Flying just 80 miles (130 kilometers) off the lunar surface, NASA’s Orion capsule fired its main engine Monday to slingshot around the moon and set a course for splashdown Dec. 11 in the Pacific Ocean to complete the Artemis 1 test flight.
The unpiloted spacecraft relayed home ethereal real-time views of the moon’s cratered surface and a crescent Earth suspended in the blackness of space a quarter-million miles away, offering a tantalizing glimpse of what’s to come on future Artemis lunar missions with the availability of 21st century technology.
In contrast to grainy, black-and-white imagery beamed back from the moon by NASA’s Apollo missions, the Orion spacecraft is fitted with a slew of color cameras capture sharp views from deep space. The 16 cameras flown on the Orion spacecraft include internal cameras and imagers mounted on the tips of the four solar array wings attached to the European service module.
The solar array cameras offer “selfie” views of the Orion spacecraft throughout its 25-and-a-half day mission as moonship looks back toward the Earth and the moon. On Monday, the selfie-cams recorded video of Orion speeding above the lunar surface at some 5,000 mph (8,000 kilometers per hour), showing the moon’s stark landscape of craters, mountains, and lava plains.
The engine burn Monday lasted 3 minutes and 27 seconds, changing Orion’s velocity by about 655 mph (961 feet per second). The engine burn and the effect of lunar gravity bent the Orion spacecraft’s trajectory to send it on a course toward Earth, targeting a splashdown in the Pacific Ocean west of San Diego on Sunday, Dec. 11.
This maneuver Monday was the final, and longest, burn of the Orion main engine on the Artemis 1 mission. The engine is a leftover from the space shuttle program, and flew as an orbital maneuvering system engine on 19 shuttle flights from 1984 through 2002. With the burn Monday, the engine’s service life is now complete.
The Orion spacecraft reached its closest point to the moon during the main engine burn Monday. The capsule will also flew over the sunlit nearside of the moon, soaring some 6,000 miles (10,000 kilometers) over several Apollo landing sites explored by astronauts more than 50 years ago.
“The part of the trajectory that is over those specific sites will be pretty far away from the moon,” said Zeb Scoville, NASA’s deputy chief flight director, in a press conference last week previewing Monday’s lunar flyby. “It’s actually about 6,000 miles above the surface when we will be passing over some of those Apollo sites. We will then dip behind the moon, and that’s where we’ll have our closest approach. That closest approach, we’ll a have a loss of signal again … and that will be as Orion goes into the eclipse and darkness.
“Then we’ll pop out of the backside, and be able to be on a trajectory back towards the west coast of the U.S. off of Los Angeles, and coming into the Pacific there,” Scoville said.
During the Orion spacecraft’s first powered flyby of the moon Nov. 21, much of the nearside of the moon was in darkness. This time, the nearside was illuminated.
“So we’ll see familiar features, the ‘man on the moon’ perhaps, and then more specifically the the craters and lava beds in the mare that we went and explored during the Apollo program,” Scoville said last week.
The Orion spacecraft’s wide-angle cameras aren’t sensitive enough to resolve any of the landers or equipment left behind on the Apollo exploration missions of the 1960s and 1970s, but the views Monday were spectacular.
The Artemis 1 test flight launched Nov. 16 from NASA’s Kennedy Space Center in Florida on the inaugural flight of the Space Launch System moon rocket, a 322-foot-tall (98-meter) behemoth that took a decade to develop.
The SLS moon rocket performed flawlessly, NASA officials said, sending the Orion capsule on a five-day track toward the moon, where it zoomed about 80 miles (130 kilometers) from the surface Nov. 21. The close flyby used lunar gravity to swing the Orion spacecraft into a distant retrograde orbit, or DRO, some 50,000 miles (80,000 kilometers) from the moon.
Another main engine burn Nov. 25 placed the Orion spacecraft into the DRO, so named because it is not a low-altitude orbit like the Apollo capsules of the 1960s and 1970s flew in, and because Orion is moving around the moon in the opposite direction the moon travels around Earth.
Mission planners chose the orbit for the Artemis 1 mission for several reasons. First, the Orion spacecraft’s propulsion system does not have the capability to steer the capsule into a low-altitude orbit around the moon as the Apollo missions did. And the DRO is stable because it is near the balance point between the pull of gravity from Earth and the moon, reducing the fuel Orion needs to burn to maintain its orbit.
The Orion spacecraft fired its engine again Thursday, Dec. 1, to leave the distant retrograde orbit and set a course for the so-called return powered flyby maneuver Monday.
The Orion spacecraft spent about six days in the distant retrograde orbit performing tests and checkouts, long enough to complete one-half of a lap around the moon. On Nov. 26, the capsule broke the distance record for a spacecraft designed to carry humans into space and return them to Earth, according to NASA.
The record was previously set on NASA’s Apollo 13 mission, which reached a distance of 248,655 miles (400,171 kilometers) from Earth when it looped around the far side of the moon with a three-man crew in 1970. Apollo 13’s moon landing was aborted when one of its oxygen tanks exploded on outbound journey from Earth, and the spacecraft steered onto a “free return” trajectory that took it farther from Earth than any of the other Apollo missions.
The Orion spacecraft reached its greatest distance from Earth on Monday, Nov. 28, at more than 268,500 miles (432,000 kilometers).
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