At first blush, the Mars rover that NASA hopes to launch in 2020 is a near twin to Curiosity, which is now exploring the Red Planet. It will use the same chassis and will be delivered to the surface with the same “sky crane” system. But today’s announcement of the seven instruments that will ride on the new rover’s payload makes it clear that the Mars 2020 rover will be much leaner.
The numbers speak for themselves: Curiosity supports a payload of 75 kilograms built at a cost of about $180 million; the Mars 2020 rover payload will weigh 40 kilograms and cost $130 million. The reductions are in part to make room for rock samples to be stashed for eventual return to Earth. Being lean will also keep the rover free of complicated, time-consuming instruments that could hamper it from assembling a diverse cache of rocks in just a few short years.
Some of the instruments offer incremental advances over their counterparts on Curiosity. For example, the Mastcam-Z will have a zoom lens, which will allow researchers to build 3D movies (something that MastCam principal investigator Mike Malin wanted to do with filmmaker James Cameron on Curiosity before that capability was descoped). More importantly, the zoom camera will allow the rover to look out farther into a planned drive and identify hazards—permitting longer and more autonomous daily traverses. And some of the instruments, such as a Norwegian-built ground-penetrating radar, are completely new.
Those new capacities may have prompted the rave review offered by John Grunsfeld, NASA’s associate administrator for science, at today’s press conference in Washington, D.C. “This really is a souped-up instrument suite compared to Curiosity,” he said.
In general, however, the Mars 2020 rover payload is stripped down. Most notably, it lacks an instrument like Curiosity’s Sample Analysis at Mars (SAM) suite, which contains ovens and a mass spectrometer that can search for specific organic molecules in a sample. Although a mass spectrometer can be incredibly powerful—SAM has yielded the very first signs of organics on Mars—they can also bog the mission down. Curiosity spent 5 months working with SAM more or less in the same spot, drilling and analyzing samples at a place called Yellowknife Bay.
So when the science definition team released its report last summer, they expressly recommended a set of scientific instruments that were not souped-up. And NASA, in evaluating and selecting winners among the 58 instrument proposals, obliged. Nowhere on the payload is anything risky or outlandish, such as proposals for a solar power helicopter and a plant germination experiment.
The Mars 2020 rover will still be able to search for biosignatures in a more limited way. Two of its instruments, SuperCam and SHERLOC, will have Raman spectrometers. These instruments excite molecules in a sample with lasers of different frequencies, and look for associated emissions from the excitations. The Raman spectrometers will be able to pinpoint areas of a rock that have interesting chemistry, whereas the SAM instrument can provide information only about a bulk, ground-up sample. The Raman spectrometers have another advantage: They work fast. Project scientist Ken Farley, an ultramarathoner who has run nine 100-mile races, knows that being speedy will be to his advantage. “Time is going to be pressing,” he says.
On the other hand, SAM can identify specific molecules, even long-chain organic molecules, whereas the Raman spectrometers will just be sensitive to generalized groups within an organic molecule, such as a carbon atom double-bonded to an oxygen atom. “There are compromises everywhere you look,” Farley says. And yet, it is the compromises of doing geochemical work on another planet that make sample return so appealing for the rover scientists: On Earth, state-of-the-art laboratory techniques could be brought to bear on the cached samples.
See here for the full list of the seven instruments and their principal investigators.