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Old February 21 2013, 09:11 PM   #61
jefferiestubes8
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Location: New York City
Re: manned Mission to Mars discussion

The first Mars mission might not actually touch down on the planet. Instead it will likely explore its two moons, Phobos and Deimos [see “To Mars by Way of Its Moons,” by S. Fred Singer; Scientific American, March 2000]. Such an expedition is essentially an asteroid mission stretched out to a two-and-a-half-year round-trip. At first glance, it might seem silly to go all the way to Mars and not land on it, but landing would enormously complicate the mission. Missions to the Martian moons allow astronauts to become adept at traveling through interplanetary space before attempting the challenge of touching down on Mars, traveling around and lifting off again.
http://www.scientificamerican.com/ar...to-mars&page=5

so by the time we land on Mars we may have already solved most of these problems with lunar landings.
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Old February 23 2013, 09:45 PM   #62
publiusr
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Re: manned Mission to Mars discussion

Tito seems to be calling for using Falcon heavy for a Mars flyby--but thatZond style mission would be very cramped.

Better to use that as a fast taxi to a cycler with more room.
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Old February 23 2013, 10:44 PM   #63
sojourner
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Re: manned Mission to Mars discussion

Yeah, I can't see anyone willing to spend close to 2 years in a space the size of a closet.
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Old February 27 2013, 11:11 PM   #64
JanewayRulz!
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Re: manned Mission to Mars discussion

Good heavens, a "private" manned mission to Mars is now being floated for an "older/married" i.e. nonfertile couple.

http://lightyears.blogs.cnn.com/2013...018/?hpt=hp_t1

Why do I get the idea that this might just be a scam?
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Old February 28 2013, 12:21 AM   #65
sojourner
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Re: manned Mission to Mars discussion

I doubt Dennis Tito would be involved if it were a scam.
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Old February 28 2013, 11:23 AM   #66
Stoo
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Re: manned Mission to Mars discussion

http://io9.com/5987372/everything-we...ission-to-mars

At first I had this down as total madness, I'm prepared to revise my estimate to just "pretty crazy".

They mention inflatable modules that would provide extra living space. Also since it's just a flyby that removes a lot of things that can go wrong with landings and orbital insertions.

Still, we have no experience at all of long term missions that far beyond the safety of earth. If it were to go ahead I would not put good odds on the crew making it back alive.
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Old February 28 2013, 12:18 PM   #67
Deckerd
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Re: manned Mission to Mars discussion

Well provided he gets the additional funding he needs (and that's a big 'if'), the people would essentially be a medical experiment. If the transportation can't shield them from radiation I think the round trip would not be at all healthy for them.
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Old February 28 2013, 03:49 PM   #68
JanewayRulz!
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Re: manned Mission to Mars discussion

IIRC, they also discuss the heat of earth re-entry from such a high speed descent is greater than any current heat shield protection would allow.

I just don't see a "billion dollars" being enough to pay for such a mssion, much less how one would solicit the funding for said mission. That's a lot of "10 dollar" donations, and something wayyyy out of the "Kickstarter.com" experience.

Perhaps "scam" was too strong a word, but I can see a lot of money being spent on prep work/studies to somebody before they decide... "gee, it IS too expensive for us to do."
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Old February 28 2013, 04:17 PM   #69
Gaith
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Re: manned Mission to Mars discussion

"Is there life on Maaaaaaaarrrrrssss?"

No.

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Old March 1 2013, 06:54 PM   #70
gturner
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Re: manned Mission to Mars discussion

JanewayRulz! wrote: View Post
IIRC, they also discuss the heat of earth re-entry from such a high speed descent is greater than any current heat shield protection would allow.
Dragon's heat shield is already designed for Mars re-entry. Using PICA or PICA-X it's not much of a problem.

The entry velocity would be between 15 and 21 km/sec, versus a lunar entry velocity of 11 km/sec or a low-orbit entry velocity of 7.9 km/sec, and the re-entry window is easy to hit even with mid-1960's technology.

