NASA is preparing to launch its Artemis Moon mission next month. The mission will launch the Orion spacecraft into lunar orbit, where it will travel hundreds of thousands of miles before returning to Earth. As part of its trip to the moon, Orion will follow a distant retrograde orbit (DRO), which will give it enough time on the moon to ensure all its systems are operational and capable of supporting the next mission to return upon return Crew before Earth will also head to lunar orbit.
The Artemis 1 mission was due to lift off at the end of August, but a problem with the Space Launch System (SLS) rocket’s temperature sensor forced the NAA to cancel the attempt because of the potential risk to the engine due to erroneous readings. The next launch attempt in September was canceled because the hydrogen fuel that powers the rocket engines continued to leak to dangerously high levels.
After the second launch attempt, engineers repaired the rocket on the launch pad and successfully tested it, but then fate struck in the form of Hurricane Ian, which forced them to roll the rocket back to the launch pad. Now, they’ve set a new launch date of November 14, and the Orion spacecraft is ready to fly to the moon on NASA’s DRO.
The orbit was originally studied as part of the Asteroid Redirection Experiment, which NASA had hoped to use to redirect an asteroid close to Earth and make it orbit the moon instead. At the time, scientists had estimated that if an asteroid were placed in a DRO, it could potentially orbit the Moon for hundreds of years due to its stability.
The Asteroid Redirection Program (ARM) is a prelude to NASA’s planned Mars mission, as through it the agency hopes to evaluate the operation of a “space tugboat.” It was originally intended to reduce the cost of transporting people to the Red Planet, and was intended to first send cargo via an electrically powered ion propulsion engine. ARM will test these engines and, as a bonus, place an asteroid in a DRO around the moon.
This orbit is stable because it includes two equilibrium points between the Earth and the Moon, allowing the celestial body to balance itself using the balance between the gravitational forces of the two celestial bodies. In short, this “balancing” requires minimal effort from the spacecraft to ensure that gravity does not significantly affect its trajectory. In celestial mechanics, these points are called Lagrange points, named after the Italian mathematician Joeseph-Louis Lagrange.
After separating from the SLS rocket, Orion will travel 240,000 miles to the Moon, and then another 40,000 miles to the farthest point of the DRO. It will spend nearly three weeks in lunar orbit, during which various systems onboard such as navigation, guidance, communications, power and life support systems will be tested before the next mission takes astronauts into lunar orbit.
On the return journey, the spacecraft’s heat shield will reach 5,000 degrees Fahrenheit while the spacecraft is traveling at 25,000 miles per hour. When entering Earth’s atmosphere, Orion will use parachuting to re-enter the atmosphere — in this way, it will “jump” through the upper levels of the atmosphere before attempting to land in the Pacific Ocean.