QUALIFICATION OF THE SPECULAR POINT-LIKE QUICK REFERENCE EQUIPMENT AND ACCEPTANCE TESTS FOR INSTALLATION ON THE INTERNATIONAL SPACE STATION

On February the 28th the Specular Point-like Quick Reference (SPQR) equipment was launched on board the 17P Progress flight to the International Space Station (ISS). The equipment was installed after a few days on a ISS win-dow and the experiment was successfully performed in March-May 2005, in the frame of the Italian Soyouz Mission “Eneide” (ISM). The Columbia disaster showed how critical manned missions are and how useful would be a device for imaging low Earth orbit manned satellites with a resolution of 20 cm (which would have probably been sufficient to detect the damage on the Columbia surface). Unfortunately, the Earth atmosphere blurs the images thus preventing from achieving sharp photographs of satellites. The aim of SPQR experiment is to test a procedure suitable to overcome this problem and to improve the imaging resolution to about 20 cm or less. This can be done by providing in the pic-ture a point-like light source with a high signal to noise ratio, which has been subjected to the same atmospheric dis-tortion as the target spacecraft. The point spread function of this reference can be used to process the image for ob-taining a sharp image. The SPQR equipment consists of a glass Cube Corner Reflector (CCR) inserted in a mounting designed to interface the CCR with an ISS window. The window, during the experiment allocated time, has been oriented in the nadir di-rection. The CCR has been illuminated by a ground based laser. The laser beam has been retro-reflected to the ground station by the CCR. Hence, the ground station telescope devoted to take images of the ISS, has also seen the “point-like reference” consisting of the laser beam reflected by the “specular” CCR. Although the SPQR equipment is completely passive (it is just a reflector), for uploading it on the ISS a number of issues arised, essentially due to safety considerations related with the crew presence in the ISS cabin. For this reason, some tests have been required by Rocket and Space Corporation – Energia (the company managing the ISM for the Russian Space Agency) and by the European Space Agency (ESA, managing the mission for the sponsoring institu-tions and providing additional services). The paper illustrates the tests the SPQR flight models have been submitted to as well as the relevant results. The tests, performed in January 2005, are as follows: 1. Vibration and shock tests, to simulate the vibration environment. The following tests were performed (on each axis):  Vibration test of the Flight Model (FM) inside its Transportation Bag (TB) simulating the Progress launch conditions;  Vibration test of the FM inside its TB simulating the Progress insertion conditions, i.e. the boosting phases while the Progress approaches the ISS orbit;  Shock test of the FM inside its TB simulating the Progress docking to the ISS;  Vibration test of the FM, hard mounted on the interface with the shaker, as it would have been mounted on the ISS window. This test simulated the ISS orbit conditions, i.e. the ISS re-orbiting boosting phases. 2. Interferometric test of the CCR, to verify that the vibration and shock tests did not cause any damage to the CCR glass. This test was requested by ESA safety and structures experts to have a greater safety factor about the CCR glass: in fact this is a major concern from a safety standpoint, since small glass particle in a micro-gravity environment can be lethal for the crew due to the ease of ingestion and breathing. 3. Non-destructive test of the SPQR aluminium interface, to verify the absence of cracks. 4. Off-gassing test, to prove that the SPQR equipment non-metallic materials would not have produced gases dangerous for the astronauts or affecting their capabilities. 5. Flammability tests, to verify the flame propagation on some SPQR materials. After a short description of the SPQR experiment and equipment, the paper depicts the test purposes, performances and results.