Alternate history: How would a habitable Mars and Venus have changed the space race?

Linguofreak

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I've recently been contemplating what effect other habitable planets in the solar system would have had on the history of spaceflight.

I assume that things would have started off at about the same time as in actual history, but it would have given a clearer goal than just "we got there first" prestige (and would have intensified that as well). Something like the manned Venus flyby would have been something the Apollo program was actively working up to rather than a speculative project to use spare boosters. The USSR probably would have persisted with its moonshot despite the trouble with the N1, and we probably would have seen other countries than the US and USSR starting up space programs (cooperatively with neighbors if they couldn't manage it on their own).
 

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I recomend the book "A world Af difference" by Harry Turtledove. In this novel Mars is habitable and in fact habited. The first probe that is sent to Mars (Minerva as it is called in the book) sends a picture of a creature welding a stick back to Earth, shortly before the earth loses signal. So the USA and the USSR decide to sent manned missions to that planet...
 

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I honestly don't think NASA would have wanted to send a probe to Mars, but would still try to make it to the moon instead. This way, they could prove that they could successfully land on another body. After all, if they couldn't land on a body without an atmosphere, imagine landing on a planet with one.
 

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I thought the same thing the other day.
If Mars or even better, Venus was habitable, there would be humans on that planets a long time ago.

The only real reason for the human race not to be on that planets, other than finance is that Mars or Venus is not habitable.
Mars problem is its atmosphere.
And Venus is to hot with a dense crushing atmosphere.
 

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I think the short answer is that humanity would have conquered space.

The long answer;

By the time people are doing spectroscopic observation of the Martian or Venusian atmospheres, it's still the '40s or '50s. These planets are by no means reachable yet (not even LEO is at this point) so noone is going to blunder forth and attempt to land on them immediately.

The Moon is a good 'first step', it's very clear in the sky and it holds a special place in the global consciousness; it's a nice goal to set oneself towards, and it will likely be the site of landings before Venus and Mars. It always was a 'first goal', even dating back to the days of Verne, so a change in Venus and Mars probably won't change things all that much.

The development of the US and Soviet moon programs might be affected somewhat, in the sense that a post-lunar goal of landing on either planet would be of more importance. But probes can land on either planet far sooner than humans can, and can be launched on rockets far smaller than the ones needed to brute-force a manned lunar landing.

Venus is an obvious first choice of the two, due to the more numerous launch windows and shorter travel time. In our history, the first explorations of Venus were made by the USSR, though the dynamics of this history could change based on the higher importance of the planet (the USA only launched Venus landers in the late 1970s, roughly a decade after the first successful Soviet landing). Flybys would presumably precede landings.

In this scenario Venus may still be swathed in cloud, but Mars would likely be more observable (and could also garner more interest, especially with more obvious features of habitability). Rather than images of a barren lunar landscape, images of familiar landforms like bodies of water, rivers, and mountain ranges could spur further public interest in the planets.

Post-Apollo (or post-N1/L3, this is alternate history after all, though one could argue that the US was more likely to see success in any case), enthusiasm and funding probably wouldn't drop like they did in reality. The case after Apollo was to press on to Mars in any case (though Venus may be a better goal owing to its proximity), and the purpose of STS was to build the infrastructure in space that was to make this possible.

Undoubtedly STS would have hit the same technical hurdles that caused its unsuccess in our history, though things may differ owing to differing priorities and amounts of funding. Apollo hardware might be repurposed; a relatively simple set of alterations could have been used for a manned Venus flyby in our time, and such a mission plan may well be the first human mission to the planet in such a scenario.

It should be noted though that there is much uncertainty over interplanetary flight today, and that the maturity of long-term spaceflight science was considerably less complete in the 1970s. It would have been a dangerous mission.

Apollo (or N1/L3) hardware could be adapted to a planetary mission, though various new hardware would also have to be built (how do you land on Mars or Venus? How do you take off from either of them, especially Venus, with its near-Earthlike gravity well?).

My bet is that the Moon would be left largely ignored (relative to Mars and Venus, not necessarily relative to the interest given to it in our timeline), though it may capitalise on increased funding and R&D work for the planetary programs. It just isn't as interesting, and the next goal ahead is far more important.

