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posted by Fnord666 on Wednesday June 03 2020, @07:17PM   Printer-friendly
from the lots-of-MREs dept.

How to make the food and water Mars-bound astronauts will need for their mission:

If we ever intend to send crewed missions to deep-space locations, then we need to come up with solutions for keeping the crews supplied. For astronauts aboard the International Space Station (ISS), who regularly receive resupply missions from Earth, this is not an issue. But for missions traveling to destinations like Mars and beyond, self-sufficiency is the name of the game.

This is the idea behind projects like BIOWYSE and TIME SCALE, which are being developed by the Centre for Interdisciplinary Research in Space (CIRiS) in Norway. These two systems are all about providing astronauts with a sustainable and renewable supply of drinking water and plant food. In so doing, they address two of the most important needs of humans performing long-duration missions that will take them far from home.

[...] In short, the ISS relies on costly resupply missions to provide 20% of its water and all of its food. But if and when astronauts establish outposts on the moon and Mars, this may not be an option. While sending supplies to the moon can be done in three days, the need to do so regularly will make the cost of sending food and water prohibitive. Meanwhile, it takes eight months for spacecraft to reach Mars, which is totally impractical.

So it is little wonder that the proposed mission architectures for the moon and Mars include in-situ resource utilization (ISRU), in which astronauts will use local resources to be as self-sufficient as possible. Ice on the lunar and Martian surfaces, a prime example, will be harvested to provide drinking and irrigation water. But missions to deep-space locations will not have this option while they are in transit.

[...] Technologies like these will be crucial when it comes time to establish a human presence on the moon, on Mars, and for the sake of deep-space missions. In the coming years, NASA plans to make the long-awaited return to the moon with Project Artemis, which will be the first step in the creation of what they envision as a program for "sustainable lunar exploration."

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  • (Score: 2) by Immerman on Thursday June 04 2020, @06:38AM (2 children)

    by Immerman (3985) on Thursday June 04 2020, @06:38AM (#1003093)

    >I wonder if the orbital mechanics mean that a ship scheduled to arrive at Mars at a non-optimal conjunction would actually have to be launched before one that arrives 3 months earlier at a more optimal conjunction...

    A lot is down to timing, but about half the time it would take longer when the planets are not in the right alignment. At least unless you want to spend a ridiculous amount of excess energy, and I think you'd need to invent high-thrust ion-drives or similar to be able to pull that off practically.

    What would tend to make more sense, especially if the ships are relatively cheap, is to just launch two years worth of supplies when the planets are in alignment. You don't need a supply ship every 3 months, just send 24 months of stabilized supplies when the shipping is cheap. That's part of why Musk is talking about needing thousands of Starships, because traveling at any other time gets dramatically more expensive, and for one year out of two, is still slower anyway.

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  • (Score: 2) by JoeMerchant on Thursday June 04 2020, @12:55PM (1 child)

    by JoeMerchant (3937) on Thursday June 04 2020, @12:55PM (#1003162)

    Given drone ships' track record at Mars missions, I would think that risking 2 years of supplies on a single ship would be... inadvisable.

    Food / cargo doesn't get bored in transit - it doesn't consume resources over time, and while it would be nice to have fresh fruit, fish and steak, I think the food they send is basically permanently preserved.

    You bring up an interesting point: ion engines. Even if they're not super powerful, they would be effective on a long transit from Earth to Mars orbit, lots of time to collect solar energy. Assuming that the engines of the cargo shuttle are in a reusable section, that would be a good way to add flexibility to the transit scheduling - use a traditional chemical booster to get the bulk of the transit impulse, but use the ion stage for extra kick and possibly as a braking stage to slow down (safer than aero braking) from a fast transit.

    John Galt is a selfish crybaby [].
    • (Score: 2) by Immerman on Thursday June 04 2020, @01:43PM

      by Immerman (3985) on Thursday June 04 2020, @01:43PM (#1003182)

      Who said anything about a single ship? You send several, with essential and non-essential supplies distributed between them.

      But then, if you're getting ready to send passengers (or have already done so) then you've probably pretty much mastered the whole landing safely thing so it's not such a big deal.

      And as cheap as Starship is looking to cost, it's a pretty good bet that most of the ships you send aren't coming back - the steel would be useful on Mars, and the energy budget to refuel the thing could be better spent on Mars for other purposes. Especially if you send cargo in "flight-tested" ships that are reaching the end of their service life anyway - send them on a last hurrah to Mars. You only need to send back ships when you have passengers to return. And maybe the occasional ship full of engines salvaged from other ships - I think I've heard estimates to build the rest of the Starship are about $10M, while the engines themselves are about $5M each.

      Ion engines are indeed promissing, and something like an "orbital tugboat" could be very valuable - perhaps something like an ion-drive "SuperHeavy" alternative that could mate to the base of a Starship (or some sort of cargo module) and push it between planets. Unfortunately at present I don't think we have anything particularly suitable for moving Starship-sized payloads, at least not unless we're okay with the trip taking many years. Which could be fine for some supplies, but there's a lot of stuff that would suffer from years of intense interplanetary radiation.

      They're also (currently) basically useless as an alternative for aerobraking - even powered by a MW nuclear reactor their maximum thrust amounts to a rounding error compared to aerobraking. Once you're no longer in microgravity you need lots of raw power, and ion drives suck at that. Same issue if you use chemical engines for most of the impulse - the ion drives will take years to do what the chemical rockets do in minutes, and given how incredibly expensive they are to build they're probably not worth using except where they're the primary means of propulsion. But when transit time isn't a consideration they can really shine.