Cosmic Space

Robotic probe begins monthslong voyage to the moon

A robotic probe that’s meant to blaze a trail for astronauts has begun a slow and steady trek to the moon, thanks to a launch from New Zealand on a commercial rocket.

NASA’s Cislunar Autonomous Positioning System Technology Operations and Navigation Experiment, also known as Capstone, lifted off from Rocket Lab’s launch pad on New Zealand’s Mahia Peninsula atop an Electron rocket at 2:55 a.m. PT (9:55 p.m. local time) today.

Because Rocket Lab’s Electron has far less oomph than, say, a Saturn V or Space Launch System rocket, the microwave oven-sized spacecraft will be sent along a leisurely, looping route that takes advantage of the gravitational pulls of the moon, the sun and Earth.

Today’s launch is due to be followed next week by a push from Rocket Lab’s third-stage booster. That engine firing should put the probe into a trajectory known as a ballistic lunar transfer, or BLT. If the maneuver works as planned, Capstone will range as far as 963,000 miles from Earth — more than three times the distance between Earth and the moon — and then work its way into a special type of lunar orbit.

In the weeks ahead, Capstone’s progress can be tracked using Eyes on the Solar System, NASA’s interactive real-time 3D data visualization. NASA plans to post updates about when to see Capstone in the visualization on the Ames Research Center’s home page as well as on Twitter and Facebook.

It’ll take about four months for Capstone to settle into its targeted 6.5-day orbit around the moon. The path that Capstone will trace is called a near rectilinear halo orbit. It’s the same type of orbit that NASA intends to use for its moon-orbiting Gateway space station. The first elements of the Gateway are due for launch in the 2024 time frame.

The halo orbit is attractive because it always keeps a spacecraft within view of Earth, and because the elliptical path makes it easier to transfer people and payloads to the lunar surface for NASA’s Artemis program. At its farthest, Capstone will be 43,500 miles above the moon’s south pole. At its closest, it’ll be just 1,000 miles above the north pole.

Mission planners intend to study the dynamics of the halo orbit over the course of at least six months.

“Capstone is a pathfinder in many ways, and it will demonstrate several technology capabilities during its mission time frame while navigating a never-before-flown orbit around the moon,” Elwood Agasid, project manager for Capstone at NASA’s Ames Research Center in California, said in a news release. “Capstone is laying a foundation for Artemis, Gateway, and commercial support for future lunar operations.”

Colorado-based Advanced Space owns and operates the Capstone probe on NASA’s behalf. One of the experiments aboard the spacecraft is a spacecraft-to-spacecraft navigation and communication system that was developed by Advanced Space with NASA’s support.

The Cislunar Autonomous Positioning System will work with NASA’s Lunar Reconnaissance Orbiter to test techniques that could allow future spacecraft to determine their positions in space without having to rely exclusively on tracking from Earth.

In addition to Advanced Space, the commercial partners contributing to the $30 million Capstone mission include Tyvak Nano-Satellite Systems, Stellar Exploration, Space Dynamics Lab, Tethers Unlimited and Orion Space Systems.

By Alan Boyle

Mastermind of Cosmic Log, contributor to GeekWire and Universe Today, author of "The Case for Pluto: How a Little Planet Made a Big Difference," past president of the Council for the Advancement of Science Writing.

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