The Crew Dragon spacecraft, manufactured by private company SpaceX, is scheduled to return from the International Space Station (ISS) and disperse into the Atlantic Ocean on August 2. Weather-friendly forecast and a successful final week contingent at ISS, NASA. Astronauts Robert Biehanken and Douglas Hurley will begin the delicate process on August 1 and re-enter the Earth’s atmosphere the next day – a total of 64 days since the lift has been shut down.
The historic launch took place on May 30 from NASA’s Kennedy Space Center in Florida, which marked the first time a commercial space company orbited humans into Earth’s orbit. But while the launch was a nail-biting experience to watch, reentry would be even more risky to present stressful moments for mission control. SpaceX founder Elon Musk said Reentry is indeed his “biggest concern”.
The joint SpaceX and NASA mission was successful in docking with the ISS, so that astronauts could complete scientific and maintenance work, including four spacewalks.
Crucially, the mission’s primary objective is to test and demonstrate the ability of the vehicle to safely transport the crew from Earth orbit, as a first step in plans to undertake regular ISS missions and commercial space flights. To do.
Rantry danger points
Extreme velocity and temperature should present a major challenge for the vehicle and reproduce the most dangerous part of the mission.
The threat 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 lethal G-forces, and the friction of air drag can cause the spacecraft to burst. If it is too shallow, the capsule will instead destructively leave the atmosphere and return to Earth’s orbit.
The spacecraft will enter an upper atmosphere of 27,000 km / h. This is 7.5 km / s, or 20 times the speed of sound. Whichever units you prefer – it’s fast. At these velocities, a very strong shock wave is formed in front of the vehicle, compressing and superheating the air. The management of immense thermal loads is a huge retry engineering challenge.
At the most extreme stage, the air temperature in the shock layer exceeds 7,000 ° C. In comparison, the temperature on the Sun’s surface is about 5,500 ° C. This makes the heat shield of the vehicle so hot that it starts to glow – a process called incandescent. SpaceX’s new and improved PICA-X material has managed to protect the capsules in heat shield test flights, which have since been recovered in a very sacred condition.
The air molecules around the vehicle also break down into positively charged atoms and free electrons – a so-called plasma. When some molecules recombine, the excess energy is released as photons (light particles) – giving the air around the vehicle a glow.
This plasma layer can be beautiful, but it can cause radio blackouts. When an electron travels along a conductive 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 radiation trying to reach the spacecraft.
The blackout is not only a loss of connection to on-board crew and flight data, it can also make remote control and guidance impossible. The Apollo mission, Mars Pathfinder and the recently failed 2018 Soyuz rocket blacked out all communications on the order of minutes. Crew Dragon’s return to NASA’s mission control anticipates a six-minute nervous blackout during the extreme heating phase – if anything goes wrong during this time, it’s in the hands of astronauts.
Another risky phase is parachute-assisted landing. The crew will deploy the Dragon’s four parachutes in the final stages, as the vehicle descends from the coast of Florida toward a soft splash in the Atlantic Ocean. This maneuver has been tested by SpaceX 27 times before next week’s landing, so it should work.
A successful landing would have enormous implications – reducing the cost of space exploration through the use of reusable rockets and enabling private space exploration. While SpaceX manufactured the Crew Dragon vehicle under contract with NASA, the company is free to use the spacecraft for commercial flights without NASA 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 commercial activities proposed for the station are extensive: from space research and manufacturing to space exploration support.
Then there is space tourism. Private citizens are already in the queue for their ticket to space, and with a successful crew dragon splashdown, they won’t wait long. The American space tourism company, Space Adventures (partnering with SpaceX), plans to offer zero-gravity atmospheric flights, orbital flights with the spacewalk option, and the adoption of the moon by the end of 2021.
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Are the costs, environmental impacts, and hazards of spaceflight justified for space tourism. As this article suggests, the security briefing required for Space Adventure ticket holders will be a lot more comprehensive than your regular “Please take a moment to read the security card in your front seat pocket”.