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45

Most of the propellant expended in sending a spacecraft to Mars immediately returns to Earth -- the fuel and oxidizer are combusted, combining into (typically) water vapor, CO2, and other simple compounds -- and ejected out the back of the rocket at high speed. The six month trip to Mars is "coasting", with only very small amounts of fuel used for ...


39

I am Jose Juan Lopez Moreno, co-I (co-investigator) of TGO-NOMAD and I feel obliged to respond to PearsonArtPhoto's answer. There is something real: TGO carries 2 independent instruments with a sensitivity high enough to detect methane with a low limit of 0.05 ppbv. Those independent instruments are led by different and independent teams. They are far from ...


36

There's a lot to unpack here, so let's look at the various discoveries of methane on Mars. The first discovery came from multiple groups in 2003-2004 using first Mars Express, followed by Earth based instruments. The measured amounts were small, and being from Earth, could be tricky to know for sure. Mars Global Surveyor data was studied, and it seemed to ...


11

There is far more material to be gained from space exploration than will be lost from Earth in collecting it. A primary reason to explore space is to exploit mineral and organic resources that occur in abundance off earth. Within the "few centuries" you mention, the net change of mass on Earth may very well be positive due to an influx of precious ...


11

There are currently (June 2018) two new papers (links may be paywalled): "Organic matter preserved in 3-billion-year-old mudstones at Gale crater, Mars", Eigenbrode et al., Science 360, 1096–1101 (2018) "Background levels of methane in Mars’ atmosphere show strong seasonal variations", Webster et al., Science 360, 1093–1096 (2018) The first is looking for ...


8

Let's turn the question on its head and see what exhaust velocity we need to if Titan's entire (mostly nitrogen) atmosphere were used as a propellant. $\Delta v = v_e log(m_i / m_f)$ Wikipedia tells us that the atmosphere of Titan is about 1.19 times as massive as that of Earth so we get about 6.13e18 kg of atmosphere (propellant) in a total mass of about ...


7

Let's do a Fermi estimate: Rockets bring about 2-5% of their start mass to orbital velocity. To cancel out Titan's orbital velocity, you're looking at two orders of magnitude more fuel and oxidizer than Titan's mass. Earth's atmosphere weighs $10^{18}$ kg, or 1/200,000 of Earth's total mass. Titan's is 1.5 times as dense, so if Titan's atmosphere were ...


6

The reason is because it wasn't part of the science objectives. It is a Discovery Mission, which has a constrained total budget to start with, and what was selected was very close to a build-to-print version of the Phoenix Lander, which is a big selling point in terms of cost as well as flight heritage of the instruments. As easy as it sounds to just add ...


6

Wikipedia says of the composition of the lower atmosphere: Because methane condenses out of Titan's atmosphere at high altitudes, its abundance increases as one descends below the tropopause at an altitude of 32 km, leveling off at a value of 4.9% [the rest is mostly nitrogen] between 8 km and the surface. and in a separate article The average ...


6

Image from the informative presentation Progress on the RRM3 Cryogen Demonstration System The cryocoolers were commercial units, electrically powered Sunpower Cryotel CT 11 watt units. There is a lengthy data sheet here which includes these performance plots. Full disclosure: I had no idea what "lift" is in this context but there's a quote Lift is a ...


6

At low temperatures, the activation energy for pure CH4 O2 oxidization is about 170kj/mole. (See figure 1 here) That’s about 1.8eV per atomic reaction. 1.8eV can be provided by 688nm red light, or any shorter wavelength. So generally, visible light can initiate reactions. I can’t quantify how many photons/cm2 it’ll take to start a runaway reaction from ...


5

To my knowledge, while a variety of institutions have looked at producing Methane on Mars by combining native CO2 with imported H2 using the Sabatier Reaction, no experiments have actually been carried out on the planet. Backup evidence: NASA's In Situ Resource Utilization talks about MOXIE but does not have any information on methane-based experiments Same ...


5

The Lunar Starship will have to be refueled from Earth, for each mission, and will brings its fuel for return with it, when it lands. As noted, while there may be Hydrogen available in ice in craters, there is no expectation of easily available carbon in a format appropriate for methane manufacture on the moon. Thus ISRU (In-Situ Resource Utilization aka - ...


5

Would it be possible to pinpoint the source of the Methane with current technology Yes. The purpose of ESA's ExoMars Trace Gas Orbiter mission is to locate the sources of trace gases, including methane: http://exploration.esa.int/mars/46475-trace-gas-orbiter/ http://exploration.esa.int/mars/48523-trace-gas-orbiter-instruments/ The spacecraft arrived at Mars ...


