Author Topic: NASA - Cassini updates  (Read 355732 times)

Offline racshot65

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Re: NASA - Cassini updates
« Reply #240 on: 01/27/2012 06:45 am »
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Cassini Significant Events 01/18/2012 - 01/24/2012

Capture of the telemetry data that is carried on Cassini's 1-way downlink signal, whose frequency is based on the Auxiliary Oscillator in the absence of an operable Ultrastable Oscillator (USO), continues to be normal. The most recent spacecraft tracking and telemetry data were acquired on Jan. 24 from the Deep Space Network 70 meter Deep Space Station 43 at Canberra, Australia. The Cassini spacecraft is in an excellent state of health with all subsystems operating normally except for the Cassini Plasma Spectrometer remaining powered off and the anomalous USO. 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/.

While the spacecraft started inward from apoapsis, Saturn and Titan were again observed with the Optical Remote Sensing (ORS) instruments. The Cassini Infrared Spectrometer (CIRS) measured oxygen compounds (H2O, CO2) in Saturn's stratosphere as a function of latitude, and the Imaging Science Subsystem (ISS) measured winds. The Ultraviolet Imaging Spectrograph imaged Titan and Saturn in the extreme- and far-ultraviolet parts of the spectrum, and ISS led a joint-ORS photometric measurement of Saturn known as an emission-angle scan. CIRS acquired a Saturn mid-infrared map to determine upper troposphere and tropopause temperatures. On Tuesday, ISS observed the small, irregular moon Siarnaq from approximately 26 million kilometers away. Preparations were made for the 56th Project Science Group meeting to be held next week at JPL.
 

Wednesday, Jan. 18 (DOY 018)

Today the Spacecraft Operations Office opened Incident-Surprise-Anomaly report (ISA) #51031, "Z-Sigma Spike on 2012-013" to document an incident that occurred on Jan. 13. In Cassini's Attitude & Articulation Control Subsystem, the Z-sigma ratio compares the measured brightness of a star in the Stellar Reference Unit (SRU) to that expected. It reached a high value of 11, and persisted for 41 realtime interrupts (1/8 second each) during a rotation of the spacecraft. There were no bright bodies in the SRU field of view at the time, which is usually the cause for Z-sigma excursions. The excursion was not sufficient to trigger a fault response, and analysis of the event is continuing.

The Encounter Strategy Meeting for Titan encounters T-81 and T-82 was held today.


Thursday, Jan. 19 (DOY 019)

This week, the Navigation team has been re-converging Cassini's trajectory solution based on tracking data acquired after execution of Orbit Trim Maneuver #306.


Friday, Jan. 20 (DOY 020)

The S72 Background Sequence Part 1 was uplinked today. Its 6,743 timed commands will execute over a period of 37 days. A Reaction Wheel Bias activity for DOY 024 was uplinked separately.

As part of the investigation of ISA #50901, "Loss of Cassini spacecraft 1-way Downlink Signal", the Ultrastable Oscillator (USO) was enabled today for about an hour (recall the USO was power cycled Jan. 9). Deep Space Station 43 in Canberra, Australia, was tracking Cassini, but observed no normal signal from the USO. The Radio Science team observed a wide swath of the radio spectrum at X-band and S-band frequencies using Station 43's Radio Science Receiver, and their results were as expected for a nonfunctioning USO. There was no loss of science telemetry data since the playback had been commanded to pause.
 

Sunday, Jan. 22 (DOY 022)

Cassini's X-band radio receiver was utilized today in a test of the Deep Space Network's uplink polarization isolation. This test was designed to troubleshoot problems experienced with the New Horizons Spacecraft Radio Science Experiment in 2011 (New Horizons encounters Pluto in 2015). The uplink from Station 14 at Goldstone, California, was configured four ways: right- and left-hand circular, each with and without the dichroic plate (a frequency-band separating device) extended into the microwave path. The test provided data that, along with design analysis of the dichroic plate, will be used to characterize DSN performance.

 
Monday, Jan. 23 (DOY 023)

The feature "Cassini Sees the Two Faces of Titan's Dunes" was published on the Cassini public website:

http://saturn.jpl.nasa.gov/news/cassinifeatures/feature20120123/


Tuesday, Jan. 24 (DOY 024)

Background command sequence S71 completed execution today. The start of S72, expected at 4:14 p.m. PST Earth-receive time, could not be verified because of a shortened tracking station allocation.

Contingency S72-deactivate commands were approved and placed on the shelf, as standard preparation in case of an anomaly.

The Attitude and Articulation Control Subsystem executed a Reaction Wheel Bias activity while Cassini's High-Gain Antenna was off Earth-point.

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Re: NASA - Cassini updates
« Reply #241 on: 01/30/2012 05:27 pm »

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Re: NASA - Cassini updates
« Reply #242 on: 02/03/2012 04:10 pm »
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Cassini Significant Events 01/25/2012 - 01/31/2012

The most recent spacecraft tracking and telemetry data in this reporting period were acquired on Feb. 1 from the Deep Space Network 34 meter Station 26 at Goldstone, California. The Cassini spacecraft is in an excellent state of health with all subsystems operating normally except for the known issues with the Cassini Plasma Spectrometer and the Ultrastable Oscillator. 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/.

