It\u2019s big business.<\/p>\n
Which is why megacorporations like Elon Musk\u2019s SpaceX and superpowers like China are determined to pump tens of thousands more of these metallic boxes into increasingly crowded space lanes.<\/p>\n
Like cars and trucks, each one is an accident waiting to happen.<\/p>\n
Unlike cars and trucks, an orbital accident doesn\u2019t end with the initial pile-up.<\/p>\n
The wreckage keeps flying. And one prang can cause tens of thousands of others. <\/p>\n
<\/p>\n
It canons around the Earth for weeks, months, years \u2013 possibly even centuries. <\/p>\n
The odds of them eventually hitting something are high. And every hit adds more ammunition to the orbital cannonade. <\/p>\n
Ground-based traffic controllers are struggling to keep up.<\/p>\n
The odds of an orbital prang must constantly be calculated for about 14,000 active satellites. This is already complicated by the need to include the paths of 32,000 other objects (dead satellites, rocket debris and collision wreckage) bigger than 10cm.<\/p>\n
Most modern satellites now have tiny thrusters. <\/p>\n
These are vital.<\/p>\n
They\u2019re needed to dodge impending collisions.<\/p>\n
Statistics suggest that each of Starlink\u2019s 10,300 active satellites must swerve to avoid an accident an average of 41 times a year. That\u2019s a total of 422,300 near-misses, or one every 1.8 minutes.<\/p>\n
So what happens if their traffic controllers go offline?<\/p>\n
All it would take is a solar storm. A war. Or a cyberattack.<\/p>\n
An as-yet unreviewed study published in the digital science journal arXiv<\/a> warns a catastrophic crash that could trigger a relentless orbital pile-up: \u201cOur calculations show the CRASH Clock is currently 5.5 days, which suggests there is limited time to recover from a widespread disruptive event, such as a solar storm.\u201d<\/p>\n Traffic snarl<\/b><\/p>\n \u201cThe number of required manoeuvres continues to increase; temporary lapses in collision avoidance capabilities, whether that be from inaccurate orbital determination or even a small miscommunication between operators in manoeuvre decision-making, will become increasingly catastrophic in their potential consequences,\u201d the study, led by astrophysicist Sarah Thiele, reads.<\/p>\n \u201cWe propose a new metric, the CRASH Clock, that measures such stress in terms of the time it takes for a catastrophic collision to occur if there are no collision avoidance manoeuvres or there is a severe loss in situational awareness.\u201d <\/p>\n Put simply, without active and effective traffic control, a serious smash is inevitable.<\/p>\n Low-Earth Orbit (LEO) is a narrow band of space between 400km and 800km high. It is popular for being close to the ground for speedy communications and sharper photos, but high enough to minimise drag from the dregs of Earth\u2019s atmosphere.<\/p>\n The researchers report that LEO is already so crowded that it is experiencing a \u201cclose approach\u201d (when one object passes another within a kilometre) every 36 seconds.<\/p>\n An encounter of less than 100m happens every 69 minutes.<\/p>\n And satellite tracking accuracy is measured in the tens of metres.<\/p>\n A LEO satellite generally orbits at about 27,000km\/h. Which is why all it took to punch a hole in the Chinese Space Station\u2019s \u201clifeboat\u201d Shenzhou-20 capsule last year was a 1mm metal shaving.<\/p>\n An estimated 140 million<\/a> such \u201cuntrackable\u201d objects under 10cm in size are cannoning through the space lanes. <\/p>\n Those numbers keep rising.<\/p>\n On April 30, SpaceX fed another 29 new Starlink satellites into the traffic flow. That brings its total for the year to 1200.<\/p>\n More are being launched every month.<\/p>\n Starlink traffic controllers are reportedly having to double the number of satellite evasive manoeuvres every six months. Space operations management is a booming business, with companies such as Australia\u2019s Saber Astronautics needed to chart paths through crowded skies. <\/p>\n \u201cSimulations have shown that altitudes above 600-800 km altitude in LEO are already above the unstable threshold for long-term runaway debris growth,\u201d the study reads.<\/p>\n \u201cStrikingly, given the density and surface area, the main Starlink shell (about 550 km altitude) is also within the runaway threshold, meaning a single collision could<\/p>\n have catastrophic long-term consequences.\u201d<\/p>\n Perfect storm<\/b><\/p>\n \u201cIn the short term, a major collision is more akin to the Exxon Valdez oil spill disaster than a Hollywood-style immediate end of operations in orbit,\u201d the researchers conclude. \u201cIndeed, satellite operations could continue after a major collision, but would have different operating parameters, including a higher risk of collision damage.\u201d<\/p>\n