Timeline of Cassini–Huygens

This page lists a chronology of events which have occurred or are expected to occur during the Cassini-Huygens Mission to Saturn and Titan.

Cassini image of Saturn, February 2004

1997

October 15 — Cassini launched at 08:43 UTC.

1998

April 26 — Gravity-assisted flyby of Venus

1999

June 24 — Gravity-assisted flyby of Venus.

Picture of Moon during flyby

August 18 03:28 UTC — Gravity-assisted flyby of Earth. An hour 20 minutes before closest approach, Cassini made the closest approach to the Moon at 377,000 km, and took a series of calibration images.

2000

January 23 — flyby of Asteroid 2685 Masursky around 10:00 UTC. Cassini took images (click here to see press release) 5 to 7 hours before at 1.6 million km distance and estimated a diameter of 15 to 20 km.

Jupiter flyby picture

December 30 — Gravity-assisted flyby of Jupiter. Cassini was at its closest point to Jupiter at this date, and performed many scientific measurements. It also produced the most detailed global color portrait of Jupiter ever produced (seen on the right); the smallest visible features are approximately 60 km (37 miles) across.

2001

May 30 — 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.

2002

July 23 — 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 the hoped 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 July 9, a picture showed that the removal procedure was completed successfully, which was announced on July 23 (Press release).

2003

October 10 — 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.

2004

February 27 — A new, high-resolution picture of Saturn taken by Cassini on February 9 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. (See Press Release Image) Another picture, in infrared light, taken on February 16 shows cloud height differences and the same disturbance visible throughout the 1990s in Hubble Space Telescope images.

March 12 — Pictures taken February 23 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 show a set of "clumps" moving along the "F" ring.

March 26 — The Cassini science team published a 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. (Large GIF sequence file from JPL). The pictures were taken during the days from February 15 to February 19.

April 8 — 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 March 19 to March 20. Both storms had a diameter of about 1,000 km (620 mi) before they merged.

File:PIA05387 modest.jpg

'F' Ring and shepherd moons

April 15 — NASA announced today, that two moons discovered by Voyager 1 were sighted again by Cassini in pictures taken on March 10: Prometheus and Pandora. These are no ordinary moons, but their gravitational effects on the "F" ring led scienties to call them "shepherd moons." They fascinate all researchers interested in the dynamic 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.

May 18 — Cassini entered the Saturn system. The gravitational pull of Saturn began to overtake the influence of the Sun.

Titan seen from Cassini

May 20 — The first picture of Titan with better resolution than any Earth based observation was released. It was taken May 5 from a distance of 29.3 million kilometers (18.2 million miles).

May 27 — 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 34.7 m/s (78 mph), setting up a flyby of the moon Phoebe June 11.

The picture above was taken by Cassini spacecraft at 16:10 UT on 2004-Jun-11

June 11 — Cassini flew by the moon Phoebe at 19:33 UT in SCET at 2068 kilometers distance. All of the 11 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 will take scientists several days to pour over the data to make more concrete conclusions.

June 16 — 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 June 21 was cancelled.

July 1 — The Saturn Orbit Insertion burn was successfully executed. It began at 01:12 UT in SCET and ended at 02:48 UT. Right after that burn, pictures of the rings were taken and sent back to mission scientist.

File:Cassini SOI ring pic9.jpg

Ring edge as seen by Cassini

Scientist were surprised by the clarity and detail of the pictures and will be pouring 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."

July 2 — 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. However, during a press conference on June 3, mission scientist presented pictures that are already forcing 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.

August 16 — 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. Currently called "S/2004 S1" and "S/2004 S2", these objects are small compared to other moons and they orbit inbetween Mimas and Enceladus.

August 23 — The last major firing of the main engine took place to adjust the next closest approach to Saturn and avoid the particles in the ring system. After a 51 minute burn, that distance was moved about 300,000 km 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.

September 14 — Final checkout of the Huygens lander was completed successfully. The separation of the probe stays scheduled for December 25 with the landing anticipated on January 14, 2005.

October 26 — Second flyby of Titan. Reception of first data is anticipated for 01:30 UTC, October 27).

2005

January 14 — Huygens enters Titan's atmosphere at 03:04 UT and lands on its surface in two or more hours.

