Manned Landing on Phobos/Deimos?

[Swigert]

When I am near Mars in Orbiter, I usually fly over to Phobos or Deimos. I've always wondered if man could successfully land and preform EVA on one of the moons. Man has already walked on a moon before, but Phobos and Deimos are very different than Luna, Earth's moon. I like to think of Mars's moons as asteroids; they seem like balls of rock, after all, both moons have no atmospheres, which brings me to my next idea.

Knowing that Phobos and Deimos have no atmosphere or magnetic field, landing a manned spacecraft on the surface of either would be very different than what it would be to land on our moon. However, with a lack of atmosphere comes no air nor air pressure, meaning that the spacecraft and EVA equipment wouldn't have to be specially designed to withstand any more pressure than what it would flying in empty space, like an astronaut with an MMU, which could make a landing on one of Mars's moons a bit more possible. Furthermore, landing on one of the moons would be like flying regularly in space, due to the lack of gravity. Mars's gravitational pull would not be strong enough to actually pull the spacecraft from Phobos to Mars, if I am correct, as well. So landing on Phobos or Deimos would be just like landing on a big rock in space.

"But Sweigert, what about space radiation?" This would have to be put into perspective as well. If man were to land on Phobos or Deimos, which is already very unlikely, there would be severe health effects. Observe this graph.

Note that the graph shows data for Mars, not in, basically, free space. However, being so close to Mars, Phobos, for example, which is 5826 (9380 km) miles from Mars, this may not make a difference, although Mars has an atmosphere, unlike Phobos, which may make the data differ on Phobos.

Another challenge could be a launch window. Phobos orbits closely to Mars, while Deimos orbits further away from Mars. Observe this image for a better description!

Finding, none the less, waiting for a perfect launch window can take years. The spacecraft would have to launch from Earth on a perfect track to Mars, while the moon the astronauts would be landing on (Deimos, for example) would have to be on the left a bit. While orbiting Mars, and the spacecraft traveling to what appears to be Mars, Deimos would eventually be in the perfect position for a landing.

OR, the spacecraft could remain in high orbit of Mars, and wait for the moon to drift close to them, and take it from there.

What do you guys think about this? I'm not the smartest when it comes to space yet, so sorry if I provided incorrect or inaccurate information. Of course, man landing on a moon of Mars is very unlikely, I just wanted to share this.

 

[boogabooga]

Exploration of Phobos and Deimos are certainly possible and was attempted (unfortunately unsuccessfully) just two years ago.

However, they are a poor target for a dedicated manned mission only to them. You need to spend months in the Mars system. Staying on one of the moons for the entire time would only exacerbate the health effects of long term zero g. If we are going, we need to concentrate on the Martian surface. An excursion to one of the moons might be possible, though.

 

[Swigert]

Exploration of Phobos and Deimos are certainly possible and was attempted (unfortunately unsuccessfully) just two years ago.

However, they are a poor target for a dedicated manned mission only to them. You need to spend months in the Mars system. Staying on one of the moons for the entire time would only exacerbate the health effects of long term zero g. If we are going, we need to concentrate on the Martian surface. An excursion to one of the moons might be possible, though.

I agree completely. However, if one day, (if we ever) after we've landed on Mars, we decide to learn more about the Red Planet's history, some scientific data could be waiting for us in the tough surface of Phobos/Deimos.

 

[MaverickSawyer]

I suspect that if you laid out your mission right, you could do an aerocapture, sling up to Deimos, briefly visit it and kick loose a robotic probe, aerobrake, swing by Phobos, another probe is released, then land on Mars. That way, not only do you have plenty of time to explore Mars, but if you wanted to bring samples back from the moons, you send an aeroshell with the samples to Mars, not far from your base camp, drive over in the rover, pick up the sample container, and then load it into your return vehicle. Also, minimal speed of light delay to control the probes.

 

[Swigert]

Good idea. I guess the most unreliable part of that plan is the probe landings. If you release it too soon, the probe might not even land properly. If too late, well, same thing.

