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Confronting the Credibility Gap for Crewed Exploration of Mars

caseyexaustralia.blogspot.com

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Re: Confronting the Credibility Gap for Crewed Exploration of Mars

#61

Post by avmich »

Symmetry wrote: post #52
avmich wrote: post #18

The document linked at the end of the talk currently contains summary regarding the radiation problem on the way to Mars. I've heard of the following approach. The spacecraft generates a magnetic field which spreads around it in flight, having some substantial size (order of kilometers). Relatively small amounts of matter (some gas) are constantly emitted from spacecraft, get ionized and trapped in the magnetic field…

You really want to be piling some dirt on top of your shelters for pressure containment reasons anyways.

That idea was for travel time, not when the spacecraft is already landed on Mars and the crew want protection on the surface. There, dirt will help, but in flight there is nowhere to get it from.

Re: Confronting the Credibility Gap for Crewed Exploration of Mars

#62

Post by chandmer »

coldtea wrote: post #47
semi-extrinsic wrote: post #45

Earlier quoted context omitted.

How are they going to come back? All realistic plans I've seen are for one-way trips. The thought of dying isn't the inherently problematic part, but rather the extreme isolation. People who go to war are there for only some months and have plans for going home, back to friends and family. People who dive and explore the oceans are isolated for a few days at worst; perhaps months in a nuclear sub, but there you have…

> How are they going to come back? All realistic plans I've seen are for one-way trips. Huh? " The first crewed Mars mission would be expected to have approximately 12 people, with the primary goal to "build out and troubleshoot the propellant plant and Mars Base Alpha power system" as well as a" rudimentary base." In the event of an emergency, the spaceship would be able to return to Earth without having to wait a f…

Yep. The spaceship has to come back at the very least.

Re: Confronting the Credibility Gap for Crewed Exploration of Mars

#63

Post by chandmer »

nine_k wrote: post #58
jcoffland wrote: post #39

Radiation is a huge problem. Both en route and on Mars. A lot of these problems beg the question. Is Mars really the best target? Sure it's close but there are moons around Saturn that are interesting as well. Titan for example. Sure it's cold but it has a lot of atmosphere. Presumably landing would be easier. If we could learn to live underwater we could possibly visit Ganymede or Europa.

A floating station (eventually a city?) in the atmosphere of Venus would also be fine. On certain height, the temperature and the pressure are close to Earth's surface, and sun shines brightly enough for plants to generate oxygen. There's plenty of carbon dioxide in the atmosphere to feed the plants. No roaming over the surface, though.

No access to generic raw materials and huge lifting gas overhead, even huger delta-V requirements to do anything.

I don't get Venus cloud tops. I've never seen anyone explain how to transport, fuel and launch a Saturn V rocket from a zeppelin.

Re: Confronting the Credibility Gap for Crewed Exploration of Mars

#65

Post by chandmer »

IndianAstronaut wrote: post #49
jcoffland wrote: post #39

Radiation is a huge problem. Both en route and on Mars. A lot of these problems beg the question. Is Mars really the best target? Sure it's close but there are moons around Saturn that are interesting as well. Titan for example. Sure it's cold but it has a lot of atmosphere. Presumably landing would be easier. If we could learn to live underwater we could possibly visit Ganymede or Europa.

Titan may be a very good bet. It has an atmosphere so you aren't worrying if your water resources may boil away, or if a small tear in your suit hapens, you have more time to fix the situation.

Titan is super cool, and also freezing. I think it falls into the "need infinite fusion" bin, but after that, sure!

Re: Confronting the Credibility Gap for Crewed Exploration of Mars

#66

Post by chandmer »

aedron wrote: post #33
nickparker wrote: post #17

There's a very enjoyable discussion in the comment section with my (brilliant) former colleague Max Fagin. He points out that Casey's first draft of this post neglects the curvature of Mars, and when you account for it Casey's model predicts the craft punching out the other side of the atmosphere.

Can't see those comments. Were they deleted?

They shouldn't be!

Re: Confronting the Credibility Gap for Crewed Exploration of Mars

#67

Post by chandmer »

aedron wrote: post #33
nickparker wrote: post #17

There's a very enjoyable discussion in the comment section with my (brilliant) former colleague Max Fagin. He points out that Casey's first draft of this post neglects the curvature of Mars, and when you account for it Casey's model predicts the craft punching out the other side of the atmosphere.

Can't see those comments. Were they deleted?

They're on the ITS post.

Re: Confronting the Credibility Gap for Crewed Exploration of Mars

#68

Post by Faaak »

james-watson wrote: post #34

What gets forgotten here, and something that I keep bringing up, is the lack of a Martian magnetosphere. This means long term human settlements have to be artificially shielded. This means living underground, which defeats the point of going to Mars in my opinion. Elon mentioned using a local magnetosphere generator, which is one of those ideas that is theoretically possible but whose practicality seems questionable.…

Wouldn't an alternative be genetics ? i.e. making a new "vaccine" that would cure against the dangers of a magnetosphere ?

Re: Confronting the Credibility Gap for Crewed Exploration of Mars

#69

Post by brilliantcode »

Why Mars though? Why not build a lunar base on the moon? Maybe even a hotel on the moon, I'm sure people will enjoy watching earth from the moon.

I just fail to see this obsession with Mars. We don't even have manned landing on Mars and we are already having questionable stuff like "Mars One"

And finally (one for the conspiracists): nearly 50 years ago we landed on the moon without any of the technology we have today. Why hasn't there been any strides? Shouldn't it be cheaper to go to the Moon vs Mars? Shouldn't it be possible to colonize Moon more easily and faster than Mars?

Re: Confronting the Credibility Gap for Crewed Exploration of Mars

#70

Post by Symmetry »

LeoDox wrote: post #56
james-watson wrote: post #34

What gets forgotten here, and something that I keep bringing up, is the lack of a Martian magnetosphere. This means long term human settlements have to be artificially shielded. This means living underground, which defeats the point of going to Mars in my opinion. Elon mentioned using a local magnetosphere generator, which is one of those ideas that is theoretically possible but whose practicality seems questionable.…

Mars has an iron core; it's just not molten which prevents it from being ferromagnetic. I have three questions: 1. Is it merely a question of mass? That is, if Mars were larger would the increased gravity increase pressure at the core and keep it molten? 2. If it IS merely a question of mass, is there any way to add mass to Mars which doesn't disturb its orbit? Because if you could, then you simultaneously solve both…

It's not pressure but heat from mostly radioactive decay and also tidal stresses from the Moon that allow the Earth's core to be liquid. More mass allows for more insulation and more decaying Uranium, Thorium, etc so tends to lead to higher internal temperatures.
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