Of course, it gets tougher to speculate the further you go from the 'point of divergence'. One may well speculate- entirely within the bounds of what could be agreed on as plausible- quite wacky scenarios involving grand spaceships and great exoatmospheric epics (or on the slightly more humorous side of the scale, an epic battle between the US and USSR to wind the hearts and minds of the Martian populace).

The really interesting thing to think about is that the point of divergence, in major terms at least, would not happen too early at all- only in the '40s or '50s or so. Before that time it was perfectly plausible to speculate about habitable planets in our solar system (though steadily decreasing in plausibility with Mars as time went on). People like Goddard and von Braun did their work at a time when it would have not been preposterous to imagine dinosaur-ridden swamps on Venus. After centuries of exploration, and new lands being discovered, explored and conquered, it was expected that a similar trend would continue into space.

EDIT: The challenges of lifting off from Venus, along with the idea of landing on an Earth-like planet reminds me of the "Mission to Earth" idea that Linguofreak had a while back, about lunar inhabitants with 1960s technology landing a human (from the Moon, of course) on Earth.
 
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Linguofreak

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I recomend the book "A world Af difference" by Harry Turtledove. In this novel Mars is habitable and in fact habited. The first probe that is sent to Mars (Minerva as it is called in the book) sends a picture of a creature welding a stick back to Earth, shortly before the earth loses signal. So the USA and the USSR decide to sent manned missions to that planet...

Sounds like a first-contact type story. I'm more interested in the economic/political and technical development of the world's space programs in a Solar System including a habitable Mars and Venus (which I think would provide enough additional impetus to space exploration just by being habitable, without any need for intelligent life). The habitability of Mars and Venus could be discovered without probes: The presence of significant amounts of oxygen in the atmosphere could be detected from Earth, and oxygen requires the presence of plant life.

I'm interested in questions like the following:

Would the pre-Moon US spaceflight program have received additional funding and developed differently, or would the point of divergence have come after Apollo (with the Apollo program being extended to include the extra missions that were never flown in our timeline, etc)?

How would the Soviet program have changed (would the N1 project have fared better with more and/or earlier funding, would the Soviets have scrapped it and moved on to something else, or would they still have given up)?

Who else would have made moonshots in hopes of moving on to Mars and Venus?

What would the evolution of launch infrastructure have looked like? Would the US, moving on from Apollo, have used a derivative of the Saturn V designed for mass production or something entirely different? Would the Saturn V even have been developed in the first place?

What would the interplanetary transport infrastructure look like?

Etc.

Mars problem is its atmosphere.

Mars' problem is a bit bigger than that. First of all, it's gravity well isn't deep enough to hold a significant atmosphere, secondly, it's far enough away from the Sun that it would be difficult, if not impossible, to get it to stay warm enough to be habitable, no matter how you tweaked it.

In my musings on the issue, I've been assuming that Mars has a very large iron core such that it is twice as dense as the real Mars with the same radius (thus, twice the mass). This gives it just enough gravity to hold on to a significant atmosphere in the long term. The temperature issue I'm solving by assuming a relatively high (but still breathable) CO2 fraction in the atmosphere, combined with a fairly dark surface (though liquid water implies that there will be significant polar caps, 'cause the temperatures still won't be balmy, and the reflectivity of the polar caps may just cause a runaway icehouse effect across the entire planet).

And Venus is to hot with a dense crushing atmosphere.

It's rotation rate is also probably too slow, at least for how close in it is. Venus is actually to some degree easier to make habitable (in terms of presuming different characteristics for the planet in a fictional scenario, not in terms of actual terraforming) than Mars, despite its more extreme real-life surface conditions. "All" you need to do is assume an Earthlike atmosphere and rotation rate, and that the high temperatures cause enough evaporation to form a planet-wide cloud deck much like Venus actually has (except with water instead of sulfuric acid in the clouds). If you don't get a planet-wide cloud deck, then a lot of light gets absorbed by the ocean instead of reflected by the clouds, and the temperatures get too hot for humans (and probably for any life). If you do get a cloud deck, the clouds reflect enough light that temperatures, at least towards the poles, can be survivable for humans. The real-life Venus, for example, has habitable temperatures around the cloud deck, but the atmosphere isn't breathable, and it's thick enough that adiabatic heating between the level of the cloud deck and the ground makes the surface temperatures incredibly hot.

