NASA’s CAPSTONE Mission Launches to the Moon


A small NASA-financed spacecraft launched from New Zealand on Tuesday, kicking off the space agency’s plans to send astronauts back to the moon in a few years.

The spacecraft, called CAPSTONE, is about the size of a microwave oven. It will study a specific orbit where NASA plans to build a small space station for astronauts to stop at before and after going to the moon’s surface.

At 9:55 p.m. local time (5:55 a.m. Eastern time), a 59-foot-tall rocket carrying CAPSTONE lifted off from a launchpad along the eastern coast of New Zealand. Although the mission is gathering information for NASA, it is owned and operated by a private company, Advanced Space, based in Westminster, Colo.

For a spacecraft headed to the moon, CAPSTONE is inexpensive, costing just under $30 million including the launch by Rocket Lab, a U.S.-New Zealand company.

The first two stages of Electron rocket placed CAPSTONE into an elliptical orbit around Earth. For this mission, Rocket Lab essentially added a third stage that will methodically raise the altitude of the spacecraft over the next six days. At that point, CAPSTONE will head on its way to the moon, taking a slow but efficient path, arriving on Nov. 13.

The full name of the mission is the Cislunar Autonomous Positioning System Technology Operations and Navigation Experiment.

For Artemis, NASA’s program to send astronauts back to the moon, NASA decided to include Gateway, a small space station around the moon. That would make it easier for astronauts to reach more parts of the moon.

This outpost is to be placed in what is known as a near-rectilinear halo orbit.

Halo orbits are those influenced by the gravity of two bodies — in this case, the Earth and the moon. The influence of the two bodies helps make the orbit highly stable, minimizing the amount of propellant needed to keep a spacecraft circling the moon.

The gravitational interactions also keep the orbit at about a 90-degree angle to the line-of-sight view from Earth. (This is the near-rectilinear part of the name.) Thus, a spacecraft in this orbit never passes behind the moon, where communications would be cut off.

The orbit that Gateway will travel comes within about 2,200 miles of the moon’s North Pole and loops out as far as 44,000 miles away as it goes over the South Pole. A trip around the moon will take about one week.

No spacecraft has ever traveled in this orbit. Thus, CAPSTONE will provide data to NASA to confirm its mathematical models for operating its Gateway outpost in a near-rectilinear halo orbit.

NASA did not design or build CAPSTONE, nor will it operate it. The spacecraft belongs to and will be managed by Advanced Space, a 45-employee company just outside of Denver. Advanced Space actually bought the 55-pound, microwave oven-size satellite from another company, Terran Orbital.

It is also being launched not by SpaceX or any of NASA’s other big aerospace contractors, but by Rocket Lab, a U.S.-New Zealand company that is a leader in delivering small payloads to orbit. The company has its own launch site on New Zealand’s North Island for its Electron rockets.

NASA spent about $20 million for Advanced Space to build and operate the spacecraft as well as just under $10 million for Rocket Lab’s launcher.

After arriving at the moon, the mission will last six months, with the potential to be extended another year or more.

Is main task is to explore how best to stay in the desired orbit. By measuring how long it takes radio signals to travel back and forth to Earth, the spacecraft triangulates its position, then nudges itself if it is off course.

This might take some trial and error because no spacecraft has traveled this orbit before, and without a global positioning system at the moon, the uncertainty in the spacecraft’s location at any moment is greater.

CAPSTONE will also test an alternative method of finding its position by working with other spacecraft circling the moon. Advanced Space has been developing this technology for more than seven years, and now it will test the concept with CAPSTONE sending signals back and forth with NASA’s Lunar Reconnaissance Orbiter.

The biggest launch to the moon expected this year is Artemis 1, the first major test flight of NASA’s systems for returning astronauts to the lunar surface. As early as late August, NASA could launch a giant rocket, the Space Launch System, which would carry an astronaut capsule, Orion. The capsule will travel around the moon and back to Earth with no astronauts aboard.

Also in August, South Korea could launch a spacecraft, the Korea Pathfinder Lunar Orbiter. The spacecraft would be the country’s first moon-bound visitor and would study facets of lunar geology using a variety of scientific instruments.

Other missions expected this year are less certain to occur. Russia has said it plans to return a robotic lander to the moon for the first time since 1976. A Japanese company, ispace, aims to carry cargo from Japan and a variety of other countries to the lunar surface as well. Two American companies, Intuitive Machines and Astrobotic, also have similar missions, having been contracted by NASA to transport lunar cargo in much the same way that SpaceX now launches cargo to the International Space Station.

NASA has also awarded SpaceX a major contract to build the next moon lander for astronauts. While that lander is years from being ready, in the coming months, the company could try an orbital test flight of Starship, the spacecraft that will be the basis for that lander.



Source: https://www.nytimes.com/2022/06/28/science/capstone-nasa-launch-moon.html