Posted on 05/18/2018 6:47:08 PM PDT by MtnClimber
On the Saturday afternoon of July 4, 2015, NASA’s New Horizons Pluto mission leader Alan Stern was in his office near the project Mission Control Center, working, when his cell phone rang. He was aware of the Independence Day holiday but was much more focused on the fact that the date was “Pluto flyby minus 10 days.”...
Glancing at his ringing phone, Alan was surprised to see the caller was Glen Fountain, the longtime project manager of New Horizons. He felt a chill because he knew that Glen was taking time off for the holiday, at his nearby home, before the final, all-out intensity of the upcoming flyby. Why would Glen be calling now? Alan picked up the phone. “Glen, what’s up?” “We’ve lost contact with the spacecraft.” Alan replied, “I’ll meet you in the MOC; see you in five minutes.” Alan hung up his phone and sat down at his desk for a few seconds, stunned, shaking his head in disbelief. Unintentional loss of contact with Earth should never happen to any spacecraft. It had never before happened to New Horizons over the entire nine-year flight from Earth to Pluto. How could this be happening now, just 10 days out from Pluto?
Throughout the nine long years of travel toward the ninth planet, the radio link to New Horizons was the lifeline that allowed its team to contact and control the craft and to receive spacecraft status and data from its observations. As New Horizons kept going farther to the outer reaches of the solar system, the time delays to communicate with it increased, and the link had lengthened to what was now a nine-hour round trip for radio signals, traveling at the speed of light.
(Excerpt) Read more at nautil.us ...
Wow, I followed this mission and never knew they lost communication with the satellite. They must have been in panic mode since they only get one fly by.
Here's a link to the article.
Is there a link to the rest of the story? Thanks.
Missed some fields. This is from Nautilus, URL:
http://nautil.us/issue/60/searches/how-nasas-mission-to-pluto-was-nearly-lost
So sorry, see post 5.
Got it, thanks. An interesting story
I vaguely remember this. It didn’t seem like a big deal at the time, though. I guess it was to the NASA staff.
Stuff happens.
The ESA inadvertently turned off the main data reporting channel on Huygens after it was jettisoned from Cassini, shortly before it was to make its descent.
Given the distances, I'm not sure that it was able to be turned back on in time.
I think the data was eventually captured from a redundant, but lower power channel via the Parkes, and other similar class antennas.
Unintentional loss of contact with Earth should never happen to any spacecraft.
What happens when you do not pay your interstellar carrier on time.
At the radio propagation time of 4.5 hours each way they were using large antennas on earth, but also must have been using very low data rates on the satellite where the transmit power would be very limited.
.
FTA: Something key they discovered very quickly was that just before the spacecraft’s signal stopped, the main computer had been doing two things at once, both of which were computationally demanding. One of these tasks was compressing 63 Pluto images taken previously, in order to free up memory space for the close flyby imaging soon to begin. At the same time, the computer was also receiving the Core load from Earth and storing it in its memory. Could the computer have become overloaded by this intense combination of computational tasks, and as a result rebooted?
Me: This happens when you use Micosoft Windows as we all know it cannot do 2 things at once without slowing to a crawl or rebooting.
FTA: It was quickly estimated that they would have to perform the equivalent of several weeks of work in just three days to start the flyby Core sequence on time on July 7. And it would all have to be done flawlessly.
Me: I remember when Scotty had to restart the warp engines from a cold start in less then 8 minutes. Normal start time was 30 minutes.
Why wasn’t all of the necessary software already on the spacecraft?
L
Not enough memory, not enough power.
According to Wickipedia it had a radioisotope thermo-electric power supply that was expected to decay to 200W by the time it got to Pluto. The transmit data rate was expected to be 38 kbit/s at Jupiter; at Pluto’s distance, a rate of approximately 1 kbit/s was expected. The memory was 8gb and was probably used as the storage of images with much less left for software.
The Voyager spacecraft have left the solar system. The most recent news was from December 1, 2017: Voyager 1 Fires Up Thrusters After 37 Years
That is very interesting. Space semiconductors have to have special redundant geometries and memory has to have error checking because cosmic rays can damage logic cells and change the state of memory devices. It usually takes three times the power for a space device compared to one used on Earth.
I didn’t know about the much greater power requirements in space applications. Thanks.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.