Cassini Thruster Swap Planned

Feb 02, 2009
Artst concept of Cassini spacecraft. Image credit: NASA/JPL

(PhysOrg.com) -- The Cassini spacecraft will swap to a backup set of propulsion thrusters in mid-March due to degradation in the performance of the current set of thrusters.

The thrusters are used for making small corrections to the spacecraft's course, for some attitude control functions, and for making angular momentum adjustments in the reaction wheels, which also are used for attitude control.

The current set of eight thrusters, referred to as branch A, has been in use since Cassini's launch more than 11 years ago. The redundant set, branch B, is an identical set of eight thrusters.

Propulsion engineers began to see a lower performance from one of the thrusters on branch A in October. A second branch A thruster is also now showing some degraded performance.

An extensive review with the propulsion system contractor, Lockheed Martin Space Systems, Denver, Colo., the thruster manufacturer, Aerojet, Sacramento, Calif., and propulsion experts at NASA's Jet Propulsion Laboratory, Pasadena, Calif., was completed last week. The recommendation was made to swap to side B as soon as is practical.

Mid-March is the earliest practical opportunity to make the swap. This allows time for the team to properly test and prepare the sequence of commands that will be sent to the spacecraft. Science planners have identified a period where no high-priority science will be lost during the switch, which will be done over a seven-day window. It also is a time when no navigation maneuvers are required to maintain the spacecraft's trajectory.

The swap involves commanding a latch valve to open hydrazine flow to the B side, and powering on some thruster control electronics. No pyrotechnic devices are involved in the swap, and the action is fully reversible if necessary.

Almost all Cassini engineering subsystems have redundant backup capability. This is only the second time in Cassini's 11 years of flight that the engineering teams have gone to a backup system. The backup reaction wheel was brought online a few years ago and is currently functioning as one of the three prime wheels.

Cassini successfully completed its four-year planned tour and is now in extended mission operations.

More information on the mission is available at: saturn.jpl.nasa.gov and www.nasa.gov/cassini .

Provided by JPL/NASA

Explore further: Total lunar eclipse before dawn on April 4th

Related Stories

Cassini Swaps Thrusters

Mar 12, 2009

(PhysOrg.com) -- Early this morning the Cassini spacecraft relayed information that it had successfully swapped to a backup set of propulsion thrusters late Wednesday.

Recommended for you

Total lunar eclipse before dawn on April 4th

9 hours ago

An unusually brief total eclipse of the Moon will be visible before dawn this Saturday, April 4th, from western North America. The eclipse happens on Saturday evening for Australia and East Asia.

Cassini: Return to Rhea

22 hours ago

After a couple of years in high-inclination orbits that limited its ability to encounter Saturn's moons, NASA's Cassini spacecraft returned to Saturn's equatorial plane in March 2015.

Comet dust—planet Mercury's 'invisible paint'

Mar 30, 2015

A team of scientists has a new explanation for the planet Mercury's dark, barely reflective surface. In a paper published in Nature Geoscience, the researchers suggest that a steady dusting of carbon from p ...

It's 'full spin ahead' for NASA soil moisture mapper

Mar 30, 2015

The 20-foot (6-meter) "golden lasso" reflector antenna atop NASA's new Soil Moisture Active Passive (SMAP) observatory is now ready to wrangle up high-resolution global soil moisture data, following the successful ...

What drives the solar cycle?

Mar 30, 2015

You can be thankful that we bask in the glow of a relatively placid star. Currently about halfway along its 10 billion year career on the Main Sequence, our sun fuses hydrogen into helium in a battle against ...

User comments : 3

Adjust slider to filter visible comments by rank

Display comments: newest first

Edylc
1 / 5 (1) Feb 02, 2009
And then it will crash into the planet unloading all kinds of plutonium that will possibly turn it into a little sun. But probably not. I've done my research....
Doug_Huffman
not rated yet Feb 02, 2009
Michio KaKaU is that you?
LuckyBrandon
not rated yet Feb 02, 2009
yea that small sun idea is simply idotic...no jovian plant (since it contains the only gas capable of collapsing into a small sun, i assume thats what you speak of by "planet") is going to turn into a small sun from a tiny bit of plutonium that it will immediately consume and disintegrate.

Now for my comment...I would think that making sure its engines are working properly is MUCH more important than gathering a couple days worth of scientific data. Within our own solar system, were not losing much information by doing so. If the thing crashes down somewhere, or gets "lost in space", well have a much bigger waste of time and money than a couple days of lost data due to readjustment of the engines.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.