I'm more familiar with the phrase "spanking the monkey", but I much prefer "smacking the beef" now. Gives a better impression of the scale of the event.
Dude you are going to drag all the mass of a CEV all the way to Mars and back just so they can use it to reenter the Earth's atmosphere. I dont suppose it occured to you, with all this modularity and docking stuff that if thats all you are using it for you could dock a CEV with the Mars return craft when it gets back to earth orbit and save the mass on the round trip to Mars for something useful on mars?
I don't suppose it occurred to you to compare the weight cost of carrying a CEV modification capable of making a direct reentry into the Earth's atmosphere (like Apollo did) versus the weight of the fuel necessary to brake the returning astronauts into Earth orbit. I bet you'd discover that direct entry works out a lot better.
Better believe it. I've read the Apollo Lunar Surface Journal where one of the astronauts mentions that the skin of the lander was so thin that when they decompressed it to commence an EVA it would make popping noises like a jerry can. That's not much protection between you and vacuum.
No one is going to put Zubrin's plans into effect in the way he wants, but having him out there certainly raises the chances of us getting to Mars at all.
I would dispute this. I don't think it 'certainly' improves our chances at all. I think his plan is fatally flawed, and if some numbnuts in DC decided to push him hard, the unworkability of it would soon become apparent.
Mars Direct says to me that Zubrin has the mentality of a toddler. He wants to go to Mars now. That's NOW NOW NOW NOW NOW!!! Despite his claims to the contrary, it's a huge Apollo-style blockbuster designed to get there quickly without farting about with things like near Earth infrastructure and the like.
Let's use one of my favourite analogies for the state of spaceflight. In the first decade of the 20th century, heavier than air flight became possible. Wild eyed dreamers talked about transatlantic passenger flights. Let's say some loon decides that he really, really wants to do this in 1910. He could try to browbeat people into building a series of aircraft cariers or anchored landing platforms across the Norh Atlantic in order to let the primitive planes of the day move in short, slow hops across the ocean at great expense in resources and probably lives. Well, there's the plan. The engineering principles are 'sound'. Let's build it NOW NOW NOW!!
The Apollo program was, to a degree, just such a solution. It pushed the available tech to the absolute limit in order to get there before anybody else. Guess what? We're not still there. Far better to build Lagrangian depots, develop nuclear propulsion (the only way we will realistically get to Mars, IMHO)and build ourselves up to a state where we can do it regularly, rather than as a showy one shot.
Just to point out how things have changed, the upcoming Delta IV heavy will have a payload capacity greater than that of the STS.
The Delta 4 Heavy may have a way to go before all the bugs are ironed out. In any case, development of a Saturn class superlifter would be a really, really good idea. Relying on 20-30 tons per throw EELVs would require way too many launches.
Anyway, for those who haven't read it, I highly recommend Dr. Zubrin's book, The Case For Mars
Karma to burn, so...
Zubrin is a barking mad cult leader labouring under the messianic misapprehension that he and only he can get us to Mars. Anybody who says otherwise is a fool and a communist.
If you read his statements made after the release of the basic outline of the current Bush space plan, he stops just short of calling treasonous any effort to go to the Moon as a first step or staging post rather than directly to Mars. He's not interested in consensus building, just his own (dubiously costed and hand-wavingly engineered) master plan. There are a growing number of people in space advocacy who consider him as mad as a bus. In a field full of dogmatic fantasists, he dwarfs all others for sheer cultish zealotry.
Mod me "-1 uncomfortable truth shut up shut up lalalalala"
Wow, dude! You read books about space science when you were a kid! The other guy just does it for a living now he's a grown up.
Your original post talked about how scientists "always thought" pictures were pure PR and "prefer unpronounceable devices". I think pedroloco was well within his rights to call shenanigans on that, given his stated specialty. Your second post grudgingly acknowledges that not all scientists need to be forced to view pictures at gunpoint, but do so backhandedly by saying they "enjoy" them, implying they do so purely from an eyecandy perspective. You speak in the present tense about a situation that no longer applies. Yes, early probes had cameras forced on them for PR purposes, because space programs, even scientific ones, were cold war propaganda weapons. In more recent times, important probes like Ulysses are launched without cameras when there is no reason to take them, even when it would be travelling past photogenic locales like Jupiter.
