Thomas Pesquet flies to the ISS with SpaceX: his minute-by-minute take-off program

It's D-Day. This Friday, April 21, 2021, French astronaut Thomas Pesquet takes over the direction of the stars. Destination the International Space Station (ISS) aboard a supersonic taxi, capable of traveling at more than 27,000 km / h, designed by the American company SpaceX founded by Elon Musk.

Take-off, initially scheduled for Thursday at 12:11 p.m. (Paris time) was postponed by just under 24 hours due to unfavorable weather. It must intervene this morning at 11:49 am, still from the Kennedy Space Center, in the State of Florida, in the United States.

This Crew-2 mission, nicknamed Alpha by the European Space Agency, also includes two American astronauts, Shane Kimbrough and Megan McArthur, as well as a Japanese astronaut, Akihiko Hoshide. This is SpaceX's second mission to the ISS since the United States resumed manned spaceflight, and the first with a European on board, in the person of Thomas Pesquet. It is indeed a Russian spacecraft, the Soyuz MS-03, which had transported the astronaut from Rouen for his first stay in the ISS, between November 2016 and June 2017.

The course of the historic day that awaits him this Friday is very structured and has been repeated. The protocol to be respected is decided to the nearest second to take off. Ouest-France counts the main stages with the insight of a specialist, Olivier Sanguy, editor-in-chief of the space news site of the Cité de l'espace in Toulouse.

6:40 a.m. before takeoff: the alarm clock rings

Thomas Pesquet and his teammates will have to get up very early because takeoff is scheduled for 5:49 a.m. local time. In order to complete all the steps of the protocol, the Normand will have to be up… at 11 p.m. "He has shifted his sleep in recent days to get into the rhythm of this take-off day and because he will get jet lag once up there since Florida has a four-hour time difference with the ISS", indicates Olivier Sanguy .

4 hours before take-off: put on the suits

After a series of briefings, Thomas Pesquet and his teammates put on the futuristic white and gray suits provided by SpaceX. Checks are carried out on these tailor-made outfits then the astronauts leave the Neil Armstrong Operations & Checkout Building where they have their quarters, to head for the launch pad where the rocket is waiting.

3 h 20 before takeoff: goodbye

Leaving the Neil Armstrong Operations and Checkout Building, Thomas Pesquet and his teammates have the opportunity to greet their relatives who were able to go there. “They do a “virtual hug”, staying at a distance for health reasons, describes Olivier Sanguy. This distance to be respected is not specific to the coronavirus pandemic but to all space missions. Every precaution is always taken not to carry germs into the ISS. “There is always a quarantine before the launch”, had underlined Thomas Pesquet during his press conference given at the beginning of the week, stressing that the whole crew has also been vaccinated against Covid-19.

2 h 55 before take-off: arrival on the launch pad

The rocket is located 14 km from the Neil Armstrong Operations and Checkout Building. The astronauts are driven there in cars of the brand Tesla, the brand of Elon Musk. “The launch pad is the LC 39A. It is the former launch pad for the Apollo and Shuttle program missions. It is a NASA launch pad, but which is rented by SpaceX and which has been adapted to the Falcon 9 launcher and the Crew Dragon spacecraft, ”explains Olivier Sanguy.

2h35 before takeoff: entering the Crew Dragon capsule

To reach it, the astronauts will go up in elevator to 70 m height, along the launcher. “They will then enter the capsule, accompanied and assisted by personnel from SpaceX. They will sit in their place with a whole series of checks on the suits and the seats in particular. Then, he closes the hatch before a new series of checks”, describes Olivier Sanguy. "Mission Specialist 2", Thomas Pesquet is installed on the left. In the center, we find Megan McArthur and Shane Kimbrough, respectively pilot and commander. On the right is "Mission Specialist 1" Akihiko Hoshide.

45 minutes before takeoff: the “go/no go” survey

The SpaceX launch director makes a first tour of all the controllers responsible for monitoring each parameter. “If everyone says 'go', then we start filling the tanks with highly refined kerosene and liquid oxygen. There, it becomes serious, ”warns Olivier Sanguy.

35 minutes before takeoff: the tanks fill up

First, it is the tanks of the first stage which are filled, then those of the second stage. “We don't fill the tanks if the launcher isn't ready or if the weather isn't good. When the tanks are filled, there are only the astronauts on the launch pad, in the capsule. The capsule's emergency ejection system is armed to be triggered in the event of an explosion and the gangway is removed,” describes Olivier Sanguy. Then the motors cool down, the launcher switches to its internal power supply.

45 seconds before takeoff: last “go/no go” poll

Final human checks. “SpaceX's launch director makes a final 'go' call to his controllers. Afterwards, we switch to the automatic sequence, with computers monitoring until the last moment, continues Olivier Sanguy. The ground teams and the astronauts in the capsule can always intervene if they detect an anomaly, but all the commands to be executed are taken care of by the computers. "Human beings do not have the capacity to manage all of this alone in such a period of time", comments Olivier Sanguy.

11 h 49 m 02 s: takeoff

Three seconds before takeoff, the ignition sequence begins. “Once they're launched, it's pretty quick for the astronauts. In about twelve minutes, they will reach orbit, going from 0 km/h to 27,500 km/h”, summarizes Olivier Sanguy.

2 minutes 39 after takeoff: separation of the first stage of the rocket

Two seconds earlier, the Falcon 9 launcher's main engines shut down. The first stage detaches from the rest of the rocket while the second stage engine takes over to drive the Crew Dragon capsule into orbit. “The first floor is salvageable. Either it returns to the ground not far from the take-off location or on a barge at sea. It has moreover already been used during the first manned trip provided by SpaceX to the ISS in November 2020”, indicates Olivier Sanguy.

11 min 58 after takeoff: separation of the second stage of the rocket

A little over three minutes earlier, the second stage engine cut out. Relieved of this second stage, Thomas Pesquet and his teammates aboard the capsule spin at more than 27,000 km/h, in an environment where air and friction no longer exist. “We then open the front cover so that the docking system with the ISS is effective. And there begins a journey of about 23 hours to the ISS, which orbits about 400 km from the earth's surface, ”says Olivier Sanguy. This is the end of the dynamic phase.

"When everything has been checked, the astronauts will be able to take off their suits to put on their shirtsleeves, feed themselves, do their business because toilets are integrated on board", adds Olivier Sanguy. They will have to be put back before the docking phase with the ISS “to prevent the risk of depressurization”.

23 hours after takeoff: docking with the ISS

Again, it's fully programmed and automated, but the astronauts can intervene if necessary. “Before the appointments took rather two days, then the Russians recently did it in six hours and three hours. SpaceX remained on a more conservative flight schedule in 23 hours, ”notes Olivier Sanguy.

Once they arrive on the ISS, the four astronauts will join the seven current occupants of the station: the three crew members of the Soyuz-MS-18 mission who arrived in early April, and the four members of the Crew-1 mission, who took the first manned flight provided by SpaceX last November. These are the four that Thomas Pesquet and his companions come to relieve. Michael Hopkins, Victor Glover, Shannon Walker and Soichi Noguchi are due to return aboard their own capsule at the end of April.