Launched aboard a Titan IVB/Centaur on 15 October 1997, Cassini had a nearly 20-year life span, with 13 of these years spent orbiting Saturn.[3] The voyage to Saturn included flybys of Venus (April 1998 and June 1999), Earth (August 1999), the asteroid2685 Masursky, and Jupiter (December 2000). The probes entered orbit on 1 July 2004, and the mission ended on 15 September 2017, when Cassini flew into Saturn's upper atmosphere[4][5] in order to prevent any risk of contaminating Saturn's moons, some of which have active environments that could potentially bear life.[6][7] The mission is widely perceived to have succeeded beyond expectations. Cassini-Huygens has been described by NASA's Planetary Science Division Director as a "mission of firsts",[8] that has revolutionized human understanding of the Saturnian system, including its moons and rings, and our understanding of where life might be found in the Solar System.
Cassini's primary mission lasted for four years, from June 2004 to May 2008. The mission was extended for another two years until September 2010, under the name of Cassini Equinox Mission. The mission was extended a second and final time with the Cassini Solstice Mission, lasting until the spacecraft's destruction in September 2017.
The Huygens module traveled with Cassini until its separation from the probe on 25 December 2004; it was successfully landed by parachute on Titan on 14 January 2005. It successfully returned data to Earth for around 90 minutes, using the orbiter as a relay. This was the first landing ever accomplished in the outer Solar System and the first landing on a moon other than our own.
At the end of its mission, the Cassini spacecraft executed the "Grand Finale" of its mission: several risky passes through the gaps between Saturn and Saturn's inner rings.[1][2] The purpose of this phase was to maximize Cassini's scientific outcome before the spacecraft was destroyed.[9] The atmospheric entry of Cassini effectively ended the mission, although data analysis and production is still ongoing.
Launch and cruise phase (1997–2003)
Launch occurred at 4:43 a.m. EDT (8:43 UTC) on 15 October 1997, from Space Launch Complex 40 at Cape Canaveral Air Force Station, Florida.Animation of Cassini trajectory from 15 October 1997 to 4 May 2008 Cassini–HuygensJupiter SaturnEarthVenusSun· 2685 MasurskyThe initial gravitational-assist trajectory of Cassini–Huygens
26 April 1998 06:52 PDT – Gravity-assisted flyby of Venus at 284km, receiving a boost in speed of about 7 kilometers per second.[10]
3 December 1998 22:06 PST – Cassini fired its main rocket engine for 90 minutes, setting the spacecraft on course for its second Venus flyby in 1999. The engine burn slowed the spacecraft by close to 450 meters per second (about 1,006 miles per hour) relative to the Sun. Cassini's speed went from 67,860 kilometers per hour (42,168 miles per hour) at the start of the maneuver to 66,240 kilometers per hour (41,161 miles per hour) at the end of the engine firing.[11]
24 June 1999 13:30 PDT – Gravity-assisted flyby of Venus at 623km.[12]
18 August 1999 03:28 UTC − Gravity-assisted flyby of Earth. An hour 20 minutes before closest approach, Cassini made the closest approach to the Moon at 377,000km, and took a series of calibration images. The spacecraft flew past Earth at a distance of 1,171 kilometers (728mi), passing most closely above the eastern South Pacific at 23°30′S128°30′W / 23.5°S 128.5°W / -23.5; -128.5. Cassini received a 5.5-kilometer-per-second (about 12,000-mile-per-hour) boost in velocity.[13]
23 January 2000 – flyby of Asteroid2685 Masursky around 10:00 UTC. Cassini took images[14] 5 to 7 hours before at 1.6 million km distance and estimated a diameter of 15 to 20km.
30 December 2000 10:05 UTC − Gravity-assisted flyby of Jupiter. Cassini was at its closest point (9.7 million kilometres, 137 Jovian radii) to Jupiter at this date, and performed many scientific measurements.[15] It also produced the most detailed global color portrait of Jupiter ever produced (seen on the right); the smallest visible features are approximately 60km (37mi) across.
30 May 2001 – During the coast phase between Jupiter and Saturn, it was noticed that "haze" became visible in the pictures taken by the narrow-angle camera of Cassini. This was first seen when a picture of the star Maia in the Pleiades was taken after a routine heating period.
