# New Propulsion System = Short Mars Mission?

Status
Not open for further replies.
H

#### heyo

##### Guest
I know that one of the main hurdles to a Mars mission is the sustainablity of the crew and equipment for the length of time it would take to get there and back. (That means food, water, air, and the crew not going insane from boredom/confinement)<br /><br />I know the mission has to be quite long and mostly that is because #1 the trip is 6 months long, and #2 you can only go there or come back near the Earth/Mars opposition, which means you have to wait for the next one.<br /><br />But if we were to develop an extremely powerful propulsion system some time in the future, would it be possible, maybe by using a highly excentric Hohman transfer orbit, both there and back, to go there and come back using the same opposition? I mean taking a month to get there, spend a month, and return in a month or so, starting before the Earth passes Mars, and leaving maybe just as it does or shortly after. How much more propulsion power would it take to get out there and back in that amount of time? My totally wild uneducated guess is about 10 to 15 times the power we are able to muster now. <br /><br />If you accelerated at 1g out of Earth orbit for half the trip to Mars, and then decelerated at 1g for the other half, I wonder how fast that would get you there in.<br /><br />Seems like the bottom line is that wee need a lot more "oomph" to do any decent manned exploration, and until then we are stuck with robotic probes.<br /><br />Heyo<br /><br />PS. This has me curious about another side question I had. How much thrust would it take to leave earth orbit and put yourself in a retrogade orbit around the sun roughly the same size as Earths orbit?

N

#### najab

##### Guest
><i>But if we were to develop an extremely powerful propulsion system some time in the future, would it be possible, maybe by using a highly excentric Hohman transfer orbit, both there and back, to go there and come back using the same opposition?</i><p>You could do it now, with current technology. The thing is that it would only give you 30 days or less on the surface.</p>

V

#### vogon13

##### Guest
re retro 1 AU solar orbit:<br /><br />Ulysses probe put in high inclination (80 degree) orbit around sun with 6 year period for just the price of ticket to Jupiter(where high inclination was result of interaction with Jupiter gravity field in a very clever flyby) Seems likely an orbit that repeatedly encountererd gas giants could get you on a retrograde elliptical orbit without too much fuss. Cranking orbit down to circular beyond my ability to calculate but grazing passage thru fringe of Venusian atmosphere during perihelion might be a place to start some pencil pushing.<br /><br />Spacester, paging Spacester, we have a task for you...<br /><br /><br /><br />The movies made me do it.<br />Roger Ebert <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

S

#### spacester

##### Guest
Well see, this is why I want to get my software ported to a platform everbody has access to. I want to make it freeware so people can play around with cool scenarios like this.<br /><br />Real life has really been getting in the way of this spacester gig . . . .<br /><br />I need to re-read the questions . . . najab is correct . . . . <br /><br />The problem with 1g continuous thrust is that if you try that, you'll run out of fuel in a hurry. It is not possible without huge breakthroughs in propulsion (very high specific impulse)<br /><br />But the main point is that if you don't do the short stay, you are looking at around 900 days from Earth departure to Earth return (overall mission time). <br /><br />The next 200-days-each-way round trip has an overall mission time of 932 days. Copy and paste:<br />Away transfer insertion date is ........ 2005-AUG-09 15:27:34<br />Orbital insertion at destination date is 2006-FEB-25 15:27:34<br />Return transfer insertion date is ...... 2007-AUG-11 22:55:24<br />Orbital insertion at origin date is .... 2008-FEB-27 22:55:24<br /><br />The next 140-days-each-way round trip has an overall mission time of 883 days. Copy and paste: <br />Away transfer insertion date is ........ 2005-AUG-15 04:15:29<br />Orbital insertion at destination date is 2006-JAN-02 04:15:29<br />Return transfer insertion date is ...... 2007-AUG-27 22:16:56<br />Orbital insertion at origin date is .... 2008-JAN-14 22:16:56 <div class="Discussion_UserSignature"> </div>

H

#### heyo

##### Guest
<i>It will use a Helium-3 powered fusion reactor and will first reach Alpha Centauri with humans on board on March 31, 2109, after a two-year voyage (as measured by the people on board the ship), refueling at the robotic starship filling station on Titan with He-3 harvested from Saturn. </i><br /><br />Sweet. Where do I sign for my ticket?<br /><br />Thanks for the replies everyone. I'm back after a weekend of my internet access being down. Good to be back.<br /><br />One reason for this thread was I thought that a big obstacle to exploring Mars was the extremely long duration of the mission, and therefore crew sustainability. Keeping a crew of a few people alive, and in good air, water, and food for 900 days with no possibility of re-supply seems pretty difficult and there is a lot that could go wrong in that time. Not to mention the psychological effects as well as the detrimental effects of zero G which would have to be dealt with somehow. I thought if we could get the mission down to a much shorter duration, that would make it a little easier and less expensive. <br /><br />(Less expensive and shorter, IMO, increases the chances that politicians would be game to fund it, thereby increasing the chances it will even happen at all)<br /><br />I don't know what ya'll think, but if given the choice regarding the first mission to Mars, and the choices were 30 days on the surface, or upwards of a year and a half on the surface, I think 30 days is an adequate first step onto the surface of Mars.<br /><br />I think the very first second a human set his boot down in that dusty surface would profoundly change our outlook from a spiritual and philosophical standpoint, and a human can do a lot more science in a few days actually roaming the surface with a few tools and a spectrometer than the MER rovers (as much as I love them) could during their whole mission. 30 days would be tremendous.<br /><br />Comments?<br /><br />Heyo

V

##### Guest
one way to overcome re-fueling and re-supplying, would be to arrange waypoints along the way. Unmanned supply capsules will be strategically put in orbit between mars and earth, so that every 60 days or so, they will rendezvous with a capsule, re-provision, resupply, and re-fuel if need be. keeping fuel in space will also quicken the trip as the ship would be substantially lighter, and therefore easier to accelerate. You would not have to slow down to resupply either if a mechanism was devised that would grapple the capsule in, or the capsule was put in an orbit in such a way that would allow for the ship to dock while moving

Status
Not open for further replies.

Replies
0
Views
86
Replies
1
Views
456
Replies
1
Views
286
Replies
0
Views
861
Replies
0
Views
338