WASHINGTON — NASA’s Orion spacecraft is in the home stretch of the Artemis 1 uncrewed test flight as the agency prepares for the vehicle’s ultimate test: reentry and splashdown in the Pacific Ocean.
Project officials said at a Dec. 8 briefing that all was going well with the final phases of the Artemis 1 mission, with the 25.5-day mission set to conclude with a splashdown in the Pacific at about 12:40 p.m. Eastern Dec. 11.
One change in the mission’s final phases is the splashdown location. Judd Frieling, a flight director at NASA’s Johnson Space Center, said mission managers decided to move the splashdown from its original location off the coast of San Diego, California, by about 550 kilometers uprange, to the south. The spacecraft will instead splash down near Isla Guadalupe, west of Baja California.
He said both the primary landing site as well as alternate to the north were “no-go” because of weather conditions as a cold front is forecast to pass through the area around the time of splashdown. Mike Sarafin, Artemis 1 mission manager, later said concerns about flying the spacecraft through light rain, as well as winds and waves that could hamper recovery efforts, led them to move the landing zone.
“There was an uncertainty zone in there for the weather forecast,” Sarafin said, with conditions just on the edge of what would be acceptable, “and we moved south of the uncertainty zone.”
The change in landing location won’t affect recovery operations. The recovery team, on the U.S. Navy ship USS Portland, will arrive at the splashdown location at least 24 hours in advance to collect weather data to support reentry, said Melissa Jones, NASA landing and recovery director for the mission.
Once the capsule splashes down it will remain in the water for two hours to conduct a “soakback” test to see how the spacecraft manages the heat impulse from reentry. The recovery team, supported by small boats and helicopters, will then tow the capsule into the well deck of the USS Portland, placing it in a cradle and then draining the deck.
Testing Orion through reentry at lunar return velocities of about 40,000 kilometers per hour is the mission’s top priority. “There is no arcjet or aerothermal facility here on Earth of replicating hypersonic reentry with a heat shield of this size,” Sarafin said. “It is a safety-critical piece of equipment. It is designed to protect the spacecraft and the passengers, the astronauts on board. So the heat shield needs to work.”
Orion will also use a “skip” reentry, where the capsule reenters and descends to an altitude of about 60 kilometers, then ascends to 90 kilometers before descending again to splashdown. The maneuver is designed to reduce g-loads on the spacecraft and its occupants and also provide more flexibility in selecting a landing site.
Recovering Orion after splashdown is another major priority. That is both to study the spacecraft after its flight as well as recover several avionics units on the spacecraft that will be refurbished and reflown on Artemis 2.
Among 124 other objectives for testing Orion during the mission, Sarafin said more than 30% were complete and another 37.5% were in progress, in some cases collecting data up until reentry. The rest, he said, primarily involve objectives involved with reentry, splashdown and recovery, as well as a couple post-flight objectives, such as monitoring the spacecraft for corrosion from exposure to salt water.
The lack of major problems during the mission allowed NASA to add 14 objectives, of which 10 are complete, he said. The other four are in progress or yet to start work.
While the spacecraft has been largely healthy, officials said they are still trying to understand an issue with the spacecraft’s power system where devices called latching current limiters opened without being commanded to do so. That has happened 17 times over the Artemis 1 mission, Sarafin said.
“That is the one thing the team is working hard to understand. We have yet to achieve a root cause on that,” he said. Engineers are also monitoring degraded performance in recent days from a phased array antenna on the spacecraft that has caused some communications dropouts.