This week, command sequence S72 started its science observations with a Titan Meteorological Campaign, in which the Imaging Science Subsystem (ISS) looked for cloud events. The Ultraviolet Imaging Spectrograph (UVIS) then executed slow scans in the extreme- and far-ultraviolet across Saturn's illuminated hemisphere. The Visual and Infrared Mapping Spectrometer (VIMS) concentrated on the remains of the storm in Saturn's northern hemisphere, which has been raging since December 2010. Scientists think the String of Pearls (http://saturn.jpl.nasa.gov/news/newsreleases/newsrelease20061011/) may be hidden beneath the storm, and after the storm wanes will try to discover whether the feature may have been destroyed by the tempest. ISS then acquired images over a range of latitudes at low, medium, and high emission angles as the planet rotated. (Emission angle is the angle between the camera boresight and a line normal to the surface point being imaged; straight down is zero degrees.)

The Composite Infrared Spectrometer (CIRS) mapped Saturn's prime meridian from the north pole to the equator to determine the upper troposphere and tropopause temperatures with spatial resolutions of about two degrees of latitude and longitude. Following this, VIMS acquired a high spatial resolution map of the dynamics of Saturn's deep atmosphere. VIMS imaged the same area twice, measuring winds via motions of the clouds. Since these observations were made while the spacecraft was near periapsis, clouds as small as 300 kilometers wide were detectable.

RADAR mapped the same deep region at and around periapsis, obtaining radiometry data at microwave wavelengths much longer than those seen by VIMS. These RADAR maps looked for ammonia gas to reveal the variability of this condensable constituent over the same area where VIMS mapped clouds (formed either via chemical reaction with hydrogen sulfide, thus forming ammonia hydrosulfide clouds, or via direct condensation into ammonia clouds). Unfortunately, this carefully collected RADAR data set and most of the corresponding VIMS data were lost when heavy Australian summer rainstorms drowned out Cassini's signal while it was arriving at Earth on Sunday, January 29.

Targeted Titan encounter T-81 then executed perfectly on January 30, as detailed below.


Wednesday, Jan. 25 (DOY 025)

The S72 background command sequence went active on the spacecraft today. The Cosmic Dust Analyzer instrument turned on heaters to perform a routine 15-hour long decontamination activity.


Thursday, Jan. 26 (DOY 026)

JPL flags flew at half-mast as a NASA-wide Day of Remembrance was observed in honor of the Apollo 1, Challenger, and Columbia crews, as well as other members of the NASA family who have died supporting NASA's mission.

The S74 Sequence Implementation Process kick-off meeting was held today.

 
Attitude and Articulation Control Subsystem (AACS) engineers read out the spacecraft's Reaction Wheel Assembly revolution counter, and then reset it to 0 counts. This is done about every six months to maintain an accurate accounting of wheel usage and avoid rollover of the counter.

It was discovered that the Cassini remote Science Operations Planning Computers in the ground system were unable to obtain data from some of the servers at JPL that were upgraded last week. Additional server upgrades have been postponed, and the previous version of software was re-installed to restore service.


Friday, Jan. 27 (DOY 027)

Orbit Trim Maneuver 308, the Titan T-81 cleanup maneuver, is being prepared this week to execute on Feb. 2 local time.


Saturday, Jan. 28 (DOY 028)

Cassini passed through periapsis this morning, about 206,000 kilometers above Saturn's cloud tops, which is the closest point to the planet for this orbit. Relative to Saturn, Cassini was traveling 58,187 kilometers per hour.


Sunday, Jan. 29 (DOY 029)

AACS executed a Reaction Wheel Bias maneuver while Cassini was not being tracked from Earth. Using thrusters to maintain attitude, the reaction wheel speeds were set to the required values.


Monday, Jan. 30 (DOY 030)

During the high-altitude Titan T-81 encounter, ISS performed high-resolution observations around closest approach (31,131 kilometers) along Titan's leading hemisphere at high southern latitudes, including a late view of Ontario Lacus before the Sun sets for southern winter. ISS also "rode along" (took advantage of instrument pointing) with CIRS inbound high-phase angle observations and outbound observations over Titan's anti-Saturnian hemisphere at low phase angles. This encounter provided one of Cassini's last views of Titan's high southern latitudes. VIMS rode along with ISS looking for lakes in the south polar region.

Inbound and outbound UVIS observations obtained an image cube of Titan's atmosphere at extreme- and far-ultraviolet wavelengths by sweeping its slit across the disk. These cubes provided spectral and spatial information on nitrogen emissions, hydrogen emission and absorption, absorption by simple hydrocarbons, and the scattering properties of haze aerosols. This was one of many such cubes gathered over the course of the mission to provide latitude and seasonal coverage of Titan's middle atmosphere and stratosphere.

