SatCom Scientist
Writing occasionally about science, space missions, astronomy, planetary science, satellites, Democracy and human rights.
He/Him
science #space #technology #astronomy #satellites #Democracy
OTOH, Chinese car maker BYD saw its sales jump more than 41% in 2024, year-on-year, to a total of 4.27 million vehicles, which includes EV and hybrid cars. EV sales were at 1.76 million, close to the number for Tesla (1.79 million). BYD sells 90% of its cars in China.
President Biden imposed tariffs of 100% on electric vehicles from China in May 2024.
The NASA Voyager team today posted a summary of the events that caused Voyager 1 to switch its transmitter from X-band to S-band more than a month ago, how they recovered the system and some info on the power supply status on the spacecraft.
Please see the rest of this thread for details š
The Voyager spacecraft - takes a licking and keeps on ticking šŖ
Voyager 1 seems to have made a full recovery from its recent power-surge caused illness. It is now communicating at the normal data rate of 160 bps using its X-band transmitter.
:mastodance:
Three weeks after Voyager 1 autonomously flipped over to using the S-band transmitter for communicating with earth because of a power overload condition, it appears that it is back to communicating using X-band.
No word from NASA, but presumably the team managed to turn off the heater that caused the power surge and re-enable the X-band transmitter.
Phew š
@elaterite @simonbp
Looks like the Voyager CCS computer had just 4k 18-bit words of plated-wire memory.
Instructions consisted of a 6 bit op code and 12 bit address. This permitted 64 instructions and 4K of direct addressing.
Average instruction cycle time was 88 us (11.4 KIPS).
13 registers incl an 18-bit accumulator, 12-bit program counter, 12-bit link register that pointed to the next address to be read, and a 4-bit condition code register.
https://ntrs.nasa.gov/api/citations/19880069935/downloads/19880069935Optimized.pdf
Let's take a moment to marvel at the design of the Voyager spacecraft software - written in assembly language for a custom 1970s CPU, in less than 70 KB of RAM, able to react to failures and keep comms. up.
Possibly, NASA may have to turn off one more instrument on Voyager 1. Over the 47 years since launch, Voyager instruments have gradually been shut off as power levels have declined by over 50%.
But the Voyagers continue to boldly go where no spacecraft has gone before.
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NASA Deep Space Network (DSN) 70m antenna 63 in Madrid is currently receiving the S-band signal from Voyager 1.
Voyager 1 sequence of events contd -
Oct 19 ā Signal lost again; team suspected that Voyager fault protection system was triggered twice more and may have switched to a lower power S-band mode, not used since 1981
Oct 19 ā 3 antennas at DSN Canberra in array mode detected the faint S-band signal
Oct 22 ā Signal sent to validate S-band transmission
Now analyzing data to diagnose and fix the problem and return to X-band mode.
2/n
The aging power-challenged Voyager 1 spacecraft suffered another glitch 2 weeks ago ā it stopped calling home on its regular channel. Here is the sequence of events that transpired -
The aging power-challenged Voyager 1 spacecraft suffered another glitch 2 weeks ago ā it stopped calling home on its regular channel. Here is the sequence of events that transpired -
Oct 16 ā Command sent to turn on a heater
Oct 18 ā X-band signal lost; team surmised that the power-overload triggered the fault protection system and Voyager switched to a low-rate low-power X-band mode
Oct 18 ā DSN looked for lower-rate X-band signal and found it
(contd)
https://blogs.nasa.gov/voyager/2024/10/28/after-pause-nasas-voyager-1-communicating-with-mission-team/
#Voyager
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Here are some key metrics on the twin Voyager spacecraft.
Let's take a moment to marvel at the 1970s technology in these spacecraft - computing hardware/software, instruments, RTGs, thrusters, etc. - most of which are still operational after 47 years in the harsh environment of space, 22:53 and 19:04 light hours away resp., with no maintenance or repairs, just workarounds around few failures, quietly exploring where no spacecraft has explored before.
š
https://science.nasa.gov/mission/voyager/where-are-they-now/
Voyager
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The Voyager probes are powered by radioisotope thermoelectric generators (RTGs) which convert heat from decaying Plutonium Pu-238 into electricity using thermocouples.
In 47 years, the power level has dropped by over 50% to 223 watts.
Pu-238 has a half-life of 87.7 years, i.e., in 87.7 years, 50% of its atoms decay to uranium-234 and then to lead-206.
The bi-metallic thermocouples, which are quite inefficient to begin with, also degrade over time, leading to a net loss of 4W per year.
2/n
NASA Voyager update - on Sept 26, one more instrument aboard Voyager 2 was turned off to conserve power - the plasma science instrument.
NASA Voyager update - on Sept 26, one more instrument aboard Voyager 2 was turned off to conserve power - the plasma science instrument.
Over the 46 years since launch, Voyager instruments have gradually been shut off as power levels have declined by over 50%. Now just 4 science instruments remain active to study the region outside our heliosphere. See graphic below.
Note that the plasma science instrument on Voyager 1 failed and was turned off in 2007.
https://blogs.nasa.gov/voyager/2024/10/01/nasa-turns-off-science-instrument-to-save-voyager-2-power/
#Voyager
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