As part of the Artemis program, it is planned to create an inhabited station in orbit around the Moon. Since the gravitational field of the Earth's satellite has strong local disturbances, it is difficult for the spacecraft to stay in lunar orbits for a long time. To test one of the possible stable trajectories, NASA launched the CAPSTONE mission, but almost immediately after separation from the upper stage, communication with the probe disappeared.
The launch of the CAPSTONE spacecraft successfully took place on June 28 on a Rocket Lab Electron rocket from the Mahia cosmodrome in New Zealand. Over the next six days, the Photon upper stage made several trajectory adjustments, raising the apogee of the orbit to about 1.3 million kilometers. Then, on July 4, [...] the payload was separated, and the probe continued to move along the ballistic transition trajectory to the lunar orbit ( BLT, ballistic lunar transfer ).
However, the very next day, the US National Aeronautics and Space Administration (NASA) reported that communication with the device was disrupted. The Deep Space Communication System (DSN) has successfully exchanged data with the CAPSTONE probe only once (the station in Madrid, Spain). The second session, already with antennas in Goldstone, California, was called partially successful by NASA. The connection was restored only on July 6, but the reasons for the failure are not yet known.
The status screen of the NASA deep space communication system, which shows that one of the "plates" in Goldstone successfully exchanges data with CAPSTONE on July 6
Image Source: NASA
Based on the available information, NASA experts have established that the device is on the calculated trajectory, and its systems (with the exception of communications) are working properly: the solar panels have opened, the onboard battery is charging. The planned start of the engines on the fifth had to be postponed, but CAPSTONE has enough fuel on board to carry out trajectory correction later. At the time of writing this news, NASA it did not provide any details about the causes of the communication system problems. Whether it is a software failure or a hardware one is to be found out in the coming days.
Nevertheless, the mission management team believes that the first trajectory correction can be safely carried out today, July 7. The results of the maneuver have not yet been published; according to the plan, it was supposed to begin at 18:30 Moscow time.
Visualization of an "Almost rectilinear halo orbit": in the center is the Earth, closer to the viewer is the Moon, the white line is the movement of CAPSTONE and the Lunar Gateway Lunar station (LOP-G)
Image Source: NASA
The name CAPSTONE stands for Cislunar Autonomous Positioning System Technology Operations and Navigation Experiment — "Experiment on the operation and navigation of the circumlunar autonomous positioning system". The mission's task is to make sure that the Lunar Gateway near—lunar habitable station can be placed in a new type of orbit. It is called the "almost rectilinear halo orbit" (near-rectilinear halo orbit, NRHO), and theoretically it has many advantages. Thanks to the clever use of the gravitational influence of the Moon, the Earth and the Sun at the same time, the device can stay on such a trajectory for a long time without significant fuel costs.
Another trick of orbital mechanics that CAPSTONE uses is the ballistic transition from near—Earth orbit to NRHO. It is ideal for unmanned vehicles, because, again, due to the exploitation of gravitational disturbances from the Moon, Earth and the Sun, it allows you to get to the circumlunar space, saving a huge amount of fuel. However, such a flight takes more than four months. But in the same mass of the probe, it turns out to fit more payload like scientific instruments and repeaters.
For CAPSTONE, the engineering and scientific goal will be to practice navigation in the vicinity of the Moon and on its surface without the use of ground and near-Earth communication stations. To do this, the device will track its position in space at the expense of another probe — Lunar Reconnaissance Orbiter (LRO), which has been operating since 2009.
Although CAPSTONE is a 12U form factor cubesat - that is, it is approximately the size of a microwave oven and has a mass of about 25 kilograms — this is de facto the first full-fledged mission under the Artemis program. Interestingly, the creation, launch and management of the NASA spacecraft was completely "outsourced" to a commercial contractor. And this is also extremely characteristic of the new lunar program of the United States of America.