 

[MaverickSawyer]

Who says you just literally huck it out the door? Give it a small thruster suite, and you're good to go.

 

[Loru]

It's more like docking to both rather than landing on TBH

 

[MaverickSawyer]

True. It's also more of "coorbiting Mars" than orbiting one of those boulders... er, moons.

 

[kamaz]

Finding, none the less, waiting for a perfect launch window can take years. The spacecraft would have to launch from Earth on a perfect track to Mars, while the moon the astronauts would be landing on (Deimos, for example) would have to be on the left a bit. While orbiting Mars, and the spacecraft traveling to what appears to be Mars, Deimos would eventually be in the perfect position for a landing.

Not needed. The only constraint is the launch window for the Earth-Mars route. Once you brake into Mars orbit, you can intercept Phobos in the same way you intercept ISS.

Here is a study of a manned mission to Phobos, rendezvous and landing is discussed from page 38 onward: http://hdl.handle.net/2060/19930008927

 

[Swigert]

Not needed. The only constraint is the launch window for the Earth-Mars route. Once you brake into Mars orbit, you can intercept Phobos in the same way you intercept ISS.

True, however, I already suggested that.

OR, the spacecraft could remain in high orbit of Mars, and wait for the moon to drift close to them, and take it from there.

 

[PhantomCruiser]

http://www.easysurf.cc/cnver24.htm

The most dose I picked up the during my first outage, over the course of about 2 shifts (so 24 hours) was 32 millirem. We got far less dose than the Heath Physics people estimated (I got a coffee cup out of the deal).

I think the most I've ever picked up during the course of a year (at work, background isn't trended) is maybe 60 millirem or so?

We've got an administrative annual limit of 1 rem, far below the Federal limit of 5. The only people I know that get anywhere close to the limit would be the people who volunteer to go diving in the steam generator during outages to check the tubes. Generally these people have no risk of picking up dose any other time; "normal" maintenance people don't get this job because we'd be too close and could bust the limit during the course of our regular jobs.

My eyesight isn't what it was, but does that chart show a 350 millisievert (35 REM) for the 6 month trip out, plus another 350 for an 18 month stay? Sounds bad (well, it is bad, but still doable).

By the time were ready to take such a giant step, the shielding will have improved. Another thing to take in mind will be the age of the astronauts making the trip. I'm middle age, so am far less susceptible to damage than someone in their early 20s (or a pregnant woman).

 

[MattBaker]

For anyone else having no clue about radiation doses: xkcd's radiation chart
And for the ultra lazy ones: 32 millirem is 320 microsieverts, 60 millirem 600 microsieverts. So the Cruiser additionally gets the equivalent of something in the area of a mammogram at work per year. Or 15 NY-LA flights, which might be really few for some people.

But back to topic: As far as I understood the big problem with Mars is the atmosphere. It's quite thin and thus compared to our atmosphere can't absorb as much radiation coming in from space. Then again: If you have enough radiation shielding to survive the trip to Mars you should survive on Mars as well. Although it's like Australia: Wearing short clothing without sunscreen is discouraged.

 

[PhantomCruiser]

I was thinking that is we can get the money (all about funding), rovers and other robotic equipment can do quite a lot to prep a suitable landing site. The trick of course is enough DV to lift X-much weight. There would be some need for some heavy equipment, mainly to shovel/push soil around to cover the habitat with a layer to augment what shielding will have been developed.

When we get to Mars one of the prime mission goals will be to start burrowing underground. This meets one of the ALARA (as low as reasonably achievable) goals for time, distance and shielding. What shielding we bring, plus eventually a few meters of soil, will greatly reduce dose rates.

 

[MaverickSawyer]

We'd need an equivalent of the Saturn V for sure, no matter what path we take to Mars. Even if it's just a manned flyby, the mass of a habitat and consumables for a crew requires a LOT of lift capacity to hurl it to Mars.