'Flying eyeball' to inspect spacecraft

 作者:柳多     |      日期:2019-02-27 05:08:03
By Kelly Young (Image: NASA) A little spherical spacecraft may soon be buzzing around the exterior of the International Space Station and the space shuttles to inspect for any damage. The Miniature Autonomous Extravehicular Robotic Camera has now completed a docking test at NASA’s Johnson Space Center and could be ready for its first space mission as early as 2006 or 2007. If it is flown on space shuttle missions, Mini AERCam could hover under the orbiter’s belly to check for damage to the heat shield. But it will not fly on the next shuttle mission. Instead, astronauts aboard Discovery will use an extension of the shuttle’s robotic arm to peer underneath the orbiter. Astronauts say that the manoeuvre is awkward and there is very little clearance between the robot arm and the shuttle’s wings – using Mini AERCam in the future would avoid those problems. “The advantages of Mini AERCam are you can see anywhere you’d like to look at, from any angle, and from any standoff distance,” says Steven Frederickson, Mini AERCam’s project manager at NASA’s Johnson Space Center in Houston, Texas, US. Another advantage is that it weighs just 4.5 kilograms, much less than the robotic arm extension. The current prototype has only a digital camera system, but Frederickson says it could also be fitted with chemical sniffers to detect fuel leaks or a laser-based radar. The latter would give accurate depth measurements of any damage that the shuttle might have received from foam or ice during lift-off. Ground controllers could fly the 19-centimetre-diameter Mini AERCam, astronauts could control it from inside the spacecraft, or the craft could scan a vehicle autonomously. It can work a maximum of six hours before returning to its docking station, where it would recharge its batteries and the tanks that fuel its 12 thrusters. Frederickson says the device could also be used in longer duration space missions to the Moon and Mars to reduce the need for inspection spacewalks. The docking tests were conducted in a simulated microgravity environment, which were created by placing the Mini AERCam on a sled that hovers over a granite table by pushing jets of air downwards. The “flying eyeball” lined itself up with its docking target by flashing lights onto reflectors on the docking port. The reflected light gives Mini AERCam the exact position of the port. An electromagnetic pull between the craft and the docking port then completes the manoeuvre. NASA tested an earlier version of Mini AERCam during the STS-87 shuttle mission in 1997 – the diameter of the AERCam Sprint was 16.5 centimetres greater. From inside the Columbia orbiter, astronaut Steve Lindsay controlled Sprint in the shuttle’s cargo bay. AERCam Sprint had a layer of padding just in case it hit the shuttle but mini AERCam uses GPS to determine its location relative to the mothership,