Mars Landing: NASA's InSight is designed for absurd conditions

There really is not way to repeat landing on Mars. You can simulate it, of course, but the most valuable lessons are learned in real-life attempts. When things go wrong, these lessons are also the most expensive. The fact is that most missions on Mars do not succeed, although NASA has a better record than most others. The agency has achieved seven touchdowns on the red planet. On Monday, November 26, he will attempt to qualify for the eighth time, as he will attempt to land the $ 830 million InSight spacecraft on Elysium Planitia, a vast plain just north of the Martian equator.

If NASA succeeds, InSight (abbreviation for Inner Intelligence using seismic surveys, geodesy and heat transport) will be the first mission to explore the interior space of Mars with the help of thermal probes and seismometry. and the composition. But first, the spacecraft must land. To do this, it will have to withstand an atmospheric input several times faster than the speed of sound, weather, and avoid being crushed by its own equipment dropped. Arriving on Mars is difficult, but NASA engineers consider entry, descent and landing – the seven-minute period during which mission planners are unable to intervene, due to the huge distance between Mars and Earth – the most risky sequence of the entire mission. Here's how NASA plans to get out of it.

Monday, November 26 at 11:47 am Pacific Time

For InSight, the action will begin on Monday, November 26 at 11:47 am, Paris time (2:47 pm ET). It is at this point that the LG must reach the top of Mars' atmosphere, at an altitude of about 43 miles above the surface of the planet. In contact, the spacecraft will flare at a speed not so cool of 5,500 meters per second. It's 12,300 miles at the hour.

At these speeds, the main concern of NASA engineers is friction. The atmosphere of Mars, about 100 times thinner than that of the Earth, plays a crucial role in the arrival of InSight: bleeding the spacecraft from its kinetic energy. Yet, the atmosphere is also a major threat. The resistance that it exerts on InSight's heat shield, a 419-pound (40 kg) enclosure composed primarily of ground cork, will cause the temperature of the protective barrier to temperatures greater than 2,700 degrees Celsius. Fahrenheit, hot enough to melt steel.

11:49 PT

These temperatures will reach their maximum about 90 seconds after InSight will have detected the top of the atmosphere of Mars, around 11:49. Around the same time, InSight will experience its maximum deceleration forces, with magnitudes close to 8 times that of gravity here on Earth. For reference, people subject to as little as 4 g can lose consciousness in seconds. InSight may well know its own version of a power outage: the heat at this point of entry into the atmosphere will be so intense that NASA engineers expect it to could ionize the gas around the spacecraft, thus causing a temporary disruption of its radio transmissions to the Earth.

Thus begins the descent of InSight towards the Martian surface. Within two minutes, InSight will continue to slow down until onboard sensors determine whether it is safe to deploy the supersonic parachute from the spacecraft.

11:51 PT

Depending on local weather conditions (sandstorms are common on Mars at this time of year (InSight's heat shield, another eventuality), the chute, which measures 39 feet in diameter and is connected to the probe by 40 lines of suspension, is expected to unfold around 11: 51 o'clock Ten seconds later, the spacecraft landing radar will begin to be in line.

What follows is a series of carefully orchestrated steps that are essential to the weight loss of the undercarriage as it prepares to land. During the first 25 seconds of its parachute descent, InSight will drop its heat shield and deploy its three shock-absorbing legs for landing. Ninety seconds later, the spacecraft will begin using its radar – now fully activated – to measure its proximity to the Martian surface and the speed of its approach.

11:53 PT

The last minute of the arrival of InSight on Mars will be marked by the loss even more equipment. Forty-five seconds before touchdown, the spacecraft is expected to descend to approximately 134 km / h. At an altitude of two-thirds of a mile, as determined by its radar, InSight will separate from its parachute and, a second later, will begin to shoot a dozen descent engines. An onboard navigation software will allow these engines to operate in quadruple duty by slowing the descent of the undercarriage, guiding it to its landing zone and orienting it so that its solar panels they extend from east to west, while keeping it well out of the way of its already dumped and impending shell and chute.

11:54 PT

In the last fifteen seconds, InSight will descend from an altitude of 164 feet, while slowing its vertical speed from 17 to 5 miles to the hour: its touchdown speed. The latter, scheduled for 11:54 Pacific Time, is responsible for compressing the InSight damping legs, activating the sensors at the top of its struts. Triggering these sensors cuts the LG's retrorockets and sends two signals: one to indicate that the robot has landed and a second, seven minutes later, to indicate that the robot is functional.

Then, assuming that everything went well up to this point, comes the celebration; InSight will only start doing science weeks later. First and foremost, NASA engineers will need to use a camera, connected to the robotic arm of InSight, to analyze the environment and determine the ideal location for placing its two main scientific instruments: a thermal probe self-boring and a succession of earthquakes. Sensing Seismometers Once they have decided where to place them, they will use a five finger grab at the end of the arm to lift the search instruments from the InSight Bridge (a shelf, attached to it). lander), then lift them up into the air. , and place them on the surface of the planet – a maneuver described by an InSight payload systems engineer, which has been described as being similar to the game of the claw you play at. Arcade, to millions of kilometers away.

Fortunately for them, InSight operators will be able to practice the claw game at JPL's In-Situ Instrument Lab in Pasadena – a life-size mock-up of the LG and its landing site that mission planners will use to perfect their control of the robot before teleporting it. instructions in deep space. There may be no way to repeat the landing of a robot on Mars, but at least the engineers at InSight will be able to repeat that.

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