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Manned astroid mission?
"Dr. O" dr.o@xxxxx wrote in message
... How hard is it to send a man to land on or orbit an astroid, close to Earth? Would you need a rocket with enough oomph for a trans-lunar injection, or one more powerfull than that? How long would such a mission last? There are _no_ asteroids that are "close to Earth" - there are asteroids in "near Earth Orbits" and earth-crossing orbits, but they can travel many years to make one orbit of the Sun. For that reason, landing on or orbiting an asteroid would be costly from a logistics point-of-view (need for food, water and air), not to mention psychological problems from being so far from Earth (including being out of contact when on opposite sides of the Sun). From a practical, technical point-of-view, it would be about as difficult as sending people to Mars. -- Alan Erskine alanerskine(at)optusnet.com.au The U.S. Government is in the peculiar position of toppling foreign governments in the name of democracy. Oh, how democractic! |
#2
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Manned astroid mission?
"Dr. O" dr.o@xxxxx wrote in message
... How hard is it to send a man to land on or orbit an astroid, close to Earth? Would you need a rocket with enough oomph for a trans-lunar injection, or one more powerfull than that? How long would such a mission last? If you were content with a fly-by mission it should be easier than landing someone on the moon, because you don't need landing gear. Suppose you knew that an asteroid would fly within 1 million miles of Earth. A spaceship could go up, watch the asteroid fly by and return to Earth. You can use an elliptical orbit that doesn't stay 1 million miles from Earth. If your velocity is low at the high point, you'll get pulled back to Earth which allows you to get by with less fuel and less time in space. After the asteroid flies by Earth, it will be heading away from Earth. It would take extra rocket fuel to match its velocity so you could land on it. You would also need fuel to get off it and change direction to head back towards Earth. |
#3
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Manned astroid mission?
On Thu, 16 Oct 2003 20:13:15 +1000, in a place far, far away, "Alan
Erskine" made the phosphor on my monitor glow in such a way as to indicate that: From a practical, technical point-of-view, it would be about as difficult as sending people to Mars. No, it would be much easier, because you only have one gravity well to deal with, rather than two. -- simberg.interglobal.org * 310 372-7963 (CA) 307 739-1296 (Jackson Hole) interglobal space lines * 307 733-1715 (Fax) http://www.interglobal.org "Extraordinary launch vehicles require extraordinary markets..." Swap the first . and @ and throw out the ".trash" to email me. Here's my email address for autospammers: |
#4
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Manned astroid mission?
In article ,
Rand Simberg wrote: On Thu, 16 Oct 2003 20:13:15 +1000, in a place far, far away, "Alan Erskine" made the phosphor on my monitor glow in such a way as to indicate that: From a practical, technical point-of-view, it would be about as difficult as sending people to Mars. No, it would be much easier, because you only have one gravity well to deal with, rather than two. Two rather than three, surely? The Sun, the Earth and the rock vs S,E and Mars? It's a shame the freeware version of SBcalculator doesn't come with asteroids in... Poking through _Hazards_, I see some interesting targets: Opheus in 2005: leaves Earth 07/19/05, arrives Orpheus 12/09/05, returns on 12/19/05 and arrives Earth 03/16/06 for a total delta vee of 13 km/s and a trip time of 240 days. 1989 UQ has a slightly shorter mission in 2010, with 215 days for 10.5 km/s. For low delta vees, 1982 DB in 2009: 1490 days for 5.7 km/s. -- It's amazing how the waterdrops form: a ball of water with an air bubble inside it and inside of that one more bubble of water. It looks so beautiful [...]. I realized something: the world is interesting for the man who can be surprised. -Valentin Lebedev- |
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Manned astroid mission?
On 16 Oct 2003 11:46:53 -0400, in a place far, far away,
(James Nicoll) made the phosphor on my monitor glow in such a way as to indicate that: From a practical, technical point-of-view, it would be about as difficult as sending people to Mars. No, it would be much easier, because you only have one gravity well to deal with, rather than two. Two rather than three, surely? The Sun, the Earth and the rock vs S,E and Mars? It's not usual to consider the sun when discussing gravity wells in the solar system, any more than one talks about the water as a destination when traveling in an ocean. -- simberg.interglobal.org * 310 372-7963 (CA) 307 739-1296 (Jackson Hole) interglobal space lines * 307 733-1715 (Fax) http://www.interglobal.org "Extraordinary launch vehicles require extraordinary markets..." Swap the first . and @ and throw out the ".trash" to email me. Here's my email address for autospammers: |
#6
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Manned astroid mission?