During the flyby, the Radio and Plasma Wave Science instrument (RPWS) measured thermal plasmas in Titan's ionosphere and surrounding environment, searched for lightning in Titan's atmosphere, and investigated the interaction of Titan with Saturn's magnetosphere.

More details about this encounter are available at: http://saturn.jpl.nasa.gov/mission/flybys/titan20120130/.

Back on Earth, Cassini's 56th Project Science Group meeting convened at JPL today; about 130 scientists are in attendance at various meetings and workshops throughout the week.

Near the end of the day, AACS executed a Reaction Wheel Bias maneuver while Cassini's high-gain antenna was off Earth-point.
 

Tuesday, Jan. 31 (DOY 031)

Starting at midnight Pacific time, Deep Space Station 14, the 70 meter aperture at Goldstone, California, began capturing realtime tracking data (Doppler and range for navigation), and playback of the telemetry that had been stored on Cassini's Solid-State Recorder during the Titan T-81 encounter. All of the data were safely down by 11:00 a.m. local. For background on telecommunications in general, see: http://www.jpl.nasa.gov/basics/bsf10-1.php.

Since approach science began in January, 2004, there have been 258,340 ISS images planned, commanded, acquired, and downlinked. Of these, only 8 percent have suffered any missing data. VIMS has acquired 128,946 cubes in the same time frame, with a similar rate of loss. Raw images from ISS are always posted online soon after receipt at: http://saturn.jpl.nasa.gov/photos/raw/.

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Re: NASA - Cassini updates
« Reply #243 on: 02/08/2012 12:39 pm »

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Re: NASA - Cassini updates
« Reply #244 on: 02/09/2012 08:31 am »

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Re: NASA - Cassini updates
« Reply #245 on: 02/10/2012 08:18 am »
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Cassini Significant Events 02/01/2012 - 02/07/2012

The most recent spacecraft tracking and telemetry data in this reporting period were acquired on Feb. 8 from the Deep Space Network 70 meter Station 14 at Goldstone, California. The Cassini spacecraft is in an excellent state of health with all subsystems operating normally except for the known issues with the Cassini Plasma Spectrometer and the Ultrastable Oscillator. 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/.

This week's science activities began with multi-instrument observations of Titan from as far as 2.8 million kilometers away, as Cassini continued moving towards apoapse. These activities included a RADAR radiometry observation and a calibration, and observations by the Composite Infrared Spectrometer (CIRS), Imaging Science Subsystem (ISS) and the Visual and Infrared Mapping Spectrometer (VIMS) for atmospheric and cloud monitoring. Following this, the Cosmic Dust Analyzer (CDA) made a 13.5 hour interstellar dust observation.

Later, ISS performed observations of some of Saturn's small inner moons (part of the Satellite Orbit Campaign), including Janus and Polydeuces, to improve understanding of the orbits of these small satellites. This was followed by a 9.5 hour search for Trojan satellites around the L5 Lagrange point, 60 degrees behind Titan in its orbit.

Finally, ISS made some additional observations in the Satellite Orbit Campaign, and then CIRS, ISS and VIMS made an 11 hour Titan observation from a distance of more than 3.6 million kilometers.
 

Wednesday, Feb. 1 (DOY 032)

Yesterday the second half of the column celebrating the work of Dr. Jean-Pierre Lebreton, who before retiring was the European Space Agency Project Scientist and Mission Manager for the Huygens mission to Titan, was posted to the Cassini web site. See:

http://saturn.jpl.nasa.gov/news/cassiniinsider/insider20120131/

Today Deep Space Station 26, a 34 meter Beam Waveguide antenna at Goldstone, performed a monopulse calibration of value to Radio Science Ka-band experiments. The calibration caused unexpected antenna movement and a short loss of Cassini data.

The Reaction Wheel Assembly Bias Optimization Tool identified a segment in the S74 command sequence, which is under construction, that had to be reworked to avoid placing a redundant bias in the Radio Science Enceladus observation keep-out zone. Negotiations for Deep Space Network resource allocations for this sequence have started; the first two days of the ten-week sequence are completed.
 

Thursday, Feb. 2 (DOY 033)

Orbit Trim Maneuver #308, the Titan 81 cleanup maneuver, was successfully executed today Pacific Time (Feb. 3 Universal Time). With a burn duration of 124.37 seconds on Reaction Control Subsystem thrusters, it provided the spacecraft a delta-V of 0.137 m/sec, targeting Cassini to the T-82 aimpoint. This was the second maneuver designed using the new Monte software, and the first prepared with Maneuver Automation Software v9.2. This version of the software allows the main engine assembly heaters to be powered off for the backup maneuver opportunity, avoiding a thermal cycle.

The Instrument Operations (IO) team and Multi Mission Image Processing Laboratory (MIPL) swapped processes to and from computer hardware requiring patch and firmware upgrades. During this activity, the MIPL database, servers, Cassini Atlas, and MIPL file system were unavailable.
 

Friday, Feb. 3 (DOY 034)

Nominal IO and MIPL operations resumed.

