The endless stretch from the moment a spacecraft reaches the Martian atmosphere until the second it touches Earth on the rusted surface of the Red Planet, is what scientists call "the seven minutes of terror"
Landing a spaceship on Mars is as difficult as it seems. More than half of all missions do not reach the surface safely. Because light signals take more than seven minutes to travel 100 million miles to Earth, scientists have no control over the process. All they can do is program the ship with its best technology and wait.
Seven minutes of terror for InSight, NASA's new Mars explorer, begins on Monday just before 3 p.m. Eastern Time. It is the first mission to study seismic waves on another planet; When exploring the interior of Mars, scientists try to discover signs of tectonic activity and clues about the planet's past.
But first they have to get there.
Around 2:47 p.m. On Monday, the engineers of the Jet Propulsion Laboratory will receive a signal that indicates that InSight has entered the Martian atmosphere. The spacecraft will plummet to the surface of the planet at a rate of 12,300 miles per hour; in two minutes, the friction will have toasted its heat shield until it reaches 2,700 degrees Fahrenheit. In another two minutes, a supersonic parachute will be deployed to help the ship slow down.
From there, the most critical descent checklist unfolds at a rapid pace: 15 seconds to separate the heat shield. Ten seconds to unfold the legs. Activate the radar. Remove the rear shell. Shoot the retrorockets. Orient for the landing.
Assuming all goes well, at 12:01 p.m. Scientists will hear a small beep, a sign that InSight is active and functioning on the Red Planet.
The objective is to determine what Mars is made of and how it has changed since it was formed more than 4 billion years ago. The results could help solve the mystery of how the Red Planet became the dry and desolate world we see today.
At the beginning of its history, Mars could have looked a lot like Earth. The magnetization in ancient rocks suggests that it had a global magnetic field like Earth's, driven by a whipping mantle and a metallic core. The field would have protected the planet from radiation, allowing it to maintain a much thicker atmosphere than exists today. This in turn probably allowed liquid water to accumulate on the surface of Mars; The images of the satellites reveal the contours of the lakes, deltas and canyons dug in the river a long time ago.
But the last 3 billion years have been a slow-motion disaster for the red planet. The dynamo died; the magnetic field hesitated; the water evaporated and more than half of the atmosphere was stripped by the solar winds. The InSight mission was designed to discover why.
As InSight descends precariously, NASA can get almost real-time information about its status through the MarCo satellites, a small experimental twin spacecraft known as CubeSats that accompanied InSight on its flight to Mars. Each one has solar panels, a color camera and an antenna to transmit communications from the Martian surface to the Earth.
If the satellites are successful, they can provide "a possible model for a new type of interplanetary communications relay," systems engineer Anne Marinan said in an interview. Press release from NASA.
Even without the MarCo spacecraft, NASA should know if the solar modules of the lander have been deployed on Monday night, thanks to recordings from the Mars Reconnaissance Orbiter. Within a day, the agency will obtain its first images of the landing place of the spacecraft: a vast plain, almost without distinctive features, near the equator known as Elysium Planitia. That's where science will begin.
Unlike the Opportunity and the Curiosity, the rovers that roam Mars in search of interesting rocks, InSight is designed to sit and listen. Using their dome-shaped seismic sensor, scientists hope to detect small tremors associated with meteorite impacts, dust storms and "marsquakes" generated by cooling the interior of the planet. As seismic waves propagate, they will be distorted by changes in the materials they encounter, perhaps columns of molten rock or liquid water deposits, which reveal what is beneath the surface of the planet.
InSight also has a drill capable of digging 16 feet, deeper than any other instrument on Mars. From there, you can take the temperature of Mars to determine the amount of heat that flows from the body of the planet. Meanwhile, two antennas will accurately track the location of the lander to determine how much Mars staggers as it orbits around the sun.
The InSight information will not add to what we know about Mars. They could provide clues about things that happened on Earth billions of years ago. Most records of Earth's early history have been lost due to the inexorable rotation of plate tectonics, explained Suzanne Smrekar, the deputy principal investigator of the mission.
"Mars gives us the opportunity to see the materials, the structure, the chemical reactions that are close to what we see inside the Earth, but it is preserved," he said. "It gives us the opportunity to go back in time."
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