Placing people on Mars has been certainly one of NASA’s driving missions for years, however they’re nonetheless within the early levels of deciding what precisely that mission structure will appear to be. One main issue is the place to get the propellant to ship the astronauts again to Earth. Advocates of area exploration typically counsel harvesting the required propellant from Mars itself – some supplies can be utilized to create liquid oxygen and methane, two generally used propellants. To assist this effort, a bunch from NASA’s COMPASS staff detailed a number of eventualities of the infrastructure and applied sciences it might take to make an in-situ useful resource utilization (ISRU) system that might present sufficient propellant to get astronauts again to a Mars orbit the place they may meet up with an Earth return car. Nonetheless, there are important challenges to implementing such a system, and so they should be addressed earlier than the 8-9-year technique of getting the system up and operating can start.

To know these challenges, it’s first important to grasp a number of the necessities the staff was attempting to fulfill. The purpose was to supply 300 tons of liquid oxygen and liquid methane to a Mars Ascent and Touchdown Car (MALV) being developed at different components of NASA. That a lot propellant is important to get a crew of astronauts again into orbit, the place they are often met by an orbiting Earth return car.

Creating liquid oxygen and methane requires many ISRU programs, similar to pumps, electrolyzers, dryers, scrubbers, and important energy programs, to run all these machines. Some uncooked supplies, similar to CO2, will be pulled from the Martian environment. Nonetheless, the system may also require 150 tons of water, which may very well be trucked in from Earth or harvested from Mars.

Designing the general system structure is step one in figuring out the most effective technique for getting sufficient propellant to get the astronauts again off of Mars. A paper from the group compares 5 completely different approaches to fixing that drawback and particulars three of them, specializing in three completely different strategies of getting water to make use of within the creation of liquid propellants on the floor of Mars.

Let’s first have a look at the 2 choices for extracting water domestically on Mars. One structure makes use of a borehole drill to soften subsurface ice and pump it again to the floor, which can be utilized in electrolysis. The opposite structure makes use of floor harvesting methods, the place soil with a excessive frozen water content material will be sorted, and the water itself melted to supply ample stockpiles for creating propellant.

Drilling a borehole deep sufficient to entry subsurface ice has by no means been carried out earlier than. It does have some benefits over different water assortment strategies, together with taking much less time and requiring one much less MALV supply of kit (i.e., making it decrease value). Nonetheless, it does require extra energy crops and a few specialised tools to be developed. 

Accumulating water from floor regolith makes use of some applied sciences already being developed at NASA – together with the RAZZOR floor mining system that may very well be used on the Moon or Mars. Nonetheless, it requires as a lot time and as many launches as delivery water from Earth, with many doable unknown failure factors within the structure. 

By comparability, sending 150 tons of water instantly from Earth, whereas it could be costly when it comes to launch prices, simplifies the general structure considerably. There would nonetheless technically be ISRU on this state of affairs, because the water would nonetheless be used to create propellant from native Martian sources. Nonetheless, the added step of getting that water domestically can be eradicated.

Even that could be a extra difficult course of than the opposite two choices the staff thought-about, with out as a lot element within the paper because the precise ISRU setups. Mission designers may ship both the methane or each the methane and oxygen from Earth instantly, bypassing the necessity for any ISRU to occur. Whereas these choices require probably extra MALV landers, their general threat is minimized, as the required chemical compounds can be obtainable to be used at any level the astronauts would wish them. Nonetheless, they’d take longer to arrange – particularly the choice of sending all the propellants instantly from Earth, which may take upwards of 10 years to get arrange.

Different challenges abound for using Martian sources to create propellants – together with restricted areas the place the required water could also be discovered. This geographical restriction won’t overlap with the place astronauts could be wanted to do thrilling science, so the architects must prioritize both scientific discovery or derisking the ISRU tools – they seemingly couldn’t do each.

So, all issues thought-about, if the aim is to ship individuals to Mars and again safely, it looks as if the most effective, most dependable possibility is to ship the entire quantity of propellant from Earth. Nonetheless, in the long term, if humanity plans to make a sustainable presence on Mars, we might want to make the most of native sources. The paper from the COMPASS staff clearly defines just a few methods that might try this, and sometime, it is going to turn into the higher possibility – simply possibly not fairly but.

Study Extra:
Oleson et al – Kiloton Class ISRU Programs for LO2/LCH4 Propellant Manufacturing on the Mars Floor
UT – A Single Robotic Might Present a Mission To Mars With Sufficient Water and Oxygen
UT – Sources on Mars Might Help Human Explorers
UT – Mars Explorers are Going to Want air, and A number of it. Right here’s a Know-how That May Assist Them Breath Straightforward

Lead Picture:
Structure Design of the water from Earth supply possibility.
Credit score – Oleson et al. / NASA