4

In part because an actual methane only sensor is hard to build. The standard ones you can buy have a range of things that make them false positive*, and the older hot wire ones need oxygen at a known level to operate. Mars exploration has plenty of instrument results including the positive test for life on Viking where the results are less useful because ...


4

Methane/LOX specific impulse is only slightly better than kerosene/LOX and it's about 25% less dense. In this case I think stretching the first stage would be more likely than fattening it; furthermore it might be possible to use a common-bulkhead tank instead of the separate tanks of the S-IC, (the temperature differential between liquid methane and liquid ...


4

I know Chris Webster (at JPL) well and have discussed the TLS instruments he builds at length. They have more in common with the MIRO instrument on the ESA Rosetta spacecraft (I was a co-investigator on that instrument) than with sector or quadrupole mass spectrometers. Mass spectrometers have relatively poor mass resolution but can measure atoms or ...


4

Eventually, NASA is planning on making a moon base and they will then make rocket fuel out of the water there. We could also make fuel out of the oceans which would solve this problem. Here are some links for this: https://theconversation.com/making-space-rocket-fuel-from-water-could-drive-a-power-revolution-on-earth-65854#:~:text=Water%20is%20a%20way%...


4

This 2018 release from Georgia Tech describes one such - claimed to be more practical than previous methane-fueled cells because it operates at a lower temperature. It is a solid-oxide cell. It appears to work by catalytically cracking the methane to hydrogen, and it seems that the advance is in the cracking part. https://www.news.gatech.edu/2018/10/29/...


3

The whole Starship system is built around two fundamental ideas: Robotic refueling and A large fleet of cheap, aggressively simple, mass-produced, mostly identical vehicles driving cost down. Even Super Heavy is essentially just a strengthened, lengthened Starship with more engines and no nosecone. So, yes, the Starship will need to bring enough fuel to ...


3

Assuming the methane stays in orbit around the Earth as indicated by uhoh, it will then not do much else. Wikipedia has a fairly extensive article about methane in the atmosphere, and it mentions that the primary reaction of methane in the atmosphere is oxidation by hydroxyl radicals. Because the hydroxyl radicals come from water and water in our ...


3

A pressurized space suit is needed when the atmospheric pressure is lower than about 0.3 to 0.4 bar. Pure oxygen is breathed within the suit. So for about 0.07 bar a pressurized suit is mandatory. But a flammable or explosive mixture within the airlock needed to leave and reenter the planet lander should be avoided. So the airlock should be evacuated from ...


3

tl;dr: Except for the signal being 3x larger, at this point nothing new has been learned. The only thing new I can see is that the signal is 3x larger than the previous one recorded by Curiosity, removing any potential lingering doubt about the reality of signal, which at only 7 ppb was close to the error bars. Source Now at 21 ppb (3x larger than the 2013 ...


3

Will the Mars 2020 rover's sensitivity to methane be better than Curiosity's? No, Mars 2020 rover's sensitivity to atmospheric methane will be nonexistent. Curiosity's Sample Analysis at Mars or SAM with its quadrupole mass spectrometer (QMS), gas chromatograph (GC), and tunable laser spectrometer (TLS) will have no counterparts on the streamlined Mars 2020 ...


2

Hydrogen is liquid below 21.15 K and goes solid at 14.01 K. Helium is liquid below 4.15 K and goes solid at 0.95 K under huge pressure of 2.5 MPa. So it should be possible to use gaseous helium to sub cool liquid hydrogen. It is gaseous even below the temperature of solid Hydrogen. Methane boils at 111.65 K and solidifies at 90.7 K. Sub cooling it with ...


2

While a negative δ13C could reasonably be considered possible evidence of either current or past life and perhaps suggest good places to look, it would not be definitive proof. All you know for sure is that some process is separating isotopes, probably some form of kinetic fractionation. Although this can be biological, there are also non-biological ...


2

The atmosphere is thin at 400 km, but it's still there and the ISS is in it. The velocity of a circular orbit at that altitude is about 7700 m/s and escape velocity is the square root of 2 larger than that. So unless the gas was vented at a velocity of 3000 m/s relative to the ISS (which it certainly isn't), it would remain in orbit around the Earth. Over ...


2

The closest to this that has been done was tests to create methane in a vacuum chamber set up to simulate the atmosphere of Mars. The details of this are talked about in the book by Robert Zubrin, "The Case for Mars". It should in theory work on Mars, but the only ISRU instrument that has been sent to Mars is to make oxygen, and that is on its way ...


1

It's a fair question - and unfortunately the answers here circle around but don't quite aim straight at the nail of what I think the OP is after, which is fundamentally about rocket fuel. Because, no matter how many resources you have on Earth, when it comes to the specific question of launching rockets, you pretty much have to do that from Earth-bound ...


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