Space can be an unpredictable place; we’re continually losing pieces of vehicles that exploded on-orbit or experienced violent separation during orbit.
Probably the best-known example was when Challenger disintegrated shortly after launch in 1986, killing its crew due to an O-ring failure and rubber seal separation issues on its booster rockets.
Debris
Researchers still are unsure exactly what caused the space junk that now circles Earth, but explosions from unburned fuel in satellites and rocket upper stages appear to be one likely explanation. Such in-orbit explosions can disassemble one large object into thousands of fast-moving fragments with different masses and speeds, each moving away at different rates from each other.
Collisions between debris can create an explosive domino effect. Pieces flying at each other quickly destroy all objects in low Earth orbit, leaving none left for future space missions to use that region for missions. This scenario has come to be known as “Kessler syndrome”, named after NASA scientist Donald J. Kessler who first described it back in the 70s.
Just a single fragment can do great harm; even cutting through its delicate thermal coating and striking internal components of a spacecraft. Low Earth orbit’s small atmosphere may be able to pull pieces back down over time until reentry takes place – yet in the meantime satellites and space stations face growing clouds of debris threatening their survival.
Reentry
As spacecraft disintegrate, their pieces return to Earth as fireballs – marking an end to an adventure which began with an explosive liftoff event.
Seven astronauts aboard the Challenger met an unexpected and tragic end when it crashed at terminal velocity into the Atlantic Ocean. Tapes from its final moments have since been recovered; in one, Rick Smith, the Challenger’s commander said “Uh-oh.”
Reentry may also occur by accident. That was what happened with Apollo 13 service module after its explosion released it from its Command Module and flew upward into space.
Cold spots had stiffened a joint seal in the booster rocket, allowing hot exhaust gases to escape and weakening a strut meant to prevent too close proximity between it and its larger main rocket fuel and oxygen tank. This caused sudden, dramatic loss of stability that lead to its disintegration as it entered Texas and Louisiana airspace.
Fragmentation
Fragmentation refers to the act of breaking something up into pieces, often through various processes. The noun fragmentation comes from Latin fragmentum meaning broken piece; while fragmentate means to separate into parts.
Fragmentation analysis could shed light on what caused the loss of Space Shuttle Columbia; for instance, it might reveal that it broke apart after an exterior tank piece of foam hit one of its thermal protection system tiles and caused thermal protection to fail; shortly thereafter it disintegrated, taking all seven astronauts with it.
Frueh and her colleagues have been using light curves to monitor fragmentation from spacecraft in orbit, providing engineers with data that could assist with designing safer spacecraft to withstand collisions. Furthermore, the team is working on devising engineering techniques for clearing cislunar space around Earth and its moon of debris before it threatens human exploration – this work could ultimately help eliminate junk that hindered Columbia shuttle recovery efforts.
Impact
As soon as a spacecraft fragments, its components move apart at high-velocity. Over time, this forms a cloud of debris which changes according to orbital dynamics and laws of motion.
Since events take place so quickly, it would be impossible for someone on Earth to witness an on-orbit collision directly, but we can simulate such events using computer graphics. For instance, this video shows how debris from the Challenger disaster spread over Texas and Louisiana.
Frueh has worked closely with space agencies to enhance databases of objects in space, which helps prevent collisions with satellites belonging to other nations and enhance how telescopes detect new objects such as old rocket stages.
Building the infrastructure required to safely launch rockets into space can be a formidable task, particularly in regions surrounded by state and federally protected lands. Permitting processes could take years while creating something tailored specifically to SpaceX’s requirements.