The Attitude and Articulation Control Subsystem executed a Reaction Wheel Bias maneuver while Cassini was being tracked from Earth following the Orbit Trim Maneuver. While thrusters maintained attitude, the reaction wheel speeds were set to the required values.

On the ground, a new suite of Telemetry Channel Parameter Tables, called Tour-12, has been installed on test workstations, and on one operations workstation for "soak" testing. Plans are to distribute the files to all users next week pending a successful outcome of the testing.


Saturday, Feb. 4 (DOY 035)

JPL conducted a 5-hour training session in partnership with the California Afterschool Network for 60 leaders and site coordinators of San Bernardino Unified School District's "Creative Before and Afterschool Programs for Success" (CAPS). The attendees pursued hands-on activities from the NASA/JPL "Jewel of the Solar System" activity guide on Saturn and Cassini for grades 4 and 5. The workshop was visited by the CAPS leadership.


Monday, Feb. 6 (DOY 037)

A Y-thruster-pair calibration took place today. This annual event allows Navigation and Attitude Control teams to validate the force-balance of the coupled Y-thruster pairs. Navigation will analyze Doppler tracking data as part of the T-81 to T-82 spacecraft ephemeris reconstruction, looking for indications of any unevenness, important because the Y-Bias maneuvers are performed so often. Those maneuvers are described here:

http://saturn.jpl.nasa.gov/news/cassiniinsider/insider20091027/
 

Tuesday, Feb. 7 (DOY 038)

The Radio Science Subsystem Team performed a Radio Frequency Instrument Subsystem Periodic Instrument Maintenance activity today. The spacecraft's Ka-band transmitter was turned on and observed. Normally this kind of activity also measures performance of the Ultrastable Oscillator, but due to the current anomaly only the Auxillary Oscillator was seen.

Seventy-five packages were mailed today to the teachers whose students participated in the Cassini Scientist for a Day essay contest. Each student and teacher received a certificate of participation, and all teachers received a package of Cassini educational materials. Winners, finalists, and honorable mention recipients received special certificates as well. To see the winning essays, visit: http://saturn.jpl.nasa.gov/education/scientistforaday10thedition/winners2011/

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Re: NASA - Cassini updates
« Reply #246 on: 02/13/2012 05:17 pm »

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Re: NASA - Cassini updates
« Reply #247 on: 02/17/2012 06:47 pm »
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Cassini Significant Events 02/08/2012 - 02/14/2012

The most recent spacecraft tracking and telemetry data in this reporting period were acquired on Feb. 14 from the Deep Space Network 34 meter Station 55 in Madrid, Spain. The Cassini spacecraft is in an excellent state of health. All subsystems are operating normally except for the issues being worked with the Cassini Plasma Spectrometer and the Ultrastable Oscillator. Information on the present position of the Cassini spacecraft may be found on the "Present Position" page at: http://saturn.jpl.nasa.gov/mission/presentposition/.

This week the Cassini science instruments made several observations called TEAs - Titan Exploration from Apoapsis. This campaign makes frequent distant observations over periods of days to weeks under illumination at low to moderate phase angles. Rain clouds are infrequent on Titan, so TEA observations provide a good chance to document coincident atmospheric and surface changes. The Imaging Science Subsystem (ISS), the Composite Infrared Spectrometer (CIRS), and the Visual and Infrared Mapping Spectrometer (VIMS) participate in TEAs.

The ISS team performed another observation in its Satellite Orbit Campaign, observing several small inner moons, and the VIMS team conducted several observations in the Saturn Storm Watch series and the Titan Monitoring Campaign.


Wednesday, Feb. 8 (DOY 039)

The Attitude and Articulation Control Subsystem team performed a calibration of the prime Inertial Reference Unit, which required rotating Cassini about its X, Y, and Z axes. Gyro calibrations such as this are done about once per year as a system performance check.

The Magnetometer (MAG) performed a calibration while the spacecraft was rolling about its Z axis and keeping Cassini's High-Gain Antenna pointed on Earth for communications.

The Ultraviolet Imaging Spectrograph (UVIS) conducted an interplanetary hydrogen survey from out near apoapsis in Saturn orbit.


Thursday, Feb. 9 (DOY 040)

Today Cassini passed through apoapsis at 5,276 kilometers per hour with respect to Saturn, at an altitude of 2.9 million kilometers. This marks the start of Saturn Orbit #161, which has a period of 23.5 days and near-equatorial inclination.

The Cosmic Dust Analyzer (CDA) took advantage of Cassini's distance from Saturn to undertake several long-duration observations of the interstellar dust passing through the solar system.

The Attitude and Articulation Control Subsystem executed a reaction wheel Y-bias maneuver to adjust wheel speeds, while Cassini was off Earth point.
 
The Cassini Spacecraft Operations Office met with JPL Division 33 (Communications, Tracking & RADAR) personnel today to discuss further troubleshooting on Cassini's anomalous Ultrastable Oscillator (USO). A review will be held soon to propose a test designed to check out the USO using Deep Space Transponder-B (DST-B) on the spacecraft without turning off DST-A, which is prime.
 