---------- Post added at 22:57 ---------- Previous post was at 22:09 ----------

In this scenario Venus may still be swathed in cloud,

Insolation at Venus is high enough that it could not be habitable without being swathed in cloud. Fortunately, I think you'll get enough evaporation from an ocean that that would be the case.

but Mars would likely be more observable (and could also garner more interest, especially with more obvious features of habitability).

Making surveys to allow a safe landing would also be easier, though my bet is on water landings near coastlines, which could be surveyed for with radar.

Rather than images of a barren lunar landscape, images of familiar landforms like bodies of water, rivers, and mountain ranges could spur further public interest in the planets.

Post-Apollo (or post-N1/L3, this is alternate history after all, though one could argue that the US was more likely to see success in any case), enthusiasm and funding probably wouldn't drop like they did in reality. The case after Apollo was to press on to Mars in any case (though Venus may be a better goal owing to its proximity), and the purpose of STS was to build the infrastructure in space that was to make this possible.

Undoubtedly STS would have hit the same technical hurdles that caused its unsuccess in our history, though things may differ owing to differing priorities and amounts of funding.

My hope is that the heavy beyond-LEO focus would cause STS to be ruled out, though in working out a fictional scenario, it could be used to add drama (the US makes the first moon landing while N1 languishes, but the USSR makes the first Mars/Venus landing because difficulties with STS slow the US down).

Apollo hardware might be repurposed; a relatively simple set of alterations could have been used for a manned Venus flyby in our time, and such a mission plan may well be the first human mission to the planet in such a scenario.

It should be noted though that there is much uncertainty over interplanetary flight today, and that the maturity of long-term spaceflight science was considerably less complete in the 1970s. It would have been a dangerous mission.

Apollo (or N1/L3) hardware could be adapted to a planetary mission, though various new hardware would also have to be built (how do you land on Mars or Venus? How do you take off from either of them, especially Venus, with its near-Earthlike gravity well?).

For landings, my bet would be a capsule for dropping crew, and the offspring of the space shuttle and a flying boat for heavy equipment (unlike the Shuttle, this would be designed as a one-use deal, and I'm heavily leaning towards launching the components individually and assembling the thing in Earth orbit, because of the shortcomings of STS).

For takeoffs, especially from Venus, I imagine you'd have to have at least some sort of an established surface base, and that you'd have to field-assemble an Atlas/Titan type vehicle (whose components would be delivered in heavy equipment boats).

The first people to land would probably have to wait several years to leave, and there would be a greatly increased stranding hazard. On the other hand, being stranded would be much less of an issue than it would be on an uninhabitable body.

My bet is that the Moon would be left largely ignored (relative to Mars and Venus, not necessarily relative to the interest given to it in our timeline), though it may capitalise on increased funding and R&D work for the planetary programs. It just isn't as interesting, and the next goal ahead is far more important.

Of course, it gets tougher to speculate the further you go from the 'point of divergence'. One may well speculate- entirely within the bounds of what could be agreed on as plausible- quite wacky scenarios involving grand spaceships and great exoatmospheric epics (or on the slightly more humorous side of the scale, an epic battle between the US and USSR to wind the hearts and minds of the Martian populace).

I think that even by 2012 settlements on Mars and Venus would largely be scientific in nature, and you probably wouldn't have more than a few hundred people on either planet, so I think all of the Cold War saber-rattling would still be going on on Earth (and maybe LEO).
 

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My two cents...

In the "Earth-type Venus" scenario, the first thing to build would be an orbital station, to which crew transfer vehicles from Earth would dock, and then depart again to rotate crews. With an orbital outpost, you would have a good platform for reconaissance and observation of the surface, and a nearer target for a take-off from the surface.

There would now be a more urgent necessity for winged SSTO shuttles because once you had a couple of runways on the surface, your main issue is, er, shuttling people and equipment from the orbital station to the ground. Since you can ferry shuttles on the interplanetary CTV from Earth, we would see a boost towards research in this area.

The issue would be the fuel. On an Earth-like planet it would be less problematic to make an O2/H2 extracting facility.

Certainly, the life of the first visitors there would be... Interesting.
 

Linguofreak

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My two cents...

In the "Earth-type Venus" scenario, the first thing to build would be an orbital station, to which crew transfer vehicles from Earth would dock, and then depart again to rotate crews. With an orbital outpost, you would have a good platform for reconaissance and observation of the surface, and a nearer target for a take-off from the surface.

