Thu. Jun 20th, 2019

Journey to Mars-NASA’s InSight lander

An illustration of NASA’s InSight lander drilling into the surface of Mars. (NASA via AP)

The interminable stretch from the moment a spacecraft hits the Martian atmosphere to the second it touches down on the Red Planet’s rusty surface, is what scientists call “the seven minutes of terror”

Landing a spacecraft on Mars is as difficult as it sounds. More than half of all missions don’t make it safely to the surface. Because it takes more than seven minutes for light signals to travel 100 million miles to Earth, scientists have no control over the process. All they can do is program the spacecraft with their best technology and wait.

The seven minutes of terror for InSight, NASA’s newest Mars explorer, begins Monday just before 3 p.m. Eastern Time. It is the first mission to study seismic waves on another planet; by probing Mars’ interior, scientists aim to uncover signs of tectonic activity and clues about the planet’s past.

This photograph taken by the Mars Odyssey orbiter shows the target landing site for NASA’s InSight lander in the Elysium Planitia region of Mars. (AFP PHOTO / NASA/JPL-Caltech/ASU)

But first they have to get there.

At about 2:47 p.m. Monday, engineers at the Jet Propulsion Laboratory will receive a signal indicating InSight has entered the Martian atmosphere. The spacecraft will plummet to the planet’s surface at a pace of 12,300 miles per hour; within two minutes, friction will have roasted its heat shield to a blistering 2,700 degrees Fahrenheit. In another two minutes, a supersonic parachute will deploy to help the spacecraft slow down.

From there, the most critical descent checklist unfolds at a rapid clip: 15 seconds to separate the heat shield. Ten seconds to deploy the legs. Activate the radar. Jettison the back shell. Fire the retrorockets. Orient for landing.

Assuming all goes well, at 12:01 p.m. scientists will hear a tiny beep — a signal that InSight is active and functioning on the Red Planet.

A mobile service tower is rolled back to reveal the Atlas-V rocket with NASA’s InSight spacecraft on board at Vandenberg Air Force Base, Calif., in May. (Bill Ingalls/NASA via AP)
The objective is to determine what Mars is made of and how it has changed since it formed more than 4 billion years ago. The results could help resolve the mystery of how the Red Planet became the dry and desolate world we see today.

Early in its history, Mars may have looked a lot like Earth. Magnetization in ancient rocks suggest it had a global magnetic field like Earth’s, powered by a churning mantle and metallic core. The field would have protected the planet from radiation, allowing it to hold on to an atmosphere much thicker than the one that exists today. This in turn likely enabled liquid water to pool on Mars’ surface; images from satellites reveal the outlines of long-gone lakes, deltas and river-carved canyons.

But the last 3 billion years have been a slow-motion disaster for the Red Planet. The dynamo died; the magnetic field faltered; the water evaporated; and more than half of the atmosphere was stripped away by solar winds. The InSight mission was designed to find out why.

A mobile service tower is rolled back to reveal the Atlas-V rocket with NASA’s InSight spacecraft on board at Vandenberg Air Force Base, Calif., in May. (Bill Ingalls/NASA via AP)
As InSight makes its precarious descent, NASA may be able to get near-real-time information about its status via the MarCo satellites — tiny twin experimental spacecraft known as CubeSats that accompanied InSight on its flight to Mars. Each has solar arrays, a color camera and an antenna for relaying communications from the Martian surface back to Earth.

If the satellites are successful, they may provide “a possible model for a new kind of interplanetary communications relay,” systems engineer Anne Marinan said in a NASA news release.

Even without the MarCo spacecraft, NASA should know if the lander’s solar arrays have deployed by Monday evening, thanks to recordings from the Mars Reconnaissance Orbiter. Within a day, the agency will get its first images of the spacecraft’s landing site — a vast, flat, almost featureless plain near the equator known as Elysium Planitia. That’s where the science will start.

Unlike Opportunity and Curiosity, the rovers that trundle across Mars in search of interesting rocks, InSight is designed to sit and listen. Using its dome-shaped seismic sensor, scientists hope to detect tiny tremors associated with meteorite impacts, dust storms and “marsquakes” generated by the cooling of the planet’s interior. As seismic waves ripple through, they will be distorted by changes in the materials they encounter — perhaps plumes of molten rock or reservoirs of liquid water — revealing what’s under the planet’s surface.

InSight also has a drill capable of burrowing 16 feet — deeper than any Mars instrument has gone before. From there it can take Mars’ temperature to determine how much heat is still flowing out of the body of the planet. Meanwhile, two antennas will precisely track the lander’s location to determine how much Mars wobbles as it orbits the sun.

The insights from InSight won’t only add to what we know about Mars. They could provide clues to things that happened on Earth, billions of years ago. Most records of Earth’s early history have been lost to the inexorable churn of plate tectonics, explained Suzanne Smrekar, the mission’s deputy principal investigator.

“Mars gives us an opportunity to see the materials, the structure, the chemical reactions that are close to what we see in the interior of Earth, but it’s preserved,” she said. “It gives us a chance to go back in time.”

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