I'm not sure I understand your question. But in case it helps, Iapetus is tidally locked to Saturn. This means that like our moon it always shows the same face to the parent planet, as it completes one rotation on its axis in the same time it takes to orbit the planet.
The newfound ridge stretches the entire width of the dark hemisphere, meaning the one facing forward in Iapetus' orbital sweep around Saturn (and is thus half visible, half on the 'far side' from Saturn's perspective.)
Keep in mind that SETI is looking back in time as it looks out into the universe. The Earth lies at the centre of a shell of radio transmissions that is currently about 60 light years in radius (for signals worth picking up). Those transmissions aren't coming back. They won't pop out of existence if we all move to laser based communications. An alien SETI program 70 light years away will have to wait another 10 years before discovering that life here uses radio.
The upshot is that laser SETI should be run in parallel with radio searches, not as a replacement. We have no way of knowing how advanced any putative aliens might be, so we should scan all frequencies that we think might carry a signal. Radio SETI just had a several decade head start because that was all that was feasible at the time.
2. Saturn. Saturn's gravity well sucks asteroids and other debri into it thus protecting Titan.
Jupiter has a bigger gravity well than Saturn, and the surfaces of Ganymede and Callisto are heavily cratered. Europa has some craters, but would seem to be resurfaced by water gushing/oozing onto the surface. Io has very few craters, not unexpected for the most active surface in the solar system.
It's not like the central planet hoovers all imactors away from its moons. In fact, the greater number of objects falling into the system would likely increase the number of impacts on the moons. Yes, the majority hit Saturn, but that still leaves a lot to hit Titan. Look at the other heavily cratered moons of Saturn like Dione and Mimas.
The jury is still obviously out on the degree of activity on Titan's surface. There are some hints of linear markings visible in the latest data that some of the science team are tentatively labeling as possible evidence of tectonics.
I am totally talking out of my arse here, and anyone is welcome to slap me down, but I would guess that it would be in the ballpark of the Solar System escape velocity at the distance of the planned planetary swingby, if only because of the difficulty in arranging the celestial billiards game to squeeze even more delta v out of the system before escape.
The above phrasing probably gave conniptions to any celestial mechanics boffins in the audience.
Trollish , if partially true. Saturn sans rings is probably, though debatably, marginally less interesting than Jupiter. Stuff like the uncertainty over the length of its day shows that it has some surprises in store, though.
But Titan sure has to be the most interesting object in the Solar System at the moment, if only because it's the biggest bit of unexplored surface left. The good probability of extraterrestrial oceans is also pretty damn cool. Go, Huygens!
Hmm. You are either a physics troll or you fell asleep in class. I'm guessing a little from column A, a little from column B.
Just in case your jedi mind tricks have an effect on the weak minded, here's the skinny on rockets: They don't work by pushing against anything. Newtonian mechanics states the old saw "for every action there is an equal and opposite reaction". If you have a mass and eject part of that mass in one direction, the remaining mass will move in the opposite direction. The fundamental limit of chemical rockets has nothing to do with "thrust dissipation" or whatever you're on about, and everything to do with the limits of how much energy can be imparted to the reaction mass. Rockets are in fact more efficient in vacuum than in atmospheres, as there is no friction to be countered.
BRW, you're also dead wrong with your swinging fist example. You expend the same amount of energy accelerating your fist in both cases, it's just transferred abruptly if you hit something, and arrested by mechanical limitations of your musculature if you don't connect. Same total energy in both cases.
Sure, I'm rising to the bait. But I'd rather look like a troll tragic than risk someone taking this seriously:-P
If your science fantasy (not even science fiction, IMHO) about warp drives is just "That's all... it's not rocket science!!!", then show us how and pack your Swedish phrasebook, you're off to Stockholm. And I'm eating my hat.
