On December 19, 1972, astronauts Eugene Cernan, Harrison Schmidt, and Ronald Evans landed safely in the Pacific Ocean. The Apollo 17 lunar mission was the last in which humans traveled more than 1,000 kilometers above the Earth’s surface. About 49 years later, we’re approaching the launch of NASA’s Artemis 1 moon mission. Artemis is the latest in a long line of projects spanning many decades to attempt to return humans to the moon.
Artemis 1’s early launch attempts are currently scheduled for March 12th. Artemis 1 will not carry astronauts, but it will be the first spacecraft capable of making a return trip to the Moon with humans in nearly 50 years. The ultimate goal of the program is to establish a long-term human presence on and around the Moon. Artemis 1 is the first in a series of increasingly complex manned missions planned for the coming years.
Artemis 1 consists of an Orion spacecraft that will be launched by New Space Launch System (SLS) – Currently the world’s most powerful operational missile. Orion consists of the Crew Module, a conical capsule that can hold up to six astronauts for 21 days in deep space, and european service unit, which contains the main rocket engine Orion. The European service unit generates electrical power with special “x-wing” solar panels and contains water and air for breathing and fuel. It also controls the thermal environment in the crew unit, keeping astronauts and electrical systems within safe temperature limits.
The new Space Launch System consists of a massive liquid-fueled rocket powered by space shuttle-era engines and two powerful side-mounted solid-fuel rockets, producing nearly nine million pounds of thrust upon launch. On top of the grand stage is the intermediate cryogenic thrust stage, a smaller liquid-fueled engine that will propel Orion out of Earth’s orbit toward the Moon.
While the Space Launch System has never been tested before, the Orion spacecraft has. This was tested once in space, without astronauts, in 2014. Although this test flight in low Earth orbit was successful, it never made it to the moon. This is important, because objects returning from the Moon to Earth travel faster when they encounter our atmosphere than objects returning to Earth from low orbit. One of the main goals of Artemis 1 is to ensure that the thermal protection on Orion can withstand the enormous heat generated upon re-entry into Earth’s atmosphere.
Upon returning from a lunar mission, Orion will reach the atmosphere at a speed of 40 thousand km / h. The capsule will have to withstand temperatures up to 2760 degrees Celsius. By comparison, a spacecraft returning to Earth from the International Space Station (ISS) enters the atmosphere at 27,000 km/h and experiences 1,900°C.
When Artemis 1 launches — if all goes well — from the Kennedy Space Center on March 12, Orion will position itself 100 kilometers above the lunar surface after traveling for several days, firing its onboard engines and entering a distant retrograde orbit around the Moon. This will bring the capsule to a maximum distance of about 430 thousand km from Earth. From this distance, Earth appears to an astronaut the size of your little fingernail at arm’s length. It will be the largest distance a human-friendly spacecraft has ever reached. The current record holder is the 1970 Apollo 13 mission, which was forced to abort a lunar landing after an explosion in one of the spacecraft’s oxygen tanks.
During this time, engineers will test Orion’s systems, such as its ability to maintain air pressure and radiation levels in the crew compartment. While Artemis 1 is primarily about creating Orion’s viability for future manned missions, cameras at the ends of the ESM’s solar panels should provide stunning images of Orion in space, with Earth and the Moon as background.
After six days in lunar orbit, Orion will turn on the engines several times and fly close to the moon again before beginning its journey home. About 26 days after launch, Orion is expected to detach the European service module and then direct the flat base of the crew cabin, lined with thermal protection, toward Earth for what we hope will be a safe re-entry into the atmosphere and a parachute-assisted landing in the Pacific Ocean.
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