NASA’s Perseverance rover has been playing second fiddle to the Ingenuity helicopter in recent months. But in fairness, it’s a helicopter on Mars. Not to be outdone, Perseverance is gearing up for the next big step in its mission on the red planet. In the coming weeks, NASA will harvest the first of many samples that could one day return to Earth for study. First, the rover has to find just the right bit of rock to carve up.
The robot has an impressive suite of tools that can analyze the geology of Mars, but there’s only so much you can do on-site. Not all instruments are compact enough to make the trip bolted to a rover, and scientists might think of additional experiments long after the train (or rocket) has left the station. That’s why bringing samples back to Earth is so desirable. However, it was no simple matter to build a system to collect those samples.
The Sample Caching System includes 43 metal tubes that slide into the rover’s coring bit. The sample tubes are the cleanest things ever sent into space. That was essential to ensure the samples were not contaminated with materials from Earth. NASA even had to back off from its original decontamination protocols because it was stripping the natural layer of hydrocarbons from the metal. That made the material sticky, causing the tubes to become stuck on the drill bit. The rotary percussive drill is capable of carving out small samples of rock about the size of a piece of chalk, which is transferred instantly to the tube.
The current goal is to find a geologically interesting rock on the floor of Jezero Crater. Actually, the team needs two identical rocks. One rock will be cleaned and subjected to scans with SHERLOC, PIXL, and WATSON instruments. The Mastcam-Z will also get involved to snap high-resolution photos, and the SuperCam will use its laser to vaporize small bits of the sample to analyze the molecules.
The second rock won’t be hammered by lasers or scraped clean on Mars; it’s coming to Earth. Before collecting the core destined for a return trip, NASA will let Perseverance sit for a full Martian Sol until it can recharge its batteries. Then, it will turn the sample caching drill on the “twin” rock. That sample tube will remain in storage along with all the others Perseverance collects.
It will take at least two more missions to retrieve those samples — one to pick them up and get to Mars orbit, and one that takes the payload from Mars back to Earth. The planning process is just getting underway, but the tubes could be home as early as 2031. The first sample collection should begin in about two weeks.