23 July 2002 – In late January, a test was performed to remove the "haze" from the narrow-angle camera lens by heating it. Warming the camera to 4 degrees Celsius (39 degrees Fahrenheit) for eight days produced positive results. Later, the heating was extended to 60 days, and a picture of the star Spica showed an improvement of more than 90 percent compared to before the heating period. On 9 July, a picture showed that the removal procedure was completed successfully, which was announced on 23 July.[16]
10 October 2003 – The Cassini science team announced the results of a test of Einstein's theory of gravity, using radio signals from the Cassini probe. The researchers observed a frequency shift in the radio waves to and from the space craft, as those signals traveled close to the Sun. Past tests were in agreement with the theoretical predictions with an accuracy of one part in one thousand. The Cassini experiment improved this to about 20 parts in a million, with the data still supporting Einstein's theory.
Picture of Moon during flyby
Jupiter flyby
Primary mission (2004–2008)
Cassini image of Saturn, February 2004Animation of Cassini's trajectory around Saturn from 1 May 2004 to 15 September 2017 Cassini· Saturn·Enceladus·Titan·Iapetus
27 February 2004 – A new, high-resolution picture of Saturn taken by Cassini on 9 February was released, and it was noted that mission scientists were puzzled by the fact that no "spokes" in Saturn's ring are visible. These dark structures in the "B" section of the ring had been discovered in pictures taken by the Voyager probe in 1981.[17] Another picture, in infrared light, taken on 16 February shows cloud height differences and the same disturbance visible throughout the 1990s in Hubble Space Telescope images.[18]
12 March 2004 – Pictures taken on 23 February do show a feature discovered by Voyager: Clumps in the outer "F"-ring. What could not be ascertained at the time was the exact lifetime of these clumps, and it is hoped that Cassini will provide conclusive data about this question. The first set of pictures shows a set of "clumps" moving along the "F" ring.[19]
26 March 2004 – The Cassini science team published the first sequence of pictures of Saturn showing clouds moving at high speed around the planet. Using a filter to better see water haze on top of the dense cloud cover, motions in the equatorial and southern regions are clearly visible.[20] The pictures were taken during the days from 15 to 19 February.
8 April 2004 – The first "long-term" observation of cloud dynamics in Saturn's atmosphere were published by mission scientists. A set of pictures shows two storms in the southern latitudes merge during a period from 19 to 20 March. Both storms had a diameter of about 1,000km (620mi) before they merged.
15 April 2004 – NASA announced that two moons discovered by Voyager 1 were sighted again by Cassini in pictures taken on 10 March: Prometheus and Pandora. These are no ordinary moons, but their gravitational effects on the "F" ring led scientists to call them "shepherd moons". They fascinate all researchers interested in the dynamics of the ring system, because their orbits are close enough that they interact with each other in a chaotic manner. They have a history of defying predictions of their orbits. One of Cassini's missions will be to monitor the movements of these bodies closely.
18 May 2004 – Cassini entered the Saturn system. The gravitational pull of Saturn began to overtake the influence of the Sun.
20 May 2004 – The first picture of Titan with better resolution than any Earth-based observation was released. It was taken 5 May from a distance of 29.3 million kilometers (18.2 million miles).
27 May 2004 – TCM-20, the Phoebe approach TCM (Trajectory Correction Maneuver) was executed at 22:26:00 UTC. This was a 5-minute and 56 second burn of the main engine, which was not used since December 1998. It therefore doubled as a "dress rehearsal" for the 96 minute burn during "Saturn Orbit Insertion" (SOI). However, TCM-20 was mainly designed to change Cassini's velocity by 34.7m/s (78mph), setting up a flyby of the moon Phoebe 11 June.
11 June 2004 – Cassini flew by the moon Phoebe at 19:33 UT in Spacecraft Event Time at 2068 kilometers distance. All of the eleven onboard instruments operated as expected and all data was acquired. Scientists plan to use the data to create global maps of the cratered moon, and to determine Phoebe's composition, mass and density. It took scientists several days to pore over the data to make more concrete conclusions.
16 June 2004 – TCM-21 took place with a 38-second main engine burn. It was planned as the last correction of the trajectory of Cassini before SOI. A few days later the final TCM-22 tentatively scheduled for 21 June was canceled.
