Deep space dial-up: How NASA speeds up its interplanetary communications
On November 26, 2018 at 2:52:59 ET, NASA did it again—the agency’s InSight probe successfully landed on Mars after an entry, descent, and landing maneuver later dubbed "six and a half minutes of terror.” The moniker fits because NASA engineers couldn't know right away whether the spacecraft had made it safely down to the surface because of the current time delay (roughly 8.1 minutes) for communications between Earth and Mars. During that window of time, InSight couldn't rely on its more modern, high-powered antennas—instead, everything depended on old-fashioned UHF communications (the same method long utilized in everything from TV antennas and walkie-talkies to Bluetooth devices).
Eventually, critical data concerning InSight's condition was transmitted in 401.586Mhz radio waves to two CubeSats called WALL-E and EVE, which in turn relayed the data at 8Kbps back to huge 70 meter antennas on Earth. The CubeSats had been launched on the same rocket as InSight, and they followed along on the trip to Mars in order to observe the landing event and send back data immediately. Other Mars orbiters like Mars Reconnaissance Orbiter (MRO) were out of position and couldn't initially provide real-time communications with the lander. That’s not to say that the entire landing coverage hinged on two experimental CubeSats (each the size of a briefcase), but the MRO would have relayed InSight's landing data only after further delay.
InSight’s entire landing truly put all of NASA’s communications architecture—called the Mars Network—through its paces. The signal the InSight lander beamed back at relay orbiters was sure to reach Earth even if one or more of the orbiters failed. WALL-E and EVE were there to pass information through immediately, and they did just that. If those CubeSats didn't work for some reason, the MRO was ready to step in. Each piece worked as a node in an Internet-like network making it possible to route packages of data through multiple terminals made with different kinds of hardware. Right now, the most efficient tool is the MRO spacecraft, which can relay data at a maximum rate of 6Mbps (a current record for planetary missions). But NASA had to work with much less communications muscle in the past—it’s also going to need much more in the future.
