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I wonder whether the structure of a Mars surface rover or probe could be 3D printed from plastics on Earth and then shipped to Mars for its mission. That is, 3D printed from the common materials used today (ABS, PLA, nylon/polyamide etc.) with common techniques (FDM, SLA etc.).

The surface temperatures on Mars are mostly freezing and should allow for the plastics to not melt, which would be the first pre-requisite for success. If it could not be made entirely from plastic, are there parts of the vehicle that could be?

I can think of following potential problems:

  • melting during journey to Mars - temperature profile of the travel?
  • abrasive Martian dust - use surface paint for protection?
  • radiation (ionizing, UV) altering material properties
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  • $\begingroup$ If a printed version is heavier, it would never be built. $\endgroup$
    – Uwe
    Feb 21, 2021 at 12:53
  • $\begingroup$ UV tends to make a lot of 3D printing materials extremely brittle. $\endgroup$
    – SF.
    Feb 21, 2021 at 15:27
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    $\begingroup$ Note that it makes much more sense to do it the other way round. Send the source material, which takes up much less space and is much less fragile, and then print the rover on Mars. That way, the only fragile part you have to send is the printer, and you only have to do that once. $\endgroup$
    – Jörg W Mittag
    Feb 21, 2021 at 16:59
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    $\begingroup$ except that a rover is a full set of parts that are not all printable, it would also be necessary to send these parts and the robot that assembles the printed parts to the brought unprintable parts. $\endgroup$
    – jkztd
    Feb 21, 2021 at 17:52
  • $\begingroup$ if for some reason plastics are not valid, metals can be printed using 3d laser sintering $\endgroup$
    – jkztd
    Feb 21, 2021 at 17:59

2 Answers 2

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Plastics are great, however they don't have the temperature range or strength of metals. You need a material that is light weight, able to withstand the forces of a launch and re-entry, and able to remain strong at vicious temperature extremes.

Many plastics become brittle when cold. Mars gets down to -60°C at night at its warmest, Mars probes can expect to get exposed to -100°C repeatedly, and much colder at the poles. Not many plastics remain ductile at that temperature, meaning they crack easily. If you look at the common plastics used in 3d printing and their lowest ductile temperature you have:

  • ABS: -40°C
  • PLA: -30°C
  • Nylon: -40°C

These are great materials because they melt at a relatively low temperature, but their other properties aren't ideal.

Some plastics have a much lower temperature range, acrylic can remain as low as -150°C, it's not that strong though so it would end up heavier than metal. This page has a handy chart showing temperature ranges of common plastics.

Metal can be 3d printed, and Perseverance has some 3d printed metal parts, I don't know if they are part of the structure though.

3d printing undoubtedly has a role to play in Mars exploration when we send humans there, it would be very good to be able to make the things as it's a long way from home.

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  • $\begingroup$ How about PEEK or Polyimide/amide? Plastics which are already used in (terrestrial) extreme temperature environments such as firefighting suits or inside Down-Well bores and for containers holding the most corrosive chemicals and biologicals. $\endgroup$
    – crasic
    Feb 22, 2021 at 20:42
  • $\begingroup$ There's many plastics which may work @crasic, I don't know of any that are better than metal for this application, but my experience comes from additive manufacturing and CNC as a hobby. $\endgroup$
    – GdD
    Feb 22, 2021 at 20:56
  • $\begingroup$ Thermoplastics are pretty remarkable fluorocarbon.co.uk/products/material-overview/peek $\endgroup$
    – crasic
    Feb 22, 2021 at 20:58
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Plastics have certain durability issues. Generally you can make stronger materials two component materials -- fiberglass & resin is an example, as is carbon filament construction. Nylon gears frequently are 'glass filled' It's actually a mix of nylon and fine short glass fibers.

3D printing has the advantage that it's fast, and useful for prototyping, and verifying that the parts will fit together. I'm not impressed with it's ability to make useful parts for any critical application.

The Martian environment has two factors unfriendly to plastics:

  • High UV index. While Martian sunlight is around half strength, it has no UV shield. UV breaks the bonds in plastic. The broken bonds can either stay broken, or they can cross link. The first makes the plastic weak, the second makes it brittle. Put a white food grade pail in the sun for 3 years then kick it.

  • Low atmospheric pressure. Lots of plastics have solvents in them to deliberately reduce cross linking. This keeps them from being too brittle. You can find old plastic that even though it's been stored it has gotten brittle.

Both of these can be mitigated somewhat with by vapour depositing a thin layer of metal. Hence the gold coated mylar used on many satellite assemblies. (Gold is commonly used because it has high emissivity in IR, and low e in visible, so it's effective at reducing solar heating.

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