1 July 2004 – The Saturn Orbit Insertion burn was successfully executed. At 7:11p.m. PDT (10:11p.m. EDT), Cassini crossed the ring plane between Saturn's F and G rings. Its antenna was oriented forward acting as a shield against small ring particles. At 7:36p.m. PDT (10:36p.m. EDT), the spacecraft began a critical 96-minute main engine burn to cut its velocity by 626 meters per second and permit a 0.02 x 9 million kilometer Saturn orbit. Right after that burn, pictures of the rings were taken and sent back to mission scientist as the spacecraft approached within 19,980 kilometers (12,400 miles) from the cloud tops.[21] Scientists were surprised by the clarity and detail of the pictures and will be poring over them for quite some time. "We won't see the whole puzzle, only pieces, but what we are seeing is dramatic," said Dr. Carolyn Porco, Cassini imaging team leader, Space Science Institute, Boulder, Colo. "The images are mind-boggling, just mind-boggling. I've been working on this mission for 14 years and I shouldn't be surprised, but it is remarkable how startling it is to see these images for the first time."
2 July 2004 – Cassini's first flyby of Titan was executed and first close up pictures were sent back to Earth. Due to the planning of the initial orbit, Cassini was passing over the south pole of the moon and from a larger distance than in later flybys. Regardless, during a press conference on 3 June,[clarification needed] mission scientists presented pictures that were already causing them to rethink previous theories. It now seems that the darker and brighter albedo features on the surface do represent different materials. But in contrast to expectation, the icy regions seem to be darker than the areas where other (possibly organic) matter is mixed in with the ice.
16 August 2004 – Mission scientists announce the discovery of two new moons of Saturn, and with it the successful start of one of the programs of Cassini: Locating small and yet unknown moons. Later named "Methone" (S/2004 S 1) and "Pallene" (S/2004 S 2), these objects are small compared to other moons and they orbit between Mimas and Enceladus.
23 August 2004 – At a distance of 9 million kilometers from Saturn, the last major firing of the main engine took place to adjust the next closest approach and avoid the particles in the ring system. The 51 minute burn increased the velocity of the probe by 325 meters per second, moving the orbital periapsis point about 300,000km farther away from Saturn than its smallest distance during SOI. At the same time, the new course will bring Cassini very close to Titan on its next flyby.[22]
14 September 2004 – Final checks of the Huygens lander were completed successfully.
26 October 2004 – The second flyby of Titan (called "Titan-A") was successfully executed. Data started to arrive at the JPL mission center at 01:30 UTC, 27 October, and included the highest resolution pictures ever taken of the surface of that moon. Additionally, first high-resolution infra-red spectra and pictures were taken from the atmosphere and surface. The spacecraft successfully skimmed the hazy, smoggy atmosphere of Titan, coming within 1,176 kilometers of Titan's surface. The flyby was the closest that any spacecraft has ever come to Titan. The pictures, spectra, and radar data revealed a complex, puzzling surface. The only glitch during the "Titan-A" event involved the CIRS instrument. During playback, the instrument team observed corrupted data. A decision was made to power the instrument off to reboot it. CIRS was powered back on within 24 hours and returned to its nominal state.
23 November 2004 – The last in-flight checks of the Huygens probe before separation were completed successfully.
13 December 2004 – The "Titan-B" flyby was executed successfully.
25 December 2004 – Huygens probe separated from Cassini orbiter at 02:00 UTC.[23]
27 December – NASA published a picture of Huygens taken from Cassini two days after its release. It reported that the analysis of that picture shows that the probe is on the correct course within the expected error range. These checks were necessary in order to place Cassini in the correct orientation to receive the data from Huygens when it entered Titan's atmosphere.
28 December 2004 – OTM-10 was executed at 03:00 UTC in Spacecraft Event Time. This maneuver, also called the Orbit Deflection Maneuver (ODM), took Cassini off of a Titan-impacting trajectory and on to a flyby trajectory with the required altitude to receive data from the Huygens probe as it plunged into Titan's thick atmosphere.
31 December 2004 – Cassini's flyby of Iapetus occurred at 18:45:37 UTC at an altitude of 122645 kilometers. First raw pictures were available the next day.
14 January 2005 – Huygens entered Titan's atmosphere at 09:06 UTC and landed softly on its surface about two hours later. This was confirmed by the reception of the carrier wave emitted by the probe during its descent and touchdown. At 16:19 UTC, the Cassini orbiter started to relay the scientific data received from the probe to Earth. The first picture was released at 19:45 UTC, showing a view from about 16km above the surface. A second picture taken from the probe at rest on the surface was released a short time later.
15 February 2005 – Cassini executed a successful Titan flyby, with new regions of its surface scanned by radar. Cassini's mapping radar acquired a picture that shows a large crater on Titan, with an estimated diameter of 440km (270mi).[24]
17 February 2005 – The first close flyby of Enceladus was executed and the first closeup images were sent back to Earth. The flyby distance was about 1,180km (730mi).
