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!

"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.

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..."
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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-

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:

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! |

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! |

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! |

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"

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-