Friday, Feb. 10 (DOY 041)

Orbit trim maneuver #309 was planned for today, but it was deemed unnecessary and cancelled. The Navigation team's orbit determination solution estimated Cassini to be only about 3 kilometers from its aimpoint for the upcoming Titan T-82 flyby and 0.5 seconds off in timing without the maneuver.

MAG performed an 8-hour calibration while rotating the spacecraft about its X-axis.


Sunday, Feb. 12 (DOY 043)

The Deep Space Network conducted seven 9-hour tracking sessions with Cassini during the week without any losses of Telemetry, Tracking (Doppler and Ranging), Command or Radio Science data.


Monday, Feb. 13 (DOY 044)

The Navigation team took five images of Enceladus against the background stars for purposes of Optical Navigation.

Simulation coordination and procedure review meetings were held this week to discuss RADAR tests for the upcoming Titan T-83 and T-84 flybys in the S73 command sequence which is currently in development. In the Cassini Integration and Test Lab, command testing was conducted for both activities, and the test report for T-83 was released today. An Encounter Strategy Meeting for the Titan T-82 through Enceladus E-17 encounters also took place today.


Tuesday, Feb. 14 (DOY 045)

Today, visitors to the Cassini website http://saturn.jpl.nasa.gov/ were greeted with a fine bouquet of red roses. The artwork was later archived here: http://saturn.jpl.nasa.gov/photos/imagedetails/index.cfm?imageId=4463.

A mission planning forum was held to review propellant usage during the S71 sequence, and the status of the propellant budgets. A "consumables" status is provided on a regular basis so the Project can remain informed of propellant usage and end-of-mission margins.

In anticipation of the Titan T-82 encounter coming up Sunday, a flyby web page was set up. As usual, related images and news will be posted to it. View the page here: http://saturn.jpl.nasa.gov/mission/flybys/titan20120219/.

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Re: NASA - Cassini updates
« Reply #248 on: 02/20/2012 04:41 pm »

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Re: NASA - Cassini updates
« Reply #249 on: 02/23/2012 08:05 pm »
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Cassini Significant Events 02/15/2012 - 02/21/2012

The most recent spacecraft tracking and telemetry data in this reporting period were acquired on Feb. 21 from the Canberra, Australia, Deep Space Network 70 meter Station 43. The Cassini spacecraft is in an excellent state of health. All subsystems are operating normally except for the issues being worked with the Cassini Plasma Spectrometer and the Ultrastable Oscillator. Information on the present position of the Cassini spacecraft may be found on the "Present Position" page at: http://saturn.jpl.nasa.gov/mission/presentposition/.

The highlight for this week was the flyby of Saturn's largest moon, Titan, on Sunday. Flyby altitude was 3,803 kilometers.

The week included four PIEs -- Pre-Integrated Events. In the first two, the Imaging Science Subsystem (ISS) conducted Enceladus plume observations. In second pair, the Visual and Infrared Mapping Spectrometer (VIMS) observed two Saturn stellar occultations, acquiring spectral data while Cassini's motion caused the distant stars to go behind Saturn's upper atmosphere.


Wednesday, Feb.15 (DOY 046)

An Engineering Activities Review was held today for the S75 background sequence which is currently in development.


Thursday, Feb. 16 (DOY 047)

ISS, VIMS, and the Composite Infrared Spectrometer (CIRS) performed another observation in the Titan monitoring campaign. CIRS then observed Saturn for 12 hours to measure oxygen compounds (H2O and CO2) in the stratosphere.

Orbit Trim Maneuver 310, the T-82 approach maneuver, was commanded to execute during its backup window tonight (Feb. 17 Universal Time). This was a Reaction Control Subsystem (RCS thruster) burn with a duration of 12.88 seconds and delta-V of approximately 0.02 meters per second. The maneuver was done during the backup window because the reaction wheel speed solution was more favorable, and the need for a time of flight bias in the targeting was avoided.
 

Friday, Feb. 17 (DOY 048)

ISS, CIRS and VIMS made a 19-hour edge-on observation of the E ring at moderate phase illumination.

The main engine cover was deployed to its closed position.

The NASA Engineering and Safety Center (NESC) team, the Cassini Spacecraft Operations Office, and the CAPS team at the Southwest Research Institute in San Antonio have been meeting weekly since November 2011, to discuss the Cassini Plasma Spectrometer (CAPS) and Radioisotope Thermoelectric Generator (RTG) power bus imbalance anomaly. A preliminary assessment was given orally today. Cassini is now in the process of convening a briefing to JPL upper management for next month.
 

Saturday, Feb. 18 (DOY 049)

On approach to Titan, CIRS measured stratospheric temperatures and chemical species in Titan's atmosphere. ISS had a one-hour unilluminated prime observation primarily for photometry, i.e. measuring Titan's nighttime brightness, while VIMS stared at Titan for global mapping.


Sunday, Feb. 19 (DOY 050)

Titan encounter T-82 took place today.

