NASA’s ARTEMIS spacecraft left their orbit around Earth to arrive at new home around the Moon. Credit: NASA/GSFC - Scientific Visualization Studio
It has been a long and loopy flight for two spacecraft.
Now, after one and a half years and making more than 90 orbit maneuvers, along with numerous gravitational boosts, NASA’s ARTEMIS spacecraft have been repurposed – leaving orbit around Earth to arrive at their new home around the Moon.
And they did so making use of the skimpiest amount of fuel.
On June 27, the first ARTEMIS probe will spiral in toward the Moon and enter lunar orbit. Then on July 17, the second craft will follow, traveling in the same direction with the Moon, or in prograde. Its sistercraft will travel in the opposite direction, in retrograde.
The journey for ARTEMIS — short for Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon’s Interaction with the Sun — began in 2009. Back then the two spacecraft were part of the five-craft THEMIS mission studying Earth’s aurora.
Now the two spacecraft have new duties.
Lunar wake
As the Moon orbits the Earth, it passes in and out of the Earth’s magnetic field and the million-mile per hour stream of particles emitted by the Sun known as the solar wind.
While in these regions, the two ARTEMIS spacecraft will seek evidence for turbulence, particle acceleration, and magnetic reconnection, three fundamental phenomena that control the nature of the solar wind’s interaction with the Earth’s magnetosphere.
Employing their full complement of instruments and unique two-point vantage points, the spacecraft will study the vacuum the Moon carves out in the solar wind, and the processes that eventually fill this lunar wake.
Nearer the Moon, they will observe the effects of surface electric fields, ions sputtered off the lunar surface, and determine the internal structure of the Moon from transient variations in its magnetic field induced by external changes.
Moving masterminds
It was Vassilis Angelopoulos of UCLA that talked to teams at UC-Berkely and NASA’s Goddard Space Flight Center about moving the two spacecraft to the Moon to study the magnetic environment there.
Angelopoulos brought his idea to two engineers who had been involved with launching THEMIS in the first place: David Folta and another flight engineer at Goddard, Mark Woodard.
Even with decades of orbital mechanics experience, this journey was no easy feat.
The trip required several maneuvers never before attempted, including several months when each craft moved in a kidney-shaped path on each side of the Moon around, well, nothing but a gravitational point in space marked by no physical planet or object – what’s called an Earth-Moon libration orbit.
Given all that maneuvering, the two repurposed spacecraft will add new data regarding Earth’s next door neighbor – the Moon.
By LD/CSE