Titan Fly-by - 6 June 2009
4 June 2009
On Saturday, 6 June, the Cassini spacecraft returns to Titan for the mission's fifty-seventh targeted encounter with Saturn's largest moon: T-56. The closest approach to Titan occurs at 20:00 UTC, at an altitude of 965 kilometres above the moon's surface and at a speed of 6.0 kilometres per second. The latitude at closest approach is 32.1°S and the encounter occurs on orbit number 112.This encounter is set up with two manoeuvres: an apoapsis manoeuvre on 29 May, and a Titan approach manoeuvre, scheduled for 3 June. T56 is the fifth fly-by in a series of eleven inbound encounters and the twelfth Titan encounter in Cassini's Equinox Mission. It occurs just under three days before Saturn closest approach.
Science Highlights
- Cassini Radar (RADAR)
RADAR continues the southern hemisphere mapping sequence. The instrument captures SAR in addition to outbound altimetry, scatterometry, and radiometry. The SAR swath runs parallel to, and partly overlaps, the swath captured in the previous fly-by T55, running down from Shangri-La to southern high latitudes. - Ion and Neutral Mass Spectrometer (INMS)
INMS will be riding with RADAR on T56. This is the only dusk side observation at mid Southern latitudes. It's the only time in the mission that the spacecraft will get simultaneous coverage of the dusk side while in the wake magnetospheric interaction region. - Composite Infrared Spectrometer (CIRS)
CIRS conducts distant stratospheric composition and temperature mapping to search for seasonal changes. - Visual and Infrared Mapping Spectrometer (VIMS)
On the inbound leg, the phase angle is much larger than 90° and VIMS ride-along observations will provide information on Titan's atmospheric composition. After closest approach, VIMS will observe the South Pole region riding along with CIRS far from Titan. Only cloud monitoring will be possible. - Imaging Science Subsystem (ISS)
ISS will ride along with VIMS to observe eastern Tsegihi and to monitor clouds over Titan's trailing hemisphere at mid-southern latitudes. There will be no illuminated prime observations. - Ultraviolet Imaging Spectrograph (UVIS)
UVIS has an unusually large number of observations during the series of fly-by's T55-T60 where the instrument dictates the spacecraft's pointing. All of them are part of an ongoing sequence of requests to acquire latitude, phase angle, and time coverage of atmospheric composition, including Titan's haze. The T56 fly-by includes two stellar occultations and several EUV-FUV images. The instrument will obtain image cubes of Titan's atmosphere at EUV and FUV wavelengths by sweeping its slit across the disk. These cubes provide spectral and spatial information on nitrogen emissions, H emission and absorption, absorption by simple hydrocarbons, and the scattering properties of haze aerosols. These are a few of many such cubes gathered over the course of the mission to provide latitude and seasonal coverage of Titan's middle atmosphere and stratosphere. - Magnetospheric Imaging Instrument (MIMI)
MIMI measures energetic ion and electron energy input to Titan's atmosphere.
Table of Events
5 May 2009
| Time UTC | Time wrt T-56 |
Activity |
| 07:16:00 | -32d 13h | Start of sequence S50 that contains Titan-56 |
3 June 2009
| Time UTC | Time wrt T-56 |
Activity |
| 12:42:00 | -03d 07h | OTM #199 prime. Titan-56 targeting manoeuvre |
4 June 2009
| Time UTC | Time wrt T-56 |
Activity |
| 12:42:00 | -02d 07h | OTM #199 backup |
6 June 2009
| Time UTC | Time wrt T-56 |
Activity |
| 05:12:00 | -14h 48m | Start of the TOST segment |
| 05:12:00 | -14h 48m | Turn cameras to Titan |
| 05:52:00 | -14h 08m | New waypoint |
| 05:52:00 | -14h 08m | Deadtime, 15 minutes and 49 seconds long. Used to accommodate changes in fly-by time |
| 06:07:49 | -13h 53m | Titan atmospheric observations - CIRS. Obtain information on CO, HCN, CH4. Integrate on disk at airmass 1.5-2.0 |
| 10:00:01 | -10h 00m | Titan atmospheric observations - ISS. WAC photometry |
| 11:00:01 | -09h 00m | Titan surface observations - VIMS. Regional mapping |
| 14:50:01 | -05h 10m | RADAR. Inbound radiometry |
| 18:00:01 | -02h 00m | RADAR. Inbound scatterometry |
| 18:48:01 | -01h 12m | Transition to thruster control |
| 18:49:01 | -01h 11m | RADAR. Inbound HiSAR |
| 19:30:01 | -00h 30m | RADAR. Inbound altimetry |
| 20:18:01 | +00h 18m | RADAR. Inbound and outbound SAR |
| 19:40:51 | -00h 20m | Earth occultation, 20 minute duration |
| 19:42:00 | -00h 18m | Solar occultation, 19 minute duration |
| 20:00:00 | +00h 00m | Titan-56 Fly-by Closest Approach Time. Altitude = 965 km, speed = 6.0 kms-1, 135° phase at closest approach |
| 20:18:01 | +00h 18m | RADAR. Outbound altimetry |
| 20:20:00 | +00h 20m | Descending ring plane crossing |
| 20:32:01 | +00h 32m | Transition off of thruster control |
| 20:53:10 | +00h 53m | Titan atmospheric observations - UVIS. Titan occults Eta Uma. UVIS FUV occultation slit boresite on star for entire time |
| 21:41:01 | +01h 41m | Titan atmospheric observations - UVIS. EUV-FUV imaging of Titan |
7 June 2009
| Time UTC | Time wrt T-56 |
Activity |
| 05:00:01 | +09h 00m | Titan atmospheric observations - CIRS. Obtain information on CO, HCN, CH4. Integrate on disk at airmass 1.5-2.0 |
| 10:00:01 | +14h 00m | Titan surface observations - VIMS. Global mapping |
| Titan surface observations - ISS. Monitoring for surface/atmosphere changes; attempt to see surface colour variations; monitor limb hazes, 1-3 km/px | ||
| Titan atmospheric observations - CIRS. Obtain information on the thermal structure of Titan's stratosphere | ||
| 19:02:49 | +23h 02m | Deadtime, 14 minutes and 11 seconds long. Used to accommodate changes in fly-by time |
| 19:17:00 | +23h 17m | Turn to Earth-line |
| 19:57:00 | +23h 57m | Playback of T65 data, Goldstone 34m and 70m ground station |
8 June 2009
| Time UTC | Time wrt T-56 |
Activity |
| 01:48:00 | +01d 06h | Playback of T56 data, Canberra 70m ground station |
Last Update: 1 September 2019