New image of Uranus taken by the JWST shows its north polar cap, its exquisite rings and 14 of its moons.
The image was taken by the NIRCam camera on Sep 4, 2023 at IR wavelengths 1.4, 2.1, 3.0 and 4.6 µm. This 566x409 image is part of a larger field-of-view image.
Uranus' axis is tilted by 98°. With an orbital period of 84 years, each pole faces the Sun (and Earth) for 42 years! During the years around the solstices, we can see its rings almost face on.
Images of Uranus taken by the venerable Voyager 2 spacecraft on Jan 24/25 1986.
The fully lit image was taken on Jan 24, 1986 during approach. The pale blue-green color results from red-light-absorbing methane in Uranus' atmosphere.
The crescent image was taken from 1 million km beyond Uranus, as Voyager 2 raced away from the planet on its way to Neptune and beyond.
The image of the back-lit rings was taken about 3.5 hours after closest approach.
I got off work early today so I'm in my office watching Star Trek Voyager, I recently got the DVD set and am starting from the beginning. I'm on episode 5. The new cat Chevy has joined me, he's sitting on the chair behind me. His former human was a huge Star Trek fan so this makes me happy. #StarTrek#Voyager#CatsOfMastodon
NASA's Voyager probe stopped communicating and there's no quick fix.
Mashable reports: "This legendary Voyager probe — which has traveled farther than any other craft — can receive messages from Earth, but a computer glitch has hindered Voyager from transmitting vital information."
The venerable Voyager 1 spacecraft is experiencing another glitch. Instead of sending science and engg. data, it is sending a 0101 bit pattern.
The problem has been narrowed down to the flight data system (FDS), which is not communicating properly with the telecom unit (TMU). A reboot did not help.
Stay tuned as NASA engrs work out a fix for this 1970's era computer, which has performed magnificently during its long 46-year journey to the planets and to outer space. https://blogs.nasa.gov/sunspot/
1/n
This schematic of the Voyager telecom system shows that the FDS sends data to the comm system over 2 serial interfaces - a low rate 10 b/s interface routed to the S-band transmitter and a variable rate 10 - 115.2 kb/s interface whose bits are sent via X or S band.
Also, from the 2 diagrams (this post and post #1), the outer coding (Reed-Solomon) is done in software!
What do you think might cause the data to be stuck not at 0 or 1 but at 0101?
For those interested in failures and recovery in far away spacecraft, check out this thread in August, when Voyager 2 lost contact with earth due to a mispointed antenna (caused by operator error :mastodon_oops: ). https://fosstodon.org/@AkaSci/110831401826701180 #Voyager
5/n
Richard Stephenson of DSN Canberra explains on twitter how NASA verified that the uplink is working.
They sent a command to Voyager 1 to switch between non-coherent mode and coherent mode transmission.
In coherent mode, the Transmission clock is derived from the Rx signal instead of from the AUX oscillator. This changes the Tx RF frequency a bit which was detected at the DSN.
In the blog post at https://blogs.nasa.gov/sunspot/, Voyager engineers point out the difficulty in diagnosing problems and crafting solutions for a spacecraft with a signal round-trip-time of almost 2 days and hardware/software developed over 46 years ago using technology long since obsolete.
"Finding solutions to challenges the probes encounter often entails consulting original, decades-old documents written by engineers who didn’t anticipate the issues that are arising today."
NASA DSN in Goldstone, CA is currently receiving the downlink from Voyager 1 at a reduced rate of 40 bps. No uplink at this moment.
Apparently, Voyager 1 switched data rate (160 -> 40 bps) & did a full memory read-out of her Attitude and Articulation Control Subsystem, Flight Data Subsystem, and Command Computer Subsystems A&B.
Transmission time = 6 hours
Download size = ~108 kBytes
Here's hoping that the received data is not 0101... 🤞
NASA did not provide a date but it looks like this issue was discovered and acted upon on Dec 7 or 8.
The graphic below shows the schedule for Voyager 1 comms via DSN, generated on Dec 7. Normally, the downlink rate is 160 bps. On Dec 8, it was switched to 40 bps. And again on Dec 10. Some special commands for the FDS were also sent.
Since then, the D/L rate has been switched between 160 bps and 40 bps a few times with additional FDS commands uploaded.