Apollo to Mars?

[mikejz]

I have always been wondering this. Given that it appears as if 2/3 of the weight of a typical Apollo lunar mission was solely propellant (for lunar orbit insertion/landing/assent). If a direct-entry profile were chosen, would not an Apollo spacecraft modified with far less propellant and a logistics module, serve as an ideal way to get to Mars? <br /><br />The service module would be stripped down and converted to solar power. After launch the capsule would dock with a logistics module attached to the Saturn IVB stage. The S-IVB would be pointed towards the sun to provide maximum radiation shielding. The logisitcs modual would mainly consist of additional pressurized volume and consumables. Given that the 30,000+ lbs. of Apollo’s weight was for propellant alone, it seems that 9 months of consumables could fit inside that weight limit. <br /><br />Of course that just gets them to Mars—what they do after that is another story! <br />

 

[gunsandrockets]

I think there were some plans around 1970 for a Mars flyby mission in 1977 using some Apollo hardware.<br /><br />But using the Apollo for Mars is trying to stretch it's capabilities too far. It's more than just a question of consumables. The radiation dose the crew would receive on the long flight to Mars is something Apollo can't cope with (and what about solar flares?). And the force experienced by the crew riding in the Apollo capsule using direct reentry could be as high as 16 gees (reentry speed from Mars is higher than from the moon).

 

[JonClarke]

You could probably do a Mars flyby that way. As I recall there were some single Saturn flyby missions studied in the late 60's. You would need to have a modestly beefed up heatshield and logistics for 20 months (not 9) which is the time needed for a free return trajectory. Life support would also have to be improved over Apollo/Skylab with water recycling as a minimum.<br /><br />Using a nuclear upper stage there was even a scheme for a single Saturn Mars landing mission using an extremely adventurous flyby-lander architecture. I syuspect you could scale it back and do it ewith chemical fuels. But I suspect only a private mission by adventurer types would use such a risk architecture.<br /><br />For a good through fictional description of a realistic Mars mission using non-nuclear Apollo era technology it is hard to beat Stephen Baxter's novel Voyage.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[JonClarke]

Distributing the consumables round the cabin walls and having a central storm shelter in the logistics module would provide radiation protection. This was known in the 60's.<br /><br />A skip profile would keep the G's to acceptable limits during re-entry. This was considered for Apollo and done with Zond <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[gunsandrockets]

"A skip profile would keep the G's to acceptable limits during re-entry. This was considered for Apollo and done with Zond "<br /><br />The unmanned Zond did the skip successfully once out of several tries. Biological specimens didn't survive the other flights.<br /><br />With all the changes needed for Apollo to reenter from a Mars mission it's simpler and safer to forget the Apollo capsule and start with a clean sheet design.

 

[JonClarke]

Zond's problems were to do with the control system, not the skip rentry profile itself. Almost all US Mars mission projects from the mid 60's to early 70's used an Apooll shaped reentry vehicle. It is a lot simpler to beef up a heat shield and modify the trajectory that it is developing a whole new spacecraft, especially when the reentry velocities are only marginally higher than what would be experience from a lunar return anyway.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[darkenfast]

Further to that: Apollo's re-entry profile did in fact incorporate a skip or near-skip where the lift generated was used to gain altitude prior to the final descent. Managing the loads for a Mars return should be do-able. I also remember reading somewhere that the original idea for the CM had a lot more lift. This had to be traded away for reasons to do with dimensional limits (I forget the specifics, perhaps someone here knows). I THINK the original version had a more rounded curve where the cone and the heat shield area met. Does anyone know what the L/D ratio of the old CM and the current Soyuz Descent Apparatus is?

 

[gunsandrockets]

" Almost all US Mars mission projects from the mid 60's to early 70's used an Apooll shaped reentry vehicle. It is a lot simpler to beef up a heat shield and modify the trajectory that it is developing a whole new spacecraft, especially when the reentry velocities are only marginally higher than what would be experience from a lunar return anyway."<br /><br />I wouldn't describe a skipping reentry as simple. And a skipping reentry certainly compromises flight safety.<br /><br />The choice of the Apollo semi-ballistic capsule with a lift to drag of only 0.3 was one forced upon NASA by the time pressure of the moon race. The first choice on technical merits was a design from Martin with a lift to drag of 0.75. The Apollo capsule is a marginal design even for missions from the moon let alone a higher speed reentry.<br /><br />http://www.astronautix.com/craft/apolol2c.htm<br /><br /><br /><br /><br /><br />Note how the current NASA reference design CEV for lunar missions is not a semi-ballistic capsule, instead it is a bi-conic lifting body with a much higher lift to drag.<br /><br />http://images.spaceref.com/news/2005/biconic.cev.l.jpg

 

[liquidspace2k]

Couldn't you just use areobraking in earth orbit when coming back from mars, so the G loads aren't too big.

 

[cuddlyrocket]

I think the crew would go nuts stuck in an Apollo capsule for the year-long trip to Mars and back.<br /><br />What about washing facilties; change of clothing; space for consumables (water and food) and spare parts? Where are you going to put the exercise equipment needed to slow down bone loss etc. due to weightlessness?

