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Cassini Sends Final Close Views Of Odd Moon Hyperion


Image credit: NASA/JPL-Caltech/Space Science Institute

Image credit: NASA/JPL-Caltech/Space Science Institute

NASA’s Cassini spacecraft has returned images from its final close approach to Saturn’s oddball moon Hyperion, upholding the moon’s reputation as one of the most bizarre objects in the solar system. The views show Hyperion’s deeply impact-scarred surface, with many craters displaying dark material on their floors.

During this flyby, Cassini passed Hyperion at a distance of about 21,000 miles (34,000 kilometers) at closest approach. Cassini’s closest-ever Hyperion flyby took place on Sept. 26, 2005, at a distance of 314 miles (505 kilometers).

Hyperion is the largest of Saturn’s irregular, or potato-shaped, moons and may be the remnant of a violent collision that shattered a larger object into pieces. Cassini scientists attribute Hyperion’s peculiar, sponge-like appearance to the fact that it has an unusually low density for such a large object — about half that of water. Its low density indicates Hyperion is quite porous, with weak surface gravity. These characteristics mean impactors tend to compress the surface, rather than excavating it, and most material that is blown off the surface never returns.

Link To Full Story And Other Links

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Cassini Closes in on Saturn’s Tumbling Moon Hyperion

August 29, 2011 Leave a comment

NASA's Cassini spacecraft obtained this unprocessed image of Saturn's moon Hyperion on Aug. 25, 2011. Image credit: NASA/JPL-Caltech/Space Science Institute

NASA’s Cassini spacecraft captured new views of Saturn’s oddly shaped moon Hyperion during its encounter with this cratered body on Thursday, Aug. 25. Raw images were acquired as the spacecraft flew past the moon at a distance of about 15,500 miles (25,000 kilometers), making this the second closest encounter.
Hyperion is a small moon — just 168 miles (270 kilometers) across. It has an irregular shape and surface appearance, and it rotates chaotically as it tumbles along in orbit. This odd rotation prevented scientists from predicting exactly what terrain the spacecraft’s cameras would image during this flyby.

Full Story: http://www.jpl.nasa.gov/news/news.cfm?release=2011-266

Cassini Significant Events 08/17/11 – 08/23/11

August 26, 2011 Leave a comment

Cassini Significant Events 08/17/11 – 08/23/11

The most recent spacecraft telemetry was acquired on August 23 from the Deep Space Network tracking complex at Madrid, Spain. The Cassini spacecraft is in an excellent state of health and all subsystems are operating normally. Information on the present position and speed of the Cassini spacecraft may be found on the “Present Position” page at:http://saturn.jpl.nasa.gov/mission/presentposition/.

Wednesday, Aug. 17 (DOY 229)

Science highlights this week focused on Saturn atmospheric observations while on approach to periapsis. The Composite Infrared Spectrometer (CIRS) measured oxygen compounds in Saturn’s stratosphere as a function of latitude and performed a mid-IR limb scan to measure stratospheric thermal structure. The Imaging Science Subsystem (ISS) and the Visual and Infrared Mapping Spectrometer (VIMS) built up their Saturn wind speed measurements by observing every ten minutes to make a mosaic in longitude. The Ultraviolet Imaging Spectrograph (UVIS) completed two EUV/FUV observations, slow scans across Saturn’s visible hemisphere to form spectral images, and probe the upper atmosphere. VIMS observed an occultation of the star omiCet by Saturn. VIMS also made a nearly-20 hour observation at periapsis to measure the time variability of winds and study temporal variations of features comprising the String of Pearls (clearings in the clouds), the Saturn Ribbon feature, and the “smoke rings.” These observations over two Saturn rotations will provide valuable information on the oscillatory nature of the pearls.

Thursday, Aug. 18 (DOY 230)

The Saturn/Hyperion live Inertial Vector Propagator (IVP) update sequence was uplinked today over Canberra’s DSS-43 station. The sequence is registered and activated on board and will begin execution on 234/17:18:19 SCET.

Friday, Aug. 19 (DOY 231)

An Autorad session was approved, enabled and frozen in preparation for an uplink demo on Wednesday, Aug. 24. Autorad is a tool used for the auto-radiation of some of the command files being sent to the spacecraft. A problem publishing the Autorad List XML file to the Data Systems Operations Team (DSOT) Distributed Object Manager (DOM) was discovered in the process, indicating a parameter change on the DSOT DOM since the last use of Autorad by Cassini real time operations.