Nope. (Relevant bit about halfway down the page). My guess based on the information in the link is that the obliquity variations occur over a period of hundreds of thousands of years, so the ice migrates slowly toward the equator, while the seasonal variations occur over a period of just hundreds of days, so the ice doesn't have time to migrate back.
One correction: The obliquity cycle would seem to not exactly be highly chaotic, but rather a slow oscillation.
Scientists think they have a handle on why. Low atmospheric pressure means that water can't exist in liquid form on the surface any more. Mars' atmosphere was denser billions of years ago during what is called its Noachian period. For various possible reasons (such as a lack of a magnetic field to protect against the stripping solar wind) Mars' atmosphere was mostly lost, and all the water boiled off into vapour, and was either lost to space or deposited in the ice caps.
A lengthy and detailed overview of current theories can be found here: Part 1, Part 2. Especially cool is the stuff about Mars' "obliquity cycles", namely the fact that the planet's axial tilt appears to be chaotic, and may have been completely tipped over on its side several times in the past. During such a period Mars would not have ice caps at the poles, but rather an ice belt around its equator.
I'm hoping the next rover (or the next one to built) will sport some elegant new hack suggested by some Jane Average.
The next planned Mars rover is the Mars Science Laboratory to be launched in 2009. It will be five times larger than the current rovers and will be powered by a plutonium RTG, giving it at least a year, probably more, of operation. Check out the link for details on its proposed landing method. Very cool.
True, the pros don't have much eyepiece time, but many amateurs still do, and these spokes still show up.
Once again, I'd like to see a source for this assertion. You make it sound like they are seen all the time.
I cannot provide linkage at this time, but google on sci.astro.amateur, and check out some books in the library.
Gee, Yogi, I hadn't thought of that:-P. I googled with about a half dozen different word combos and came up with one reference to not seeing them. The wording of the Astrobiology article seems to imply that there had been no observations between Voyager and the present, but the fact they are surprised about their current no-show seems to indicate that they weren't expecting to with ground based equipment. You seem very certain, could you give me any pointers to the source of your certainty about these multiple and yet possibly illusory ground based amateur observations?
I'm just playing the skeptic given the history of the Martian canali.
From which example we can cast into doubt any observation of dark lines. It's fallacious reasoning: the dark line 'canals' were the result of an optical illusion, there were reports of dark line spokes by obviously illusion-susceptible ground based observers, ergo they are an illusion and so the Voyager CCD images are wrong.
Just because one ccd detector-software combo sees something, doesn't mean they all will or can.
The spokes were observed by both Voyagers on both the lit and unlit side of Saturn under a wide range of lighting conditions. It seems a rather specific and yet widely reproducible imaging anomaly. Do you question any of Voyager's other observations, or is it just because these are the dreaded dark lines?
But the spokes were first observed with the CCDs on Voyager. Also, no astronomer actually looks through an eyepiece any more, its all CCDs or other detectors. All of the ground-based spoke observations (could you provide a source for such images?) are thus not going to be subject to the Percival Lowell wishful thinking effect.
It's more likely to be due, as other posters have suggested, to be due to variations in Saturn's magnetic field. It would seem that Cassini is already producing interesting science before it goes into Saturnian orbit.
ESA has a long term exploration program called Aurora that aims to take humans to the Moon by 2020 and Mars by 2030. This was announced some time ago, well ahead of Bush's proclamation. The nearer term goals include ExoMars, a long-duration rover, and a Mars sample return mission with the ambitious launch date of 2011.
The airbags were designed to deflate in sequence so if the lander came to rest wrong way up after its bouncedown it could right itself before opening up to reveal the rover. If the lander got stuck upside down, like in a crevasse, then there would be no way of deploying.
The sequence of activities to ready the rover for movement off the lander were the most complex series of steps ever undertaken by a space probe. Dozens of small pyrotechnic devices had to be fired to release clamps, sever cables and so on. If any of them had failed to fire, the mission would have been severely crippled at best.
