How the forecast off the West Coast will play into Artemis II’s return to Earth
After ten days, 600,000 miles, and a historic loop around the far side of the moon, the four-person crew of Artemis II is finally coming home. But while the mission has been a triumph of orbital mechanics so far, the final "mile" depends on something that we deal with every day: the weather.
As the Orion capsule prepares for a Friday evening splashdown, NASA flight directors aren't just looking at trajectory data, but they are also closely tracking wave heights and wind speeds in the Pacific Ocean. Here's all the physics that will go into this reentry, and why the forecast is the largest "Go/No-Go" factor.
Coming home from the moon is very different than returning from the International Space Station. Orion will hit the Earth's atmosphere at a staggering 24,840 mph. If the capsule came straight down, the G-forces would be too much for the human body to handle.
To solve this, NASA uses a "skip-entry" maneuver. Orion will dip into the upper atmosphere to bleed off velocity, "bounce" back up into space briefly, and then make its final descent. This maneuver also allows NASA to pinpoint a landing site with incredible accuracy. During this process, the heat shield will endure temperatures of 5,000 degrees Fahrenheit, which is roughly half the temperature of the surface of the sun. This will create a five-minute radio blackout as ionized gas surrounds the craft.
Once Orion is through the "fire" of reentry, it enters the "chute" phase. At about 25,000 feet, two drogue parachutes deploy to stabilize the capsule. The main action begins at 9,500 feet when the three massive main parachutes, which are large enough to cover a football field, unfurl in the California sky. These chutes must slow the 16,000-pound capsule from 325 mph to a gentle 17 mph for a safe splashdown.
This is where the meteorology becomes critical. NASA has a strict checklist for a safe recovery, that being sustained winds under 25 mph, wave swells under 6 feet, and no lightning or rain within 30 nautical miles of the target.
Currently, models show favorable conditions off the coast of San Diego. Wave heights will be around 4-5 feet, and light winds at 8-12 mph are expected. However, a 20% chance of isolated showers moving through the recovery zone Friday evening remains the "wildcard." If a stray cell moves over the recovery ship, it could force a last-minute adjustment to the landing coordinates.
While the splashdown is happening thousands of miles away, Missouri's fingerprints are all over this spacecraft. From Boeing's massive presence in St. Louis to precision manufacturing in O'Fallon, St. Charles, and Washington, Missouri, engineering built the backbone of the SLS rocket and the Orion capsule.
When those chutes open on Friday night, it's a win for the crew, but it's also a win for the thousands of Missourians who helped build the ship that took us back to the moon. The splashdown is scheduled for approximately 7:07 PM CDT on Friday, April 10th.
