Tianhe
China’s Tianhe space station is a lot like the ISS – it’s modular, it’s in low-Earth orbit, and it’s got enough living space for three crew members at the moment. Unlike the ISS, it’s not complete, and is slated to receive more modules in the upcoming years. Eventually, it’s going to have life support, and it’ll ideally be able to do a lot of what the ISS does but completely under China’s control. Astronauts and scientists are already using the central Tianhe module for experiments, and of course to do so they’d need to be inside it, which is part of China’s current annoyance with SpaceX – adding human life into spacecraft maneuvers that wouldn’t have been necessary if not for new satellites intercepting the path adds ethical danger to the already political issue at hand.
The Outer Space Treaty of 1967 allows for basically everybody to peacefully explore outer space as long as they abide by a set of pretty reasonable rules, meaning China has the right to hang out in outer space so long as they’re not building a WMD up there, same as anyone else. (China’s previous issues with sliding into the ISS’s orbit are a problem, but not one that violates the treaty as long as it’s accidental, or ‘accidental’.) However, not much governs exactly where stuff is supposed to go except for data. Establishing orbit is very complicated – establishing orbit with other countries’ projects in the way is even more complicated. Because Earth has an atmosphere, things that are too close will eventually be dragged back down via friction with the little bit of air up high. Things that are too high may not perform as expected, or begin to drift away. There are sweet spots for projects, and those sweet spots have a surprising amount of stuff in them already.
China has had to perform evasive maneuvers twice to keep their Tianhe module away from Starlink satellites crossing into their path. This is really, really annoying in space for a couple of reasons. Number one, fuel is limited. Number two, people were on board, and China is in the middle of a fit of nationalism – countries take a lot of pride in their experts, from Olympic athletes to leading scientists, so disturbing or potentially risking those kinds of people when a country is invested in proving it’s the best with said people is not ideal. China responded well, all things considered.
Surveys
Surveys are being affected by the Starlink Satellites. Sky surveys can be contentious – the best spots to put the survey sites are places with good weather and low light pollution. Equatorial areas tend to meet this conditions, but some places – like Hawaii – would rather not give up even more precious (and sometimes sacred) land for these telescopes. Thus, survey sites are limited.
The survey site discussed in the article that first noted the phenomenon is the Zwicky Transient Facility in deep Southern California, a facility dedicated primarily to finding near-Earth asteroids and other cool things. Having stuff interfere with the pictures isn’t dangerous, because the odds that something would fit behind the satellite streak is near zero, but it is annoying and sometimes distracting.
Surveys are essentially long-exposure photos of the sky, with the telescope adjusting gradually to account for the Earth’s rotation. The satellites, which move at speed, appear as streaks across the photos. The last article I read on the matter says Starlink now has 1,800 or so satellites orbiting at a distance of 550 kilometers above the surface, with a final goal of 10,000 or so. ZTF says at that rate, every photo they take could have a satellite’s streak in it.
Progress takes time, and it takes bug-fixing. Right now, this is a major bug to fix.
For the Future
There’s a potential problem caused by space trash: Kessler Syndrome. This, if started, cannot be stopped. A cascade event where one satellite crashes into another, which causes that to break apart and then crashes into more satellites, and then on and on. We’ve already got enough space trash for this to be a potential problem, and unfortunately satellite launches come with a lot more stuff alongside the satellite that can end up in orbit. It’s not just the big stuff, either – while the big stuff is certainly dangerous, small pieces at great speed can also be extremely dangerous.
On Earth, if you throw a ball, it will eventually stop. The Earth’s gravity pulls it downwards, and air (or other materials in the way) gradually slows the object down until it comes to a complete stop. In space, if you throw a ball, it will go in that direction at that speed forever. If that ball is tossed into a stable orbit, the same applies. Now, picture throwing that ball at a normal speed in one direction. Other stuff in orbit is not moving at normal ball-throwing speeds. The ISS orbits the earth every 90 minutes – it moves about 4 miles every second. Things need to be moving at that speed to resist gravity, because if they slow down they start falling towards the Earth. If that ball hits something big that’s moving at that kind of speed, the speed difference may mean that ball goes straight through whatever it hits, or at the very least damages it. If it knocks pieces off, those pieces go at their own speed, and maintain some momentum from the bigger object. Now you have a handful of tiny bits of metal to track and pray they don’t end up hitting something else important. Space trash has the potential to really, really screw up major projects.
How do we handle space trash? Starlink, with it’s 10,000 satellite plan, will hopefully have an answer before it turns into a serious problem.
Sources:
https://www.caltech.edu/about/news/palomar-survey-instrument-analyzes-impact-of-starlink-satellites
https://www.nasa.gov/mission_pages/station/news/orbital_debris.html