17 March 2005 – The Cassini probe revealed that Saturn's moon Enceladus has an atmosphere. It has been described as "substantial" by its discoverers.
16 April 2005 – The fifth planned flyby of Titan with a minimum distance of about 1,025 kilometers was executed at 19:12 UTC. This was the closest flyby up to this date, and provided the opportunity to obtain more detailed data on the constituents in the upper atmosphere of Titan. The first analysis of that data showed a large range of complex carbon molecules. On 25 April a mass plot was published that demonstrates the existence of these molecules.
3 May 2005 – Cassini begins Radio occultation experiments on Saturn's Rings, to determine ring particle size distribution, on the scale of centimeters.
10 May 2005 – At the beginning of a period of focussed observation of the ring system of Saturn, slated to take until September, mission scientists announced the discovery of a new moon in the "Keeler gap" inside the "A" ring. Provisionally named S/2005 S 1 and later named Daphnis, it was first seen in a time-lapse sequence of images taken on 1 May. Imaging scientists had predicted the new moon's presence and its orbital distance from Saturn after last July's sighting of a set of peculiar spiky and wispy features in the Keeler gap's outer edge.
14 July 2005 – The closest flyby of Enceladus with a distance of 175km (109mi) was executed successfully. First raw pictures were published.
7 September 2005 – Flyby of Titan at a distance of 1,075km (668mi), data gathered partially lost due to software problem.
26 September 2005 – Flyby of Hyperion at a distance of 1,010km (630mi), the closest flyby and only visit to the moon during the primary mission.
27 July 2006 – NASA confirms the presence of hydrocarbon lakes in Titan's northern polar region.
28 May 2008 – Cassini completed its 43rd flyby of Titan, ending its primary mission. Renamed Cassini Equinox mission, Cassini observed Saturn during its equinox crossing, or summertime.[25]
'F' Ring and shepherd moons
Titan, imaged on 5 May 2004
Phoebe encounter, 11 June 2004
Encke gap, imaged just after orbital insertion on 1 July 2004
Titan in false color, imaged during Titan-A on 26 October 2004.
Huygens is released on its way to Titan.
First picture from the surface of Titan
Mass spectrum of Titan's atmosphere
First closeup view of Enceladus
Cassini Equinox mission (2008–2010)
Rings from above, with Saturn cropped
9 August, 11 August, 9 October, and 31 October 2008 – With closest approach at 50, 25, and 200km, respectively, Cassini's last three Enceladus flybys of 2008 utilized a new imaging technique named "skeet shooting" to successfully acquire very high resolution images. The flybys also allowed Cassini to directly sample Enceladus's cryovolcanic plumes.
3 November, 14 November, 5 December, and 21 December 2009 – Titan flybys 46 through 49 concentrated on radar, VIMS, and INMS sampling of Titan and its thick atmosphere. T47 involved high-resolution VIMS coverage of the Huygens landing site, while the other three flybys made use of radar and RSS. T49 allowed radar coverage of Ontario Lacus, one of the largest methane lakes on Titan.
June - October 2009 – Cassini observed Saturn during its equinox, or the time of Saturn's year where the sun is directly over its equator.[26]
2 November 2010 – Cassini was triggered into a protective standby mode, or "safe mode", after a bit flip caused it to miss an important instruction. NASA announced the interruption in scientific processes on 8 November.[27] However, by 8 November some of the craft's functionality had already been partly restored.[28] Nominal scientific instrument sequencing events were successfully started on 10 November.[29][30]Cassini was reactivated as scheduled on 24 November and has returned to perfect working order, in time for two scheduled close fly-bys with Enceladus.[31] At this point there has been no public disclosure[32] as to the data loss impact of the 11 November (T-73) flyby. However, no images were acquired on the 11 November polar flyby.
Cassini Solstice Mission (2010–2017)
On 3 February 2010, NASA announced that a second mission extension until May 2017, a few months past Saturn's summer solstice, had been funded. The schedule included an additional 155 orbits, with 54 flybys of Titan, 11 of Enceladus,[33] 2 of Rhea, and 3 of Dione. One of the flybys of Titan dipped below the ionosphere.
Saturn's moon Helene, 2011
Cassini flew by Saturn's little moon Methone in May 2012
On 15 September 2017, Cassini was deliberately disposed of by a controlled fall into Saturn's atmosphere, ending its nearly two-decade-long mission.[2][34] The last signal was received at 11:55:46 UTC.
