Today, a resupply capsule docked at the International Space Station with a cargo of supplies and research material, including some nice plants and a 3d printer. This the fourth commercial resupply mission from SpaceX, and during the launch two days ago observers got a somewhat unusual view: The inside of a liquid oxygen tank inside the rocket, beamed live back to earth from 217 km in space.
Here’s an animated GIF of the tank—you can see liquid oxygen draining from the tank until the engine is switched off, when it suddenly responds to the lack of gravity and starts floating:
When rockets like SpaceX’s Falcon 9 launch, they typically have two stages: A big rocket that gets the whole thing out of the atmosphere—in this case, a booster rocket with nine engines—which then falls away, allowing a smaller stage, with its own single engine, to handle the final maneuvering into orbit. The liquid oxygen in the image above is flowing toward this engine, to be mixed with rocket fuel and ignited—with the final outcome looking like this:
When the animation was captured, the rocket carrying space station supplies had been in flight for a little over nine minutes, is 207 km above the earth and moving at 6.7 km per second. In the next minute, the Dragon space capsule separates from the second stage; it too has small engines that allow it to maneuver close enough for the International Space Station’s grabber claw to snag it for docking.
For now, only cargo rely on this rocket to break the surly bonds, but in just a few years, these same rockets are expected to carry the next generation of manned spacecraft into orbit.