In article , Dr. O dr.o@xxxxx wrote:
How hard is it to send a man to land on or orbit an astroid, close to Earth? Given an asteroid that is passing Earth at a fairly short distance *and* a fairly low speed -- most near-Earth asteroids come by fairly briskly -- it's not significantly harder than a lunar landing. The Saturn V could launch a fully-fueled Apollo out into deep space about as easily as launching one to the Moon. Getting out to the asteroid intercept (and back) would take longer -- depends on the asteroid's orbit, but it would almost certainly be rather farther out than the Moon -- but that just means somewhat-improved life support, a change that NASA had already studied for improved Apollos. The big question is, can you find an asteroid that's going to come past within a few million kilometers, at a relative speed slow enough that the CSM+LM combination can make a rendezvous with it, and then boost back into a trajectory that intercepts Earth? Not impossible, but it does limit the choice of targets rather severely. Most asteroids move too fast. Would you need a rocket with enough oomph for a trans-lunar injection, or one more powerfull than that? Something with the capabilities of the Apollo/Saturn combination would be about the bare minimum. What you really want is either a somewhat bigger rocket, or better propulsion technology for the spacecraft, to permit rendezvous with a faster-moving asteroid. One particularly interesting choice is Toutatis. It's quite sizable by near-Earth-asteroid standards. It comes by every four years, sometimes quite close. It's almost certainly a double asteroid, two original bodies stuck together, so you get two for the price of one. But it comes past at about 10km/s, which is a bit of a challenge (and still rather low by asteroid standards). How long would such a mission last? Depends very much on the asteroid's orbit. Several weeks, almost certainly; possibly a few months. -- MOST launched 1015 EDT 30 June, separated 1046, | Henry Spencer first ground-station pass 1651, all nominal! | |
#7
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Manned astroid mission?
In article ,
Alan Erskine wrote: There are _no_ asteroids that are "close to Earth" - there are asteroids in "near Earth Orbits" and earth-crossing orbits, but they can travel many years to make one orbit of the Sun. For that reason, landing on or orbiting an asteroid would be costly from a logistics point-of-view... Only if you insist on using maximum-economy trajectories, which inherently take a long time. If you are willing to expend a lot of extra fuel, you can visit an asteroid as it goes past. The payoff for the extra fuel is short distances and a relatively brief mission. The assumption that you *must* use maximum-economy trajectories is quite unnecessary and very limiting. Fuel is cheap. Even fuel in LEO is cheap compared to the alternatives. ...not to mention psychological problems from being so far from Earth (including being out of contact when on opposite sides of the Sun). A greatly exaggerated problem. Amundsen's expedition to the South Pole involved a handful of men being completely out of contact with the rest of the world for much longer. -- MOST launched 1015 EDT 30 June, separated 1046, | Henry Spencer first ground-station pass 1651, all nominal! | |
#8
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Manned astroid mission?
In article ,
Rand Simberg wrote: From a practical, technical point-of-view, it would be about as difficult as sending people to Mars. No, it would be much easier, because you only have one gravity well to deal with, rather than two. Yes and no. The second gravity well comes with an atmosphere, which permits aerodynamic braking, and that helps a lot. How the two compare depends on the asteroid's orbit. -- MOST launched 1015 EDT 30 June, separated 1046, | Henry Spencer first ground-station pass 1651, all nominal! | |
#9
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Manned astroid mission?
Rand Simberg wrote:
(James Nicoll) wrote: Two rather than three, surely? The Sun, the Earth and the rock vs S,E and Mars? It's not usual to consider the sun when discussing gravity wells in the solar system, any more than one talks about the water as a destination when traveling in an ocean. I think he missed your point, Rand. You were of course discussing the difficulties of ascending and descending steep planetary gravity wells. James seemed to think you meant the mathematical difficulties of calculating trajectories. Trajectory calculations aren't the hard part, and can be done by people sitting here on Earth. -- Regards, Mike Combs ---------------------------------------------------------------------- We should ask, critically and with appeal to the numbers, whether the best site for a growing advancing industrial society is Earth, the Moon, Mars, some other planet, or somewhere else entirely. Surprisingly, the answer will be inescapable - the best site is "somewhere else entirely." Gerard O'Neill - "The High Frontier" |
#10
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Manned astroid mission?
In article ,
Rand Simberg wrote: On 16 Oct 2003 11:46:53 -0400, in a place far, far away, (James Nicoll) made the phosphor on my monitor glow in such a way as to indicate that: From a practical, technical point-of-view, it would be about as difficult as sending people to Mars. No, it would be much easier, because you only have one gravity well to deal with, rather than two. Two rather than three, surely? The Sun, the Earth and the rock vs S,E and Mars? It's not usual to consider the sun when discussing gravity wells in the solar system, Really? So hypothetical trips from Earth to Mars, for example, don't need to take into account the different Eps wrt Sun of the Earth and Mars? And Hohmann orbits must, unlike my faulty memory of them, be straight and not a long, curved path from one world to another. any more than one talks about the water as a destination when traveling in an ocean. Where's this 'as a destination' thing coming from? Is this a 'put stupid words into the other guy's mouth' tactic? I bet the existance of the Atlantic or Pacific played a fair role in people's plans when attempting to move a payload from the Old World to the New. Even if, or especially if, the plan did not involve the ocean as a destination. -- It's amazing how the waterdrops form: a ball of water with an air bubble inside it and inside of that one more bubble of water. It looks so beautiful [...]. I realized something: the world is interesting for the man who can be surprised. -Valentin Lebedev- |
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