Over the last nine months, Curiosity has been through a lot: the trauma of launch, the frigid vacuum of space, and the turbulent descent through the martian atmosphere. It's been a jarring journey - one that may have shaken the rover and its instruments out of the configuration that Earth-based engineers spent months planning down to the last millimeter.
Given the intensity of the transit, instrument teams are justifiably nervous about the state of their precious hardware. One of the key steps in getting Curiosity up and running is to test the instruments and confirm that they're fit and ready for duty.
The Sample Analysis at Mars (SAM) is one of the instruments being revved up. The instrument comprises more than half of the mission's scientific payload, with three different tools that, in most Earth-based contexts, would occupy an entire room. For Curiosity, the suite of instruments was miniaturized into a 40 kilogram cube: an entire lab the size of a microwave oven.
Yesterday, during sol 3, the Sample Analysis at Mars (SAM) team received a critical piece of news: its beloved instrument turned on and appeared to be intact. It may not seem like much, but it was cause for a round of applause during the day's planning meeting. The power-on test was just the first of three steps to get the instrument ready for action. In a few sols, the team will fire up the instrument's mechanical components, rotating the gears and spinning the pumps (which whirl at up to 100,000 revolutions per minute). "SAM is essentially the size of a microwave oven," says Dan Glavin, an astrobiologist at NASA's Goddard Space Flight Center, "but there are a lot of moving parts, so it's important to make sure everything's OK."
It's all in preparation for the instrument's first full measurement. The instrument will suck in atmospheric gas, sorting the constituent molecules by size, and smashing them into ionized fragments whose pattern paints a diagnostic molecular picture. "It will be the first time the atmosphere has been sampled in this way since Viking," more than 30 years ago, says Glavin. "And we'll be doing it with much higher sensitivity."
This debut will also mark the beginning of the instrument's highly anticipated search for methane gas. Martian methane gas has been detected intermittently from Earth-based telescopes, but the measurements have proven to be controversial. Skeptics point to mysterious spatial and temporal variations that seem to violate stability rules of atmospheric methane. But the detection of methane - which on Earth is frequently associated with living or once-living things - could be an important piece in the story of habitability on Mars.
Such transformative discoveries are still a distant hope for now, but yesterday's subtle signals from the Sample Analysis at Mars instrument are the first essential steps of the journey.