There would now be a more urgent necessity for winged SSTO shuttles because once you had a couple of runways on the surface, your main issue is, er, shuttling people and equipment from the orbital station to the ground. Since you can ferry shuttles on the interplanetary CTV from Earth, we would see a boost towards research in this area.

We would certainly see a boost in research. I don't think an SSTO shuttle would be a possibility in time for the first landings, though, and quite possibly not by 2012 in that timeline.

Our own space shuttle was 1.5 STO and, lacking any launch escape system, should never have been man-rated (you can man-rate a considerably less reliable launcher if you have a means of getting the crew off the stack if anything goes wrong. Without that, nothing must go wrong).

Also keep in mind that a new surface base on an otherwise uninhabited planet would most likely not have the resources to refurbish a reusable vehicle for another launch. Even if we did have an SSTO shuttle by 2012, it would pretty much exclusively be used on Earth.
 

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What would the interplanetary transport infrastructure look like?

That's a very interesting question, because the matter is quite mysterious in our day and age, even without the added uncertainty of alternate history and alternate technological development.

Mars' problem is a bit bigger than that. First of all, it's gravity well isn't deep enough to hold a significant atmosphere, secondly, it's far enough away from the Sun that it would be difficult, if not impossible, to get it to stay warm enough to be habitable, no matter how you tweaked it.

Mars should (more or less) be able to hold onto an atmosphere over geological timescales. A bigger concern is the lack of a magnetic field; a higher density would both increase the gravity, the amount of iron inside the planet, and the heating through radioisotopes.

Temperature depends on a lot of factors; terraforming often postulates 'super-greenhouse' gases, but these are not likely to form naturally in large concentrations. On the other hand, a naturally habitable Mars could be handwaved to have several conditions that are considered by most to be impractical for terraforming, such as a thicker atmosphere.

Of course, the difficulty of the job depends on the nature of the result; a Mars similar to that imagined later on would be easier to handwave than a more hospitable Lowellian Mars.

For landings, my bet would be a capsule for dropping crew, and the offspring of the space shuttle and a flying boat for heavy equipment (unlike the Shuttle, this would be designed as a one-use deal, and I'm heavily leaning towards launching the components individually and assembling the thing in Earth orbit, because of the shortcomings of STS).

What about some sort self-floating inflatable heatshield device? No runway landing is required, simply transport to a specific landing ellipse in a suitable body of water. It may be easier to construct or lift into space as well.

It sounds like it might have an easier landing than a flying boat; the landing speed of the shuttle (a vehicle built for reentry and hypersonic flight) is quite high, and may not be conducive to landing on water (though perhaps other features or differing designs could make things somewhat easier; some things like variable geometry would increase cost and failure points though).

you'd have to field-assemble an Atlas/Titan type vehicle (whose components would be delivered in heavy equipment boats).

Yikes. That's a really scary notion. At least they're not building the thing from scratch, but still; rockets are usually assembled and launched in very controlled conditions. These people are in the wilderness, they may be away from home for months or even years, the conditions may not be that good, and the parts themselves first have to be landed on the planet.

On the other hand, being stranded would be much less of an issue than it would be on an uninhabitable body.

At least you have relatively comfortable conditions, oxygen and water... but what about food? It may not be that much of a problem, but still... would you be the first to eat a Venusian slimemold?

Our own space shuttle was 1.5 STO

Effectively it was a two-stager, even though all engines (save the OMS) were burning at T-0. The boosters provided most of the impulse during the beginning of the flight, and the SSMEs provided most of their impulse during the latter phases of ascent. The Orbiter/ET combination was more like a gigantic, ground-lit second stage.

should never have been man-rated (you can man-rate a considerably less reliable launcher if you have a means of getting the crew off the stack if anything goes wrong. Without that, nothing must go wrong).

It depends on the human-rating standards... it would be perfectly fine to have a standard that does not require a LAS, if the technology and vehicle in question was mature enough not to require it (not necessarily 'nothing must go wrong'- you can still have many failures that are survivable without a LAS, as airliners demonstrate. The RTLS, TAL and AOA modes were still aborts. They just weren't very good ones).

Of course, the misconception with the shuttle was that it was safe enough not to require a LAS, which was incorrect.

There are also safety issues with the LAS itself- extra pyrotechnics, rocket motors, and seperation events that need to occur are also 'things that can go wrong'. You can get to the point (in theory at least) where the safety disadvantages of a LAS outweigh the safety advantages.

