Is it feasible to land on Mars and come back?

Bar the development of some revolutionary technology, is it realistic to
think that we can land on Mars and come back?

Say we want to bring a piece of Martian rock back to Earth. A lander
carrying a rover and an ascent module would land on the planet. The rover
would move about, pick up a rock, and bring it back to the ascent module.
The module is then launched back into space to rendezvous with a return
vehicle.

It seems to me that the size of lander would be prohibitively large, as the
ascent module would need to carry enough fuel to enter into Martian orbit.
Compared to the Moon's, Mars' gravity is much stronger. Mars also has an
atmosphere, which means thermo-shieldings on both the lander and the ascent
module.

The return vehicle would be fairly large too, as it needs to carry fuel for
returning to Earth. In addition, it would carry the reentry module and
equipment for monitoring the Martian atmosphere. Even if we use two
launches, the rockets used to carry them into space would be gargantuan.

Perhaps our current approach to Mars exploration is the only way for the
foreseeable future?

Chung Leong wrote:

It seems to me that the size of lander would be prohibitively large,
as the ascent module would need to carry enough fuel to enter into
Martian orbit. Compared to the Moon's, Mars' gravity is much
stronger. Mars also has an atmosphere, which means thermo-shieldings
on both the lander and the ascent module.

The return vehicle would be fairly large too, as it needs to carry
fuel for returning to Earth. In addition, it would carry the reentry
module and equipment for monitoring the Martian atmosphere. Even if
we use two launches, the rockets used to carry them into space would
be gargantuan.

Unless you utilize In-Situ Propellant Production. That's one of the main
points in Robert Zubrin's "Mars Direct"-plan.

Bring along some Hydrogen, which weighs next to nothing. Make it react with
Mars' CO2-atmosphere, creating Methane and water (the Sabatier-reaction).
Electrolyze the water into Hydrogen, which is cycled back into the reaction,
and Oxygen, which makes a great rocket fuel together with Methane.

--
Steen Eiler Jørgensen
"Time has resumed its shape. All is as it was before.
Many such journeys are possible. Let me be your gateway."

"Chung Leong"

Bar the development of some revolutionary technology, is it realistic to
think that we can land on Mars and come back?

It seems to me that the size of lander would be prohibitively large, as
the
ascent module would need to carry enough fuel to enter into Martian orbit.
Compared to the Moon's, Mars' gravity is much stronger. Mars also has an
atmosphere, which means thermo-shieldings on both the lander and the
ascent
module.

See this:

http://techreports.larc.nasa.gov/ltr...aa-98-2850.pdf

Jon

"Chung Leong" ,
In a message on Sat, 10 Jan 2004 13:54:26 -0500, wrote :

"L Bar the development of some revolutionary technology, is it realistic to
"L think that we can land on Mars and come back?
"L
"L Say we want to bring a piece of Martian rock back to Earth. A lander
"L carrying a rover and an ascent module would land on the planet. The rover
"L would move about, pick up a rock, and bring it back to the ascent module.
"L The module is then launched back into space to rendezvous with a return
"L vehicle.
"L
"L It seems to me that the size of lander would be prohibitively large, as the
"L ascent module would need to carry enough fuel to enter into Martian orbit.
"L Compared to the Moon's, Mars' gravity is much stronger. Mars also has an
"L atmosphere, which means thermo-shieldings on both the lander and the ascent
"L module.
"L
"L The return vehicle would be fairly large too, as it needs to carry fuel for
"L returning to Earth. In addition, it would carry the reentry module and
"L equipment for monitoring the Martian atmosphere. Even if we use two
"L launches, the rockets used to carry them into space would be gargantuan.

This would depend on how how high an orbit the assent module would need
to achieve -- assent module itself could also be abandoned, once the
crew and samples transfer to the return vehicle. One possibility would
be a several vehicle approach -- sending the return vehicle and/or its
fuel separately from the landing vehicle. We have proven the ability
to get unmanned stuff to Mars and then spot it with a reasonable degree
of accuracy.

Note: if the Mars transit vehicles were assembled and launched from
Earth orbit (or from a Lunar orbit) there would be various economies
realized, since the ships going to/from Mars would not have to contend
with Earth gravity well or Earth's atmosphere.