Cassini orbiter travel milestones
Date (UTC)
Distance from Saturn
2004 March 22, 07:42:14
50,000,000 kilometers
2004 April 12, 19:35:12
40,000,000 kilometers
2004 May 04, 02:59:09
30,000,000 kilometers
2004 May 25, 02:40:06
20,000,000 kilometers
2004 June 14, 11:15:22
10,000,000 kilometers
Detailed timeline of Huygens mission
This section needs to be updated. Please help update this article to reflect recent events or newly available information.(September 2017)
Huygens's distance from TitanAnimation of Huygens's trajectory from 25 December 2004 to 14 January 2005 Huygens·Titan·Saturn
All times given after 2005-Jan-14 09:11 UTC are expected event times and may differ from actual event times. This page will be updated after descent has occurred with corrections if they are necessary.[needs update][36][37]
The data used in this section has been slightly out of date, an updated version of ephemeris from ESA was available 2005 January 6.[citation needed]
Timeline of Huygens landing process
Date (UTC)
Description
2004 December 25, 02:00
Huygens separates from Cassini. Its flight path initially takes it away from Titan.
2005 January 03, 20:01
Huygens reaches a maximum distance of 4,658,661 kilometers from Titan.
2005 January 11, 12:00
Cassini rise in the east (azimuth = 93 degrees) as seen from the landing site
2005 January 12, 11:20
Huygens is 1,000,000 kilometers from Titan.
2005 January 13, 09:21
Huygens is 500,000 kilometers from Titan.
2005 January 14, 04:23
Huygens is 100,000 kilometers from Titan.
2005 January 14, 06:50
Cassini turns on probe radio link receivers. Huygens is 50,000 km from Titan.
2005 January 14, 07:02
Cassini begins to turn radio dish toward Titan
2005 January 14, 07:14
Cassini turn to Titan complete; 3 minutes later orbiter X-band downlink disabled
2005 January 14, 08:29
Saturn occulted by Titan as seen from Huygens
2005 January 14, 08:38
Saturn's rings occulted by Titan as seen from Huygens
2005 January 14, 08:44
Probe turns transmitters on; low power mode
2005 January 14, 08:48
Huygens is 10,000 kilometers from Titan.
2005 January 14, 09:06
Huygens enters the atmosphere of Titan
2005 January 14, 09:09
Huygens feels maximum deceleration
2005 January 14, 09:10
Huygens deploys its pilot chute, followed closely by the main chute.
2005 January 14, 09:11
Huygens begins data transmission to Cassini.
2005 January 14, 09:18
Release front shield; transmitters switch to high power mode; instruments configured for descent and measurements commence
2005 January 14, 09:25
Main parachute separates; deploy stabilizing drogue chute
2005 January 14, 09:49
Huygens activates its surface proximity sensor, allowing it to measure its altitude and spin rate.
2005 January 14, 09:57
The Gas Chromatograph Mass Spectrometer, the last instrument to be activated, begins to sample the atmosphere.
2005 January 14, 11:12
Cassini makes its closest flyby of Titan (Titan-C) at an altitude of 59,996 kilometers at a speed of 5,401 meters per second and 93 degree phase angle (azimuth = 278 degrees, elevation = 33 degrees as seen from the landing site)
2005 January 14, 11:30
Huygens turns on its descent imager lamp.
2005 January 14, 11:37
Huygens lands on the surface of Titan
2005 January 14, 13:11
Cassini sets in the west (azimuth = 272 degrees) as seen from the landing site
2005 January 14, 13:47
Cassini stops probe data collection
2005 January 14, 18:14
Cassini sends the first of Huygens' data back to Earth.
Fly-bys
Following is a list of close fly-bys of Saturn's moons (at less than 5000km). The closest approach for each moon is bolded.
