Seven Minutes of Terror

– Perseverance arrives on Mars –

After launching on July 30th from Cape Canaveral and spending over 6 months traveling through the solar system, the new Perseverance rover is about to arrive at Mars. Before it can begin to explore the surface of the red planet, however, it must endure a harrowing descent.

On February 18th Perseverance and its protective capsule will enter the Martian atmosphere at around 12,500 mph (20,000 kph). The descent will last approximately seven minutes, often referred to as the seven minutes of terror. In that time a number of steps must go right for this 2.2-billion-dollar spacecraft to touch down on the surface in one piece.

First the spacecraft will separate from the cruise stage. This contains solar panels and fuel tanks, and it allowed the spacecraft to navigate to Mars. A few minutes after stage separation the spacecraft will line up on the optimal attitude to enter the Martian atmosphere and begin the seven minutes of terror.

Upon entering the atmosphere, the spacecraft starts to slow down due to air resistance, but traveling through the atmosphere at this speed generate a whole lot of friction causing it to heat up dramatically. The spacecraft is protected by a large heat shield at this point and thrusters are used to keep it on course.

Two minutes and forty-five seconds from touchdown, a supersonic parachute is deployed and shortly thereafter the heat shield is released. The spacecraft is now moving slowly enough through the atmosphere that it is no longer necessary.

With the heatshield revealing the rover, the spacecraft can now see Mars with its cameras and will take pictures of the surface of the planet. It will use this imaging capability to ensure that it is on course for its desired landing area and that the touch down location is free of obstacles. The onboard computer can use these images to adjust the descent of the spacecraft if necessary.

With about one minute left in the descent, the back shell of the spacecraft that contains the parachute will separate and the rover will descend on what is essentially a jet pack.

Right before touchdown this jetpack will lower the rover to the surface of Mars like a flying crane. It will release the rover and fly off at an angle before running out of fuel to ensure it does not fall on the rover. Now Perseverance can get its bearings and slowly boot up for surface exploration.

If this process doesn’t sound complicated enough for you, consider this; the landing lasts seven minutes. At the current distance from Earth, about 120 million miles, the light delay is around eleven minutes. This is the time that it would take for a signal to reach the Earth from Mars, not to mention another eleven minutes for a round trip. If something were to go wrong on the descent, the Engineers would not even know until a few minutes after it was all over.

The entry, descent, and landing (called EDL by those at NASA) portion of the mission will take place without any human intervention and thousands of things could go wrong. Fortunately, the people at NASA know what they’re doing, in fact they used almost this exact EDL system to deliver Curiosity to Mars back in 2012.

Best of luck to NASA and to us all. A mission like this is for the benefit of all of humanity. Stay tuned for more posts soon about the Perseverance rover itself and its companion, the Mars helicopter.

Sources: ,

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