Jet Propulsion Laboratory is buzzing with relieved delight, welcoming Mars InSight safely to the surface of Mars. The landing today went absolutely perfect, with even the experimental live relay by the MarCo cubesats successfully delivering not just telemetry from entry, descent, and landing, but also delivering InSight’s first photograph within minutes.
I travelled over a thousand miles to arrive at Jet Propulsion Laboratory to be outside Mission Control when Mars InSight braved the final and most nerve-wracking leg of its journey to Mars. I arrived early, watching deer and enjoying the last bit of calm before an ever-thickening stream of scientists, engineers, and reporters poured in. We’re all here for the most exciting and terrifying moment in a mission: Entry, Descent, and Landing.
Six years after the mission was funded, and six months from when it was launched (when I stood witness at 03:00 to a faint growl lost in thick fog), Mars InSight faced a final six (and a half) minutes of the terror to slow down from its interplanetary rush from Earth to touch gently down on the surface.
At 11:00 local time, we gathered just outside Mission Control to watch the final moments of InSight’s approach to Mars. The mood was calm, cautious, but optimistic. No one wanted to jinx the landing, but had confidence in years of hard work and planning paying off. “I'm excited, but all the worrying that would have made any difference has been done years ago,” planetary geoscientist and instrument systems engineer Troy Lee Hudson told me the day before landing. “At this point, worrying would not change anything.”
Orbital dynamics is implacable. The final trajectory correction was made on Sunday afternoon, a quick burn to tweak InSight’s expected landing point a few kilometers further into Elysium Planitia. After that, all anyone could do is wait and trust that with decades of experience to draw on, every contingency had been anticipated.
“Landing on Mars is challenging,” Lori Glaze, acting director of Nasa’s Planetary Science Division told me on Sunday. “As a species, humankind is only about 40 per cent successful at doing Mars missions.”
After the solar arrays deploy, the next big challenge is to evaluate exactly where the robot landed. Elysium Planitia was chosen specifically to be big, flat, and boring with as few rocks as possible. Unlike previous missions where rovers and landers studied surface rocks, landforms, and geology, InSight is tasked with peering deep into the surface.
This is what makes me so fond of this robot, and why I’ve travelled a thousand miles to watch it launch, and a thousand more to be at Mission Control while it lands.
While I adore all our robotic explorers, Mars InSight is my robotic kin. I’m a field geophysicist, a type of scientist who carries fancy equipment into the wilderness, setting up fragile instruments exposed to wind, rain, and bears, all to try unravel subsurface secrets. While InSight gets to skip on the bears and swapped helicopters for a rocket, it’s equipped with a more sensitive version of the heat flow probes and seismometers I’ve used in the field. And that means that for the very first time, Mars InSight will use geophysics to probe deep into another planet to unravel the very structure of Mars and the secrets of its past.
Our solar system has just a handful of rocky planets: Mercury, Venus, Earth and Mars. “By understanding the inside of Mars, it helps us to get a better picture of how these types of rocky planets form and evolve over time,” says Glaze. Both Earth and Mars formed four and a half billion years ago, but unlike Earth where our geologic history has been eroded, deformed, and recycled through plate tectonics, Mars is frozen in time. “Mars after a few tens to hundreds of millions of years stopped and preserved what its interior looks,” says Glaze.
Mars InSight looks like a lander we’ve seen before - it actually reuses the previously-proven body of the Phoenix lander, which investigated water at the Martian north pole. But that’s where the similarities end. “On Phoenix, we picked soil up with the scoop on the robotic arm and delivered them for analysis to instruments on the spacecraft,” explains Hudson, who started working on Phoenix just three weeks before its landing in 2008. “For InSight, we're picking the instruments up off of the spacecraft and putting them on the ground, which is something that we've never done before.”
Those instruments are deceptively simple for the scientific wallop they pack. InSight carries a seismometer to detect the faint vibrations of marsquakes, a weather station, a heat flow probe (or mole) to measure how temperature changes within the Martian crust, and a radio signal that will measure the smallest wobbles in Mars’ orbit.
Mars doesn’t have plate tectonics like Earth, but that doesn’t mean it’s silent. Instead, anything from meteor impacts to the slight contraction and creaking as the planet cools can spark seismic waves, just like earthquakes produce seismic waves on Earth. Also like on Earth, different types of seismic waves will move at different speeds depending on the material they travel through, helping scientists reconstruct the thickness and composition of the Martian core, mantle, and crust.
But the seismometer is so sensitive, it won’t just measure seismic signals. “Not only can it measure small changes as the rocks move, it will also measure if the wind goes by and blows on it, or if the air pressure changes,” says Glaze. That’s why InSight has such a fancy weather station -- that way, scientists can not only study the weather, but they can ensure that the seismometer is measuring signals that tell them about the inside of Mars and not its atmospheric conditions.
The heat flow probe is unlike any other instrument that has ever gone before. Roughly the diameter of a coin and the length of a forearm, it will hammer itself three to nearly five metres into Mars, then take the planet’s temperature.
“The heat coming from the interior of the planet is indicative of the energy that's available to drive geologic process,” says Hudson. That makes scientists incredibly curious if other rocky planets started with the same ratios of radioactive elements as we did on Earth, or something different. “We know the physics of radioactive elements,” says Hudson, so once we measure what the heat is now, “We can turn the clock back and see what was Mars like four and a half billion years ago when it first formed.”
“As Mars goes around in its orbit around the Sun, it wobbles a little bit,” explains Glaze. This wobble will get picked up by the radio experiment’s signal directly to Earth. Even the tiniest changes will reveal information about if the core of Mars is solid, molten, or somewhere in between. “It's such a simple experiment, and yet will tell us so much about the what the core is like!”
Moving scientific instruments from robot to planet sounds simple, but it’s absolutely critical that the team gets it right. “If seismometer doesn't get to the ground, it can't do its job as well,” says Hudson. “The heat flow probe has to get to the ground because it can't dig through the deck.” To improve their odds of success, the team are going to take it slow. Very, very slow.
Before a single instrument is lifted from the spacecraft, the team will have run through endless scenarios with their terrestrial model in the test bed of JPL’s In Situ Laboratory. As soon as InSight runs through all its instrument checks to ensure that all systems are healthy, it’s going to focus on photographing its environment. Engineers on Earth will use those images to recreate a model of the topography using a simulated Martian regolith - a fancy sandbox - where a holographic overlay will assist them in copying the environment. Once the match is perfect, they’ll practice carefully picking up the seismometer and heat flow probe, setting them down as far away from each other and the lander as possible.
The room is buzzing now, laughter easy and cheers breaking out as each new status update is read out from Mission Control. While we’re all waiting to hear that the solar arrays deployed, making Mars InSight a sustainably powered spacecraft on the surface, optimism is high with everything going perfectly to plan so far.
Now it’s time for the real mission to begin!
This article was originally published by WIRED UK