Magic numbers

Spacecraft Event Time	Distance from Saturn
2004-Mar-22 07:42:14	50,000,000 kilometers
2004-Apr-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-Jun-14 11:15:22	10,000,000 kilometers

Cassini Encounters with Saturn’s Moons

(projected 6/04)

	Orbit	Moon	Encounter Date	Altitude
	0	Phoebe	June 11, 2004	1,997	km   (1,241 mi)
	A	Titan	Oct. 26, 2004	1,200	km   (750 mi)
	B	Titan	Dec. 13, 2004	2,358	km   (1,465 mi)
	B	Probe Release	Dec. 24, 2004		—
	C	Iapetus	Jan. 1, 2005	65,000	km   (40,000 mi)
	C	Titan	Jan. 14, 2005	60,000	km   (37,000 mi)
	3	Titan	Feb. 15, 2005	950	km   (590 mi)
	3	Enceladus	Feb. 17, 2005	1,179	km   (733 mi)
	4	Enceladus	Mar. 9, 2005	500	km   (310 mi)
	5	Titan	Mar. 31, 2005	2,523	km   (1,568 mi)
	6	Titan	April 16, 2005	950	km   (590 mi)
	11	Enceladus	July 14, 2005	1,000	km   (600 mi)
	12	Mimas	Aug. 2, 2005	45,100	km   (28,000 mi)
	13	Titan	Aug. 22, 2005	4,015	km   (2,495 mi)
	14	Titan	Sept. 7, 2005	950	km   (590 mi)
	15	Tethys	Sept. 24, 2005	33,000	km   (20,500 mi)
	15	Hyperion	Sept. 26, 2005	990	km   (615 mi)
	16	Dione	Oct. 11, 2005	500	km   (310 mi)
	17	Titan	Oct. 28, 2005	1,446	km   (900 mi)
	18	Rhea	Nov. 26, 2005	500	km   (310 mi)
	19	Titan	Dec. 26, 2005	10,429	km   (6,482 mi)
	20	Titan	Jan. 15, 2006	2,042	km   (1,269 mi)
	21	Titan	Feb. 27, 2006	1,812	km   (1,126 mi)
	22	Titan	Mar. 18, 2006	1,947	km   (1,210 mi)
	23	Titan	April 30, 2006	1,853	km   (1,152 mi)
	24	Titan	May 20, 2006	1,879	km   (1,168 mi)
	25	Titan	July 2, 2006	1,911	km   (1,188 mi)
	26	Titan	July 22, 2006	950	km   (590 mi)
	28	Titan	Sept. 7, 2006	950	km   (590 mi)
	29	Titan	Sept. 23, 2006	950	km   (590 mi)
	30	Titan	Oct. 9, 2006	950	km   (590 mi)
	31	Titan	Oct. 25, 2006	950	km   (590 mi)
	35	Titan	Dec. 12, 2006	950	km   (590 mi)
	36	Titan	Dec. 28, 2006	1,500	km   (930 mi)
	37	Titan	Jan. 13, 2007	950	km   (590 mi)
	38	Titan	Jan. 29, 2007	2,776	km   (1,725 mi)
	39	Titan	Feb. 22, 2007	953	km   (592 mi)
	40	Titan	Mar. 10, 2007	956	km   (594 mi)
	41	Titan	Mar. 26, 2007	953	km   (592 mi)
	42	Titan	April 10, 2007	951	km   (591 mi)
	43	Titan	April 26, 2007	951	km   (591 mi)
	44	Titan	May 12, 2007	950	km   (590 mi)
	45	Titan	May 28, 2007	2,425	km   (1,507 mi)
	46	Titan	June 13, 2007	950	km   (590 mi)
	47	Tethys	June 27, 2007	16,200	km   (10,070 mi)
	47	Titan	June 29, 2007	1,942	km   (1,207 mi)
	48	Titan	July 19, 2007	1,302	km   (809 mi)
	49	Rhea	Aug. 30, 2007	5,100	km   (3,200 mi)
	49	Titan	Aug. 31, 2007	3,227	km   (2,006 mi)
	49	Iapetus	Sept. 10, 2007	1,000	km   (620 mi)
	50	Titan	Oct. 2, 2007	950	km   (590 mi)
	52	Titan	Nov. 19, 2007	950	km   (590 mi)
	53	Titan	Dec. 5, 2007	1,300	km   (810 mi)
	54	Titan	Dec. 20, 2007	953	km   (592 mi)
	55	Titan	Jan. 5, 2008	949	km   (590 mi)
	59	Titan	Feb. 22, 2008	959	km   (596 mi)
	61	Enceladus	Mar. 12, 2008	995	km   (618 mi)
	62	Titan	Mar. 25, 2008	950	km   (590 mi)
	67	Titan	May 12, 2008	950	km   (590 mi)
	69	Titan	May 28, 2008	1,316	km   (818 mi)

External links

• Cassini-Huygens press release archives
• Cassini's distance from Saturn in realtime
• Cassini-Huygens Saturn Arrival June 2004 (pdf)