Synchronized Satellites To Form Giant Space Telescope
April 17, 2013

Proba-3 To Create Giant Space Telescope By Precision Syncing Satellites

Watch the video "Proba-3 Mission Spacecraft Will Fly In Formation"

April Flowers for - Your Universe Online

The European Space Agency's (ESA) Proba-3 mission, a world first in precise formation flying, is being led by Spanish industry. The aim of the project is to demonstrate that two satellites can be synchronized to move as one object with sub-millimeter precision, enabling the creation of enormous space telescopes with the lens and detector hundreds of feet apart.

"Proba-3 will be the first mission in which two spacecraft will fly through space as a single unit, pointing at selectable directions, and with sub-millimetre precision, in other words, relative position accuracy to within less than one millimetre," Salvador Llorente, director of this project in SENER, the first Spanish company to lead an ESA mission.

So far, there have been very few formation satellite missions. The formation missions that have been attempted have only been in the near-Earth environment with a level of precision of tens of centimeters. The Proba-3 team wants to change that.

Proba-3 consists of two satellites, weighing approximately 750 pounds and 440 pounds, which will be launched in 2017. Several launchers are being evaluated, including one from India and another from the US. The two will travel in tandem until they separate in a highly eccentric orbit. Their nearest point, or perigee, during this orbit will only be a little over 370 miles from Earth where they will pass each through the zone in free flight with well-controlled trajectories.

The apogee, or most distant section of the orbit, is over 37,000 miles from Earth. The operations and technology associated with precise formation flight will be tested in this region. The gravitational disturbances at this distance are minimized and will not complicate the maneuvers, or make them too costly.

One experiment to test the scientific applications of Proba-3 will be to use one satellite to block out the Sun so that the other, at approximately 500 feet away, can examine the sun's corona in unprecedented detail. The satellite blocking the Sun will thereby create an artificial solar eclipse to facilitate the data collection of its companion, the coronograh.

"In any case, the primary objective of this mission is to validate the precision formation flight technology, and to be able to position both craft between 20 and 250 meters apart (65 feet and 820 feet), yet always working together as if they formed a rigid structure," Llorente emphasized. The details of the Proba-3 mission have been presented in the journal, Acta Astronautica.

"If you wanted to build telescopes with long focal length, you could mount the lens on one of the satellites and the detector on the other, which was already proposed — for instance — in the case of the Xeus x-ray telescope."“¯ This would allow the team to avoid the need for large deployable structures, reducing the mass of the launch as well as improving the position stability when compared with thermo-elastic distortion of the larger structures.

The Proba-3 mission will also validate several optical and laser sensors in addition to the algorithms required to launch future formation flight missions. The operations team will use different experiments to confirm that this system works properly, varying the distances between the satellites and their pointing direction.

With an eye to Mars mission applications, the satellites will also perform rendezvous tests — orbital approach maneuvers between spacecraft in highly elliptical orbit. These are geared specifically towards a mission known as "Mars Sample Return," which plans to pass a Martian rock from one craft to another.

To avoid the risk of the satellites colliding, which according to Llorente would end any mission, the research team will test prevention and emergency systems with the activation of engines and other devices.

SENER is taking the lead on this project, with the cooperation of other major partners: Astrium CASA Espacio and GMV from Spain, as well as QinetiQ Space and Spacebel from Belgium.