US Moon Landing: How to Watch and What to Know

On Wednesday morning, a robotic lunar lander launched by a Houston company moved closer to reaching the moon.

The company, Intuitive Machines, announced that its Odysseus spacecraft fired its engine for six minutes and 48 seconds, slowing it down enough to be pulled by the moon's gravity into a circular orbit 56 miles above the surface.

The landing on the moon is planned for Thursday. If all goes well, it will be the first private spacecraft to ever make a soft landing there and the first U.S. mission to arrive there since Apollo 17 in 1972.

When is the landing and how can I watch it?

Odysseus is expected to land on the moon's surface Thursday at 5:49 PM Eastern Time. Although it is a private mission, its main customer is NASA, which paid $118 million to deliver six instruments to the moon. NASA TV will stream the coverage of landing begins Thursday at 4:15 p.m.

Where will the spacecraft land?

Odysseus targets a spot in the Antarctic, a flat plain outside the Malapert A crater. (Malapert A is a satellite crater of the larger Malapert crater, named after Charles Malapert, a 17th-century Belgian astronomer.)

The landing site is about 300 kilometers from the moon's south pole.

Some of the craters in that area remain perpetually in shadow and are particularly interesting because water ice has been found in them. Previous US lunar missions have landed in the equatorial regions.

How will Odysseus land?

The spacecraft will fire its engine so that the circular orbit changes to an elliptical orbit, and will descend to within about six miles of the moon's surface. From this point on in the landing sequence, Odysseus will operate completely independently. After an hour of coasting, the engine will restart and the spacecraft will begin its powered descent. It will have to slow down from its original speed of about 6,000 kilometers per hour.

Odysseus will track its position via cameras, match the patterns of craters with stored maps and measure its height by bouncing laser beams off the surface.

About 2 km from the landing site, the spacecraft will spin upright, with sensors searching for a safe place.

During the last fifty feet of the descent, Odysseus will rely solely on his inertial measurement units, which act as the spacecraft's inner ear and measure acceleration forces. He stops using the camera and altitude measuring laser to avoid being fooled by dust kicked up by the engine's exhaust.

What will the lander do on the moon?

Because solar panels power the spacecraft, the mission will only last about seven days until the sun sets on the landing site. That's when a two-week, frigid moon night begins, and Odysseus was not designed to survive those conditions.

The six NASA instruments that Odysseus brought to the moon and what their tasks are:

• A laser retroreflector array that reflects laser beams.

• A LIDAR instrument that accurately measures the spacecraft's altitude and speed as it descends to the moon's surface.

• A stereo camera capturing video of the dust plume produced by Odysseus' engines during landing.

• A low-frequency radio receiver that measures the effects of charged particles on radio signals near the lunar surface and provides information that can help in the design of future radio observations on the moon.

• A beacon, Lunar Node-1, that will demonstrate an autonomous navigation system.

• An instrument in the propellant tank that uses radio waves to measure fuel levels.

The lander also carries other payloads, including a camera built by students at Embry-Riddle Aeronautical University in Daytona Beach, Florida; a precursor instrument for a future lunar telescope; and an art project by Jeff Koons.

How is the mission going so far?

Usually very good.

On February 14, a SpaceX Falcon 9 rocket sent Odysseus on a trajectory towards the moon. After the spacecraft broke away, it successfully turned itself on. An initial engine burn to test the propulsion system was postponed because the liquid oxygen propellant took longer to cool than ground tests had predicted.

Engineers adjusted ignition procedures and the burn was successfully performed on February 16.

Along the way, the spacecraft transmitted photos taken of both Earth and the moon.

Flight controllers fired the engine twice more, on February 18 and 20, to fine-tune the spacecraft's trajectory toward the moon. The second attempt was so precise that the flight controllers decided to skip a planned third correction.

How big is the spacecraft?

The Intuitive Machines lander is a hexagonal cylinder with six landing legs, approximately 4.5 meters high and 1.5 meters wide. For fans of “Dr. Who,” the science fiction television show, the lander's body is about the size of the Tardis, the time-traveling spacecraft that looks on the outside like an old British police telephone booth.

At launch, the lander, with a full charge of propellant, weighed approximately 4,200 pounds.

Why isn't NASA doing this mission?

Odysseus is part of NASA's Commercial Lunar Payload Services program, which allows private companies to send experiments to the moon and saves NASA from having to build and operate its own lunar landers.

The space agency hopes this approach will be much cheaper, allowing it to fly more frequent missions as it prepares to return American astronauts to the moon as part of its Artemis program.