Tag Archives: JPL

5,000 Martian Sunrises

Mars Exploration Rover B “Opportunity” has blown away all predictions for longevity.  I mean, NASA/JPL/APL always design their spacecraft to last as long as possible within budget constraints, but even by their own high standards, this thing has lasted a long, long time.  And just a few days ago, it saw something nobody thought it ever would — it’s 5,000th Martian sunrise.

And it finally took its first selfie.  😉  Well, not exactly the first, since it has taken pictures from its mast before.  But this was the first selfie taken using Opportunity’s robot art, similarly to how Curiosity regularly takes selfies.  Opportunity’s arm doesn’t have as good of a camera; it’s really meant for up-close microscopic images.  But it was a nice way of commemorating Sol 5,000:

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A lost NASA satellite has been recovered!

This is an amazing story.  An amateur satellite hunter, Scott Tilley, was looking for signs that the Zuma spacecraft might have actually survived the Falcon 9 launch that supposedly dumped it into the ocean.  After all, the only word we have that it failed to separate was an unnamed congressional staffer; in these circles, that amounts to nothing more than rumor.  So Tilley was looking for unaccounted for radio signals that might be consistent with the Falcon 9 launch.  He didn’t find Zuma, but he did find something else: a NASA satellite named IMAGE that had lost contact years ago.

IMAGE was built as a highly capable space weather forecasting and research tool, but in 2005, it suddenly stopped communicating.  NASA had hoped that an upcoming eclipse season (where the spacecraft would spend relatively long periods in the Earth’s shadow) would cause its batteries to drain, forcing it to reboot, but no signal was recovered.  So eventually the project had to disband and move on.

Now, years later, it seems IMAGE has finally managed to reboot itself after all.  NASA is calling on old engineers, pulling up old drawings and specs, and preparing to try and regain routine control of the spacecraft.  If successful, it would be a huge benefit to space weather forecasting.  So cross your fingers!

Long Dead NASA Spacecraft Wakes Up

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Voyager 1’s main thrusters still work!

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.

https://voyager.jpl.nasa.gov/news/details.php?article_id=108

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Cassini’s last images have been taken

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.

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Cassini: just a little over a day left

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 . . . .

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Cassini’s “Goodbye Kiss” of Titan is complete

One step closer to the bittersweet end of a magnificent mission….  Cassini said goodbye to Titan today, where its companion, the Huygens probe, rests permanently.  There was a final sequence of images taken, which have now been downlinked to Earth.  Here’s one of the raw images in the sequence, this one taken through the CL1 and CB3 filters, which allows it to peer a bit through the smog to make out a hazy glimpse of Titan’s surface features:

Goodbye, Titan….I hope we visit again soon.  😉

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Cassini’s on the home stretch — the last periapse is complete

Cassini’s final orbit is underway.  Yesterday, Cassini made its final (survivable) dip into Saturn’s atmosphere, completing its final periapse.    Sixteen hours from now, it will encounter Titan for one last time.  This will not be a close flyby, but it will be close enough to feel Titan’s gravity, which is the point of the exercise — Titan’s gravity will give the spacecraft a little nudge, transforming the next close approach into a kamikaze plunge.  Here’s a brief timeline of Cassini’s last few days, from the mission website (times given in UTC, which is used for spacecraft time, and in PDT, since the mission is run out of JPL in California):

September 11, 12:04 PM PDT (19:04 UTC) – the “goodbye kiss”, as Cassini passes 119,049 km from Titan

September 11, 10:27 PM PDT (September 12, 05:27 UTC) – final apoapsis, 1.3 million km from Saturn

September 12, 4:56 PM PDT (23:56 UTC) – final Titan data downlink begins

September 12, 6:19 PM PDT (September 13, 01:19 UTC) – signal from Titan data downlink reaches Earth

September 14, 12:38 PM PDT (18:38 UTC) – Cassini takes its last picture

September 14, 1:22 PM PDT (20:22 UTC) – Cassini slews its main antenna to Earth to begin the final downlink of data from its recorder; this data stream will be continuous until the end of the mission

September 14, 2:45 PM PDT (21:45 UTC) – signal from the final transmission begins reaching Earth

September 14, 8:15 PM PDT (September 15, 03:15 UTC) – Canberra, one of the three Deep Space Network sites, begins receiving the signal; Canberra will be the last station to receive signals from Cassini

September 14, 10:08 PM PDT (September 15, 05:15 UTC) – Cassini passes the orbit of Enceladus for the last time

September 15, 12:14 AM PDT (07:15 UTC) – Cassini rolls to allow its instruments to allow its INMS instrument to sample particles.  Spacecraft also configures itself for real-time data transmission; no more data will be stored in the recorder

September 15, 12:22 am PDT (07:22 UTC) – Cassini passes the distance of the F-ring for the last time

September 15, 1:37 AM PDT (08:37 UTC) – Cassini’s real-time data stream begins to reach Earth

September 15, 3:31 AM PDT (10:31 UTC) – Cassini begins to enter the atmosphere, with thrusters firing at 10% to maintain signal lock on Earth

September 15, 3:32 AM PDT (10:32 UTC) – Cassini will increase thruster firing to maintain lock until 100% capacity is reached; at that point, it will no longer be able to maintain the lock, and signal will be lost

September 15, 4:54 AM PDT (11:54 UTC) – Canberra receives the signals indicating that Cassini has reached the atmosphere and is firing its thrusters

September 15, 4:55 AM PDT (11:55 UTC) – Cassini’s signal stops being received; end of mission.

At this point, Cassini will have spent nearly 20 years in space, and conducted an impressive 293 orbits of Saturn.  It’s one of the most impressive and capable space probes we’ve ever sent out into the cosmos.  It’s bittersweet to think of its demise in this way, but nothing lasts forever, and at least Cassini is getting to go out with a bang, collecting some priceless data that could not be obtained any other way.

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