[Yeah, sorry for the mixed Arnold metaphor in the title.]
[Wait! No! I'm not sorry at all. It's the best headline maybe ever.]
Last week, NASA announced it's sending a helicopter to Mars. And unlike the title for this article, that's not a joke. It'll be one part of an ambitious mission called Mars 2020, the next big spacecraft the American space agency is sending to the Red Planet.
Mars 2020 is a geology mission, a rover (based on the Curiosity rover engineering) equipped with a suite of instruments whose primary purposes are to look for evidence of past microbial life on Mars, assess the Martian climate, look at the geology of the planet, and to prepare for eventual human exploration of Mars — for example, it carries a package called MOXIE, or Mars Oxygen In-Situ Resource Utilization Experiment, which will try to convert the carbon dioxide in the Martian atmosphere into oxygen that can be breathed and used for rockets.
One of the primary mission objectives is to use a drill to obtain samples of interesting rocks that may contain evidence of past habitable conditions (including mineral changes due to the influence of water, and possible organic (carbon-based) molecules that can be identified by other instruments onboard (like SHERLOC)). The samples will be stored on the rover as it moves around its landing site until scientists can identify a good place to store them on the planet's surface. The idea is that another mission sometime in the future will pick them up and bring them back to Earth for analysis.
I'll be honest: I have some issues with this. It relies on there being a sample-return mission, which will be complex, no doubt very expensive, and sometime in the vague future. It also delays gratification on the science for an indeterminate amount of time. I understand that of course it's impossible to set up a full chem and bio lab on the surface right now, so this way at least the samples are obtained and placed somewhere, but this still seems like an odd choice to me. The sample return mission will have to go to a place already explored, and the redundancy concerns me as well. However, plans on the future mission and how to do all this are starting to firm up, which is nice (though there has been criticism, too). Note that I'm not saying this is the wrong way to go! Just that I will reserve judgment until plans are firmed up.
Be that as it may, the other goals are certainly interesting and scientifically worthy, so overall the mission appears well thought-out and should be a step along the way to understanding the planet far better, and to eventually let humans explore it as well.
And now NASA is adding a helicopter to the mix. How cool is that?
Mind you, this isn't a huge device. In fact, it's wee: The copter body will be a cube only 14 centimeters across, and it'll have a mass of just less than two kilos (about four pounds on Earth, or a little over a pound in the weaker Martian gravity). The lift will be provided by two sets of counter-rotating blades roughly a meter in span.
They'll have to spin fast: Atmospheric pressure on the surface of Mars is a meager 0.6% that of Earth, so the thinner air provides only a small amount of lift for the blades (which is why they're so long, in fact). It won't have to travel far, though. It's designed to hop ahead of the rover and scout out the lay of the land ahead of it on its journey, so it may only go a few hundred meters at most. The power will be provided by a solar panel on the top of the craft that generates about 200 Watts, and it'll have a heater to keep it from having trouble in the frigid nights of Mars.
The folks at JPL put together a short video showing you this little puddle sand jumper in action:
The helicopter will be mounted on the underside of the rover, and deployed when a suitable spot on the surface is found. It's a technology testbed, an experiment to see first if it works at all (it's been thoroughly tested, so it should), and also how it behaves once it's operating on an alien world. It'll probably only be used a half-dozen times or so, but if it performs up to snuff bigger and more powerful ones may be sent to Mars in the future. They would be able to take on more tasks, like surveying or measuring varying atmospheric characteristics versus altitude.
Mars 2020 will launch in July of that year, when the Earth and Mars are in the right spots in their orbits for an easy trip, and arrive at its destination in early 2021. I'll note that these planetary alignments happen roughly every 26 months (due to the orbital periods of Earth and Mars; think of it like the minute hand catching up to the second hand of a clock), and the current Mars mission en route, Mars InSight, launched a week or so ago, and will land in November 2018.
So there's plenty to do between now and taking helicopter rides on Mars.