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Crew Dragon returns to Earth – here’s when to catch your breath

The spaceship Crew Dragon, produced by the private company SpaceX, is scheduled to return from the International Space Station (ISS) and splash into the Atlantic on 2 August. Depending on a favorable weather forecast and a successful last week on the ISS, NASA astronauts Robert Behnken and Douglas Hurley will begin the undocking process on August 1 and re-enter Earth’s atmosphere the next day – a total of 64 days after takeoff.

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 transported humans into orbit around the Earth. But while the launch was a nail-biting experience to watch, feedback will be even more risky ̵

1; presenting a tense moment for mission control. SpaceX founder Elon Musk said the return is really his “biggest concern”.

The joint mission SpaceX and NASA succeeded in docking with the ISS, so that astronauts could complete scientific and maintenance work, including four spacewalks.

Picture of astronauts Bob and Doug on the ISS.
Astronauts Bob and Doug on the ISS.
NASAhandout / EPA

Most importantly, the mission’s primary purpose is to test and demonstrate the vehicle’s ability to safely carry the crew to and from Earth orbit, as the first step in the plan to embark on regular ISS missions and commercial spaceflight.

Repress danger

The extreme speeds and temperatures that the vehicle must withstand are a major challenge for engineers and make return to the most dangerous part of a mission.

The danger begins with finding the right angle on the orbit when the spaceship enters the upper atmosphere. If it is too steep, astronauts will experience potentially lethal g-forces, and the friction of the traction can cause the spacecraft to explode. If it is too shallow, the capsule will instead catastrophically jump over the atmosphere and back into the earth.

The spaceship enters the upper atmosphere at 27,000 km / h. It is 7.5 km / second, or more than 20 times the speed of sound. In which devices you prefer – this is fast. At these speeds, a very strong shock wave forms around the front of the vehicle, which compresses and overheats the air. Managing the enormous thermal load is a huge challenge for reentry engineering.

In the most extreme step, the air temperature in the shock layer exceeds 7000 ° C. By comparison, the temperature at the surface of the sun is about 5 500 ° C. This makes the vehicle’s heat shield so hot that it begins to glow – a process called light bulb. SpaceX’s new and advanced PICA-X material heat shield has succeeded in protecting the canister in test flights and is later recovered in a very charred state.

The air molecules around the vehicle are also broken down into positively charged atoms and free electrons – a so-called plasma. When some of the molecules are recombined, excess energy is released as photons (light particles) – which gives the air around the vehicle an amber.

This plasma layer can be beautiful, but it can cause radio interruptions. When an electron travels along a conductive wire, we have electricity. Similarly, when free electrons move through 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 spaceship.

Blackout not only leads to loss of connection to the onboard crew and flight data, it can also make remote control and guidance impossible. The Apollo missions, Mars Pathfinder and the recently failed 2018 Soyuz rocket launched all communication darkers in the order of magnitude. NASA mission control predicts a nervous six-minute blackout during the peak warming phase of Crew Dragon’s return – if anything goes wrong during this time, it’s in the hands of astronauts.

Another risky step is parachute-assisted landing. Crew Dragon will deploy four parachutes in the final stages of re-entry, as the vehicle descends toward a gentle splash in the Atlantic off the coast of Florida. This maneuver has been tested by SpaceX 27 times before next week’s crew landing, so it should work.

Future goals

A successful landing will have major consequences – reducing the cost of space exploration through the use of reusable rockets and enabling private space exploration. While SpaceX designed the Crew Dragon on a contract with NASA, the company is free to use the spacecraft for commercial flights without NASA participation after operational certification.

SpaceX has a partnership with the 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 research and manufacturing in space to support space exploration.

Then there is space tourism. Private citizens are already queuing for their ticket to space, and with a successful Crew Dragon splash, they will not wait long. The American space tourism company Space Adventures (in collaboration with SpaceX) plans to offer atmospheric flights with zero weight, orbital flights with a spacewalk alternative and lunar orbits at the end of 2021.

Read more: Elon Musk’s Starship could be more of a moral disaster than a bold step in space exploration

Whether the costs, environmental impact and dangers of space flight are justified for space tourism can be discussed. As stated in the articles, the necessary safety information for Space Adventure ticket holders will be much more comprehensive than your usual “please take a moment to read the security card in the seat pocket in front of you”.

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