Have you ever wondered how data and communication signals get from spacecraft to NASA mission control on Earth? It's not as simple as pointing an antenna at NASA and hitting "send." Earth rotates, so you might not always have direct line of sight to mission control. That's why NASA started deploying a fleet of Space Network satellites in the 1980s. It's now into the third generation of these satellites, and a new one has just headed into space(Opens in a new window) where it will relay data from the International Space Station and Hubble Space Telescope. It may be the last one, though.
NASA launched the first Tracking and Data Relay Satellite (TDRS) in 1983 aboard a Space Shuttle. That was TDRS-A (renamed to TDRS-1 in orbit), and we're now up to TDRS-M. NASA continued sending the TDRS satellites up aboard shuttles until the early 2000s when the program switched to much cheaper Atlas rockets. That's also when the second-generation TDRS satellites were deployed with vastly improved capabilities like tri-band communications and autonomous anomaly recovery.
TDRS-M is part of the third-generation TDRS fleet -- when it officially enters operation, it will be renamed TDRS-13. It was launched early on August 18th aboard an Atlas V rocket operated by United Launch Alliance. The satellite is heading up to a geosynchronous orbit at an altitude of 22,300 miles (35,800 kilometers), allowing NASA to enhance the network coverage.
Third generation TDRS satellites are mostly the same as the second-gen that began launching in the early 2000s. The one notable difference is support for multiple-access beamforming on the ground. This is similar to technology in Wi-Fi routers that focus signals where they are needed to increase throughput. All satellites in the TDRS network beam signals down to a number of tracking stations on the surface in places like Guam and the South Pole.
There are currently four functional first-gen TDRS satellites, but two other satellites were retired several years ago and de-orbited. There was also a TDRS satellite aboard the Challenger Shuttle when it exploded during liftoff. All three satellites from the second generation are still operational, and now there are three third-gen satellites. That works out to ten total TDRS satellites in operation. Or rather, it will be ten once TDRS-M is fully online and becomes TDRS-13.NASA says this satellite will be vital to the future of its space communications. Even if no new satellites are launched, TDRS-M should keep the space network operational through at least the mid-2020s. TDRS-M is the last third-gen satellite planned, and the agency may not have to launch more. The hope is commercial space communication networks will be online by the time the TDRS is retired.