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The newest robotic resident of Mars defied the odds and landed safely on the surface, despite the thin atmosphere and strong gravity. On 26 November, Mars InSight faced six and a half minutes of terror, charring its heat shield, flinging its parachute out at supersonic speeds, and finally burning thrusters to set down gently at the end of its six-month journey from Earth. Unlike every other spacecraft that has visited Mars, InSight won’t explore the surface – this time it’s a mission to explore what’s inside Mars.

“Mars has so many missions that have been able to explore the exterior by orbiting or by roving around on the surface,” says Elizabeth Barrett, science system engineer with the mission. “InSight is going to be that first mission that will look further into the interior.”

For this landing, Mars InSight is recycling the method that worked for the Phoenix polar lander in 2008. Despite an entirely new payload of instruments and destination, InSight shares the Phoenix spacecraft’s body shape and characteristics. But this time, we had a real-time stream of data relayed by a pair of cubesats – lunchbox-sized satellites collectively known as Mars Cube One (MarCO) – that have accompanied InSight since its launch in May 2018.

The MarCO satellites were designed for a special trick: a bent pipe configuration lets them immediately shoot data back to Earth. While other orbiters like Mars Odyssey stand in silent sentinel during landing, only able to report back on their following orbit, MarCO A and B can observe and report at the same time. This means that for the first time, we received real-time reports of a Mars landing limited only by the speed of light.

Not only did the cubesats ease nerves stressed thin in anticipation, they also delivered the first photograph taken by InSight from the surface of Mars. But without fuel and engines to burn to enter orbit, the pair are hurtling past Mars and will be out of range before confirming the final critical stage of InSight’s solar array deployment.

Pins and needles

Like any landing, this one was full of nerves and excitement. At mission control in NASA’s Jet Propulsion Laboratory in California, the room was full of delighted relief, a celebratory feeling with a hint of shock that it all happened so quickly. With each new report of incoming data and beeps, cheers and clapping spread again. It’s perfect so far, an ideal landing to start InSight’s new adventure on Mars.

But that doesn’t mean the nervous anticipation is over. The wait isn’t done until the NASA control room in California gets confirmation that Mars InSight successfully deployed its solar panels. “Seeing those solar arrays open is what is going to guarantee that we can survive on the surface for an extended time,” says Barrett.

Now that touchdown is complete, NASA’s Entry, Descent, and Landing team can finally celebrate after years of dreaming up nightmare scenarios and putting fixes in place to avoid them. Next, it’s time for the rest of the team to assess the spacecraft’s health, ensure all the instruments are functional and figure out where exactly Mars InSight landed in Elysium Planitia.

This was selected as a landing site in the hopes it would be a big, flat, barren plain of sand. The team wants the landing site to have as few rocks as possible, because Mars InSight will use its robotic arm to gently pluck instruments from the spacecraft to nestle them onto the surface.

Diving deep

Mars InSight is equipped with an array of geophysics tools: a seismometer to detect vibrations as small as the diameter of an atom, a heat flow probe that will burrow like a mole into the depths, a weather station, and a radio experiment that will unmask even the tiniest slosh within the molten Martian core.

Each is geared to explore the Mars’s structure. Some will help determine the thicknesses and materials of the crust, mantle, and core, and others will tell us how much heat the planet has now, allowing scientists to detangle its history of eruptions. By studying the inside of Mars, scientists will have a better understanding of how rocky planets form, and the differences and similarities in how Earth and Mars first formed.

This isn’t the first seismometer to go to Mars. Both the Viking missions in 1975 carried seismometers, although only one of them was functional after landing. But the Viking seismometer was mounted on the spacecraft’s deck.

“Unfortunately, the deck of the spacecraft is cushioned by springs that are dampening the landing, and it’s rocked by the wind as it blows past,” explains Barrett. “The seismometer was very good at measuring the wind rather than any actual seismicity of Mars!” She explained that one of the scientists saw his duty to InSight as ensuring they put the seismometer another three feet further down on the ground.

Today was a major celebration for Mars InSight, but Barrett says it’s hopefully just the first of many to come. She’s looking forward to the first pictures beamed back of Elysium Planitia. But most of all, she’s excited for those big milestones like hammering the heat flow probe into the ground, or recording the first marsquake on the seismometer.

Read more: NASA has chosen the landing site for its life-hunting 2020 Mars rover