The Dragon crew spacecraft, built by the private company SpaceX, is scheduled to return from the International Space Station (ISS) and launch in the Atlantic Ocean on August 2. It depends on a favorable weather forecast and a successful last week on the ISS, NASA. Astronauts Robert Behnken and Douglas Hurley will begin the shutdown process on August 1 and re-enter the Earth’s atmosphere the next day – a total of 64 days after the lift.
The historic launch took place on May 30 from NASA’s Kennedy Space Center in Florida, the first time a commercial space company has brought people into orbit around Earth. But while launching was a nail experience, reentry will be even riskier ̵1; a tense moment to control the mission. SpaceX founder Elon Musk said the return was indeed his “biggest concern”.
The joint mission of SpaceX and NASA was successful in docking with the ISS so that astronauts could complete scientific and maintenance work, including four spacewalks.
Importantly, the main goal of the mission is to test and demonstrate the vehicle’s ability to safely transport the crew to Earth’s orbit and as a first step in the plan to launch regular ISS missions and commercial space flights.
Re-insert the hazardous locations
The extreme speeds and temperatures that the vehicle has to withstand are a major challenge for engineers and make them the most dangerous part of the mission.
The danger begins by finding the right angle of the trajectory as the spaceship enters the upper atmosphere. If it is too steep, astronauts will experience potentially deadly g-forces, and friction in air resistance can cause a spaceship to explode. If it is too shallow, the capsule will jump catastrophically from the atmosphere and back into Earth’s orbit instead.
The spacecraft enters the upper atmosphere at a speed of 27,000 km / h. That’s 7.5 km / s or more than 20 times the speed of sound. In any unit, you prefer – it’s fast. At these speeds, a very strong shock wave is created around the front of the vehicle, which compresses and overheats the air. Managing a huge thermal load is a huge challenge for technical engineering.
At the most extreme stage, the temperature of the air in the impact layer exceeds 7,000 ° C. In comparison, the temperature on the surface of the Sun is around 5,500 ° C. SpaceX’s new and improved PICA-X heat shield was able to protect the capsule during test flights and later appeared in a very burnt state.
The air molecules around the vehicle also decompose into positively charged atoms and free electrons – the so-called Plasma. When some of the molecules recombine, excess energy is released like photons (light particles), giving the air around the vehicle an amber glow.
This plasma layer can be beautiful, but it can cause radio outages. When an electron passes through a conductive wire, we have electricity. Similarly, when free electrons move through the plasma around a vehicle, we have an electric field. If the electric field is too strong, it can reflect and attenuate radio waves trying to reach the spaceship.
Eclipse not only leads to a loss of connection with the flight crew and flight data, but can also prevent remote control and guidance. The Apollo missions, the Mars Pathfinder, and the recently failed 2018 Soyuz missiles triggered all communication outages in the order of minutes. NASA is monitoring the mission for six minutes of nerve outage during the maximum warm-up phase of the Dragon crew’s return – if anything goes wrong during this time, it’s in the hands of the astronauts.
Another risk level is parachuting. The Dragon crew deploys four parachutes after the final phase of return as the vehicle descends toward a slight spray in the Atlantic Ocean off the coast of Florida. This maneuver was tested by SpaceX 27 times before landing with a crew for next week, so it should work.
A successful landing will have huge consequences – reducing the cost of space exploration through the use of reusable rockets and enabling the exploration of private space. While SpaceX designed the Crew Dragon under contract with NASA, the company has the option of using a spacecraft for commercial flights without NASA’s participation after operational certification.
SpaceX has partnered with the commercial airline Axiom Space, whose main goal is to build the world’s first commercial space station. The proposed business activities for the station are broad: from space industry research and manufacturing to space exploration support.
Then there is space tourism. Private citizens are already waiting in line for a ticket to space, and after the successful crash of the Dragon crew, they will not wait long. The American space tourism company, Space Adventures (in collaboration with SpaceX), plans to offer zero gravity atmospheric flights, space flight orbital flights and the moon’s wheels by the end of 2021.
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The question of whether the costs, the environmental impact and the dangers of space travel are justified for space tourism is questionable. As this article shows, the required security briefings for space adventure ticket holders will be much more comprehensive than your usual “take a moment to read the security card in the seat pocket in front of you.”