A small NASA spacecraft is launched to test a new orbit around the moon

Early this morning, a small NASA spacecraft the size of a microwave oven set out at the beginning of a four-month journey to the Moon, where it will eventually settle into a unique, elongated lunar orbit that no NASA mission has visited before. . The spacecraft’s goal is simple: test out this special orbit and see what it’s like. This is because it is the same orbit that lunar astronauts can use in the coming decade.

This characteristic path is called “near the straight halobane,” or abbreviated NRHO. It is a special seven-day orbit that spacecraft can take around the moon, bringing vehicles relatively close to the moon’s surface for one day before turning far from the moon for the other six.

NASA is considering using this orbit for its Artemis program – the agency’s efforts to send the first woman and the first color to the surface of the moon. Over the next decade, NASA wants to build a new space station around the Moon called the Gateway, a place that will serve as a training platform and living space for future astronauts on their way to the moon’s surface. And the space agency wants to park the Gateway on this loop road around the moon.

Since NASA has not sent any spacecraft into this orbit before, the agency has no experience of what it is like to operate a vehicle there. This mission, called CAPSTONE, is meant to serve as a pathfinder. It can also be considered the first mission of the entire Artemis program, starting an intricately planned timeline that could culminate in people walking on the Moon again after more than half a century. “We look at the CAPSTONE mission as a whole as a valuable forerunner,” Nujoud Merancy, head of the Exploration Mission Planning Office at NASA’s Johnson Space Center, said during a news conference.

When astronauts went to the moon during Apollo, their path to the moon was a more or less straight shot on a massive rocket called Saturn V. When they arrived, they eventually sat in a relatively circular orbit around the moon, one that brought them within 62 miles from the surface. That way, they could get down to the ground and back in orbit relatively quickly.

This approach got them quickly to the Moon, but required a lot of resources. “Unfortunately, one of the things you have to look at when it comes to bringing spacecraft and equipment to the moon using the typical approach is the significant amount of fuel required,” said Elwood Agasid, vice president of small spacecraft technology at NASA. Ames Research Center, narrator The Verge.

An infographic that compares the different orbits that spacecraft can take around the moon
Image: NASA

With Artemis, NASA wants to try some new approaches to lunar exploration. By parking the gate in NRHO, the future lunar space station will come within 1000 miles from the moon’s south pole and swing out to 43,500 miles from the other pole each week. This close pass is a much larger distance than the Apollo astronauts had to cover to reach the ground. But NRHO offers other important benefits. Spacecraft in NRHO have a constant line of sight with Earth, which enables continuous communication. This is something the Apollo astronauts did not have; when in orbit, they passed on the other side of the moon, blocking their signals with the earth for almost an hour during each round.

Perhaps the biggest advantage is that staying in NRHO does not require as much fuel as it does to stay in a circular orbit around the moon. This is because this type of track is known as a three-body track; spacecraft on this route are affected by the gravitational force of the earth, the sun and the moon. As a result of this balancing act, this trajectory is relatively stable for spacecraft to maintain, and they do not need to use much fuel to stay on track or to travel down to the surface.

“It has the net benefit of low energy to get in and low energy to get out of,” Chris Baker, program director for NASA’s small spacecraft technology program, said during a news conference. Baker describes spacecraft in this orbit as “to ride on this balance point between the earth’s gravitational force and the moon’s gravitational force.”

Finding this balance is key, and NASA wants to verify when the Earth’s towing force increases on orbit and when the moon begins to enter. CAPSTONE will provide the mission team with real-time experience on what kind of maneuvers are needed and when fuel must be burned to keep a spacecraft on this trajectory.

A graphic, developed by Advanced Space which produced CAPSTONE, showing the ballistic lunar orbit the spacecraft will take to the moon
Image: Advanced Space

With CAPSTONE, NASA will also test a fairly long way to get to the moon. Since the vehicle is so small, it does not have much space for fuel, even if it is filled to the brim with what it can hold. “It’s a pretty tight package, mostly because the propulsion system takes up a lot of the mass, space and volume of the spacecraft,” says Agasid. ‘It’s packed. It’s a technological marvel. ” The spacecraft was also launched from New Zealand on a relatively small rocket called Electron, manufactured and operated by the American space company Rocket Lab. While Rocket Lab provides extra thrust with an extra booster called Photon, it still does not have much fuel to burn compared to, for example, a massive rocket like Saturn V.

So over the next four months, CAPSTONE will reach the moon through a route known as ballistic lunar transmission, or BLT. By using the sun’s gravitational effects, CAPSTONE will loop far from the Earth’s and lunar system, and spiral out farther and farther until it reaches the point where it can settle into the NRHO. It requires much less fuel to do, but much more time to complete.

CAPSTONE is scheduled to reach NRHO on 13 November. Once in orbit, it will remain for at least six months so that NASA can capture critical data about this lunar orbit. The agency also plans to test a new navigation option, where the spacecraft will try to determine its own position and speed in space. In this way, the vehicle requires less input from people on the ground, an ability that may prove useful for future interplanetary exploration.

When the mission is complete, NASA will send CAPSTONE on a crash course with the Moon, its historical work done. But for now, the mission team has to wait while the tiny satellite cars orbit the moon. “The benefits of NRHO are clear and we are pleased to see CAPSTONE test and validate this path for the first time,” said Merancy.