Astrobotic Peregrine Mission One: Pittsburgh-based aerospace firm’s Peregrine lunar lander has suffered anomalies due to defects in the propulsion system, and propellant leak, but continues to remain operational in space. As of January 10, 2024, Peregrine has been operational in space for 55 hours. However, there is no chance of the lander making a soft landing on the Moon, Astrobotic has said.
Had Peregrine made a soft landing on the Moon, it would have become the United States’ first lander to make a lunar landing in 50 years, and the world’s first commercial lander to achieve this.
Astrobotic Peregrine Mission One: What Went Wrong?
Launched on January 8, 2024, Peregrine suffered an anomaly a few hours after launch. However, Astrobotic successfully re-established communications with Peregrine, and conducted a correction manoeuvre to reorient Peregrine’s solar array towards the Sun. An anomaly in the propulsion system had prevented the lander from achieving a stable Sun-pointing orientation.
In a mission update dated January 9, Astrobotic said that Peregrine experienced a propellant loss, as a result of which the Attitude Control System (ACS) thrusters have been operating beyond their expected service life to keep the lander stable, and from tumbling.
The space firm stated that if the thrusters could not keep the spacecraft in a stable Sun-pointing state for about 40 hours, the mission would be jeopardised. However, this did not happen, and Peregrine has continued to remain operationally stable for 55 hours.
The amount of fuel consumed by thrusters to maintain a stable orientation for Peregrine will determine how long the lander remains in the correct orientation.
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After Peregrine had been operational for about 32 hours, Astrobotic said in a mission update that the spacecraft had started to tilt away from the Sun, and its power generation was reduced, but ground control stations updated the control algorithm to fix the issue and fully charge the batteries.
However, due to the propellant leak, there is no chance of a soft landing on the Moon, according to Astrobotic. The amount of propellant left is enough to allow the firm to continue operating the vehicle as a spacecraft.
The anomaly was that a valve between the helium pressurant and the oxidiser failed to reseal after actuation during initialisation.
In a rocket’s pressurant tank, a gas such as helium is put at pressures as high as 60 MPa, and is called a pressurant gas. An oxidiser is one of the two types of propellants used by liquid chemical rockets, the other being a fuel. An oxidiser could be nitrogen tetroxide, liquid fluorine, nitric acid, and liquid oxygen, according to NASA.
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The process of putting something into motion is called actuation.
Since the valve between the helium pressurant and the oxidiser failed to reseal, the pressure of helium caused the pressure in the oxidiser tank to go beyond its operating limit.
This ruptured the oxidiser tank, Astrobotic has theorised.
The space firm has clarified that the anomaly did not occur due to any problems with the launch, and that the United Launch Alliance’s (ULA’s) Vulcan Centaur successfully inserted Peregrine into the planned translunar trajectory.
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Will Peregrine Reach The Moon?
In its latest mission update, Astrobotic has said that Peregrine is about 1,92,000 miles (3,08,994 kilometres) from Earth, which means that the spacecraft has covered 80 per cent of its path to the Moon.
Peregrine is approaching lunar distance, but will not reach the Moon. The lander continues to remain on its nominal trajectory for the mission.
In this trajectory, there is a phasing loop around the Earth. This means that Peregrine is moving towards lunar orbit, will subsequently swing back around the Earth, and then cruise out towards the Moon.
A spacecraft on this trajectory takes 15 days to reach the Moon post launch.
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Despite the fact that Peregrine had been leaking propellant, it remains operationally stable, and continues to obtain valuable data.
Astrobotic expects Peregrine to run out of propellant in about 35 hours. Still, efforts are on to extend the lander’s life.
The data received from Peregrine, and the mistakes learnt from this mission will allow Astrobotic to prepare better for the firm’s next lunar lander mission, Griffin.
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