Primary mission
Body
Date (UTC)
Altitude (kilometer)
Phoebe
2004 June 11, 19:33
1,997
Passage through rings
2004 June 30, (twice)
0
Orbital insertion
2004 July 1, 02:48
0
Titan
2004 October 26, 15:30
1,200
Tethys
2004 October 28
256,000
Titan
2004 December 13, 11:38
1,200
Probe Release
2004 December 25, 02:00
Titan
2005 January 14, 11:12
59,996
Titan
2005 February 15, 06:58
1,577
Enceladus
2005 February 17, 03:30
1,176
Polydeuces
2005 February 17, 08:48
6,447
Enceladus
2005 March 9, 09:08
500
Titan
2005 March 31, 20:05
2,402
Titan
2005 April 16, 19:12
1,025
Enceladus
2005 July 14, 19:58
175
Titan
2005 August 22, 08:53
3,758
Titan
2005 September 7, 08:01
1,025
Tethys
2005 September 24, 01:36
1,500
Hyperion
2005 September 26, 01:46
500
Dione
2005 October 11, 17:59
500
Titan
2005 October 28, 04:04
1,451
Rhea
2005 November 26, 22:37
500
Titan
2006 January 15, 11:41
2,043
Titan
2006 February 27, 08:25
1,813
Titan
2006 March 19, 00:06
1,951
Titan
2006 April 30, 20:58
1,855
Titan
2006 May 20, 12:18
1,879
Titan
2006 July 2, 09:21
1,906
Titan
2006 July 22, 00:25
950
Titan
2006 September 7, 20:13
950
Methone
2006 September 9, 19:17
15,100
Titan
2006 September 23, 18:54
950
Titan
2006 October 9, 17:25
950
Titan
2006 October 25, 15:53
950
Titan
2006 December 12, 11:37
950
Titan
2006 December 28, 10:02
1,500
Titan
2007 January 13, 08:36
950
Titan
2007 January 29, 07:13
2,726
Titan
2007 February 22, 03:10
950
Titan
2007 March 10, 01:47
950
Titan
2007 March 26, 00:21
950
Titan
2007 April 10, 22:57
950
Titan
2007 April 26, 21:31
950
Titan
2007 May 12, 20:08
950
Titan
2007 May 28, 18:51
2,426
Titan
2007 June 13, 17:46
950
Titan
2007 June 29, 17:02
1,944
Titan
2007 July 19, 00:37
1,300
Titan
2007 August 31, 06:35
3,212
Iapetus
2007 September 10, 12:34
1,227
Titan
2007 October 2, 04:54
950
Titan
2007 November 19, 00:58
950
Titan
2007 December 5, 00:06
1,300
Titan
2007 December 20, 22:53
950
Titan
2008 January 5, 21:25
950
Methone
2008 January 15, 21:11
15,600
Titan
2008 February 22, 17:39
950
Enceladus
2008 March 12, 19:07
1,000
Titan
2008 March 25, 14:35
950
Titan
2008 May 12, 10:10
950
Pallene
2008 May 25, 22:06
28,000
Titan
2008 May 28, 08:33
1,348
Janus
2008 June 30, 08:58
30,000
Extended (Equinox) mission
Body
Date (UTC)
Altitude (kilometers)
Titan
2008 July 31, 02:13
1,613
Enceladus
2008 August 11, 21:06
54
Enceladus
2008 October 9, 19:07
25
Pallene
2008 October 17, 02:58
29,000
Enceladus
2008 October 31, 17:15
197
Titan
2008 November 3, 17:35
1,100
Titan
2008 November 19, 15:56
1,023
Titan
2008 December 5, 14:26
960
Titan
2008 December 21, 13:00
970
Titan
2009 February 7, 08:51
960
Titan
2009 March 27, 04:44
960
Titan
2009 April 4, 01:48
4,150
Titan
2009 April 20, 00:21
3,600
Titan
2009 May 5, 22:54
3,244
Titan
2009 May 21, 21:27
965
Titan
2009 June 6, 20:00
965
Titan
2009 June 22, 18:33
955
Titan
2009 July 8, 17:04
965
Titan
2009 July 24, 15:34
955
Titan
2009 August 9, 14:04
970
(Equinox)
2009 August 11
(Sun illuminates north side of rings)
Titan
2009 August 25, 12:52
970
Titan
2009 October 12, 08:36
1,300
Enceladus
2009 November 2, 07:42
99
Enceladus
2009 November 21, 02:10
1,603
Titan
2009 December 12, 01:03
4,850
Titan
2009 December 28, 00:17
955
Titan
2010 January 12, 23:11
1,073
Calypso
2010 February 13, 11:45
21,000
Mimas
2010 February 13
9,500
Rhea
2010 March 2, 17:41
101
Helene
2010 March 3, 13:41
1,823
Dione
2010 April 7, 05:16
503
Enceladus
2010 April 28, 00:11
99
Enceladus
2010 April 28, 00:11
198
Titan
2010 May 20
1,400
Titan
2010 June 5, 02:26
2,044
Titan
2010 June 21, 01:27
880 (below the ionosphere)
Titan
2010 July 7
1,005
Kiviuq (light-curve data)
2010 July 15
9.3 million
Albiorix (light-curve data)
2010 July 31
?? million
Enceladus
2010 August 13
2,554
Solstice mission
The second extended mission was scheduled from 2010 October 12 through the Saturnian summer solstice in May 2017, followed by two dozen proximal orbits of Saturn and the rings. Cassini's final optical navigation image of the mission was taken on 20 September 2016.[38] The Cassini mission ended on 15 September 2017, when the craft disintegrated in Saturn's atmosphere.[34]
The Mariner program was conducted by the American space agency NASA to explore other planets. Between 1962 and late 1973, NASA's Jet Propulsion Laboratory (JPL) designed and built 10 robotic interplanetary probes named Mariner to explore the inner Solar System – visiting the planets Venus, Mars and Mercury for the first time, and returning to Venus and Mars for additional close observations.
