CEV dreams. Good or bad idea?

[darkenfast]

A question for you more astronomically-minded. As an intermediate step between the Moon and Mars, what about a mission to a near Earth asteroid? Using the CEV and a modified lander (for use as a Hab and for some of the propulsion). Perhaps the astronauts could land on the asteroid using a MMU-type backpack, while the spacecrat orbited. The lander then, would not carry any landing gear, saving the weight for other uses. Are there any candidates that would be worthwhile during the 2018-25 time frame? I'm not sure it would be worth doing, I'm just enjoying thinking out-of-the-box.

 

[nacnud]

Maybe, is there a NEO that could be reached and returned from with say a six month total stay in space, a time lenght simmilar to ISS missions...

 

[nexium]

An asteroid that orbits between Earth orbit and Mercury orbit can have a 6 month year. but every other 'far from the sun' will be about 200 million kilometers from Earth, so it appears one year is the shortest possible round trip to an asteroid. Matching the speed is at about the limit of technology this decade, as it would pass Earth at high speed. Neil

 

[najab]

><i>Are there any candidates that would be worthwhile during the 2018-25 time frame? </i><p>Near-Earth Asteroid 3753 Cruithne</p>

 

[henryhallam]

I think this would be a really interesting mission, and quite possibly achievable with infrastructure designed for lunar missions (though I haven't run the numbers)

 

[darkenfast]

NajaB, thanks for that link. I was totally unaware of "horseshoe" orbits. I had assumed that Near Earth Asteroids would be either in an independent orbit or a Trojan relationship. That was a very interesting link. On a practical basis, I think it would be a good idea to find a target which could be reached and returned from with a minimum of time inside the Earth's orbit, because of the increase in solar radiation. This was something I was thinking about when I mentioned modifiing the Lander: shielding. Again, for the astronomers: would a manned mission to an asteroid be a worthwhile scientific goal? Would it help us understand solar system formation? I have been looking at it in terms of experience-building for something like a Mars mission, given the huge jump in magnitude between the difficulty of Lunar and Martian trips, but there should be a scientific goal as well. I also think that this could be done with a minimum of new systems (by modifying the existing lander). Hence it could be done while planning and preparation for Mars was in progress, and hopefully provide answers to various problems.

 

[darkenfast]

I've just noticed that Dr. Griffin's speech the other day mentioned Near Earth Asteroids, as well as the Moon and Mars. I'd like to think it was a good example of great minds thinking alike, but modesty prohibits that! I still think it would be a good stepping stone to Mars, because it could be done with a minimum of new hardware, would build experience in deep space, and (I think) would provide some good science returns. I would like to hear from some scientists on that. Would it be worth it?

 

[josh_simonson]

The moons OF mars would be a great intermediate place to go. It'd be much cheaper than landing on mars, since phobos' escape velocity is only 11m/s. And while there the astronauts could do stuff on phobos (which is thought to hold considerable water) and also control mars rovers in real time, supercharging their capability while there are people nearby.

 

[darkenfast]

I was hoping to avoid going too much further inwards. I may wander over to the astronomy section for some more info, like that kindly provided above regarding Cruithne, courtesy of NajaB.

 

[spacester]

It is in fact astonishing how much deltaV it takes to rendezvous with anything inside Venus' orbit.<br /><br />darkenfast, what you're looking for are the Arjuna class NEOs - but you're not gonna find 'em cuz we can't see 'em.<br /><br />Well actually we have found a few. But it's really tough because they are almost always in the daytime sky and they have a low albedo (they are dark in color). They spot 'em from Mauna Loa at dusk and dawn as we get lucky enough to get a glimpse of objects near their apoapse. IOW, it's no way to make sure we see them all, but it's a start.<br /><br />They're lots and lots and lots of NEOs we can get to easily in terms of dV. The problem is timing. Since the ones that are "close" in terms of orbital radius - so that matching speeds for rendezvous is 'easy' - also have a period close to Earth's, the problem is the timing.<br /><br />It takes a long time for a <i>particular NEO</i> to get lined up for a simple trajectory to it because it goes around the sun at about once per year too. So the 'phase angle' changes slowly. Anyway . . . <br /><br />But there are lots and lots of NEOs to go to, so when you get around to leaving Earth, you can pick out a target at that time. It's just tricky to continue to do business at the same rock.<br /><br />It can be done of course, but essentially you're looking at approx. doubling the trip time from 6 months to 12 months (approx). It's a double Hohmann - you burn for a transfer to an intermediate orbit, coast for six months, and then you burn for the second six-month Hohmann transfer to your rock. (Speaking in very rough terms here)<br /> <div class="Discussion_UserSignature"> </div>