Yes, goback. The mainstream media has been doing pieces on this for months now.
Some of the early plans are a bit out there
on
Dreams of the Moon
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· Score: 5, Interesting
My personal favourite is the One Way Manned Space Mission scheme from 1962 that would involve putting a man on the Moon and then launch supplies to him for the several years needed to develop a two-way retrieval system. All in the name of planting a flag first.
So, hands up. Who would accept this mission if it was offered?
Slashdot Mirror
I'm more familiar with the phrase "spanking the monkey", but I much prefer "smacking the beef" now. Gives a better impression of the scale of the event.
The story's about Australia, so the Southern Hemisphere, obviously.
I don't suppose it occurred to you to compare the weight cost of carrying a CEV modification capable of making a direct reentry into the Earth's atmosphere (like Apollo did) versus the weight of the fuel necessary to brake the returning astronauts into Earth orbit. I bet you'd discover that direct entry works out a lot better.
Better believe it. I've read the Apollo Lunar Surface Journal where one of the astronauts mentions that the skin of the lander was so thin that when they decompressed it to commence an EVA it would make popping noises like a jerry can. That's not much protection between you and vacuum.
I would dispute this. I don't think it 'certainly' improves our chances at all. I think his plan is fatally flawed, and if some numbnuts in DC decided to push him hard, the unworkability of it would soon become apparent.
Mars Direct says to me that Zubrin has the mentality of a toddler. He wants to go to Mars now. That's NOW NOW NOW NOW NOW!!! Despite his claims to the contrary, it's a huge Apollo-style blockbuster designed to get there quickly without farting about with things like near Earth infrastructure and the like.
Let's use one of my favourite analogies for the state of spaceflight. In the first decade of the 20th century, heavier than air flight became possible. Wild eyed dreamers talked about transatlantic passenger flights. Let's say some loon decides that he really, really wants to do this in 1910. He could try to browbeat people into building a series of aircraft cariers or anchored landing platforms across the Norh Atlantic in order to let the primitive planes of the day move in short, slow hops across the ocean at great expense in resources and probably lives. Well, there's the plan. The engineering principles are 'sound'. Let's build it NOW NOW NOW!!
The Apollo program was, to a degree, just such a solution. It pushed the available tech to the absolute limit in order to get there before anybody else. Guess what? We're not still there. Far better to build Lagrangian depots, develop nuclear propulsion (the only way we will realistically get to Mars, IMHO)and build ourselves up to a state where we can do it regularly, rather than as a showy one shot.
The Delta 4 Heavy may have a way to go before all the bugs are ironed out. In any case, development of a Saturn class superlifter would be a really, really good idea. Relying on 20-30 tons per throw EELVs would require way too many launches.
Karma to burn, so...
Zubrin is a barking mad cult leader labouring under the messianic misapprehension that he and only he can get us to Mars. Anybody who says otherwise is a fool and a communist.
If you read his statements made after the release of the basic outline of the current Bush space plan, he stops just short of calling treasonous any effort to go to the Moon as a first step or staging post rather than directly to Mars. He's not interested in consensus building, just his own (dubiously costed and hand-wavingly engineered) master plan. There are a growing number of people in space advocacy who consider him as mad as a bus. In a field full of dogmatic fantasists, he dwarfs all others for sheer cultish zealotry.
Mod me "-1 uncomfortable truth shut up shut up lalalalala"
Wow, dude! You read books about space science when you were a kid! The other guy just does it for a living now he's a grown up.
Your original post talked about how scientists "always thought" pictures were pure PR and "prefer unpronounceable devices". I think pedroloco was well within his rights to call shenanigans on that, given his stated specialty. Your second post grudgingly acknowledges that not all scientists need to be forced to view pictures at gunpoint, but do so backhandedly by saying they "enjoy" them, implying they do so purely from an eyecandy perspective. You speak in the present tense about a situation that no longer applies. Yes, early probes had cameras forced on them for PR purposes, because space programs, even scientific ones, were cold war propaganda weapons. In more recent times, important probes like Ulysses are launched without cameras when there is no reason to take them, even when it would be travelling past photogenic locales like Jupiter.