Pioneer 11 is a NASA robotic space probe launched on April 5, 1973, to study the asteroid belt, the environment around Jupiter and Saturn, the solar wind, and cosmic rays. It was the first probe to encounter Saturn, the second to fly through the asteroid belt, and the second to fly by Jupiter. Later, Pioneer 11 became the second of five artificial objects to achieve an escape velocity allowing it to leave the Solar System. Due to power constraints and the vast distance to the probe, the last routine contact with the spacecraft was on September 30, 1995, and the last good engineering data was received on November 24, 1995.
Saturn is the sixth planet from the Sun and the second largest in the Solar System, after Jupiter. It is a gas giant, with an average radius of about nine times that of Earth. It has an eighth the average density of Earth, but is over 95 times more massive. Even though Saturn is almost as big as Jupiter, Saturn has less than a third the mass of Jupiter. Saturn orbits the Sun at a distance of 9.59 AU (1,434 million km), with an orbital period of 29.45 years.
Titan is the largest moon of Saturn and the second-largest in the Solar System. It is the only moon known to have an atmosphere denser than the Earth's and is the only known object in space—other than Earth—on which there is clear evidence that stable bodies of liquid exist. Titan is one of seven gravitationally rounded moons of Saturn and the second-most distant among them. Frequently described as a planet-like moon, Titan is 50% larger in diameter than Earth's Moon and 80% more massive. It is the second-largest moon in the Solar System after Jupiter's Ganymede and is larger than Mercury; yet Titan is only 40% as massive as Mercury, because Mercury is mainly iron and rock while much of Titan is ice, which is less dense.
Rhea is the second-largest moon of Saturn and the ninth-largest moon in the Solar System, with a surface area that is comparable to the area of Australia. It is the smallest body in the Solar System for which precise measurements have confirmed a shape consistent with hydrostatic equilibrium. Rhea has a nearly circular orbit around Saturn, but it is also tidally locked, like Saturn's other major moons; that is, it rotates with the same period it revolves (orbits), so one hemisphere always faces towards the planet.
Cassini–Huygens, commonly called Cassini, was a space-research mission by NASA, the European Space Agency (ESA), and the Italian Space Agency (ASI) to send a space probe to study the planet Saturn and its system, including its rings and natural satellites. The Flagship-class robotic spacecraft comprised both NASA's Cassini space probe and ESA's Huygens lander, which landed on Saturn's largest moon, Titan. Cassini was the fourth space probe to visit Saturn and the first to enter its orbit, where it stayed from 2004 to 2017. The two craft took their names from the astronomers Giovanni Cassini and Christiaan Huygens.
Tethys, or Saturn III, is the fifth-largest moon of Saturn, measuring about 1,060 km (660 mi) across. It was discovered by Giovanni Domenico Cassini in 1684, and is named after the titan Tethys of Greek mythology.
Iapetus is the outermost of Saturn's large moons. With an estimated diameter of 1,469 km (913 mi), it is the third-largest moon of Saturn and the eleventh-largest in the Solar System. Named after the Titan Iapetus, the moon was discovered in 1671 by Giovanni Domenico Cassini.
Huygens was an atmospheric entry robotic space probe that landed successfully on Saturn's moon Titan in 2005. Built and operated by the European Space Agency (ESA), launched by NASA, it was part of the Cassini–Huygens mission and became the first spacecraft to land on Titan and the farthest landing from Earth a spacecraft has ever made. The probe was named after the 17th-century Dutch astronomer Christiaan Huygens, who discovered Titan in 1655.