CIRS performed a wide variety of observations, including limb sounding and mapping of surface and atmospheric temperatures. Far-infrared limb sounding near closest approach reached the most northerly latitude of the Solstice Mission so far, at 75 degrees. This provides insights into the atmospheric circulation in Titan's north polar region as it transitions from spring to summer, and helps search for possible condensates. VIMS rode along to detect clouds, monitoring climatic changes after the equinox.
 
T-82 was a dusk sector equatorial flyby across Titan's magnetic tail. Similar in geometry, but at a lower altitude than T-78 last September, it enables Cassini to better characterize the magnetotail by sampling it at different radial distances from Titan at a fixed local time.

In addition to scientific investigation of Titan, each targeted Titan flyby also provides an orbital momentum exchange that modifies Cassini's orbit about Saturn according to plan. T-82 reduced Cassini's orbit period from 23.5 days to 17.9 days.

The T-82 page will be populated with data from the encounter, available here: http://saturn.jpl.nasa.gov/mission/flybys/titan20120219/.


Monday, Feb. 20 (DOY 051)

Cassini passed through periapse of Saturn Orbit #161 at 68,375 kilometers per hour early today. At this closest point to Saturn, the spacecraft was about 54,000 kilometers outside the F ring.

Cassini turned its High-Gain Antenna toward Earth and downlinked all the T-82 telemetry data in 9.5 hours. Deep Space Station 63 at Madrid, Spain, captured every bit.

The Ultraviolet Imaging Spectrograph (UVIS) was prime for observations of Saturn's aurorae.
 

Tuesday, Feb. 21 (DOY 052)

The Ion and Neutral Mass Spectrometer (INMS) measured neutral molecules in Saturn's equatorial plane.

The main engine cover was stowed in its open position. This marks the 71st in-flight cycle.

During the week, 312 VIMS cubes were generated and distributed, as were 343 ISS images, including one image for optical navigation and 64 for support imaging.

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Re: NASA - Cassini updates
« Reply #250 on: 02/26/2012 09:06 am »

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Re: NASA - Cassini updates
« Reply #251 on: 02/27/2012 04:14 pm »
« Last Edit: 02/28/2012 05:57 pm by racshot65 »

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Re: NASA - Cassini updates
« Reply #252 on: 03/01/2012 08:25 am »
Rev162: Mar 1 - Mar 18 '12

http://www.ciclops.org/view/7097/Rev162

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Re: NASA - Cassini updates
« Reply #253 on: 03/02/2012 07:14 am »
Quote
Cassini Significant Events 02/22/2012 - 02/28/2012

The most recent spacecraft tracking and telemetry data in this reporting period were acquired on Feb. 29 from the Goldstone, California, Deep Space Network 34 meter Station 26. The Cassini spacecraft is in an excellent state of health. All subsystems are operating normally except for the issues being worked with the Cassini Plasma Spectrometer and the Ultrastable Oscillator. Information on the present position of the Cassini spacecraft may be found on the "Present Position" page at: http://saturn.jpl.nasa.gov/mission/presentposition/.

During Cassini's current orbit of Saturn, many observations have centered on Magnetospheric and Plasma Science (MAPS). Measurements made this week by these direct-sensing instruments included equatorial inner magnetosphere sampling, low latitude prime pointing for MAPS as the spacecraft nears apoapsis, and Cassini Apoapses for Kronian Exploration (CAKE) observations. The objective is to acquire nearly complete and continuous measurements of Saturn's outer magnetosphere and magnetosheath. By doing this once every four to six months, MAPS can sample and measure Saturn's magnetosphere over a solar cycle, from one solar minimum to the next, and investigate magnetospheric periodicities and how the Saturn kilometric radiation (SKR) period is imposed on the magnetosphere.
 

Wednesday, Feb. 22 (DOY 053)

The Ultraviolet Imaging Spectrograph (UVIS) and the Visual and Infrared Mapping Spectrometer (VIMS) enjoyed a period of fixed pointing at Saturn's auroral oval, then UVIS surveyed interplanetary hydrogen from its vantage point a million kilometers above Saturn's atmosphere.

An Attitude & Articulation Control Subsystem Reaction Wheel bias maneuver was executed today, setting wheel speeds as needed while thrusters maintained the spacecraft's attitude. Last week's report skipped mention of three such maneuvers during that period.

Today's Orbit Trim Maneuver 311, a cleanup maneuver for last week's Titan T-82 flyby, was canceled. Cancellation was made possible by the T-82 miss being small and in a favorable direction.

Cassini Instrument Operations Multi Mission Image Processing Laboratory (MIPL) used a downtime today to swap the database and File Exchange Interface servers to alternate hardware to continue firmware and patch updates.
 

Thursday, Feb. 23 (DOY 054)

Normal MIPL processing resumed.

The feature "The Many Moods of Titan" was published on the Cassini website:

http://saturn.jpl.nasa.gov/news/cassinifeatures/feature20120223/

The S73 command sequence developers held a Sequence Change Request (SCR) disposition meeting. Four SCRs were approved.

