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.