Return to the Moon with Artemis

FAS Astronomers Blog, Volume 30, Number 11.

Humans last set foot on the Moon in December 1972 when Apollo 17 landed in the Taurus-Littrow region. After three lengthy EVAs on the surface, Eugene Cernan returned to the Lunar Module on the morning of December 14. They lifted off from the Moon later that evening. This was 50 years ago, and no one has returned to the Moon since then.

There have been many lunar robotic explorers over the years. The United States has been studying the Moon from orbit since 2009 with the Lunar Reconnaissance Orbiter (LRO). Recently the Chinese have been exploring the surface of the Moon with their Chang’e series of spacecraft.

However, we’re going back! NASA is planning on returning humans to the Moon in 2025 with the Artemis program. The hardware supporting Artemis includes the Space Launch System (SLS), Orion spacecraft, Commercial Landing Craft, and Commercial Payload Services. In addition, a Lunar Gateway is in the works.

Space Launch System (SLS)

The Space Launch System (SLS) is the successor to the Saturn V rocket. It stands 365 Feet high, about the same as the Saturn V. The core rocket is powered by four RS-25 engines, each providing around 500,000 lbs. of thrust. Two solid rocket boosters will burn for two minutes and provide an additional 3.6 million lbs. of thrust each during the initial SLS launch period.

SLS will have three iterations, Block 1, Block 1B, and Block 2, each with a crew and cargo configuration. The Block 1 will include an Interim Cryogenic Propulsion Stage (ICPS) with a RL-10 engine that generates 24,750 lbs. of thrust. For the Block 1B and 2 configurations, the initial stage will send an Exploration Upper Stage (EUS) into deep space. This upper stage is powered by four RL-10 engines for a total thrust of 97,000 lbs.

Orion Spacecraft

Sitting on top of the SLS complex is the Orion spacecraft. Orion is the successor to the Apollo capsule of the 1960s and 1970s. It looks much like Apollo but is larger and more sophisticated. Orion will carry a crew of four to deep space including destinations such as the Moon and possibly Mars. Its configuration is similar to Apollo with a crew module, service module, and launch abort system.

In December 2014, NASA performed the first test flight of the Orion spacecraft. Although, the test was launched from a Delta IV rocket (not the SLS) and the flight lasted only 4 ½ hours.

Human Landing System (HLS)

SpaceX’s Starship HLS will handle the initial landings on the Moon. This will be very different than the way in which the Apollo missions landed using the fragile lunar module (LM). The SpaceX configuration is much larger and is designed to land and take off in its entirety, while the LM had distinct decent and ascent stages. Starship HLS will launch from the Earth using a Super Heavy booster rocket and after being refueled in orbit, will fly to the Moon. The LM, on the other hand, traveled to the Moon attached to the Apollo spacecraft. The Orion spacecraft will rendezvous with the Starship HLS in lunar orbit, and it will then transport two astronauts to the lunar surface. Once on the surface, the Starship HLS will act as a base for the astronauts, providing more room and resources than the LM.

In March 2022, NASA announced that it will consider employing a second landing system from an alternative supplier for future Artemis missions.

Lunar Gateway

In the longer term, NASA plans on putting a Lunar Gateway into orbit around the Moon. This will be the rendezvous hub for future Artemis missions. The Orion spacecraft and the Starship HLS will dock at the gateway, and transfer crew and materials for landings and eventual return to the Earth.

Artemis Program

The SLS and Orion spacecraft are the primary hardware for the Artemis missions to the Moon.

Three test missions are currently scheduled over the next few years.

• Artemis I was an uncrewed circumlunar flight and the first full test of SLS and Orion. It flew in November and December 2022.
• Artemis II will be a crewed circumlunar flight. It is currently scheduled for 2024.
• Artemis III will be the first human landing sometime in 2025.

Artemis I

The Artemis I flight was a four 1/2-week mission designed to test all facets of the Artemis spacecraft. It travelled to the Moon and performed a close loop followed by a push out beyond the Moon. After several days to a couple weeks, Artemis again looped around the Moon and then head for home. It landed in the Pacific Ocean off the coast of Baja, California.

After two unsuccessful launch attempts (August 29 and September 3), NASA was hoping to launch Artemis I on Tuesday, September 27^th during a window starting at 11:37 am EDT. They were able to fix the hydrogen fuel leak that caused the second delay. The line seals were replaced, and they performed a successful test of the system. NASA also received permission from the U. S. Space Force to extend the certification of the batteries for the flight termination system. Then came hurricane Ian, which forced NASA to roll the rocket back into the Vehicle Assembly Building. Once the hurricane passed, NASA was looking at three possible launch dates, although, the first was cancelled because of tropical storm Nicole.

• Monday, November 14 starting at 12:07 am EST
• Wednesday, November 16 starting at 1:04 am EST
• Saturday, November 19 starting at 1:45 am EST

After another delay, Artemis I launched from the Kennedy space center early on Wednesday, November 16. NASA has a nice video summarizing the first part of the flight at https://youtu.be/fNSmLNWyojA. Artemis I completed around 25 days in space before splashing down in the Pacific Ocean on Sunday, December 11.

Artemis III Landing Site(s)

In March 2019, Vice-President Mike Pence announced that Artemis III will land near the Moon’s South Pole to take advantage of water ice that might be hiding in permanently dark craters. NASA repeated this goal over subsequent months. Then, in September 2020, NASA administrator Jim Bridenstine suggested that the earlier Apollo landing sites could be alternative choices for Artemis landings. However, in August 2022, NASA announced that 13 potential landing sites, all near the Moon’s South Pole, have been chosen for the Artemis III mission.

To explore these possible landing sites, NASA will send the rover VIPER (the Volatiles Investigating Polar Exploration Rover) to the Moon’s South Pole in late 2023 and search for water ice.

SpaceX

NASA isn’t alone with a focus on deep space. SpaceX is developing its Starship, which at almost 400 feet tall, will rival NASA’s SLS. Starship will eventually be SpaceX’s primary means of traveling beyond Earth orbit to the Moon and Mars.