NASA CAPSTONE CubeSat was launched Wednesday morning and is on track to test a longer, more fuel-efficient route to the Moon, driven primarily by gravity.
NASA’s CAPSTONE (Cislunar Autonomous Positioning System Technology Operations and Navigation Experiment) took off from New Zealand aboard a Rocket Labs rocket Wednesday morning. As of Wednesday evening, the CubeSat is safely in low Earth orbit and is on track to test a longer, more fuel-efficient route to the Moon and a revolutionary new lunar orbit, both of which will allow future manned missions to the Earth. Moon.
What’s new – CAPSTONE will go where many spaceships, and several humans, have gone before, but it will arrive in a whole new way. The CubeSat mission will test a very long but very fuel-efficient route to the Moon, called the ballistic lunar transfer trajectory.
It will also test a lunar orbit that has not been tested before, called an almost rectilinear halo orbit: an oval stretched from an orbit that passes over the north and south poles of the Moon. This very stable orbit will allow future missions such as Gateway to further stretch their fuel supplies and stay in constant radio contact.
While in lunar orbit, CAPSTONE will also test a communications system that will help future lunar missions control their positions in space without relying on Earth-based tracking. CAPSTONE will work with NASA’s Lunar Reconnaissance Orbiter to constantly measure the distance between the two spacecraft, and then use it as a basis for calculating the positions of the spacecraft.
The vessel CAPSTONE, seen at Tyvak Nano-Satellite Systems, Inc. before its release. Dominic Hart
Why does it matter – Everything CAPSTONE is doing will directly pave the way for future manned missions to the Moon.
The nearly rectilinear halo orbit 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 landers. and supply missions, as well as communications. and other supports for Artemis’ missions to the Moon.
And the ballistic lunar transfer orbit will help keep Artemis and Gateway running. Crewed Artemis missions will take the most direct route, meaning they will fire their thrusters to transfer the spacecraft from Earth orbit to lunar orbit. But for unmanned missions, such as deliveries of supplies to future lunar outposts, the ballistic lunar transfer orbit will be more fuel efficient and less expensive.
This illustration shows CAPSTONE orbiting the Moon.NASA
Exploring the details – When the Apollo spacecraft traveled to the Moon, it was approximately a three-day trip, but the CAPSTONE trip will last four months in the lunar ballistic transfer trajectory. The route is “gravity driven,” as NASA says, meaning CAPSTONE will mostly use gravity, not its own thrusters, to change its speed and position.
In six days, CAPSTONE’s third stage Lunar Photon booster will launch the satellite on a long cruise into deep space. Eventually, Earth’s gravity will drag the spacecraft toward Earth and the Moon, the “ballistic” part of the route’s name.
Once 1.5 million miles from home, the Sun’s gravity will increase CAPSTONE to an extremely wide orbit around the Earth; the lowest point in the orbit will intersect with the Moon. As CAPSTONE returns to Earth and the Moon, it will only need a few small strokes from its thrusters to stay the course. One last small maneuver will change the speed of CAPSTONE so that the gravity of the Moon can capture it in the lunar orbit: this is the “transfer” part.
On paper, physics works very well, and NASA engineers flew tens of thousands of simulations to plan and practice CAPSTONE’s long but surprisingly fuel-efficient path to the moon. But the spacecraft flies this route to make sure it works in practice as well.
And once it reaches the Moon, CAPSTONE will settle in a strange orbit around the poles of the Moon. It is called an almost rectilinear halo orbit, or NRHO: “own rectilinear” because the orbit is an oval so long and stretched that its sides are almost straight, and “halo” because it is orbiting the poles of the Moon instead of its equator. In its closest approach, CAPSTONE will pass about 1,600 km above the North Pole of the Moon; 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. Advanced space
The gravitational influence of both the Earth and the Moon will help keep the spacecraft stable in this orbit, so CAPSTONE will not need to fire its thrusters very often or for a long time.
“Burns will be scheduled to give an extra boost to the spacecraft, as it naturally generates momentum; this requires much less fuel than a more circular orbit,” said Elwood Agasid, deputy director of the Small Spaceship Technology program. at NASA’s Ames Research Center. a statement.
This means that a spacecraft can stay in orbit much longer with the same amount of fuel as in a more conventional orbit. NASA estimates that a large spacecraft like 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 Gateway, in constant radio contact with the Earth and the lunar surface. During the Apollo missions, the command module lost communications with both Mission Control and astronauts on the lunar surface for about 48 minutes at a time, while its orbit was carried to the other side of the Moon. . Gateway computers will not have this problem.
What follows – CAPSTONE will spend the next four months on its way to the moon. For six months after that, the small spacecraft will send data home about orbital dynamics and its communications project with LRO, along with some other experiments.
NASA has scheduled the provisional launch of the first Gateway components in late 2024. NASA will begin with the power and propulsion model and the Advanced Habitat and Logistics site, which will combine crew quarters, scientific facilities, docking and command and control ports for the rest. of the station.
Meanwhile, NASA has not yet set a date for the launch of Artemis 1; Engineers are still reviewing data from a key pre-launch test on June 20th.
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