ISS Astronauts Fire-Up Awesome 'Cubesat Cannon' 52
astroengine writes "As if the International Space Station couldn't get any cooler, the Japanese segment of the orbiting outpost has launched a barrage of small satellites — known as "cubesats" — from their very own Cubesat Cannon! Of course, the real name of the cubesat deployment system isn't quite as dramatic, but the JEM Small Satellite Orbital Deployer (J-SSOD) adds a certain sci-fi flair to space station science."
Re:rotation right from when shot? (Score:5, Informative)
Yep, perfectly normal. Most (if not all) cubesats tumble when they're jettisoned from their launcher.
For them not to tumble when they're jettisoned, they would have to have their center of mass perfectly on top of the spring and they'd need to have the exact same friction against the launcher on all four sides. It's much easier to just fit them with a de-tumbling system, e.g. a magnet on a spring.
Re:Won't they hit the ISS on a future orbit? (Score:4, Informative)
Unlikely. The synodic period would be on the order of decades I believe, and it would only be the one intersection point - the other near-approach wouldn't intersect.
So, every synodic period they would have a close approach, and it would have to happen at just the wrong spot.
Re:Won't they hit the ISS on a future orbit? (Score:5, Informative)
They're launched from the nadir side in a nadir-aft 45-degree direction to prevent collision with the ISS. That imparts a small negative delta-V (with insertion velocity between 1.1 and 1.7 m/s), so their orbit would begin just slightly below the ISS. Additionally, one of the requirements for CubeSats launched from J-SSOD is that they have a ballistic coefficient of 120 kg/m^2 or less. This means that their orbits will decay faster than the ISS orbit, precluding any potential for collisions over time.
(The life expectancy on orbit of a CubeSat launched from J-SSOD is something like 100-150 days, depending on orbital parameters as of deployment, solar activity, etc.)