"L
"L Perhaps our current approach to Mars exploration is the only way for the
"L foreseeable future?
"L
"L
"L

\/
Robert Heller ||InterNet:
http://vis-www.cs.umass.edu/~heller ||
http://www.deepsoft.com /\FidoNet: 1:321/153

In article ,
Chung Leong wrote:
Bar the development of some revolutionary technology, is it realistic to
think that we can land on Mars and come back?

It's certainly feasible, just relatively costly.

It seems to me that the size of lander would be prohibitively large, as the
ascent module would need to carry enough fuel to enter into Martian orbit.
Compared to the Moon's, Mars' gravity is much stronger. Mars also has an
atmosphere, which means thermo-shieldings on both the lander and the ascent
module.

This has been studied at some length. It's a manageable problem, although
a painful one. Remember that the ascent module doesn't need to carry a
terribly *large* payload into Martian orbit; that helps.

Another approach that helps considerably is fueling the ascent module from
fuel manufactured on Mars, rather than having to lug the fuel all the way.

The return vehicle would be fairly large too, as it needs to carry fuel for
returning to Earth. In addition, it would carry the reentry module and
equipment for monitoring the Martian atmosphere.

The reentry module is quite small, and there is no atmosphere monitoring
on the sample return mission -- the return vehicle's job is sample return,
not orbital science.

Even if we use two
launches, the rockets used to carry them into space would be gargantuan.

Not really. It's almost certainly feasible with a pair of Titan-class
launches; they're just expensive. Doing it with a pair of Deltas is a
rather marginal project, which is one reason why it hasn't happened.
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |

Chung Leong wrote:
Bar the development of some revolutionary technology, is it realistic to
think that we can land on Mars and come back?

Yes. All you really need is the willingness to spend a lot of money on
launching fuel tanks to LEO. strictly speaking, could have done decades
ago. Just nobody has been willing to cough up the money so far, either
for a brute force mission or otherwise.


Say we want to bring a piece of Martian rock back to Earth. A lander
carrying a rover and an ascent module would land on the planet. The rover
would move about, pick up a rock, and bring it back to the ascent module.
The module is then launched back into space to rendezvous with a return
vehicle.

provided you want a separate return vehicle and the rendezvous. You may very
well not want that.

--
Sander

+++ Out of cheese error +++

"Chung Leong" wrote:
The return vehicle would be fairly large too, as it needs to carry fuel for
returning to Earth. In addition, it would carry the reentry module

I assume by "reentry module", you mean, "reentry to Earth's atmosphere"?
If so, it's not really needed. The return vehicle could park itself in
Earth orbit and a shuttle (or other vehicle) could rendezvous with it to
get the cargo.

In article ,
Roy Smith wrote:
I assume by "reentry module", you mean, "reentry to Earth's atmosphere"?
If so, it's not really needed. The return vehicle could park itself in
Earth orbit and a shuttle (or other vehicle) could rendezvous with it to
get the cargo.

Unfortunately, decelerating *into* low Earth orbit is extremely expensive
in fuel. No, the return vehicle can't just "park itself" in LEO, not if
it has any ordinary propulsion system.

For at least some sets of assumptions, it's mass-competitive to have a
minimal sample capsule (*not* the whole return vehicle) decelerate into a
very high Earth orbit, for retrieval by a station-based tug. The trouble
is that no suitable high-performance tug currently exists.
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |

Roy Smith wrote:

"Chung Leong" wrote:
The return vehicle would be fairly large too, as it needs to carry fuel for
returning to Earth. In addition, it would carry the reentry module

I assume by "reentry module", you mean, "reentry to Earth's atmosphere"?
If so, it's not really needed. The return vehicle could park itself in
Earth orbit and a shuttle (or other vehicle) could rendezvous with it to
get the cargo.

Which requires carrying fuel for retrobraking into Earth orbit. If
you're willing to pay that penalty, then yes.

--

You know what to remove, to reply....

Henry Spencer wrote:

Unfortunately, decelerating *into* low Earth orbit is extremely
expensive in fuel.

Unless you bring an aeroshell and use aerobraking.

--
Steen Eiler Jørgensen
"Time has resumed its shape. All is as it was before.
Many such journeys are possible. Let me be your gateway."