A Cassini-internal meeting was held today to discuss procedure and scheduling options for turning the Cassini Plasma Spectrometer (CAPS) instrument back on (recall it was turned off last June due to concerns over some problems internal to the instrument and others associated with RTG #3). Final approval will depend on the outcome of a review with JPL upper management next week.
 

Friday, Feb. 24 (DOY 055)

The Composite Infrared Spectrometer (CIRS), the Imaging Science Subsystem (ISS), and VIMS carried out Titan Monitoring Campaign observations to look for long term cloud activity, then VIMS and ISS conducted Saturn Storm Watch observations. The Navigation team acquired an Optical Navigation image of Enceladus with two cataloged stars in the background. It has since been processed on the ground in preparation for the March 27 flyby of Enceladus at 75 kilometer altitude.
 

Saturday, Feb. 25 (DOY 056)

Viewed from anywhere on Earth these days, Saturn and Titan are a delight to see in a small telescope. With good optics you might also see moons Dione, Tethys, Rhea, and even Iapetus if it happens to have enough of its bright side facing Earth. Saturn rises in the east before midnight, and is well placed for viewing in the hours before dawn, sharing the sky with bright red Mars. Find out more about this month's night sky here: http://www.jpl.nasa.gov/video/index.cfm?id=1060


Sunday, Feb. 26 (DOY 057)

During the week the Deep Space Network carried out Cassini tracking activities from all three of its worldwide complexes using 70 and 34 meter apertures, and had zero data loss. The one-way light time to Cassini is currently one hour and fifteen minutes, and is decreasing as Earth moves closer to Saturn in its orbit around the sun.


Monday, Feb. 27 (DOY 058)

The Realtime Operations team uplinked Part 2 of the S72 background sequence and verified that the spacecraft properly received and stored all 6,114 of its commands.

A unique image is featured today. "Beside a Giant" shows Titan next to Saturn, and the small F ring shepherd moon Prometheus with its shadow on Saturn, and the shadow of the other shepherd Pandora, along with shadows of the main rings and the thin F ring. View the image here:

http://saturn.jpl.nasa.gov/photos/imagedetails/index.cfm?imageId=4470

Cassini is discussed in a PBS OpEd article as an example of international collaboration in space:

http://to.pbs.org/wXVGpM
 

Tuesday, Feb. 28 (DOY 059)

During the week, 454 ISS images and 41 VIMS cubes were received and distributed.

Offline jacqmans

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Re: NASA - Cassini updates
« Reply #254 on: 03/03/2012 09:03 am »
Cassini Detects Hint of Fresh Air at Dione

The full version of this story with accompanying images is at:
http://www.jpl.nasa.gov/news/news.cfm?release=2012-056&cid=release_2012-056

NASA’s Cassini spacecraft has “sniffed” molecular oxygen ions around Saturn’s icy moon Dione for the first time, confirming the presence of a very tenuous atmosphere. The oxygen ions are quite sparse – one for every 0.67 cubic inches of space (one for every 11 cubic centimeters of space) or about 2,550 per cubic foot (90,000 per cubic meter) – show that Dione has an extremely thin neutral atmosphere.

At the Dione surface, this atmosphere would only be as dense as Earth’s atmosphere 300 miles (480 kilometers) above the surface. The detection of this faint atmosphere, known as an exosphere, is described in a recent issue of the journal Geophysical Research Letters.

“We now know that Dione, in addition to Saturn’s rings and the moon Rhea, is a source of oxygen molecules,” said Robert Tokar, a Cassini team member based at Los Alamos National Laboratory, Los Alamos, N.M., and the lead author of the paper. “This shows that molecular oxygen is actually common in the Saturn system and reinforces that it can come from a process that doesn’t involve life.”

Dione’s oxygen appears to derive from either solar photons or energetic particles from space bombarding the moon’s water ice surface and liberating oxygen molecules, Tokar said. But scientists will be looking for other processes, including geological ones, that could also explain the oxygen.

“Scientists weren’t even sure Dione would be big enough to hang on to an exosphere, but this new research shows that Dione is even more interesting than we previously thought,” said Amanda Hendrix, Cassini deputy project scientist at NASA’s Jet Propulsion Laboratory, Pasadena, Calif., who was not directly involved in the study. “Scientists are now digging through Cassini data on Dione to look at this moon in more detail.”

Several solid solar system bodies – including Earth, Venus, Mars and Saturn’s largest moon Titan – have atmospheres. But they tend to be typically much denser than what has been found around Dione. However, Cassini scientists did detect a thin exosphere around Saturn’s moon Rhea in 2010, very similar to Dione. The density of oxygen at the surfaces of Dione and Rhea is around 5 trillion times less dense than that at Earth’s surface.

Tokar said scientists suspected molecular oxygen would exist at Dione because NASA’s Hubble Space Telescope detected ozone. But they didn’t know for sure until Cassini was able to measure ionized molecular oxygen on its second flyby of Dione on April 7, 2010 with the Cassini plasma spectrometer. On that flyby, the spacecraft flew within about 313 miles (503 kilometers) of the moon’s surface.