I'm not sure I understand your question. But in case it helps, Iapetus is tidally locked to Saturn. This means that like our moon it always shows the same face to the parent planet, as it completes one rotation on its axis in the same time it takes to orbit the planet.
The newfound ridge stretches the entire width of the dark hemisphere, meaning the one facing forward in Iapetus' orbital sweep around Saturn (and is thus half visible, half on the 'far side' from Saturn's perspective.)
Keep in mind that SETI is looking back in time as it looks out into the universe. The Earth lies at the centre of a shell of radio transmissions that is currently about 60 light years in radius (for signals worth picking up). Those transmissions aren't coming back. They won't pop out of existence if we all move to laser based communications. An alien SETI program 70 light years away will have to wait another 10 years before discovering that life here uses radio.
The upshot is that laser SETI should be run in parallel with radio searches, not as a replacement. We have no way of knowing how advanced any putative aliens might be, so we should scan all frequencies that we think might carry a signal. Radio SETI just had a several decade head start because that was all that was feasible at the time.
You do know that Australia isn't part of America, don't you?
Jupiter has a bigger gravity well than Saturn, and the surfaces of Ganymede and Callisto are heavily cratered. Europa has some craters, but would seem to be resurfaced by water gushing/oozing onto the surface. Io has very few craters, not unexpected for the most active surface in the solar system.
It's not like the central planet hoovers all imactors away from its moons. In fact, the greater number of objects falling into the system would likely increase the number of impacts on the moons. Yes, the majority hit Saturn, but that still leaves a lot to hit Titan. Look at the other heavily cratered moons of Saturn like Dione and Mimas.
The jury is still obviously out on the degree of activity on Titan's surface. There are some hints of linear markings visible in the latest data that some of the science team are tentatively labeling as possible evidence of tectonics.
I am totally talking out of my arse here, and anyone is welcome to slap me down, but I would guess that it would be in the ballpark of the Solar System escape velocity at the distance of the planned planetary swingby, if only because of the difficulty in arranging the celestial billiards game to squeeze even more delta v out of the system before escape.
The above phrasing probably gave conniptions to any celestial mechanics boffins in the audience.
Trollish , if partially true. Saturn sans rings is probably, though debatably, marginally less interesting than Jupiter. Stuff like the uncertainty over the length of its day shows that it has some surprises in store, though.
But Titan sure has to be the most interesting object in the Solar System at the moment, if only because it's the biggest bit of unexplored surface left. The good probability of extraterrestrial oceans is also pretty damn cool. Go, Huygens!
Hmm. You are either a physics troll or you fell asleep in class. I'm guessing a little from column A, a little from column B.
Just in case your jedi mind tricks have an effect on the weak minded, here's the skinny on rockets: They don't work by pushing against anything. Newtonian mechanics states the old saw "for every action there is an equal and opposite reaction". If you have a mass and eject part of that mass in one direction, the remaining mass will move in the opposite direction. The fundamental limit of chemical rockets has nothing to do with "thrust dissipation" or whatever you're on about, and everything to do with the limits of how much energy can be imparted to the reaction mass. Rockets are in fact more efficient in vacuum than in atmospheres, as there is no friction to be countered.
BRW, you're also dead wrong with your swinging fist example. You expend the same amount of energy accelerating your fist in both cases, it's just transferred abruptly if you hit something, and arrested by mechanical limitations of your musculature if you don't connect. Same total energy in both cases.
Sure, I'm rising to the bait. But I'd rather look like a troll tragic than risk someone taking this seriously :-P
If your science fantasy (not even science fiction, IMHO) about warp drives is just "That's all... it's not rocket science!!!", then show us how and pack your Swedish phrasebook, you're off to Stockholm. And I'm eating my hat.
