ISS Astronauts Fire-Up Awesome 'Cubesat Cannon'

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."

Comments

Portal

[SJHillman]

I just pictured a cannon firing weighted companion cubes. But their picture is cool too.

Re:Portal

[kelemvor4]

In space they're weightless companion cubes.

Re:Portal

[SJHillman]

But there's no sense crying over every mistake.
You just keep on trying till you run out of dehydrated cake.
And the Science gets done.
And you make a neat space gun.
For the astronauts who are still alive.

Re:Portal

[ericloewe]

In the unlikely event that you do hear one screaming, the Enrichment Center urges you to disregard its advice.

Getting My Own Cubesat

[DexterIsADog]

Do I have to show my tits to get them to fire a cubesat at me?

That would be way ugly.

Re:Getting My Own Cubesat

[K. S. Kyosuke]

Not if they have a "tit for tat" policy. In that case, you'd only get tats for your tits, and you'd have to offer something else to exchange for a cubesat.

Propellent Questions

[Demonantis]

They use springs. The J-SSOD click through in the article has a lot more information on the inner workings of the contraption. Its more like a nerf gun than a cannon. http://iss.jaxa.jp/en/kiboexp/jssod/

Won't they hit the ISS on a future orbit?

[Goldenhawk]

Won't they circle back around and hit the ISS on a future orbit? I'm no rocket scientist, but I recall the idea that anything that departs from a given point in orbit will cross it again, and two objects leaving the same orbital point will both cross it again.

Maybe solar or atmospheric drag is enough to alter the cubesat orbits, and I know the ISS orbit is raised periodically, but since they were launched FROM the ISS by expelling them, instead of having a propulsive system, both the ISS and the cubesats left a single point in space and ought to converge there again.

I'd welcome an explantion from a real rocket scientist.

Re:Won't they hit the ISS on a future orbit?

[X0563511]

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?

[ClayJar]

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.)

Re:rotation right from when shot?

[ThreeKelvin]

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.