Nobody's panicking, yet, but NASA has lost contact with Voyager 2. They expect it to be temporary.
About a week ago, operators of the Voyager 2 spacecraft sent a series of commands that inadvertently caused the distant probe to point its antenna slightly away from Earth. As a result, NASA has lost contact with the spacecraft, which is nearly half a century old and presently 19.9 billion km away from the planet.
For the time being, NASA and the mission's scientists aren't panicking. In an update posted Friday, the space agency said Voyager 2 is programmed to reset its orientation several times a year to keep its antenna pointing at Earth. It is scheduled to do so again on October 15, which should allow communication to resume. In the meantime, NASA said it does not anticipate the spacecraft veering off course.
The definition of "slightly away" is 2 degrees off Earth. That 19.9 billion kilometers (12.4 billion miles) from Earth works out to 18.49 light-hours, the time it takes a radio transmission to go each way between us and Voyager. I could tell you how many miles off the antenna is pointed but two degrees means as much. It tells you how precarious the link is if being two degrees off drops the communications link. The sizes of the deep space network's dishes tell us those are very, very narrow beamwidth. Back in '17, I did an article on Voyager looked at from radio frequency signal link perspective. I pointed out the antennas on Voyager had 57 dB of gain. Those antennas are tiny compared to the deep space network. The DSN has much more gain, and gain is inversely proportional to beamwidth; the higher the gain, the smaller the beamwidth.
One of the NASA Deep Space Network Dishes. The wide angle lens ruins the perspective on this, making it look small. All of the DSN dishes I know of are 70 meter (240 feet) diameter.
I liked that line about NASA not expecting Voyager to veer off course. That doesn't happen without a source of thrust to change its course. Newton's first law is still a law.
Hopefully Voyager can reacquire signal from Earth in October. It would be a shame to lose contact. But at that distance two degrees is a LARGE discrepancy between where it's pointing and where Earth actually is.
ReplyDeleteIt was good foresight to write in a regular pointing reset in its control software. Proof against future idiots who send it bad commands!
ReplyDeleteWhen you consider how long the Voyage mission has been going on and some of the original team is still working on it, I'm a little surprised they'd make mistakes. I wonder if this is the grandchild of one of the original engineers?
DeleteI wonder if the "inadvertently" sent instructions caused anyone to lose their job...
ReplyDeleteDave of EEVblog has a 3 part series on the deep space network and Voyager 2 - visiting on site at the Australia site.
ReplyDeletehttps://youtu.be/586Zn1ct-QA
Thanks for that. That first video is full of great details on how everything works. On to the other two!
DeleteArecibo is gone, neglected to death, but the Chinese have a 500m scope, so 51x the sensitivity.
ReplyDeleteSomeone should give them a call.
Toward the end of that video Fladave posted, the guy from Canberra says Voyager 2 is only reachable from the southern hemisphere. They're the only one of the three Deep Space Network stations that can communicate with it.
Delete59 degrees south, yikes. Should have watched more before shooting my mouth off.
DeleteLast transmission: "Ohmigod. It's full of stars!"
ReplyDelete