Nope. (Relevant bit about halfway down the page). My guess based on the information in the link is that the obliquity variations occur over a period of hundreds of thousands of years, so the ice migrates slowly toward the equator, while the seasonal variations occur over a period of just hundreds of days, so the ice doesn't have time to migrate back.
One correction: The obliquity cycle would seem to not exactly be highly chaotic, but rather a slow oscillation.
Scientists think they have a handle on why. Low atmospheric pressure means that water can't exist in liquid form on the surface any more. Mars' atmosphere was denser billions of years ago during what is called its Noachian period. For various possible reasons (such as a lack of a magnetic field to protect against the stripping solar wind) Mars' atmosphere was mostly lost, and all the water boiled off into vapour, and was either lost to space or deposited in the ice caps.
A lengthy and detailed overview of current theories can be found here: Part 1, Part 2. Especially cool is the stuff about Mars' "obliquity cycles", namely the fact that the planet's axial tilt appears to be chaotic, and may have been completely tipped over on its side several times in the past. During such a period Mars would not have ice caps at the poles, but rather an ice belt around its equator.
I'm hoping the next rover (or the next one to built) will sport some elegant new hack suggested by some Jane Average.
The next planned Mars rover is the Mars Science Laboratory to be launched in 2009. It will be five times larger than the current rovers and will be powered by a plutonium RTG, giving it at least a year, probably more, of operation. Check out the link for details on its proposed landing method. Very cool.
About 30 seconds after posting the above I found this link, to an abstract of a scientific paper detailing Hubble observations of the spokes.
Once again, I'd like to see a source for this assertion. You make it sound like they are seen all the time.
Gee, Yogi, I hadn't thought of that :-P. I googled with about a half dozen different word combos and came up with one reference to not seeing them. The wording of the Astrobiology article seems to imply that there had been no observations between Voyager and the present, but the fact they are surprised about their current no-show seems to indicate that they weren't expecting to with ground based equipment. You seem very certain, could you give me any pointers to the source of your certainty about these multiple and yet possibly illusory ground based amateur observations?
From which example we can cast into doubt any observation of dark lines. It's fallacious reasoning: the dark line 'canals' were the result of an optical illusion, there were reports of dark line spokes by obviously illusion-susceptible ground based observers, ergo they are an illusion and so the Voyager CCD images are wrong.
The spokes were observed by both Voyagers on both the lit and unlit side of Saturn under a wide range of lighting conditions. It seems a rather specific and yet widely reproducible imaging anomaly. Do you question any of Voyager's other observations, or is it just because these are the dreaded dark lines?
But the spokes were first observed with the CCDs on Voyager. Also, no astronomer actually looks through an eyepiece any more, its all CCDs or other detectors. All of the ground-based spoke observations (could you provide a source for such images?) are thus not going to be subject to the Percival Lowell wishful thinking effect.
It's more likely to be due, as other posters have suggested, to be due to variations in Saturn's magnetic field. It would seem that Cassini is already producing interesting science before it goes into Saturnian orbit.
ESA has a long term exploration program called Aurora that aims to take humans to the Moon by 2020 and Mars by 2030. This was announced some time ago, well ahead of Bush's proclamation. The nearer term goals include ExoMars, a long-duration rover, and a Mars sample return mission with the ambitious launch date of 2011.
The airbags were designed to deflate in sequence so if the lander came to rest wrong way up after its bouncedown it could right itself before opening up to reveal the rover. If the lander got stuck upside down, like in a crevasse, then there would be no way of deploying.
The sequence of activities to ready the rover for movement off the lander were the most complex series of steps ever undertaken by a space probe. Dozens of small pyrotechnic devices had to be fired to release clamps, sever cables and so on. If any of them had failed to fire, the mission would have been severely crippled at best.
Yes, go back. The mainstream media has been doing pieces on this for months now.
My personal favourite is the One Way Manned Space Mission scheme from 1962 that would involve putting a man on the Moon and then launch supplies to him for the several years needed to develop a two-way retrieval system. All in the name of planting a flag first.
So, hands up. Who would accept this mission if it was offered?