Perhaps the real question is... would the Venusian or Martian Space Races have reached us first...?

Considering that Earth has been without a space race for much of its history, the liklihood of inhabitants of either planet visiting Earth probably low.

Of course, the old idea was that planets further from the sun were older than planets closer to the Sun- hence why Venus had primitive societies or even prehistoric beasts on its surface, why Earth had humans, and why Mars had intelligent squid-people waiting to steal our water (hence the birth of the "I am smarter than you, earthling" trope)...
 
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Linguofreak

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Mars should (more or less) be able to hold onto an atmosphere over geological timescales.

Not according to anything I've ever read on the subject, nor according to available observational data (which, I will concede, has a sample size of 1).

At least you have relatively comfortable conditions, oxygen and water... but what about food? It may not be that much of a problem, but still... would you be the first to eat a Venusian slimemold?

Well, first of all, it depends on how mad you're willing to make Greenpeace. :)

They *could* bring seeds for planting crops with them. Of course, there are ecological dangers there (though just sewage from your colony could present similar ecological dangers).

Even if you don't do that, there's the possibility of repeated food shipments: Stranding can be because you're having trouble getting your on-planet launch infrastructure working, or because Earth is having issues. The latter could be a serious problem, but in the former (and, in my opinion, more likely) case you can still be resupplied.

It depends on the human-rating standards... it would be perfectly fine to have a standard that does not require a LAS, if the technology and vehicle in question was mature enough not to require it (not necessarily 'nothing must go wrong'- you can still have many failures that are survivable without a LAS, as airliners demonstrate. The RTLS, TAL and AOA modes were still aborts. They just weren't very good ones).

In this case what I meant by "nothing can go wrong" was "nothing can go wrong that has a significant chance of causing a loss of vehicle accident". Soyuz has had such accidents without losing the crew. The Challenger scenario (breakup of the launcher) would have been survivable with an LAS, and, arguably, even with parachutes and no LAS. The Columbia scenario was caused by the Shuttle's exposed heatshield, which wouldn't have been an issue with any capsule design I've ever seen.

There are also safety issues with the LAS itself- extra pyrotechnics, rocket motors, and seperation events that need to occur are also 'things that can go wrong'. You can get to the point (in theory at least) where the safety disadvantages of a LAS outweigh the safety advantages.

As far as I'm aware, LAS's have never caused a fatality, and have saved two crews.

And note that, as I said above, even a LAS that failed to activate properly might have saved the Challenger crew. The two fatal elements in the Challenger accident were the crew cabin not being able to hold pressure after the breakup, and the impact of the cabin with the water. A capsule with a failed LAS might still have kept together through the breakup (being designed as a pressure-tight whole, as opposed to the shuttle crew cabin), and would have had parachutes.
 

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One thing I believe is that the Space Race and related tech would have had a very different pace and branching out. The main argument against space exploration is, usually, that "there's nothing out there". With two, or even one, inhabitable world rich in resources this changes dramatically. We would have a set destination and the Moon missions would have been stepping stones to learn about deep space travel instead of an end goal.

An inhabitable Mars poses different technological challenges, for instance even with a breathable atmosphere you still have lower gravity to contend with so HTOL-SSTO shuttles would be more feasible to ferry stuff from the surface to the orbital station(s) and the interplanetary ferries (cyclers) that would cover the Earth-Mars route.

Inhabitable Venus, instead, poses the same lift-off to orbit problems we have on Earth with roughly the same gravity. HTOL-SSTO would be more of a challenge. However, with one or two usable worlds in the Solar System, there would have been a HUGE incentive to come up with a way to reach and colonize them. Politically, it would have been "interesting" at least. I don't think the "Moon Treaty" would have ever been signed, except by the nations which would have had no hope to ever reach the place.

Which brings out the topic of a hot space race between various world powers. If you think the old wars between colonial powers for control of Earth resources were bad, this one would probably heat up the skies a lot.
 

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Oh yes: Another interesting question:

What would the surface exploration infrastructure look like?

You don't have existing roads, runways, or oil rigs. If your orbital imagery shows something of interest, how do you get to it? It's not something we have a good analogue to in our universe, because by the time modern technology developed, there was existing transportation infrastructure covering much of the Earth's surface, and even the parts with no such infrastructure were fairly well explored.
 

