Now the real science begins.
PASADENA, Calif. — NASA’s probe InSight survived its perilous descent to the surface of Mars today, marking another successful landing on the planet known for destroying inbound spacecraft.
Cheers filled the mission control room at the Jet Propulsion Lab as the lander relayed the first signs that the landing is a success, signals relayed by experimental CubeSats.
A transmission from InSight’s X-band antennae reached Earth, signaling that the vehicle was healthy. More information and imagery are coming as the orbiters over Mars pass over the site and relay data back to Earth. It will take at least five hours to confirm the solar panels deployed correctly.
But these X-band signals are sweet music to engineers and scientists, not just here in California but to project collaborators across the nation and in Europe.
“I think we’re in the Golden Age of space exploration,” InSight principal investigator Bruce Banerdt told Popular Mechanics.
The landing on Mars entered its final phase on Sunday, when the InSight team gathered to examine the parameters of the landing. They had a very specific target in mind, marked with a red “X” on Elysium Planitia, a flat and dreary stretch of Mars the team has affectionately dubbed a “parking lot.”
The spacecraft has already positioned itself for a very precise entry into the planet’s atmosphere with a series of trajectory correction maneuvers (TCMs). But on the eve of landing, the calculations show the landing bull’s-eye was 11 miles off. That’s not bad, considering, but the team votes to make a final TCM late Sunday. The final TCM was a gentle nudge, a few centimeters per second of thrust—“almost a breath of air” according to NASA project manager Tom Hoffman—that closed the 11-mile landing-site gap.
Mars has a habit of killing visitors as they land, and more than half of the missions there have ended in failure. “We are, of course, worried,” noted Thomas Zurbuchen, NASA’s associate administrator for the science mission directorate, the day before the landing.
InSight first used the atmosphere to slow down, relying on a heat shield to handle the extreme 3,000 degrees Fahrenheit temperature. But Mars’ atmosphere is thin, and it doesn’t slow down the craft enough. The lander needs a parachute to cut velocity, one that can open at supersonic speeds.
When the chute opened, these signals from the lander abruptly changed frequency. The sudden drop in speed causing a Doppler effect shift that earthbound observers could detect, the first sign that the chutes worked.
At this point in the landing, it became time for the secondary, demonstration mission to shine. Two experimental CubeSats, Mars Cube One A and Mars Cube B, launched with InSight and flew to Mars on their own.
This mission was the first to use small sats in deep space. Maneuvering on their own, using cold gas propulsion (a.k.a. fire extinguisher fuel) thrusters, the pair did their own TCMs to get into position for today. They had one key job: Capture the UHF signal from the lander as it’s descending and rebroadcast it on an X-band frequency toward Earth.
The word came across the control room: Both CubeSats locked onto their target, the first milestone passed. The UHF acquisition came next, everything was going well. “We are now reading Insight’s telemetry using the MarCo relay,” mission control announced.
It’s 11:47 in California when the spacecraft starts entry. The air is being pushed aside so quickly that it forms a super-hot gas, a plasma shield that blacked out the InSight’s communications. This is the moment of peak heating, relying on a heat shield to handle the extreme 3,000 degrees F.
The lander separated, the parachute and heat shield ejected, and then it was just the lander alone, free-falling toward the Martian ground for a long, long second.
An onboard radar scanned the area below, locked on, and fed data to the lander. Cued by that data, the legs deployed, ready for the shock of landing. A burst of retrorockets slowed the lander at the last seconds, bringing its speed to just 5 mph during the touchdown. That’s impressive considering that just five minutes before, the lander had been tearing along at 12,300 mph.
The MarCo data connection with InSight stayed strong as the landing unfolded. The telemetry confirmed the landing’s success, starting the first celebration of the day at JPL.
It was all courtesy of the MarCo small sats. They soon relayed the first images from InSight, a view of the Martian surface blurred by a dust cover. Jubilation followed.
“We’re not risk junkies,” said Zurbuchen, “But it takes that risk to get this reward.”
Now data will come in waves, as the orbiters around Mars pass overhead, collect data, and beam it back to eager eyes on Earth.
The first up will be the Mars Reconnaissance Orbiter (MRO), which was overhead during the entire EDL sequence. This satellite captured the action as it crossed over the Martian horizon, and earthlings will have to wait until it comes back so the spacecraft can beam its full recording of the landing. If something went wrong, this would serve as the Martian equivalent of an airplane’s “black box.”
The next satellite to play is Odyssey, swinging overhead five hours after landing. This is the craft that will confirm that the solar arrays are deployed and working. There may have been cheering now that the lander is on Martian ground, but without power it’s not good for much science.
Hoffman warned not to get expectations too high for stunning images, since Elysium Planitia seems fairly nondescript.
“We’ll will land on Elysium Planitia, which means Heavenly Plain, and it is just that, plain,” Hoffman quipped to reporters the say before the landing. “Not the most exciting place to be. But safe.”
This is not a mission about the surface, but what lurks below. InSight will be the first probe to explore the interior of Mars, using a specialized seismometer to measure S-waves of Marsquakes and a drill to burrow 16 feet into the ground to measure heat flow. A radio experiment will measure the way the planet wobbles on its axis. The geology of Mars unlocks its history. These details are the basis of knowing how the planet got to be the uninviting place we see today, versus the cradle of life that is Earth.
Answers will take time, and InSight principal investigator Bruce Banerdt says it may take the entire two-year mission to gather the data. “Once we get to the surface, we become a slow-motion mission,” he said. “It could be six months before we get even a glimmer of what we are looking for.”
But the first step is behind the InSight team, and the long hours of work ahead is welcome. They are living the best-case scenario, assuming the solar panels deploy. The craft is on Mars. If it is like similar missions, milestones and challenges lie ahead.
“This seems like the climax,” said Banerdt. “But it’s only a beginning.”