NASA's Galaxy Evolution Explorer successfully opened its telescope cover this morning at 4:32 a.m. Eastern Daylight Time (1:32 a.m. Pacific Daylight Time).
The cover deployment sequence involved the heating of a thermal actuator, which melted a wax pellet. When the wax melted, it pushed a mechanical pin, which in turn released the cover. This release enabled a spring-loaded hinge to swing open the cover. The cover is now safely stowed against the side of the spacecraft, where it will remain for the duration of the mission. Confirmation of successful cover deployment was received in real time at the Mission Operations Center at Orbital Sciences Corporation in Dulles, Virginia.
On Sat., May 3, engineers began the process of turning on the science instrument. So far, they have powered up both the digital processing unit, which houses the main computer, and the detector front-end electronics box, which contains the photon discrimination and processing logic. The procedure went very smoothly. The spacecraft computer, mechanisms and heaters are operating properly, and telemetry and data have been routinely transmitted to Earth.
The rest of this week ground controllers will put the spacecraft through its paces by sending it simulated sequence commands. Next week, the high voltage power supply will be gradually brought up to operational voltage. High voltage is essential for the telescope to gather the ultraviolet photons that will help scientists piece together the story of how and when stars form inside galaxies.
The two weeks after launch serve as a decontamination period, when moisture and other materials absorbed by the spacecraft's paint and thermal blankets bleed away, or "outgas."
Once the optic wheel is rotated into position, the telescope will begin gathering photons -- a milestone known as first light. This will occur on or about May 19.
The Galaxy Evolution Explorer mission will image millions of galaxies across 10 billion years of cosmic history, which is 80-percent of the way back to the Big Bang. Additional information about Galaxy Evolution Explorer is available at http://www.galex.caltech.edu . JPL, a division of the California Institute of Technology in Pasadena, manages the Galaxy Evolution Explorer mission for NASAs Office of Space Science, Washington, D.C.