This Week in Space: Help Wanted on Bone-Dry Mars
These days, our Mars rovers roll through water-carved flood channels and canyons that are now bone-dry. The evidence suggests that Mars was once a warm, wet world like Earth, but over billions of years it became the dry, inhospitable world it is today, with only tiny trickles of briny water appearing seasonally on the surface.
It turns out that it’s all the sun’s fault, according to new research from NASA’s MAVEN mission, which has a satellite orbiting Mars and analyzing its atmosphere.
The sun doesn’t just radiate its life-giving heat and light to all parts of the solar system. It’s also constantly sending out the solar wind — a stream of particles blowing outward at a million miles per hour in all directions.
On Earth, we’re shielded from that solar wind by a magnetic field that surrounds and protects the planet. But Mars doesn’t have one of those.
Photo: NASA.gov
Without that protective shield, MAVEN’s observations have shown, the solar wind has been eroding Mars’s atmosphere for billions of years, to the point where it’s now way too thin to support flowing water. On a normal day, the solar wind is ripping away a quarter of a pound of Martian atmosphere every second. That doesn’t sound like a lot, but it adds up over time “like the theft of a few coins from a cash register every day,” according to Bruce Jakosky, MAVEN principal investigator at the University of Colorado Boulder.
And during a solar storm, when the sun is feeling particularly feisty, the atmospheric loss gets even worse: MAVEN got to witness a solar storm firsthand during March 2015 and noticed an accelerated loss of atmosphere. (Earth’s protective field channels particles from solar storms toward the planet’s poles, forming auroras.)
Scientists have known for a long time that Earth’s magnetic field protects us from radiation and other harmful stuff that the sun throws our way. But, it turns out, it’s also keeping our atmosphere from shredding away under the constant pounding of the solar wind. Without it, Earth might look a whole lot like Mars, and you wouldn’t be reading this now.
Mars needs astronauts
So Mars may not be the most hospitable place in the solar system. It’s still our nearest planetary neighbor and the target for the next wave of crewed space missions. NASA’s already working on the Orion for deep-space exploration, and it’s also staffing up for the arrival of two new spacecraft built by SpaceX and Boeing.
So many spaceships, so few astronauts! That’s why NASA announced that it’s seeking new recruits for space travel. It will start accepting applications next month.
Photo: NASA.gov
But NASA isn’t turning this into some kind of space-based reality show: The qualifications to be an astronaut candidate are still pretty specific. You need a science degree (ideally an advanced one), three years of related professional experience, or 1,000 hours of pilot-in-command time in a jet aircraft. And couch potatoes, take note, you also “must pass the NASA long-duration spaceflight physical.”
If you think you’ve got the right stuff, you can apply online through the U.S. government’s USAJOBS website. But you should probably watch NASA’s astronaut recruitment video first.
Momentum trumps funding
Being a robot, the New Horizons mission to Pluto didn’t need to apply for its job through a government website. But it does depend on government funding to keep operating. The laws of physics don’t work on the same timetable as bureaucracies do, so the New Horizons team has been steering the spacecraft toward a new encounter despite not having the money to actually explore it.
This week New Horizons completed its fourth course correction, putting it on course for a rendezvous with an icy object named 2014 MU69, located more than a billion miles past Pluto, in about three years. The outer solar system is littered with these small, cold objects, and it’s only in the past decade or so that we’ve really gotten to know more about them. Since New Horizons is (at least vaguely) in the vicinity, it’s worth a look. You never know when we’re going to be out this far again.
Photo: NASA.gov
There’s just the one bureaucratic catch: This “extended mission” past Pluto hasn’t been funded by NASA. According to the Johns Hopkins University Applied Physics Laboratory, which is managing New Horizons, it will be submitting a formal proposal for funding to NASA early next year. It seems likely that the funding will be granted, but if the team had waited for approval before nudging the spacecraft onto a new trajectory, it would have been too late.
In other words, New Horizons has learned a lot about surviving in a big bureaucratic organization: Thrust first, ask for funding later.
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Jason Snell is a longtime technology journalist and podcaster who blogs at Six Colors and co-hosts the space podcast Liftoff.