Monday, Aug. 22 (DOY 234)

Orbit Trim Maneuver (OTM) #288 was performed today. This was the periapsis maneuver setting up for the Titan 78 encounter on Sept. 12. The Reaction Control Subsystem (RCS) burn began at 9:30 AM PDT. Telemetry immediately after the maneuver showed a burn duration of 83.75 seconds, giving a delta-V of 0.092 m/s. All subsystems reported nominal performance after the maneuver. The next maneuver, OTM288a, is scheduled to execute on September 1; still targeting T-78, it will clean up any dispersions resulting from OTM288.

The Mission Sequence System (MSS) team delivered the D14.3.1 software patch today. MSS software is used to generate sequence files and timelines for distribution as intermediate review products, and Sequence of Events, DSN Keyword File and the Space Flight Operations Schedule as formal review products. Also generated are the Command Packet File and the Command DSN file, which is the command file radiated to the spacecraft. This minor delivery was to identify and alert MSS users of improperly constructed array parameters in the Spacecraft Activity Sequence File (SASF).

Tuesday, Aug. 23 (DOY 235)

A mission planning forum was held today to discuss the official release of the updated reference trajectory by the navigation team. This update covers fiscal years 2013 and 2014 and allows for minor changes in DSN tracks and maneuver locations as well as minimizing changes to targeted flybys. This reference trajectory will be implemented starting with S72 which begins execution in January 2012.

The Spacecraft Operations Team (SCO) held an internal meeting today to review the progress on the Cassini Plasma Spectrometer (CAPS) problem. A Project follow-up meeting with the CAPS instrument team is tentatively scheduled for Sept. 22.

Non-targeted flybys of Epimetheus and Atlas occurred today.

Cassini Significant Events 08/10/11 – 08/16/11

August 19, 2011 Leave a comment

The most recent spacecraft telemetry was acquired on August 16 from the Deep Space Network tracking complex at Goldstone, California. The Cassini spacecraft is in an excellent state of health and all subsystems are operating normally. Information on the present position and speed of the Cassini spacecraft may be found on the “Present Position” page at:http://saturn.jpl.nasa.gov/mission/presentposition/.

 

Wednesday, Aug. 10 (DOY 222)

 

This week in science was dominated by observations of Saturn by the Composite Infrared Spectrometer (CIRS), the Imaging Science Subsystem (ISS), and the Visual and Infrared Mapping Spectrometer (VIMS) while the spacecraft was near apoapsis in its orbit. The observations were designed to track wind speeds and study atmospheric composition. The Ultraviolet Imaging Spectrograph (UVIS) also performed an observation to study the upper atmosphere of Saturn, and ISS and VIMS observed Titan twice (1.5 hr each) as part of the cloud monitoring campaign. ISS made a 14-hour observation of the small irregular outer moon Tarqeq to study its light curve.

 

Thursday, Aug. 11 (DOY 223)

 

In the last week, 771 ISS images and 43 VIMS cubes were generated and distributed.

 

Monday, Aug. 15 (DOY 227)

 

The Navigation Team delivered an orbit determination (OD) solution today in support of an unplanned Saturn/Hyperion live Inertial Vector Propagator (IVP) update, tentatively scheduled for uplink on DOY 230. The need for this live IVP update was not predicted at the start of S69, but pointing offsets were discovered resulting from small execution errors at OTM-287 that propagated as trajectory dispersions over the nearly two months since OTM-287.

 

Tuesday, Aug. 16 (DOY 228)

 

Commands were uplinked to the spacecraft today over Goldstone’s DSS-15 station in support of S69 for the Cosmic Dust Analyzer (CDA) parameter update due to execute on DOY 234. This parameter adjustment is done to avoid saturating one of the instrument’s detectors.

 

The Spacecraft Operations (SCO) team delivered the Cassini Operations Reference Encyclopedia (CORE) V6.1 software today. This is the command and flight rules dictionary. Analysts are given the opportunity to view command and flight rule information associated with a particular sequence through formatted Oracle queries. CORE was updated to remove unused telemetry channel hyperlinks in displayed commands and printed reports.

 

A kickoff meeting was held today for the S72 Sequence Implementation Process. Port 1 for the first set of input files from the teams occurs August 31.