NASA scientists are experimenting with a process known as Additive Manufacturing. Essentially, this means that scientists want to be able to create custom metal parts on the go without the need for a full workshop setup. They also hope that the customization, in terms of ingredients, will allow them to adjust parts for various weather conditions on different planets, like Mars.
See the NASA 3D printer in action:
They have already 3D printed 11 metal parts that they sent aboard the NASA rover, Perserverance, which is scheduled to arrive on Mars in 2021. They're hoping to test these parts as "secondary structures," which will not ruin the whole mission should they not work. You can learn more about the specific parts and structures that they will be testing on Mars, by reading the full NASA article here.
Long term implications
NASA already has plans to establish a permanent human presence on or near the Moon by 2024. The hope is that, should NASA be able to use 3D printers to print...well...just about anything, then it makes the likelihood of launching a Phase 2 mission from the Moon to Mars a reality.
We're going to have to wait and see, of course. But it's definitely a cool time to be alive!
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