As Firefly Aerospace prepared to close out a two-week mission on the moon, its lander had one final gift to beam home: the first high-definition images of a lunar sunset.
The company's Blue Ghost robotic spacecraft powered down on March 16 after completing a successful landing and operating 10 NASA experiments. But before going to sleep for the brutally cold lunar night, it conducted a study of the sunset. After the lander captured pictures from different camera angles, the Texas-based space company stitched them into a video (posted farther down in this story) to show the sun slipping below the horizon.
Scientists will study the images for a mysterious phenomenon known as "horizon glow," thought to be created when solar influences cause moon dust to levitate. The theory was established by an Apollo 17 astronaut, Gene Cernan, who sketched his observations into his field notes.
Following sundown, Blue Ghost operated for five more hours through the darkness of lunar night, continuing to take pictures, to monitor how the dust's behavior changed.
"What we see as the glow phenomenology looks very similar to what I've seen other astronauts put only in notes," said Jason Kim, Firefly's CEO, during a news conference, "and it does look green."
Many of the still frames reveal a bright light emanating from the sun, with another bright orb above it, Earth. Sandwiched between them and slightly to the right is a tiny point of light from Venus.
Firefly's Blue Ghost lander, named after an exotic type of firefly, touched down on March 2. It sits at Mare Crisium, a lunar plain made from an ancient hardened lava flow. The area is next to a volcanic feature, Mons Latreille, in the northeast quadrant on the near side of the moon.
The difficulty of that feat was underscored last week when Intuitive Machines, the first company to land on the moon last year (albeit tilted), was not able to even duplicate its partial success on its return. Intuitive Machines' Athena lander seemingly toppled in a crater, with its solar panels not pointing toward the sun. With the spacecraft unable to generate and replenish power, the company announced the mission was over.
"We didn't just get our foot in the door," Kim said. "We got all four feet fully planted on the moon, service stable, and upright. And so I think what that does is it really just validates our company model."
NASA paid Firefly $101.5 million to build the spacecraft and deliver experiments to the moon through its Commercial Lunar Payload Services program. The space agency wants to see a regular cadence of moon missions to prepare for astronaut-led Artemis expeditions in 2027 or later. Blue Ghost was the longest commercial mission on the moon to date.
"The Firefly Blue Ghost Mission-1 is what I would call an existence proof of how we wanted Commercial Lunar Payload Services to work," said Joel Kearns, a NASA deputy associate administrator.
Firefly engineers don't expect the spacecraft to survive the lunar night, but they will try to turn the lander back on in early April anyway. The company plans to launch another spacecraft to the moon as early as next year.
