Successful launch! Americans are used to successful launches to Mars, but amateurs and professionals alike are always apprehensive because the operation is obviously delicate. Here is the sequence of events that took place today (Western European Time):
1:50 p.m., firing and take-off performed at the scheduled time of the Atlas V rocket carrying the Mars 2020 mission (Cape Canaveral, Florida);
13:52, separation of the booster propellant (SRB for “Solid Rocket Booster”) required for takeoff;
1:54 p.m., opening and ejection of the fairing (supplied by RUAG) protecting the payload, in this case the “spaceship” comprising the service module, the lander with its heat shield and inside, the rover (mobile laboratory ) Perseverance ; NB the structure of the rover is identical to that of Curiosity, the instruments are a little different.
1:55 p.m., separation of 1is stage (CCB for “Comon Core Booster”) and release of the second stage “Centaur” carrying the spaceship, firing of this second stage;
2:04 p.m., end of the first combustion of the Centaur;
2:43 p.m., end of the second combustion of the Centaur which injects the spacecraft into its interplanetary trajectory towards Mars at a speed of 3.5 km / s in addition to the speed of the Earth around the Sun (about 30 km / s);
2:48 p.m., separation of the second stage of the rocket from the spacecraft;
3:17 p.m. establishment of radio contact between Earth and the spacecraft.
We are now awaiting the arrival of the spacecraft in the field of gravitational attraction of the planet Mars and we will have to face another difficulty, much greater than the takeoff sequence, that of the EDL (“Entry, Descent, Landing ”). This sequence should allow in less than 8 minutes to gently land the 1000 kg of the Perseverance rover (mobile laboratory) on the ground, that is to say to descend from an altitude of about 120 km to zero in using a heat shield, then a parachute and finally retro rockets over the last hundreds of meters… by adapting at the beginning to the irregularities of density of the Martian atmosphere and by avoiding any obstacles on the ground at the last moment. These operations must be carried out without human intervention, by means of automatisms finely regulated in advance, since the distance will be such that direct control will be impossible (time shift of a duration greater than that of the maneuver due to the finiteness of the speed of light and the distance to be crossed).
We understand that until now only the Americans have succeeded in the operation. I don’t want to put the Russians in the same category since their only probe that landed on Mars only survived 224 seconds. It can be inferred that “something” was wrong.
Then the adventure of robotic exploration of Mars will resume with Perseverance evolving in the magnificent setting of the river delta of the Jezero crater… until the fall of 2022 when the Terrans will send a new flock of robots. Among them the ESA should finally figure with its beautiful project Rosalind Franklin.
Title illustration: Separation of the spacecraft from the Centaur second stage. Notice the small size of this ship compared to the rocket. Credit NASA TV (screenshot).
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