When NASA astronauts return to the surface of the moon in the Artemis III mission, the plan is to use a modified SpaceX Starship as their lunar lander. NASA announced last week that SpaceX has now demonstrated an important capability of the vacuum-optimized Raptor engine that will be used for the lander: an extreme cold start.

A test last month successfully confirmed the engine can be started in the frigid conditions of space, even when the vehicle has spent an extended time in space, where temperatures will drop lower than a shorter low-Earth orbit mission. The Raptor vacuum engine was chilled to mimic conditions after a long coast period in space, and then was successfully fired.

SpaceX has a video on X (formerly Twitter) showing the test firing.

NASA said that one challenge that differentiates Artemis missions from those in low Earth orbit is that the landers may sit in space without firing for an extended period of time, "causing the temperature of the hardware to drop to a level below what they would experience on a much shorter low Earth orbit mission.

On Sept. 5, 2022, NASA's Parker Solar Probe soared gracefully through one of the most powerful coronal mass ejections (CMEs) ever recorded—not only an impressive feat of engineering, but a huge boon for the scientific community.

A study published in npj Microgravity, finds an engineered compound given to mice aboard the International Space Station (ISS) largely prevented the bone loss associated with time spent in space.

The study, led by a transdisciplinary team of professors at the University of California at Los Angeles (UCLA) and the Forsyth Institute in Cambridge, Massachusetts, highlight a promising therapy to mitigate extreme bone loss from long-duration space travel as well as musculoskeletal degeneration on Earth.

Microgravity-induced bone loss has long been a critical concern for long-term space missions. Decreased mechanical loading due to microgravity induces bone loss at a rate 12-times greater than on Earth. Astronauts in low Earth orbit may experience bone loss up to 1% per month, endangering astronaut skeletal health and increasing risk for fractures during long-duration spaceflight and later in life.

The current mitigation strategy for bone loss relies on exercise-induced mechanical loading to promote bone formation but is far from perfect for crew members spending up to six months in microgravity.

Exercise does not always prevent bone loss, takes up valuable crew time, and may be contraindicated for certain types of injuries.