1966 NASA report on re-entry from Mars
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Old March 2 2013, 08:16 PM   #71
publiusr
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Re: manned Mission to Mars discussion

Stoo wrote: View Post
http://io9.com/5987372/everything-we...ission-to-mars


They mention inflatable modules that would provide extra living space.
That makes Dragon look even more like Soyuz--its where that spherical living compartment usually is (except for the Zond circumlunar versions)

If anything, the Mars fly-by dragon looks a bit like the Soyuz 7K-LOK http://www.astronautix.com/craft/soy7klok.htm

The inflatable nose might just be a good idea. There is supposed to be a massive 50 km comet that looks to either hit or just miss Mars in 2014: http://up-ship.com/blog/?p=19134

http://www.economist.com/blogs/babba...et-headed-mars

So that mini-transhab might just see some use as a meteor bumper.

I don't like the idea of a married couple, in case one gets sick, it is a live tragedy (light delay aside).

I would volunteer for a flyby mission. I have no dependents, so if I croak, it's no big deal. More resources for one--no fights, and I live alone anyway. Moreover, even if I did break down, I would ask mission control not to report it, so as to not cast doubt on manned spaceflight, and suffer in silence if worse comes to worst. Once I pass the point of no return, and there is a leak, I might hope to set the capsule down on the surface as has been contemplated, so I might die on the surface after gathering some rocks. If I crash because the Dragon wasn't prepped to land on Mars, that's fine. If I continue to loop through space, that's fine.

But you don't want a Harlequin romance turning to divorce or a worse tragedy.
We already saw Baumgartner put spaceflight down after his balloon jump.

That I would never do, even if I knew I wouldn't be coming home.
Stoicism and
fatalism are required for such a stunt.

Last edited by publiusr; March 2 2013 at 08:32 PM.
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Old March 3 2013, 10:14 PM   #72
publiusr
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Re: manned Mission to Mars discussion

Max distance went from 0.0079 to 0.0021--but the chance of impact will decrease as the "uncertainty has decreased."


It just dropped in size though "Estimation by Jakub Černý is 2.7-5.4 km."


Crap.
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Old March 4 2013, 03:46 AM   #73
JanewayRulz!
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Re: manned Mission to Mars discussion

gturner wrote: View Post
JanewayRulz! wrote: View Post
IIRC, they also discuss the heat of earth re-entry from such a high speed descent is greater than any current heat shield protection would allow.
Dragon's heat shield is already designed for Mars re-entry. Using PICA or PICA-X it's not much of a problem.

The entry velocity would be between 15 and 21 km/sec, versus a lunar entry velocity of 11 km/sec or a low-orbit entry velocity of 7.9 km/sec, and the re-entry window is easy to hit even with mid-1960's technology.

1966 NASA report on re-entry from Mars
Huh?

The "blogger" suggested it was still quite a problem.

[/QUOTE]Besides life support for the crew, one of the biggest challenges would be the return into the Earth's atmosphere. Heat shielding for a high speed re-entry hasn’t been tested. NASA isn’t even testing its new system on the Orion spacecraft until next year at the earliest. Orion is in development to take astronauts back to the moon and on to Mars.[/QUOTE]
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Old March 4 2013, 05:01 AM   #74
gturner
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Re: manned Mission to Mars discussion

Oh, PICA heat shielding on the Stardust sample mission worked fine at a re-entry velocity of 12.6 km/sec and a heating rate of 1,200 W/cm^2. The Dragon's PICA-X heatshield is already 3 inches think and only about a half-inch burns off during re-entry from orbit, so they have a huge margin. Re-entry from Mars might get into the 3,500 W/cm^2 range, and PICA hasn't been experimentally tested at those heating rates, but it's not predicted to be a serious issue. They would have to conduct such testing, though, and might have to switch to a different material. If need be, they can go up to 10 inches thick with the PICA shield.

Probably the main issue is that they'll want to very accurately model the aero-thermodynamics so they don't waste mass on an unnecessarily thick shield. Getting a heat-shield to survive a re-entry is obviously possible since meteors make even more extreme entries with an accidental shield. Their existence made Robert Goddard suggest an ablator back in the 1920's.

Besides, heat shield design is fun.
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Old March 8 2013, 10:55 PM   #75
publiusr
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Re: manned Mission to Mars discussion

Now, if that comet does hit Mars and kickstart some warming--that might allow for a thicker atmosphere which would ease spacecraft design parameters.

One can hope...
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