NASA’s uncrewed Orion capsule splashed down on Sunday on the final return leg of its voyage around the moon and back, winding up the inaugural mission of the Artemis lunar program 50 years to the day after Apollo’s final moon landing.
The gumdrop-shaped Orion capsule, carrying a simulated crew of three mannequins wired with sensors, parachuted into the Pacific around 4.40am (AEDT) off Mexico’s Baja California peninsula, three main parachutes clearly visible over the ocean as the capsule returned to Earth.
The Orion spacecraft approaching Earth on Sunday.Credit:NASA via AP
Orion completed its 25-day mission less than a week after passing within 127 kilometres of the moon during a lunar fly-by and about two weeks after reaching its farthest point in space, nearly 434,500 kilometres from Earth.
During its fiery re-entry, the capsule plunged back to Earth at 39,400 km/hr.
Orion blasted off on November 16 from the Kennedy Space Centre at Cape Canaveral, Florida, atop NASA’s towering next-generation Space Launch System (SLS), now the world’s most powerful rocket and the biggest NASA has built since the Saturn V of the Apollo era.
The debut SLS-Orion voyage kicked off Apollo’s successor program, Artemis, aimed at returning astronauts to the lunar surface this decade and establishing a sustainable base there as a stepping stone to future human exploration of Mars.
By coincidence, the return to Earth of Artemis I unfolded on the 50th anniversary of the Apollo 17 moon landing of Gene Cernan and Harrison Schmitt on December 11, 1972. They were the last of 12 NASA astronauts to walk on the moon during a total of six Apollo missions starting in 1969.
Hitting a penny with a football
Re-entry marked the single most critical phase of Orion’s journey, testing whether its newly designed heat shield would withstand atmospheric friction expected to raise temperatures outside the capsule to nearly 2760 degrees Celsius.
It was also a test of the advanced guidance and thruster systems used to steer the capsule from the moon to its proper re-entry point and through descent, maintaining the spacecraft at just the right angle to avoid burning up.
“It’s essentially like throwing a football 300 yards and hitting a penny,” Eric Coffman, Orion propulsion senior manager at Lockheed Martin Corp, which built Orion under contract with NASA, said prior to the re-entry.
An internal navigation and control system commands 12 on-board thrusters, fixed in recessed positions along the base of the capsule, to fire bursts of propellant as needed to keep the capsule oriented correctly and on course, he said.
The heat, speed and forces exerted on Orion on its return from the moon exceeded those endured by spacecraft making more routine descents from the International Space Station (ISS) or other flights from low-Earth orbit.
NASA officials had stressed the experimental nature of the Artemis I mission, marking the first launch of the Boeing-built SLS and the first combined with Orion, which previously flew a brief two-orbit test launched on a smaller Delta IV rocket in 2014.
Though the capsule encountered some unexpected communication blackouts and an electrical issue during its voyage around the moon, NASA has given high marks to the performance of both SLS and Orion so far, boasting that they exceeded the US space agency’s expectations.
If Artemis I is deemed a success, a crewed Artemis II flight around the moon and back could come as early as 2024, followed within a few more years by the program’s first lunar landing of astronauts, one of them a woman, with Artemis III.
Compared with Apollo, born of the Cold War-era US-Soviet space race, Artemis is more science driven and broad-based, enlisting commercial partners such as Elon Musk’s SpaceX and the space agencies of Europe, Canada, and Japan.
It also marks a major turning point for NASA, redirecting its human spaceflight program beyond low-Earth orbit after decades focused on space shuttles and the ISS.
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