 

[CalliArcale]

<blockquote><font class="small">In reply to:</font><hr /><p>The unmanned Zond did the skip successfully once out of several tries. Biological specimens didn't survive the other flights. <p><hr /></p></p></blockquote><br /><br />Actually, I think I remember reading that it succeeded three times, but on one of those flights, the vehicle had depressurized long before reentry, killing the biological specimens onboard, and on the other the vehicle was commanded to self-destruct because it was coming down on the wrong course and there was concern about the vehicle falling into enemy hands. (Orders were changed afterwards to permit landings in international waters, because the risk of an enemy getting the vehicle was considered less than the risk of losing an expensive experiment.)<br /><br />I'll have to check later; I was going to right now, but work calls. <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[CalliArcale]

Okay, since sometimes there's conflicting information on Russian stuff, I checked with my two favorite websites for this stuff: astronautix.com and russianspaceweb.com. The problem is complicated by the fact that "Zond" actually describes more spacecraft than you might think, thanks to the Soviet tendency to obscure their intentions in case of failure. The one's we're actually interested in are Zonds 4-8. These were Soyuz 7K-L1 spacecraft launched by Proton rockets. There were additional 7K-L1 spacecraft which either did not reach orbit (and which consequently received no descriptor at all) and ones used for other testing in Earth orbit (which received Cosmos designators).<br /><br />Zond 4 - self-destructed<br />The guidance system failed, making the double-skip reentry impossible. Capsule could still acheive a theoretically-survivable ballistic descent, but it would be outside the Soviet Union. Automated self-destruct package had been armed, and the vehicle destroyed itself over the Gulf of Guinea at an altitude of 12 km when the computer detected that the intended mission would not be achieved. After some dispute, it was decided that if there was a repeat of this circumstance, the vehicle would be allowed to reenter for an attempted recovery by Soviet naval vessels.<br /><br />Zond 5 - splashdown in the Indian Ocean<br />The star tracker failed and the mission controllers had to revert to using the less accurate earth tracker. This made a double-skip reentry impossible. The self-destruct package was not armed, and the vehicle survived a 20-G reentry, after which it was recovered in the Indian Ocean. Given how long it was at 20Gs, this would probably not have been survivable.<br /><br />Zond 6 - depressurized and then crashed<br />After a series of problems, Zond 6 depressurized during the cruise back to Earth. It did, however, manage the first successful double-skip reentry. But when it returned, a parachute malfunction caused it to crash violently into Kazakh <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[mattblack]

It would have been do-able, but a very bloated architecture. The following pictures come from Stephen Baxter's fantastic alternate-history novel "VOYAGE" published in 1996. <div class="Discussion_UserSignature"> <p> </p><p>One Percent of Federal Funding For Space: America <strong><em><u>CAN</u></em></strong> Afford it!!  LEO is a <strong><em>Prison</em></strong> -- It's time for a <em><strong>JAILBREAK</strong></em>!!</p> </div>

 

[mattblack]

bump <div class="Discussion_UserSignature"> <p> </p><p>One Percent of Federal Funding For Space: America <strong><em><u>CAN</u></em></strong> Afford it!!  LEO is a <strong><em>Prison</em></strong> -- It's time for a <em><strong>JAILBREAK</strong></em>!!</p> </div>

 

[john_316]

Here we go again... Using chemical means and a year trip and year back for a crew to visit Mars.<br /><br />A clean sheet with a Nuclear Vessel and detachable lander that can also return to orbit is a better idea...<br /><br />We need to get away from basic chemical means and go nuke power for a Mars journey...<br /><br />We need to think outside the box and have a robust Mars program not a Apollo always program...<br /><br />We can use methane powered landers but we would be better off witha Nuclear Rocket going there for the mission duration...<br /><br /><img src="/images/icons/smile.gif" /><br />

 

[mattblack]

Yeah, that was Baxter's point in the novel, too. That's one of the reasons such a plan didn't get a go-ahead in the late 60's & early 70's. <div class="Discussion_UserSignature"> <p> </p><p>One Percent of Federal Funding For Space: America <strong><em><u>CAN</u></em></strong> Afford it!!  LEO is a <strong><em>Prison</em></strong> -- It's time for a <em><strong>JAILBREAK</strong></em>!!</p> </div>

 

[darkenfast]

Yes, but then we can watch while the Luddites and the Tofu and Granola Tribe delay the program for years with lawsuits against nasty nuclear power. I can hear the Hollywood starlets on the networks now: "I mean, like, it's just terrible! They've ruined our planet, and now they want to contaminate Mars! They should spend that money on the poor!"

 

[john_316]

we could always pay alec baldwin off and make him a secret member of our fraternity though....<br /><br />and he can preach space is better than here...<br /><br />hehehe<br /><br /><img src="/images/icons/smile.gif" /><br />

 

[kane007]

Oh god, how uncomfortable. 6 months cramned into that sardine can of capsule out and another 6 months back again.<br /><br />Someone open a window!

 

[mattblack]

No, the Habitation Module would be a Skylab-type roomy design. <div class="Discussion_UserSignature"> <p> </p><p>One Percent of Federal Funding For Space: America <strong><em><u>CAN</u></em></strong> Afford it!!  LEO is a <strong><em>Prison</em></strong> -- It's time for a <em><strong>JAILBREAK</strong></em>!!</p> </div>

 

[kane007]

Oh, thank the Lords of Kobul for that!

 

[tohaki]

<blockquote><font class="small">In reply to:</font><hr /><p>I'm not sure what went wrong with this mission, since astronautix.com calls Zond 7 the "only completely successful L1 flight that could have returned cosmonauts alive or uninjured to earth" as their entry on Zond 8 does not elaborate on any failures.<p><hr /></p></p></blockquote>I have been wondering about the same thing.