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Planes, helicopters, airships, hovercrafts, plain old tractors, you name'em...

Airships and planes have been extensively used in the exploration of the Earth Poles, why not use them on other planets as well. Anyone fancies piloting a Pilatus Porter on Venus?
 

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Not according to anything I've ever read on the subject, nor according to available observational data (which, I will concede, has a sample size of 1).

Correlation between Mars being a small planet and lacking a thick atmosphere does not necessarily imply causation; currently the loss of atmosphere is mainly attributed to the lack of a magnetosphere, allowing the solar wind to interact directly with the atmosphere and sputter it away.

This gas retention plot on the University of Nebraska-Lincoln's website shows Mars as just being able to retain oxygen and nitrogen, but not water vapour. On the other hand, the plot shows Titan as being unable to retain methane and nitrogen, when the moon has a substantial amount of both gases in its atmosphere.

Of course, increasing the size of the iron core, or the amount of radioisotopes to create radiogenic heating (helpful for stimulating flow in the core and atmosphere-replenishing volcanic activity) would both increase mass, assuming that diameter remained unchanged.

They *could* bring seeds for planting crops with them. Of course, there are ecological dangers there (though just sewage from your colony could present similar ecological dangers).

Just walking onto the planet without a very impressive bio-suit will lead to its contamination with terran microoganisms, so unless you're taking very stringent precautions you're going to be causing some level of damage anyway. The question is how much damage you're willing to cause.

Some food items could be grown in greenhouses for a degree of isolation from the local biosphere. Space-farming usually requires far more artificial conditions, so this may not be too much to ask.

Depending on the nature of available organisms, one could... experiment with using them as food...

Even if you don't do that, there's the possibility of repeated food shipments: Stranding can be because you're having trouble getting your on-planet launch infrastructure working, or because Earth is having issues. The latter could be a serious problem, but in the former (and, in my opinion, more likely) case you can still be resupplied.

Well, spaceflight proposals to far less hospitable locations often face durations of a year or more, so it likely isn't all that unreasonable. On the other hand, one would have to prevent food spoilage in the humid, warm Venusian conditions.

Soyuz has had such accidents without losing the crew

So has the shuttle; the RTLS, TAL, AOA and ATO abort modes were all intended for failures (like engine-outs) that would compromise the mission but not lead to an instant LOCV; STS-51F was an ATO, though the mission was a success despite the lower than intended orbit.

Of course, even the limited abort modes had limitations; the RTLS, risky in itself, was impossible until SRB seperation...

The Columbia scenario was caused by the Shuttle's exposed heatshield, which wouldn't have been an issue with any capsule design I've ever seen.

There are failure modes for capsule spacecraft that can compromise the integrity of the TPS or prevent a safe reentry; there was concern during Apollo 13 that the explosion cracked the heat shield, and seperation failures during Soyuz 5 and Soyuz TMA-11 caused the vehicle to start reentry facing the wrong way (fortunately the connection to the service module burnt through before the reentry module hatch did).

As far as I'm aware, LAS's have never caused a fatality, and have saved two crews.

Assessing safety isn't done by comparing how many or how few lives something has claimed; there are failure modes that have not even occured, but are regarded as considerable risks, while there are also disasters that have been caused by previously unconcerning occurances.

The fact is that there are several elements of a LAS that can cause problems (potentially even fatal ones). There are a whole lot of other elements onboard a launch vehicle that can claim the lives of the crew as well, and the LAS is 'sure-fire' way to escape numerous failure modes. However, as safety of the system is increased, eventually the extra complexity of the LAS will reduce, rather than increase, overall safety. This tipping point is, of course, entirely within the realm of theory for the forseeable future.

An example might be how mounting ejection seats on airliners would do far more harm than good.

A capsule with a failed LAS might still have kept together through the breakup (being designed as a pressure-tight whole, as opposed to the shuttle crew cabin), and would have had parachutes.

Depends on various factors (like the nature of the breakup). A severe explosion could destroy a capsule even if it has a LAS to pull it off of the stack, and unstable tumbling mass may not be conducive to safe parachute deployment. I believe one USAF simulation showed hot fuel fragments from an Ares I SRB failure melting the capsule's parachutes during an abort.
 
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Linguofreak

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Correlation between Mars being a small planet and lacking a thick atmosphere does not necessarily imply causation; currently the loss of atmosphere is mainly attributed to the lack of a magnetosphere, allowing the solar wind to interact directly with the atmosphere and sputter it away.

