Capping off a 25-day trip around the moon, NASA’s Artemis 1 spacecraft edged closer to Earth on Saturday, on track for a 25,000mph re-entry on Sunday that will subject the unmanned capsule to hellish hell of 5,000 degrees before splashing off Baja California.
In an unexpected but symbolic coincidence, the end of the Artemis 1 mission, expected at 12:39 p.m., will occur 50 years to the day after the final Apollo moon landing in 1972.
Testing the Orion capsule’s 16.5-foot-wide Apollo-derived Avcoat heat shield is the Artemis 1 mission’s top priority, “and it’s our top priority for a reason,” said mission leader Mike Sarafin.
“There is no arc jet or aerothermal facility here on Earth capable of replicating hypersonic re-entry with a heat shield of this size,” he said. “And it’s a whole new heat shield design, and it’s safety critical equipment. It’s designed to protect the spacecraft and (future astronauts)…so the heat shield has to work.”
SpearOn the maiden flight of NASA’s massive new Space Launch System rocket, the unmanned Orion capsule was blasted out of Earth orbit and onto the moon for an exhaustive series of tests, putting its propulsion, navigation systems , power and computer-proof in the deep space environment.
As flight controllers encountered as-yet-unexplained problems with its power system, initial “funnies” with its star trackers, and degraded performance of a phased array antenna, the Orion spacecraft and its service module built by the European Space Agencyachieving virtually all of their main goals so far.
“We have collected an immense amount of data characterizing system performance from the power system, propulsion, GNC (guidance, navigation and control) and so far the flight control team has performed downlink to over 140 gigabytes of engineering and imagery data,” said Jim Geffre, Orion Vehicle Integration Manager.
The team is already analyzing this data “to help not only understand the performance of Artemis 1, but also to move forward for all subsequent missions,” he said.
If all goes well, NASA plans to follow the Artemis 1 mission by sending four astronauts around the moon on the program’s second flight – Artemis 2 – in 2024. The first moon landing would follow in the 2025-26 timeframe when NASA announces the first woman and the next man will set foot on the lunar surface.
The unpiloted Artemis 1 capsule completed half an orbit around the moon that took it farther from Earth – 268,563 miles – than any previous human-sized spacecraft. Two critical ignitions of its main engine set up a low-altitude lunar flyby last Monday which, in turn, set the craft on course for splashdown on Sunday.
NASA originally planned to take the ship west of San Diego, but an expected cold front bringing stronger winds and rougher seas prompted mission officials to move the landing site south. about 350 miles. Splashdown is now expected south of Guadalupe Island, about 200 miles west of Baja California.
Approaching from nearly full south, the Orion spacecraft, traveling at 32 times the speed of sound, is expected to re-enter the perceptible atmosphere at an altitude of 400,000 feet, or about 76 miles, at 12:20 p.m.
NASA planners have devised a unique “entrance jump” profile that will blast Orion to the top of the atmosphere like a flat rock jumping across calm water. Orion will plunge from 400,000 feet to about 200,000 feet in just two minutes, then climb back up to about 295,000 feet before resuming its computer-guided fall toward Earth.
Within a minute and a half of entry, atmospheric friction will generate temperatures across the heat shield reaching nearly 5,000 degrees Fahrenheit, enveloping the spacecraft in an electrically charged plasma that will block communications with flight controllers for approximately five minutes.
After another two-and-a-half-minute communications blackout during its second fall into the lower atmosphere, the spacecraft will continue to decelerate as it nears the targeted landing site, slowing to around 650 mph, about the speed of sound. , about 15 minutes after the start of the entry.
Finally, at an altitude of approximately 22,000 feet and at a speed of approximately 280 mph, small drug parachutes will deploy to stabilize the spacecraft. The ship’s main parachutes will deploy at an altitude of around 5,000 feet, slowing Orion to around 18 mph for the splashdown.
Expected duration of the mission: 25 days 10 hours 52 minutes, covering 1.4 million miles since takeoff on November 16.
NASA and Navy recovery teams aboard the amphibious docked ship USS Portland will be within sight of the splashdown, ready to secure the craft and tow it into the “well deck “flooded from the Navy ship.
Once the bridge doors are closed, the water will be pumped out, leaving Orion on a custom stand, protecting his heat shield, for the return trip to Naval Base San Diego.
But first, the recovery team will wait up to two hours while engineers collect data on how the heat of re-entry entered the spacecraft and what effects, if any, it might have on crew cabin temperature.
“We’re on track to have a fully successful mission with some bonus goals we’ve achieved along the way,” Sarafin said. “And on the day of entry, we will achieve our overriding goal, which is to demonstrate the vehicle in lunar re-entry conditions.”
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