On the morning of May 5, 2018, cheers of excitement went up over the prospect of landing a robot on the most boring part of Mars imaginable. The target location wasn’t picked because we’re running out of interesting features to look at on Mars of course, but because we wanted a relatively “quiet” place for the Interior exploration using Seismic Investigations, Geodesy, and Heat Transport (InSight) lander to learn about what’s under Mars. To do that, the lander will essentially listen to the planet’s seismic activity for a year just north of the equator, trying to weed out other disruptions from the activity happening deep in the planet’s core.
Digging in the dirt
For this extended listening session, InSight will land in one spot, then set up shop. In a first, a robotic arm will lower its two primary instruments to the ground where they can then go to work for at least a year of data collection. The Heat Flow and Physical Properties Probe (HP3) will be inserted over 10 feet underground, where it will both heat the surrounding dirt and then measure how quickly that heat travels through the surrounding material. These measurements will then give researchers a good idea about the geological composition of Mars’ surface.
Super-sensitive seismic sensor
The second instrument will sit on the ground in a vacuum chamber further protected by a small dome. This will help block out wind, dust, and other possible sources of “noise.” This is important, because the Seismic Experiment for Interior Structure (SEIS) is so sensitive to vibrations it pick up the movement of ocean waves from as far away as Colorado. Even the movement of a single hydrogen atom is said to be detectable, which is why a tiny leak in the protective vacuum chamber required the entire InSight mission be delayed by two years— to truly be effective, the SEIS data must be as free of unexpected disruptions as possible.
On Mars, those vibrations will tell us a lot about the planet. Unlike the Earth’s moving, crunching and melting geology, Mars stopped churning 20 to 50 million years after it was formed. The quakes the Red Planet does experience are tied to the gradual cooling and contraction of the planet as a whole, and measuring the frequency and intensity of those quakes will tell us more about how the planet was formed in the first place. Naturally, a device as sensitive as SEIS will pick up other activity as well, meaning we can look forward to a log of asteroid impacts around the planet as they happen.
If this weren’t enough, we’ll also be tracking how our stationary lander’s position shifts throughout the year. Nobody is expecting a marsquake to start moving InSight around, but Mars’ axis of rotation is known to be gradually changing. So as we track signals from the lander, we’ll be able to detect how that telemetry shifts over time.
Some of that will be made easier by the two other bots sent to space with InSight. Two mini-satellites in a class often referred to as “cubesats,” will be going into orbit around Mars to help track and report on InSight’s landing process. They’re not strictly necessary for InSight’s success, which is great since they’re actually an experiment themselves. While many cubesats now orbit the Earth, MarCO-A and MarCO-B (aka Wall-E and Eva, thanks to their gas propulsion thrusters’ resemblance to a certain fire-extinguisher) will be the first such devices to visit another planet. If they prove up to the task, they could herald a new way for us to explore our solar system in a more modular, inexpensive manner.
My five-year-old asked: What kind of spaceship did they send the lander on?
InSight and the two cubesats were sent on an Atlas V rocket. The relatively lightweight payload and powerful rocket enabled the mission to launch from Vanderberg Air Force Base in California, rather than Cape Canaveral in Florida. While an east coast launch is generally beneficial to help push interplanetary missions out of Earth’s orbit, InSight planners wanted to avoid crowded schedule in Florida, opting for a bigger rocket from California instead. As such, this was the first time an interplanetary mission launched from the west coast.
Source: Meet InSight: The Mission To Measure Marsquakes and Unlock the Red Planet by Emily Lakdawalla, Popular Mechanics