After 16 months of orbiting the Moon, the European Space Agency's SMART-1 spacecraft is preparing for the end of its scientific research phase
After 16 months of orbiting the Moon, the European Space Agency's SMART-1 spacecraft is preparing for the end of its scientific research phase. On June 19, the controllers began a series of ignitions and maneuvers, aiming to direct the spacecraft to obtain improved scientific information as it approaches the end of the journey.
The SMART-1 spacecraft, Europe's first successful mission to the Moon, is scheduled to crash on the lunar surface like previous spacecraft on September 3, 2006, nearly three years after its 2003 launch.
The series of maneuvers was intended to prevent the spacecraft from hitting the moon at a time that is inappropriate from a scientific point of view, and if it weren't for these maneuvers, it would have crashed on August 17. Instead, this time extension provides the mission with an opportunity for low-altitude observations that will yield optimal science results, after which the spacecraft will crash in a controlled crash on the moon.
In preparation for the end of the spacecraft's mission, controllers at ESOC, the agency's facility in Darmstadt, intend to begin a series of engine firings to provide "delta-velocity," or changes in the spacecraft's speed of about 12 meters per second. The process will raise the perihelion (the closest point above the surface of the moon) by about 90 kilometers, and as mentioned, will postpone the impact to September 3rd.
"Changing the date, time and location of the impact also allows for optimization of the possibility to observe what is happening from Earth," says Gerhard Sveham, director of the SMART-1 program on behalf of the European Space Agency. "The predictions according to the current trajectory showed that if the spacecraft remained in its previous position, it would have hit the far side of the moon, far from eye contact and the ability to observe from Earth. The new site is on the near side in southern mid-latitudes.
The scientists could not use the spacecraft's ion engine (an electric engine) for the ignition maneuvers, because the remainder of the xenon material, which was used for propulsion, was already used up during the mission, so they had to develop another creative means.
"The maneuvering strategy involved a series of charging the flywheel for about three hours, centered on the spacecraft at its aphelion (farthest point from the Moon) during 74 revolutions," says Octavio Camino, director of spacecraft operations at ESOC. "The charging involved stopping spinning wheels inside the spaceship, something of which has the effect of transferring angular momentum from the wheel to the spaceship, which causes a rapid change. We performed an asymmetrical activation of the pitch thrusters, to produce a small change in speed in a direction corresponding to the direction of flight. This action gradually changed the trajectory," Camino said.
"After the maneuvers, the scientific studies will be renewed until the time of the impact, with "small interruptions" for the purpose of performing two delicate maneuvers for better control at the time of the impact, one towards the end of July and the other at the beginning of September." added
The current series of maneuvers and the subtle maneuvers will make it possible to predict the time and place of the spacecraft's impact on the surface of the moon, with greater precision.