Dione, also designated Saturn IV, is the fourth-largest moon of Saturn. With a mean diameter of 1,123 km and a density of about 1.48 g/cm3, Dione is composed of an icy mantle and crust overlying a silicate rocky core, with rock and water ice roughly equal in mass. Its trailing hemisphere is marked by large cliffs and scarps called chasmata; the trailing hemisphere is also significantly darker compared to the leading hemisphere.
Enceladus is the sixth-largest moon of Saturn and the 19th-largest in the Solar System. It is about 500 kilometers in diameter, about a tenth of that of Saturn's largest moon, Titan. It is mostly covered by fresh, clean ice, making it one of the most reflective bodies of the Solar System. Consequently, its surface temperature at noon reaches only −198 °C, far colder than a light-absorbing body would be. Despite its small size, Enceladus has a wide variety of surface features, ranging from old, heavily cratered regions to young, tectonically deformed terrain.
The Comet Rendezvous Asteroid Flyby (CRAF) was a cancelled plan for a NASA-led exploratory mission designed by the Jet Propulsion Laboratory during the mid-to-late 1980s and early 1990s, that planned to send a spacecraft to encounter an asteroid, and then to rendezvous with a comet and fly alongside it for nearly three years. The project was eventually canceled when it went over budget; most of the money still left was redirected to its twin spacecraft, Cassini–Huygens, destined for Saturn, so it could survive Congressional budget cutbacks. Most of CRAF's scientific objectives were later accomplished by the smaller NASA spacecraft Stardust and Deep Impact, and by ESA's flagship Rosetta mission.
Pallene is a very small natural satellite of Saturn. It is one of three small moons known as the Alkyonides that lie between the orbits of the larger Mimas and Enceladus. It is also designated Saturn XXXIII.
Carolyn C. Porco is an American planetary scientist who explores the outer Solar System, beginning with her imaging work on the Voyager missions to Jupiter, Saturn, Uranus and Neptune in the 1980s. She led the imaging science team on the Cassini mission in orbit around Saturn. She is an expert on planetary rings and the Saturnian moon, Enceladus.
The exploration of Saturn has been solely performed by crewless probes. Three missions were flybys, which formed an extended foundation of knowledge about the system. The Cassini–Huygens spacecraft, launched in 1997, was in orbit from 2004 to 2017.
Titan Saturn System Mission (TSSM) was a joint NASA–ESA proposal for an exploration of Saturn and its moons Titan and Enceladus, where many complex phenomena were revealed by Cassini. TSSM was proposed to launch in 2020, get gravity assists from Earth and Venus, and arrive at the Saturn system in 2029. The 4-year prime mission would include a two-year Saturn tour, a 2-month Titan aero-sampling phase, and a 20-month Titan orbit phase.
The Cassini space probe was deliberately disposed of via a controlled fall into Saturn's atmosphere on September 15, 2017, ending its nearly two-decade-long mission. This method was chosen to prevent biological contamination of any of the moons of Saturn now thought to offer potentially habitable environments. Factors that influenced the mission end method included the amount of rocket fuel left, the health of the spacecraft, and funding for operations on Earth.
A flyby is a spaceflight operation in which a spacecraft passes in proximity to another body, usually a target of its space exploration mission and/or a source of a gravity assist to impel it towards another target. Spacecraft which are specifically designed for this purpose are known as flyby spacecraft, although the term has also been used in regard to asteroid flybys of Earth for example. Important parameters are the time and distance of closest approach.
Oceanus is a NASA/JPL orbiter mission concept proposed in 2017 for the New Frontiers mission #4, but it was not selected for development. If selected at some future opportunity, Oceanus would travel to Saturn's moon Titan to assess its habitability. Studying Titan would help understand the early Earth and exoplanets which orbit other stars. The mission is named after Oceanus, the Greek god of oceans.
The Enceladus Orbilander is a proposed NASA Flagship mission to Saturn's moon Enceladus. The Enceladus Orbilander would spend a year and a half orbiting Enceladus and sampling its water plumes, which stretch into space, before landing on the surface for a two-year mission to study materials for evidence of life. The mission, with an estimated cost of $4.9 billion, could launch in the late 2030s on a Space Launch System or Falcon Heavy with a landing in the early 2050s. It was proposed in the 2023–2032 Planetary Science Decadal Survey as the third highest priority Flagship mission, after the Uranus Orbiter and Probe and the Mars Sample Return program.
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Picture of Moon during flyby
Jupiter flyby
