CAPSTONE of NASA CubeSat launches on Wednesday morning and is set to test a longer, more economical route to the moon, powered mostly by gravity.
NASA’s CAPSTONE (Cislunar Autonomous Positioning System Technology Operations and Navigation Experiment) took off from New Zealand aboard the Rocket Labs rocket on Wednesday morning. As of Wednesday night, CubeSat is safely in low Earth orbit and is on track to test a longer, more economical route to the moon and a revolutionary new lunar orbit, both of which will allow future manned lunar missions.
What’s new – CAPSTONE will go where many spaceships – and several people – have gone before, but it will get there in a whole new way. The CubeSat mission will test a very long but very fuel-efficient route to the moon, called a ballistic lunar transfer trajectory.
He will also test an unprecedented lunar orbit, called an almost rectilinear halo orbit: a stretched oval in an orbit that passes over the moon’s north and south poles. This very stable orbit will allow future missions such as the Gateway to further expand their fuel reserves and remain in constant radio contact.
While in lunar orbit, CAPSTONE will also test a communications system that will help future lunar missions monitor their positions in space without relying on Earth-based tracking. CAPSTONE will work with NASA’s Lunar Reconnaissance Orbiter to continuously measure the distance between the two spacecraft, then use this as a basis for calculating the ship’s positions.
The ship CAPSTONE, seen in Tyvak Nano-Satellite Systems, Inc. before its launch. Dominic Hart
Why it matters – Everything CAPSTONE does will directly pave the way for future manned missions to the moon.
The near-rectangular orbit of the halo is the same orbit that NASA plans to use for the Gateway space station, which will eventually orbit the moon with a full-time crew of astronauts to provide a docking station for lunar landings and delivery missions. and communications and other support for Artemis’ missions to the moon.
And the ballistic orbit to transfer the moon will help keep Artemis and Gateway in working order. The Artemis crew missions will take the more direct route, which means they will activate their pushers to transfer the spacecraft from Earth orbit to lunar orbit. But for unmanned missions, such as deliveries to future lunar posts, ballistic orbital lunar transfer orbit will be more economical and cheaper.
This illustration shows CAPSTONE in orbit around the moon. NASA
Understanding the details – When the Apollo spacecraft traveled to the moon, it was an approximately three-day voyage, but the CAPSTONE voyage will take four months on the ballistic trajectory of a lunar transfer. The route is “gravity-driven,” as NASA puts it, which means that CAPSTONE will use primarily gravity rather than its own engines to change speed and position.
In six days, CAPSTONE’s Lunar Photon third-stage accelerator will launch the satellite on a long deep space cruise. Eventually, Earth’s gravity will pull the spacecraft back to Earth and the Moon, the “ballistic” part of the route’s name.
Once 1.5 million kilometers from home, the Sun’s gravity will push CAPSTONE into an extremely wide orbit around the Earth; the lowest point in orbit will intersect with the moon. As CAPSTONE swings back to Earth and the Moon, it will only take a few small thrusts from the thrusters to stay on course. One last small maneuver will change CAPSTONE’s speed so that the Moon’s gravity can catch it in lunar orbit – that’s the “transfer” part.
On paper, the physics work great, and NASA engineers flew tens of thousands of simulations to plan and practice CAPSTONE’s long but surprisingly fuel-efficient journey to the moon. But the spacecraft flies this route to ensure that it works in practice.
And once it arrives on the moon, CAPSTONE will orbit in a strange orbit around the moon’s poles. It is called an almost rectilinear orbit of the halo, or NRHO: “almost rectilinear” because the orbit is so long, an elongated oval that its sides are almost straight, and a “halo” because it orbits the moon’s poles instead of its equator. At its closest approach, CAPSTONE will travel about 1,600 km above the moon’s north pole; at the other end of its orbit, the spacecraft will be about 76,000 km from the moon’s south pole.
This animation shows CAPSTONE’s new orbit around the moon. Extended space
Gravitational influence from both the Earth and the Moon will help maintain the stability of the spacecraft in this orbit, so CAPSTONE will not need to shoot very often or for very long.
“The burns will be scheduled to give the spacecraft an extra boost, as it naturally gains momentum – it requires much less fuel than a more circular orbit,” said Elwood Agassid, deputy program manager for small spacecraft technology. at NASA’s Ames Research Center. declaration.
This means that a spacecraft can stay in orbit much longer with the same amount of fuel than in a more conventional orbit. NASA estimates that a large spacecraft like the Gateway will be able to remain in lunar orbit for about 15 years.
Meanwhile, orbiting the poles of the moon will keep CAPSTONE – and later the Gateway – in constant radio contact with the Earth and the lunar surface. During the Apollo missions, the command module lost communication with both the mission control and the lunar surface astronauts for about 48 minutes at a time as its orbit moved to the far side of the moon. Portal teams will not have this problem.
What next – CAPSTONE will spend the next four months on its way to the moon. For six months after that, the small spacecraft will send home data on orbital dynamics and its communication project with the LRO, along with several other experiments.
NASA plans to launch the first components of the Gateway at the end of 2024. NASA will begin with the power and propulsion model and Habitation and Logistics Outpost, which will combine crew rooms, scientific facilities, docking ports and command and control for the rest of the the station.
Meanwhile, NASA has not yet set a date for the launch of Artemis 1; engineers are still reviewing key test data before launching on June 20th.
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