I doubt it: Venus is closer to the Sun than the Earth, a bit smaller, lacks a magnetosphere, and has an atmosphere 90 times thicker.

In any case, escape velocity is a factor for all atmospheric escape processes, and Mars' escape velocity is only 5 km/s.

Some food items could be grown in greenhouses for a degree of isolation from the local biosphere. Space-farming usually requires far more artificial conditions, so this may not be too much to ask.

Depending on the nature of available organisms, one could... experiment with using them as food...

You probably could at least get a broad idea of the chemical suitability of the local life as food with unmanned probes. Figuring out the full range of species that exist and which of the edible ones grow the best would take humans on site to perform experiments though.

Well, spaceflight proposals to far less hospitable locations often face durations of a year or more, so it likely isn't all that unreasonable. On the other hand, one would have to prevent food spoilage in the humid, warm Venusian conditions.

I've generally assumed the first landings would be in polar regions: You'd still need to worry about spoilage, but, depending on how well the atmosphere and oceans transferred heat to the poles, there's a good chance you wouldn't be landing in an absolute jungle. I use the program at the bottom of this page for quick-and-dirty climate sims (actually, for the past few weeks, I've been using a Linux port I wrote using the source package he gives), and it suggests 56C at the equator and 15C at the poles. That's pretty much pure guesswork, though.

Depends on various factors (like the nature of the breakup). A severe explosion could destroy a capsule even if it has a LAS to pull it off of the stack, and unstable tumbling mass may not be conducive to safe parachute deployment. I believe one USAF simulation showed hot fuel fragments from an Ares I SRB failure melting the capsule's parachutes during an abort.

Oh, it would certainly be a crapshoot, but I still judge a capsule designed for an LAS where the LAS fails to fire as being more survivable in a Challenger-type event than STS was. If the LAS actually fires, it will be significantly more survivable. (Now, one significant factor in a launcher failure is whether the launcher just breaks up a la Challenger, or whether it actually explodes: an explosion will send a lot more debris flying upwind).
 

T.Neo

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I doubt it: Venus is closer to the Sun than the Earth, a bit smaller, lacks a magnetosphere, and has an atmosphere 90 times thicker.

In any case, escape velocity is a factor for all atmospheric escape processes, and Mars' escape velocity is only 5 km/s.

Escape velocity alone is meaningless in this case; loss is dependant on a relationship between many factors- molecular weight and temperature have to be considered as well.

If the logic of 'more mass, thicker atmosphere' held true, one would be pressed to explain why Earth does not have an atmosphere yet thicker than that of Venus. The reason for the disparity is related to far more complex factors; planetology as a whole is a very complex science, and one that is fairly primitive.

Firstly, we must consider that Venus is a victim of a runaway greenhouse effect; primordial oceans would have boiled away, smothering the planet in a thick atmosphere of water vapour. After a while, the hydrogen dissasociated, was lost to space, and the atmosphere was replaced by carbon dioxide (if all the carbon in the carbonate rocks of Earth were liberated, the resulting gas would also likely create a fairly thick atmosphere).

We must also consider that Venus shows signs of considerable volcanic activity; its surface is relatively young, and it is thought to undergo 'resurfacing events' every few million years. This activity should serve to replenish the atmosphere somewhat. On Mars, however, there is thought to be considerably less volcanic activity, at least in recent times.

And the Venusian atmosphere is being stripped away to space at a high rate (it has been measured) due to its exposure to the solar wind. However the atmosphere is so massive that even considerable loss will not remove it over considerable timescales. Furthermore there are phenomena specific to Mars that may accelerate atmospheric loss in the absence of an Earth-like magnetosphere (see here and here).

Titan is an example of a low mass body with a considerable atmosphere; it is only ~20% the mass of Mars, but has an atmosphere with a pressure of 1.5 bar at the surface. It can hold onto such an atmosphere at its small size due to its low temperature and distance from the Sun.

I use the program at the bottom of this page for quick-and-dirty climate sims (actually, for the past few weeks, I've been using a Linux port I wrote using the source package he gives), and it suggests 56C at the equator and 15C at the poles. That's pretty much pure guesswork, though.

That program looks interesting, at least. Thanks for bringing it to my attention.

