Post Content The Artemis II crew—NASA astronauts Reid Wiseman, Victor Glover, Christina Koch, and Jeremy Hansen from the Canadian Space Agency—are getting ready for re-entry aboard the Orion spacecraft. (Image: Nasa)
After a historic journey around the Moon, the four astronauts onboard NASA’s Artemis II mission returned to Earth this morning, having become the people to have gone the farthest-ever from the Earth’s surface.
The Orion spacecraft, carrying astronauts Reid Wiseman, Victor Glover and Christina Koch of the United States, and Jeremy Hansen of Canada, made a splashdown in the Pacific Ocean, off the coast of southern California shortly after 5 am India time on Saturday.
The four astronauts were the first to venture near the Moon in more than five decades, and even though they did not make a Moon landing, the trajectory of their spacecraft took them further in space than any of the Apollo missions that made the Moon landings in the 1960s and 1970s. Their spacecraft reached 252,760 miles (406,778 km) from the Earth at its furthest, which was about 4,105 miles (6,606 km) fa1.12rther than the distance Apollo 13 mission reached in 1970.
In all, during their 10-day journey, the astronauts on Artemis II mission travelled a distance of 694,481 miles (about 1.12 million km), which incidentally is not the maximum by a manned mission. The Apollo 17 mission, the last of the Apollo missions, for example, travelled a total distance of about 1.48 million miles (2.38 million kilometres). The average distance of Moon from the Earth is about 384,400 kilometres, so a point-to-point return journey would be at least 768,800 kilometres. But spacecraft have circuitous complicated trajectories, and the distance between Moon and Earth is also changing because they are both moving in elliptical orbits. The actual distances completed by space missions depends on mission design, including the time spent in lunar and Earth orbits, and the specific geometry of the Earth-Moon system during the journey.
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At the time of re-entry into the Earth’s atmosphere, the Orion spacecraft were travelling at a speed of about 11-12 km/sec (about 40,000-42,000 kmph). This is much higher than the 26,000-28,000 kmph speeds at which the spacecraft coming from the International Space Station (ISS) or other similar low-Earth orbits re-enter the atmosphere. This is because the lunar missions, coming from much further distances, spend far more time under the Earth’s gravity before re-entry, and thus get accelerated to higher speeds. The International Space Station, where astronauts regularly go to and spend time, is only about 400 km from the Earth, while the Moon is close to 400,000 km away. Higher speeds means higher energies because of which spacecraft coming from lunar orbits need to be much tougher to withstand the greater physical stress while making the re-entry into the Earth’s atmosphere.
Once inside, the Orion spacecraft, like any other spacecraft, was made to decelerate quickly. The first set of parachutes to slow down the spacecraft were deployed at an altitude of about 6 km, and another set was unfurled when the spacecraft was about 2 km from the surface. By this time, the spacecraft had been slowed down to a speed of about 200 km per hour. At the time of splashdown, the spacecraft was travelling at barely 30 km an hour. Teams from NASA and the US military were deployed at multiple locations near the site of the landing in the Pacific Ocean to extract the crew after the splashdown, and fly them to a ship placed nearby.
The success of Artemis II mission clears the deck for the first human Moon landing in more than five decades, tentatively scheduled for 2028 right now. Artemis II was the first crewed mission of the Artemis programme of NASA that seeks to get human beings back on the Moon, over than five decades after the Apollo programme got 12 astronauts, in six different historic missions, to walk on the Moon. The first mission of the Artemis programme, in 2022, was an uncrewed spacecraft that went around the Moon and came back. Artemis II successfully completed the dress rehearsal for the actual Moon landing mission in 2028. The Artemis programme marks the beginning of a new era in human spaceflight that is aiming at creating a permanent settlement on the Moon, and frequent travels by humans to the lunar surface.
© The Indian Express Pvt Ltd
