with proper funding than I am by some theoretical work. While I have no reason to believe that laser propulsion will not work, it is at a TRL level of 2 from everything I can tell, while VASIMR is at TRL 6.
As someone looking at what I actually want to use to complete a mission, I'm much more interested in something that can cut my costs in half and is likely to be available within the next 10 years, than I am with something that has some paper concepts and a few basic lab experiments. I try not to be too much of a naysayer of new technology, but at the same time , comparing something entirely theoretical to something with significant amounts of development is absurd. Yes, if laser propulsion (or any other kind of new method to reach orbit) turns out to be a practical development it will be a much bigger deal, but in the meantime I find something that (almost) exists and reduces launch costs by half pretty valuable.
What this and other EP do is reduce the amount of fuel needed to get from LEO to where ever you're going. If you can reduce the mass fraction from say 2:1 to 1:2, you've cut your on-orbit mass in half, and thus can use a launch vehicle that's half the size.
While reducing the cost of the access to orbit is important, it doesn't mean that this is 'idiotic' and doesn't solve anything. I have issues with VASIMR (its always seemed very vapor-ish), but if its eventually capable of doing what it requires it will be a great tool for interplanetary missions. Something that can cut your launch costs in half isn't something to sneeze at.
In addition, it has one big advantage over, say, a space elevator. It is likely to eventually work in the next few decades(even if it is late and overbudget), and doesn't require materials that don't exist.
Space-based nuclear reactors aren't far fetched, but they are even more of vaporware than VASIMR as far as I'm concerned. I say this because it is at a lower TRL (Technology Readiness Level), and because there is less of a clear path forward for its development.
As you say, the reasons for this are largely political, but that doesn't mean that its not still an undeveloped technology with no clear path forward after JIMO got axed. VASIMR has prototypes and a proposed use, so its further along, but I still would like to see some flight-ready hardware that shows that it can really be as useful as its proponents claim before I get too excited about it. I've been hearing about it for 5 years, and I expect I'll keep hearing about it for a long time before it proves its utility.
None of this is to say it won't eventually be useful, but at present it doesn't seem like news worth mentioning to me.
I think my thought was more specifically "Oh God, not another VASIMR story."
I'll get excited when I see flight hardware, otherwise its just another slightly vaporish technology. The vapor is made particularly thin by its dependence on other development, specifically the very high power requirements that are likely to require advancements such as space-based nuclear reactors. From what I know, without this kind of power, it will be little more than an incremental improvement on current flight-proven EP methods.
My 2002 Nissan Altima gets 500 miles easily on a 20 gallon tank. But really, I'm pretty sure anything over 150 miles is overkill, since thats about the maximum you'd expect from a heavy day of local driving. Long-distance road trips are always going to be the big "but" for any pure EV, until some real fast-charging technology appears. You can claim that most trips are going to fall within the 500 mile range, and its true that I can get from my college to my home town in about 450 miles, but that doesn't mean I don't go further on occasion. If you have multiple people driving on a cross country drive out west its not hard at all to imagine going 18 hours and 1200 miles without anything more -- in fact I plan on doing it in a couple of months. You'll always have instances of going a bit further than a pure battery can handle -- without a fast loading energy reserve (biodiesel?) you can never achieve the freedom of travel a gas-powered car affords.