Reports have emerged this week of a near-collision between an Australian satellite and a suspected Chinese military satellite. This incident highlights the growing concern surrounding the increasing amount of space debris in Earth’s orbit.
In a separate development, the US government issued its first-ever fine for space junk. The Federal Communications Commission penalized the DISH Network, a satellite TV service provider, with a fine of $150,000. Surprisingly, the fine was not related to recent debris but rather to a communications satellite that has been in space for over 21 years. This satellite, EchoStar-7, failed to meet the orbit requirements outlined in a previously agreed-upon debris mitigation plan.
This fine is likely the first of many as the number of active satellites in space is expected to increase by 700% by the end of the decade. As the space environment becomes more crowded, it becomes crucial to monitor and manage the thousands of satellites and space debris in orbit.
There are three main types of orbits for satellites around Earth: low Earth orbit (LEO), medium Earth orbit (MEO), and geosynchronous orbit (GEO). LEO is the most common orbit for satellites, with approximately 5,900 active satellites residing up to 1,000km above Earth’s surface. MEO is home to important satellites, such as the GPS constellation, and is situated between 10,000 and 20,000km above Earth. GEO, which includes geostationary Earth orbit (GEO), is the highest altitude orbit at over 35,000km above Earth. GEO satellites match the rate of Earth’s rotation and appear stationary from the ground.
In addition to active satellites, there is a significant amount of space junk in orbit. Estimates suggest there are over 130 million pieces of debris, although only 35,000 of them are large enough to be tracked regularly. Tracking these objects is essential for space domain awareness, which involves detecting, tracking, and monitoring objects in Earth’s orbit.
Ground-based tracking systems, such as radar and telescopes, are used to monitor objects in orbit. Radar is effective for tracking objects in LEO, while optical sensors are needed for higher orbits like MEO and GEO. Multiple sensors worldwide contribute to space domain awareness, and Australia has a unique opportunity to contribute due to its location and dark night skies.
Australia is currently involved in a space domain awareness technology demonstrator funded by SmartSat CRC. This initiative aims to develop technology that can monitor space activities in real-time, allowing for better tracking and coordination of objects in orbit.
Addressing the issue of space debris is crucial because inactive objects in orbit pose a collision risk and can create more debris. It is essential to ensure the safety and sustainability of Earth’s space domain to continue using it effectively.