What's missing to get humans to Mars? - Orbit 11.28


#101

it’s a fake.
Or was it a joke? :face_with_raised_eyebrow:


#102

Field generators are a real technology spinning ball s hold air but create centrifugal forces

How introducing microbial life to Mars can make it livable for humans
https://bigthink.com/surprising-science/using-bacteria-to-terraform-mars

Australian ai startup
https://spaceport.ai

A crazy, kid-friendly Mars exhibition just opened in Shanghai
http://www.timeoutshanghai.com/family/features/Family-Family_news/63656/A-crazy,-kid-friendly-Mars-exhibition-just-opened-in-Shanghai.html


#103

Nope, it’s somewhere in the top of our worries. Of course main obstacle is funding. Having appropriate space economy, stable transportation system (infrastructure), etc… Then lack of gravity, then radiation. We still know nothing about 1/3 gravity on human body. On mars you get a lot more radiation too and not just from the sun but high energy cosmic rays as well. During trip to mars you can shield some solar radiation but you can’t do the same with high energy cosmic rays. Well, in theory you can but it will not be a practical stuff.
On the other hand we all live in more or less radioactive environment here on earth.


#104

Lol, yes it’s a joke… I thought everyone here would recognise the gravity drive from event horizon, classic sci-fi, and one of my favourites!! (Along with the core)

But you can make a real generator, even build it into the skin of craft(like the b2 bomber does if I remember rightly, even provides thrust.


#105

What kind of field is it? Is it generates EM field? How strong is it and how heavy and complicated device should be to generate appropriate EM to deflect or at least mitigate cosmic rays radiation significantly?


#106

You got me :blush:
Lol, thx


#107

I think a big issue we need to overcome is mass production of power for a permanent base.

Let’s say we are going to convert water ice into Oxygen and Hydrogen for breathing and fuel Just running rough numbers. If we want to convert 1 mole of water (18 grams) into 16 grams of Oxygen and 2 grams of Hydrogen this 286 kjoules/ mole. 1 watt is equal 1 joule per second. The radio isotope generator on the curiosity rover puts out a 110 watts. We will need a much larger source for a permanent base. A permanent premade structure with the capacity of producing kilowatts or megawatts might have to be delivered ahead of the permanent settlement. Lets take a submarine as an example this vessel has a power plant that provides air and power for a 100 crew members or more. Power for operations, ability to make oxygen, and a source as well as for propulsion of the ship. The cost of getting something that big there would be an undertaking but it could be broken down into smaller units and put together by robotic or the first settlers until a more in-depth infrastructure is created.


#108

Aye see my ramble Here


#109

I totally agree. Thanks.


#110

Some back of the envelope sanity checks:

First off, we should use Methane and O2 instead of H2 and O2. So we’ll need to calculate the energy input.

formula
co2 + 2 * h2o -> 2 * o2 + ch4

enthalpies
o-h 463 kj/mol x4 = 1852 kj/mol
c=o 803 kj/mol x2 = 1606 kj/mol
in = -3458 kj/mol

c-h 413 kj/mol x4 = 1652 kj/mol
o=o 495 kj/mol x2 = 990 kj/mol
out = 2642 kj/mol

in + out = -816 kj/mol

Thus we need 816 kj/mol to convert CO2 to methane.
ch4 = 16 g/mol

SpaceX Starship (aka BFR spaceship) takes ~240,000 kg CH4.

240,000,000 g / 16 g/mol = 15.0 Mmols
15.0 Mmol * 816 kj/mol = 12.24 Tj per fuel tank

Since refuels are around 2.17 years apart, we have:
2.17 * 365.25 * 24 * 60 * 60 = 68,374,800 seconds between refuels

This amounts to an average needed power of:
12.24 Tj / 68374800 sec = 179 kilowatts

If we assume 200 watts per square meter from a solar panel (assuming ~35% efficiency and clear skies on Mars), that would mean we need:
179000 watts / 200 watts/meter^2 = 895 square meters of solar panels (in direct sunlight all the time)

We should multiply this by 4 to account for cosine losses and night-time darkness.
4 * 895 meter^2 = ~3580 meter^2

After adding walk ways for maintenance this would occupy an area in the shape of a square about 70-80 meters on a side (more for higher latitudes). If we use flat, rolled-out thin-film-solar-arrays we might need to double or triple this again to account for even more cosine losses.

Thin-film panels are looking to weigh about 1 kg/meter^2 (or less), this gives us somewhere between 4 to 10 tonnes of mass using thin-film solar (not including the mass of the power distribution system). Given SpaceX Starship’s 150 tonne cargo capacity. This is very doable.

P.S.
This doesn’t account for inefficiency in the chemical processing… so energy needs could easily be double this.


Technology pieces which turns dreams into reality
#111

Meanwhile, the fission fueled Kilopower…


…is promising 1 kw for 134 kg.
…or 10 kw for 226 kg (according to wiki).

If we use these instead, we get:
179 kw / 10 kw = 18 reactors
18 * 226kg = 4.07 tonnes using gas cooled fission

And as a side bonus output does not depend on day or night and is unaffected by dust.

Very doable.

P.S.
Because weight efficiency tends to improve as it scales up, a 100 kw reactor (or two) would probably be even lighter.