The Crew Dragon spacecraft, produced by the private company SpaceX, is scheduled to return from the International Space Station (ISS) and splash into the Atlantic Ocean on August 2. astronauts Robert Behnken and Douglas Hurley will begin the attack procedure on August 1 and re-enter the Earth’s atmosphere the next day, a total of 64 days from ascent.
The historic launch took place on May 30 from NASA’s Kennedy Space Center in Florida, marking the first time a commercial space company has taken humans into orbit around Earth. But while the launch was a nail-biting experience, the re-entry will be even riskier, presenting a tense moment for mission control. Elon Musk, founder of SpaceX, said re-entry is in fact his “biggest concern.”;
The joint SpaceX and NASA mission was successful in achieving the ISS with the ISS, so the astronauts were able to perform scientific and maintenance work, including four spacecraft.
It is important to note that the main objective of the mission is to test and demonstrate the ability of the vehicle to transport the crew safely to and from Earth orbit, as a first step in the plan to initiate periodic ISS missions and flights. commercial spaces.
Re-entry danger points
The extreme speeds and temperatures the vehicle has to endure pose a major challenge for engineers and make re-entry the most dangerous part of a mission.
The danger begins with finding the correct angle of the trajectory as the spacecraft enters the upper atmosphere. If it is too steep, astronauts will experience potentially fatal g-forces and the friction of the air drag could cause the spacecraft to explode. If it is shallow, the capsule will jump catastrophically into place from the atmosphere and return to Earth orbit.
The spacecraft will enter the atmosphere at more than 27,000km / h. That is, 7.5 km / second, or more than 20 times the speed of sound. In the units you prefer, this is fast. At these speeds, a very strong shock wave forms around the front of the vehicle, compressing and overheating the air. Managing the immense thermal load is a huge challenge in reentry engineering.
At the most extreme stage, the temperature of the air in the shock layer exceeds 7,000 ° C. In comparison, the temperature at the surface of the Sun is about 5,500 ºC. This makes the vehicle’s heat shield so hot that it starts to glow, a process called incandescence. The new and advanced thermal protector of SpaceX’s PICA-X material has managed to protect the capsule on test flights, then recovering in a highly carbonized state.
The air molecules around the vehicle also break down into positively charged atoms and free electrons, a so-called plasma. When some of the molecules recombine, the excess energy is released into photons (light particles), giving the vehicle air an amber glow.
This layer of plasma can be beautiful, but it can cause radio blackouts. When an electron travels through a conducting wire, we have electricity. Similarly, when free electrons move through the plasma around the vehicle, we have an electric field. If the electric field becomes too strong, it can reflect and attenuate the radio waves trying to reach the spacecraft.
Shutdown not only results in a loss of connection to the crew and flight data on board, but can also make remote control and orientation impossible. The Apollo missions, the Mars Pathfinder and the recent failed Soyuz rocket of 2018 launched the entire shutdown of communications based on the order of the minutes. NASA mission control predicts a nervous six-minute hiatus during the maximum warm-up phase of Crew Dragon’s return – if there’s anything wrong during that time, it’s in the hands of astronauts.
Another risky stage is the parachute-assisted landing. The crew’s Dragon will deploy four parachutes in the final re-entry phase as the vehicle descends toward a gentle splash in the Atlantic Ocean off the Florida coast. SpaceX has tested this maneuver 27 times before the crew disembarked next week, so it should work.
A successful landing will have huge implications: lowering the cost of space exploration through the use of reusable rockets and allowing private space exploration. While SpaceX designed the NASA-contracted Crew Dragon vehicle, the company is free to use the spacecraft for commercial flights without NASA’s involvement after operational certification.
SpaceX has a partnership with commercial aerospace company Axiom Space, which has the ultimate goal of building the world’s first commercial space station. The proposed commercial activities for the station are broad: from space research and manufacturing to support for space exploration.
Then there is space tourism. Private citizens are already queuing for their ticket into space and, with a successful Crew Dragons splash, they won’t wait long. The American space tourism company Space Adventures (associated with SpaceX) plans to offer zero-gravity atmospheric flights, orbital flights with the option of a spacewalk and Moon vaults by the end of 2021.
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Whether the cost of tourism, the environmental impact, and the dangers of space flow are justifiable for space tourism is debatable. As this article shows, the security information required for Space Adventure ticket holders will be much more extensive than you needed “please take a moment to read the security card from the seat pocket in front of you”.