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When it comes to Mars, we’ve all gotten spoiled. Back in 1976, it was huge news when Viking 1 and 2 became the first spacecraft to land on the Red Planet. But these days just getting stationary metal on Mars isn’t so exciting, not when we’ve got an SUV-sized rover like Curiosity driving across the Martian plains and craters. A spacecraft that lands and then just sits there is something of a cosmic meh.

At 7:05 AM ET on May 5, however, that may change as NASA launches the Mars InSight lander, a sit-there ship that will explore a part of the planet no other spacecraft has studied in detail: its interior. The innards of Mars could teach us not only about the origin and development of the planet itself, but of other rocky worlds in our solar system, as well the countless ones we now know are orbiting other stars. What’s more, two little fly-along spacecraft, officially known as Mars Cube One (or MarCO), but wonderfully nicknamed WALL-E and Eva—after the characters in the exquisite Pixar film—will provide the first-ever test of miniature satellites in deep space.

For all its potential, InSight is a small and inexpensive spacecraft, as these things go. Weighing just 790 lbs. (358 kg), standing a maximum of 43 inches (108 cm), and with a width of 19 ft., 8 in. (6 m) with its solar array extended, it cost just $813.8 million, $163.4 million of which is attributed to its Atlas V launch vehicle. But there’s impressive stuff packed into the comparatively modest machine.

The InSight name tells you a lot. It’s a somewhat labored acronym for “Interior Exploration using Seismic Investigations, Geodesy and Heat Transport.” (Washington is notorious for such so-called backronyms, and NASA is a chief contributor. Just three days before InSight’s launch, the agency issued a press release touting a new power-generating system called Kilowatt Reactor Using Stirling Technology—or, yes, KRUSTY.)

Still, insight is indeed what InSight will provide. The principal instruments on board the spacecraft include the first ever seismographs placed directly on the surface of Mars. The Viking seismographs were mounted on top of the spacecraft, which made their readings less-than-entirely reliable. InSight’s, by contrast, will detect Martian quakes or temblors that jostle the spacecraft by the width of a single atom. Also aboard will be a radio communications system that will take measurements of the precise distance between the Earth and Mars, revealing information about Martian wobbles that could provide clues to whether the planet’s core is still partly molten.

Most important, however, will be InSight’s temperature probe, which will conduct direct studies of the Martian interior. The probe is about 18 in. (.45 m) long and is equipped with a spring loaded hammer that will pound it about 15 ft. (4.5 m) below ground, far deeper than any Mars instrument has gone before. This will allow InSight to measure heat flow which, in addition to analyzing the frequency and propagation patterns of Marsquakes that the seismometers detect, will provide a sort of x-ray of the Martian interior.

InSight’s Bruce Banerdt, the mission’s principal investigator, boasts that taken together, the spacecraft’s instruments will give Mars its “first health checkup in more than 4.5 billion years.”

“We’ll study its pulse by ‘listening’ for marsquakes with a seismometer,” he says. “We’ll take its temperature with a heat probe. And we’ll check its reflexes with a radio experiment.”

WALL-E and Eva, both about the size and shape of a briefcase, have more modest goals. They will take off aboard the same Atlas V that will loft InSight, then be released into space and follow just behind the spacecraft all the way to Mars. They are proof-of-concept machines more than anything else, and when they reach the planet they will simply fly by it, heading for an eternity in deep space. Before they do, however, they will try to help InSight down to the surface of the planet, relaying data about its descent back to NASA. Any contribution they make in that regard will be nice, but not essential. The real data-relay work will be done by NASA’s Mars Reconnaissance Orbiter, which has been in orbit around the Red Planet since 2006.

That fact alone says something quiet but remarkable about human planetary exploration. There are currently eight active spacecraft—most of them American—orbiting or on the surface of Mars, with InSight representing a potential ninth when it at last arrives next November 26. A nation that struggles to keep its roads, bridges and airports from crumbling has nonetheless built a sort of mini-infrastructure on another world. InSight promises to teach us new and important things about solar system science. But the mere business of its getting to Mars to do that job is already impressive.

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Write to Jeffrey Kluger at

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