Cassini scientists are also analyzing data from Cassini’s ion and neutral mass spectrometer from a very close flyby on Dec. 12, 2011. The ion and neutral mass spectrometer made the detection of Rhea’s thin atmosphere, so scientists will be able to compare Cassini data from the two moons and see if there are other molecules in Dione’s exosphere.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency, and the Italian Space Agency. NASA's Jet Propulsion Laboratory, Pasadena, Calif., a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The Cassini plasma spectrometer team and the ion and neutral mass spectrometer team are based at Southwest Research Institute, San Antonio.

For more information about the Cassini mission, visit: http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov .
Jacques :-)

Offline bolun

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Re: NASA - Cassini updates
« Reply #255 on: 03/05/2012 03:25 pm »
Saturn and Titan

05 Mar 2012

Titan, Saturn's largest moon at 5150 km across, looks small here, pictured to the right of the gas giant in this infrared image taken by the Cassini spacecraft.

http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=50112

and

http://www.esa.int/esaCP/SEMPWD7YBZG_index_0.html

Offline racshot65

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Re: NASA - Cassini updates
« Reply #256 on: 03/06/2012 09:11 am »

Offline racshot65

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Re: NASA - Cassini updates
« Reply #257 on: 03/10/2012 10:25 am »

Offline dsmillman

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Re: NASA - Cassini updates
« Reply #258 on: 03/10/2012 12:04 pm »
There is a spectacular flyover video of Enceladus at:

    vimeo.com/37689757




Offline racshot65

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Re: NASA - Cassini updates
« Reply #259 on: 03/12/2012 07:19 pm »
Quote
Cassini Significant Events 02/29/2012 - 03/06/2012

The most recent spacecraft tracking and telemetry data were collected March 7 using the Deep Space Network's 34 meter Beam-Waveguide Station 25 at Goldstone in the California desert. The Cassini spacecraft is in an excellent state of health. All subsystems are operating normally except for the issues being worked with the Cassini Plasma Spectrometer and the Ultrastable Oscillator. 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/.

Twice this week, Cassini rotated to point its Imaging Science Subsystem (ISS), Composite Infrared Spectrometer (CIRS), and Visual and Infrared Mapping Spectrometer (VIMS) telescopes toward Saturn's largest satellite for more Titan Monitoring Campaign observations. At other times, the instruments were pointed toward Saturn for the Ultraviolet Imaging Spectrograph (UVIS) and ISS to measure and monitor the planet's aurorae.


Wednesday, Feb. 29 (DOY 060)

UVIS surveyed the abundance of interplanetary hydrogen by remote sensing from 2.4 million kilometers above Saturn.
Commands were sent to the spacecraft to do a "live" update of the running Inertial Vector Propagator. This ensures best instrument pointing for an observation of Saturn's large icy satellite Rhea next week.


Thursday, March 1 (DOY 061)

Apoapsis passage early today (Universal Time) marked the start of Cassini's 162nd orbit of Saturn. Having slowed to 5,463 kilometers per hour relative to the planet, the spacecraft begins its nine-day plunge, still in the equatorial plane, gathering speed on its arc back toward Saturn.


Friday, March 2 (DOY 062)

The Cosmic Dust Analyzer made direct measurements of interstellar dust particles as they interacted with the instrument. ISS carried out an 18-hour observation of the outer irregular satellite Thrymr to measure the rotational phase curve.

The feature "Cassini Detects Hint of Fresh Air at Dione" was posted online: http://saturn.jpl.nasa.gov/news/cassinifeatures/feature20120302/
The Attitude and Articulation Control Subsystem executed a Reaction Wheel Y-Bias maneuver to adjust wheel speeds while Cassini was off Earth point.


Saturday, March 3 (DOY 063)

The spacecraft rolled about its Z axis to perform a Magnetometer (MAG) calibration. There is an animation of a typical MAG roll here: http://1.usa.gov/xlYR7U


Sunday, March 4 (DOY 064)

Still some 2.2 million kilometers from Saturn, UVIS again surveyed the hydrogen in interplanetary space.

Cassini rolled for several hours to perform another MAG calibration, this time keeping its High-Gain Antenna dish trained on Earth to maintain two-way communications.

Commands for Orbit Trim Maneuver 312 were uplinked to the spacecraft using Deep Space Station 14 at Goldstone, California. The maneuver will execute March 9, but was uplinked early as a precaution; there would be a heavy delta-V cost if it were delayed.


Monday, March 5 (DOY 065)

Commands for the Cassini Plasma Spectrometer (CAPS) are still being issued from the S72 background sequence that is running, but since the instrument is turned off, there are no results. Pending the outcome of a review next week, it may be possible to turn CAPS back on before the sequence ends.
 

Tuesday, March 6 (DOY 066)

Cassini passed 717,800 kilometers from Titan on its way inbound toward Saturn; this occurred during a Deep Space Network tracking pass.

An "Insider's Cassini" article, "How to Plan Your Flyby" was published here:
http://saturn.jpl.nasa.gov/news/cassiniinsider/insider20120306/

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