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Titan Flyby - 26 March 2007

Titan Flyby - 26 March 2007

23 March 2007

Just 16 days after Titan-26, Cassini returns to Titan for its twenty-eighth targeted encounter. The closest approach to Titan occurs on Monday, 26 March 2007 at 00:23 UT at an altitude of 1010 kilometres above the surface and at a speed of 6.2 kilometres per second. The latitude at closest approach is 41.1° N and the encounter occurs on orbit number 41.

Around closest approach, Cassini passes behind Titan for approximately 35 minutes as seen from Earth. This flyby configuration allows for radio observations to be made of Titan's atmosphere, with a radio signal passing through the atmosphere which is subsequently received on Earth. In addition bistatic radio measurements will be made of the moon's surface, by sending a radio signal at grazing angles, which after bouncing of Titan's surface is received on Earth and provides information on the surface properties.

This encounter is set up with two manoeuvres: an apoapsis manoeuvre on 17 March, and an approach manoeuvre, scheduled for 22 March. This is the third in a series of outbound Titan encounters (series ends with T33, 29 June 2007) and occurs about 3 days after Saturn closest approach.

Science Activities

  • Radio Science Subsystem (RSS)
    A T27 ingress/egress occultation of Titan's atmosphere will provide a high-spatial-resolution electron number density profile of the ionosphere, temperature-pressure and absorption profiles of the neutral atmosphere, as well as information about the small-scale structure of the atmosphere. The ingress latitude is -71.3° and the egress latitude is 54°. The previous two RSS Titan occultations had ingress latitudes of -29° and -30.9°. The previous egress latitudes were -49° and -32.5°. T31 (28 May 2007) will be the fourth and final RSS Titan occultation and it will have an ingress latitude of -75.4° and an egress latitude of 74.6°.
    In addition, inbound and outbound RSS bistatic scattering observations of Titan's surface will provide information about the dielectric constant, nature, and roughness of the region probed. This RSS bistatic observation is in the deep southern hemisphere, over one of the very large dark regions shown in the imaging data. In the north, these large dark regions have turned out to be most likely hydrocarbon seas and lakes.
  • Ultraviolet Imaging Spectrograph (UVIS)
    UVIS will perform several slow scans across Titan's visible hemisphere to form spectral images.
  • Imaging Science Subsystem (ISS)
    Extending coverage north of Belet and Adiri.
  • Composite Infrared Spectrometer (CIRS)
    Inbound CIRS is doing a far-IR composition integration and a mid-IR limb composition integration. Outbound CIRS is doing a far-IR limb composition integration, far-IR surface temperature scan, and a mid-IR composition integration.

Table of Events

17 February 2007

Time UTC Time wrt
Titan-27
Activity
10:52:00 -36d 14h Start of sequence S28 which contains Titan-27

22 March 2007

Time UTC Time wrt
Titan-27
Activity
14:30:00 -03d 10h OTM #100 prime. Titan-27 targeting manoeuvre
15:46:00 -03d 09h Descending ring plane crossing

23 March 2007

Time UTC Time wrt
Titan-27
Activity
11:57:00 -02d 12h Saturn periapse, r = 12.1 RS, latitude= -54°, phase = 83°
23:20:00 -02d 01h OTM #100 backup

25 March 2007

Time UTC Time wrt
Titan-27
Activity
08:50:00 -15h 33m Turn cameras to Titan
08:50:00 -15h 33m Deadtime, 17 minutes 27 seconds long; used to accommodate changes in flyby time
09:07:27 -15h 16m Titan atmospheric observations. Obtain information on the thermal structure of Titan's stratosphere
11:23:27 -13h 00m Titan atmospheric observations. Obtain information on trace constituents in Titan's stratosphere
14:23:27 -10h 00m ISS imaging. WAC photometry
15:23:27 -09h 00m Titan atmospheric observations. Obtain information on trace constituents in Titan's stratosphere
19:23:27 -05h 00m ISS imaging. Search for and monitor lightning/aurora
20:23:27 -04h 00m Transition to thruster control
20:49:27 -03h 34m Titan atmospheric observations. Several slow scans across Titan's visible hemisphere to form spectral images
23:12:27 -01h 11m New waypoint
23:25:27 -00h 58m RSS observations. Bistatic scattering measurements at three radio wavelengths to determine the physical properties of Titan's surface, including reflectivity, dielectric constant, and roughness

26 March 2007

Time UTC Time wrt
Titan-27
Activity
00:00:03 -00h 23m RSS occultation of Titan's atmosphere on ingress, atmosphere and ionosphere on egress
00:23:27 +00h 00m Titan-27 flyby closest approach time.
Altitude = 1010 km, speed = 6.2 kms-1; 150° phase at closest approach
00:28:00 +00h 05m Ascending ring plane crossing
00:35:25 +00h 12m RSS observations. Bistatic scattering measurements at three radio wavelengths to determine the physical properties of Titan's surface, including reflectivity, dielectric constant, and roughness
01:23:27 +01h 00m New waypoint
01:56:27 +01h 33m Titan atmospheric observations. Vertical sounding of stratospheric compounds on Titan, including H2O. Integrations at two locations on the limb displaced vertically
02:38:27 +02h 15m Titan atmospheric observations. Obtain information on surface & tropopause temperatures
03:23:27 +03h 00m Titan atmospheric observations. Several slow scans across Titan's visible hemisphere to form spectral images
08:23:27 +08h 00m ISS imaging. Global map and WAC photometry
09:23:27 +09h 00m Titan atmospheric observations. Obtain information on trace constituents in Titan's stratosphere
11:23:27 +11h 00m ISS imaging. Monitoring for surface/atmosphere changes
13:23:27 +13h 00m Titan atmospheric observations. Global mapping
21:38:27 +21h 15m Deadtime, 13 minutes 33 seconds long. Used to accommodate changes in flyby time
21:52:00 +21h 29m Turn to Earth-line
22:22:00 +21h 59m Playback of T27 data. Goldstone 70M

Observation Results

Cassini Instrument: Imaging Science Subsystem (ISS)

Date: 1 May 2007

Credit: NASA/JPL/Space Science Institute

Image Notes: Combining multiple images taken with the Narrow-angle camera improves resolution and allows to see Titan surface features beyond the terminator

Date: 27 April 2007

Credit: NASA/JPL/Space Science Institute

Image Notes: Narrow-angle camera image, taken in visible violet light, showing bands of clouds in Titan's fast rotating stratosphere at high northern latitudes

Last Update: 1 September 2019
18-Jan-2022 09:26 UT

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