On Monday, a spacecraft called InSight will arrive at Mars and, if all goes well, land on the surface. Insight is the latest in a long line of probe that have been investigating the planet, carrying instruments that will build on what earlier spacecraft have discovered.
But this satellite isn’t alone. Its mission is not only redefining what humanity knows about Mars, it is breaking new ground in the way our species explores the solar system.
When InSight launched on May 5, 2018, two briefcase-sized vehicles were tucked off to the side of the lander-a pair of Cubesats called Mars Cube One, or MarCO. “Once InSight got deployed of a launch vehicle, each of the two MarCO’s got deployed as well,” Tim Linn, the InSight deputy program manager for Lockheed Martin, tells Popular Mechanics. “So basically all three spacecraft were basically all flying in basically the same direction, toward Mars.”
Now that the trio of spacecraft has arrived at Mars, it’s official: The small satellite revolution we’ve been seeing in Earth orbit has reached other parts of the solar system.
Mothership Connection
The two CubeSats proved themselves just by getting this far. Their list of accomplishments include becoming the first CubeSats to provide images of Earth, the Moon, and Mars; proving out radios, high-gain antennas, and propulsion; and performing the first trajectory correction maneuvers by CubeSats when they steered toward Mars. In short, they proved this class of small, affordable spacecraft can survive in deep space.
Now it’s time for the pair of small sats to do the job they came to do: relay data from InSight as it enters the Martian atmosphere and lands. NASA says this “could represent a new kind of communication capability.”
Probes that travel with their own small data relays are obviously more self-sufficient as one-off missions. Linn says it’s now possible to imagine future missions in which the main spacecraft acts as a sort of mothership, carrying CubeSats that it deploys once it reaches the destination.
“It’s Still Terrifying”
Even with the pair of helper telemetry sats in tow, the landing outcome for Mars InSight will be uncertain for a full frightening eight minutes, due to the lag time of the communication at long distances. “It’s still terrifying,” Linn says.
No conversation with engineers involved in Mars landings is complete without a warning about how hard it is. There is a large percentage of failures, worldwide, when it come to landing on the Red Planet.
Mars has a thin atmosphere, just 1 percent of Earth’s, and that leaves little friction to slow down InSight during the landing. “When we enter this 80-mile-point above the surface, we’re going at about 13, 000 miles per hour,” Linn says. “When we touch down, we’re going at about five miles per hour.”
The high speed is a necessary evil. The process is determined by the location of the landing site and constrained by physics. InSight has an “Entry Flight Path Angle” of minus 12 degrees. If it comes in too steep, it will burn up. Too shallow, it will skip out of the Martian atmosphere.
NASA says that only about 40 percent of the missions ever sent to Mars by any space agency have been successful, but notes that the U.S. is the only nation whose missions have survived. Those probes-like InSight, built by Lockheed-have provided some useful lessons. The spacecraft shares a real engineering heritage with the Mars Phoenix Lander, which landed a decade ago. But no landing is identical, and Insight has more mass and a very different landing angle than its Mars-proven ancestor.
“We’re leveraging as much from Phoenix as we can for these kind of missions, but because of the unique nature of what we’re doing on InSight, there are a lot of things that we’ve had to modify,” Linn says.
The vehicle will use various tricks to stay safe during the trip to the surface, using a parachute to slow down. “We have a heat shield to slow us down, to take out most of the energy, and we have a parachute to take out a lot more, and keep us stable as we go supersonic to subsonic,” Linn says. “And then we have the last 45 seconds, where 12 large thrusters will fire to really set ourselves down softly on the surface.”
The heat shield is a critical piece of hardware, and is the chief way to slow the probe down. But the proven heat shield used on earlier Mars missions wasn’t going to be tough enough to handle this entry, and the main reason is dust.
“We’re also actually landing in dust season, because of when we launched and where we wanted to arrive,” Linn says. “So we had to actually increase the thickness of the heat shield. As we’re reentering, that dust can peel off a lot of our thermal protection system. We get sandblasted by these dust storms.”
Linn calls it a dance in which every step has to be correct. “That’s what make it kinda unique,” he says. ”And it all has to go right. We can’t accommodate a hiccup in any of the systems.”
The Discoveries to Come
Once the probe lands, the science can begin. InSight carries a slew of sensors to measure things like seismic activity, wind velocity, and the planet’s magnetic field. The most groundbreaking experiment really does crack the planet’s surface-a drill that will twist 5 meters into the surface to take the first measurements of Mars’ geothermal heat flux.
And that’s what all this extreme engineering is about: finding out why two neighboring planets that should be so similar are so different. One is vibrant with life, the other a place where life didn’t gain purchase, has died off, or is hiding in extremophile clusters.
“Unlike Earth, which has gone through a lot of plate tectonics, Mars has preserved a lot of that information,” Linn says. “So we’re trying to look on the inside, trying to understand from core to crust, what Mars looks like.”
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