Oh, it would certainly be a crapshoot, but I still judge a capsule designed for an LAS where the LAS fails to fire as being more survivable in a Challenger-type event than STS was. If the LAS actually fires, it will be significantly more survivable. (Now, one significant factor in a launcher failure is whether the launcher just breaks up a la Challenger, or whether it actually explodes: an explosion will send a lot more debris flying upwind).

That depends on many factors; for example if your parachutes do not deploy, you are pretty much no better off than the crew of Challenger was. And if the LAS fails to operate, this could mean other failures as well, such as failure of the boost protective cover to seperate from the vehicle (note that not all LAS designs incorperate such a cover), or the vehicle to seperate from the launcher. Such a case would likely preclude a safe recovery. The only advantage is that, providing a lack of pressure loss and/or the presence of pressure suits, the crew could still be conscious as the vehicle plummets to the ocean.

It does partially raise the half-idea of an escape system that relies on a disentegration of the vehicle to liberate the (suitably reinforced and designed) crew compartment, but one would probably want to shy away from a LAS that relies on the vehicle blowing up. Even if it were effective, it would not provide for on-pad or low velocity aborts.

There are still situations where a LAS could fail to save the crew (such as SRB casing failures, though fortunately this is a low probability event), but LAS hardware is built to be simple and reliable. There's not much point in relying in a failed LAS to save the lives of the crew, but there is a good point in relying on a working LAS to save lives.

You don't have existing roads, runways, or oil rigs. If your orbital imagery shows something of interest, how do you get to it? It's not something we have a good analogue to in our universe, because by the time modern technology developed, there was existing transportation infrastructure covering much of the Earth's surface, and even the parts with no such infrastructure were fairly well explored.

The best suggestion would probably be to land in the most interesting place one can find. Beyond that, there's either shipping fuel to the planet, or using some other form of energy (Venusian sailing, perhaps? Or primitive electric power?). Another possibility is teleoperated robots; they would be smaller than human-bearing vehicles, and thus require less energy for transport, but could still be operated relatively efficiently by nearby humans, and perhaps return samples to scientists on Venus for more in-depth analysis.
 

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That depends on many factors;

As I said: crapshoot.

There's not much point in relying in a failed LAS to save the lives of the crew,

Certainly not: you rely on the LAS working. My point was the unsafety of STS (no options at all between launch and booster separation, so that you actually have a better chance with a capsule and an LAS that fails), not the safety of a failed LAS (where the capsule just might survive and parachute safely into the ocean).

The best suggestion would probably be to land in the most interesting place one can find. Beyond that, there's either shipping fuel to the planet, or using some other form of energy (Venusian sailing, perhaps? Or primitive electric power?).

The option of distilling alcohol for fuel also strikes me.
 

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Certainly not: you rely on the LAS working. My point was the unsafety of STS (no options at all between launch and booster separation, so that you actually have a better chance with a capsule and an LAS that fails), not the safety of a failed LAS (where the capsule just might survive and parachute safely into the ocean).

Yes, but in that case you'd be banking on the system conveniently failing in a way that makes survival possible. A capsule may be designed as a self contained unit, unlike the STS crew cabin, but staying intact is no use if you crash into the water at hundreds of kilometers per hour; it's the stop that kills, not the fall.

In any case, it is not much of an issue; it is far more probable that a LAS failure will lead to LOC, but also more likely that the LAS will work correctly and save the lives of the crew. In practice, a LAS is certainly an important and required safety feature.

The option of distilling alcohol for fuel also strikes me.

That is an interesting possibility, but what would you ferment into alchohol? Dead Venusian organisms? Kitchen scraps?

Maybe Venusian plants could be burnt for fuel (not necessarily in vehicles, but for other, more 'low tech' features... like heating water or keeping predators at bay). That is assuming that whatever exists on Venus that is similar to plants can be used effectively as fuel...
 
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Linguofreak

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That is an interesting possibility, but what would you ferment into alchohol? Dead Venusian organisms? Kitchen scraps?

Probably Venusian plants. It would depend on the local life using sugar as its energy source, but that would be fairly likely assuming that it uses oxygen for an oxidizer and water as a solvent, which would both be necessary for human habitability in the first place.

Finding the species with the best yield and growing characteristics would take work though, much the same as with food.

I suppose you could run into trouble if all the local life contains some chemical that kills yeast: then you'd have to look for a local microorganism to do the fermentation with.
 
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