This gave me enormous joy on a rather tense day.
This gave me enormous joy on a rather tense day.
The ISS is going into another busy period with upcoming cargo ship movements. First off, the latest Cygnus spacecraft, SS Gene Cernan, was unberthed and released to fly on its own. SS Gene Cernan now moves into the second part of its mission: deploying nanosatellites, conducting another fire test (Saffire-III, the third and final in the series), and then deorbiting itself safely over the ocean.
The next bit of news is SpaceX preparing for their next flight to the ISS. This will mark the return to flight of LC-40, the Cape Canaveral launchpad that was badly damaged in a Falcon 9/Dragon mishap last year. Liftoff is currently scheduled for December 12, and their traditional pre-flight test fire was conducted yesterday, reinaugurating LC-40’s flame trench (skip ahead two minutes for the fire):
The Voyager 1 spacecraft has been flying for over 40 years now, an incredible history. But recently, mission controllers at JPL have found that the attitude control thrusters appear to have degraded performance. Concerned they might not last out the last few years of expected performance, JPL decided to try something else — to use the trajectory correction maneuver thrusters. These thrusters were responsible for changes to the spacecraft’s actual trajectory, and are larger than the attitude control thrusters. More importantly, they have a lot fewer hours of operation. But there was a catch — the last time these thrusters fired, it was to set up the flyby of Saturn in 1980. Could they still find the documentation to write a program to fire the thrusters in tiny pulses for attitude control? And would the thrusters still work after being asleep for so long?
Well, the answer to both was “yes”, and JPL believes they’ve bought at least another 2-3 years for the spacecraft. With the expected end of mission (or, end of extended-extended-extended-n-times-extended-mission) in 2020 or so, that’s pretty significant; this means they are back to expecting that declining electrical power output will be what kills the spacecraft.
At any rate, these magnificently engineered engines are working like a champ, and they will continue to be used, possibly for the remainder of the mission, with the attitude control thrusters now relegated to a backup role. Meanwhile, they are exploring the same option for Voyager 2, although its attitude control thrusters still appear healthy.
The Delta II rocket was the main workhorse for NASA launches for a long time; now, after this launch, there is just one of them left on Earth. (That last one left will fly next year, carrying ICESat-2.) It has been a phenomenally successful rocket, with the highest launch-to-success rate of any launch vehicle ever flown, except Saturn V (which only flew a handful of times in any case). This was the 155th Delta II, and the 99th consecutive successful flight; Delta II holds that record by a considerable margin, and if all goes well with the last mission next year, it will end its storied career with 100 consecutive successful missions.
JPSS-1, meanwhile, is the first of the Joint Polar Satellite System spacecraft. Intended to replace the POES constellation, JPSS was born out of the NPOESS (National Polar Orbiting Environmental Satellite System) program that would have shared polar-orbiting weather data responsibilities with the Department of Defense. With that program dissolved, NASA/NOAA agreed to cover the afternoon orbit with JPSS, while the DoD would cover the morning orbit first with the Defense Meteorological Satellite Program (their current and severely aging constellation) and then with the Defense Weather Satellite System. DWSS was subsequently cancelled, and there remains no replacement for the aging DMSP; so NOAA has signed a deal with Eumetsat, where Eumetsat will cover the morning orbit.
JPSS-1 is flying into a critical role, as we have become intensely dependent upon accurate forecasting, and the massively successful Delta II was a perfect vehicle to place it into orbit.
Cassini took its last pictures, including a stirring set of images showing Enceladus off the limb of Saturn, and has been downlinking them to Earth. JPL is putting them up as quickly as possible. The main communications currently are still through the big Mars antenna at Goldstone, but the big dish at Canberra has started to pick up the carrier signal and will soon take over the task of talking to Cassini; that dish will be dedicated to Cassini for the remainder of the mission. Around midnight here in Central Daylight Time, Cassini will pass the orbit of Enceladus and begin moving once more into the domain of the ring system. Finally, at 5:32 CDT, Cassini is expected to lose its lock on Earth due to excessive aerodynamic forces, and at 6:55 CDT, the signal received on Earth will cut off. It will be over.
But it will not be soon forgotten.
The Cassini spacecraft has just one day and eight hours left to live, and after thirteen years in Saturn orbit, it’s hard not to feel a little choked up thinking about it. I just rewatched this animation, and I gotta admit . . . it got awfully dusty in here . . . .
Soyuz MS-06 launched today! And actually, by the time I’m writing this, they’re at the ISS, docked and preparing to board. Here’s the spectacular nighttime launch from Baikonur Cosmodrome:
On board are Alexander Misurkin, Mark Vande Hei, Joe Acaba. They are expected to stay in space until late February.