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The Planetary Society Blog
By Emily Lakdawalla
Rosetta Mars flyby timeline
Feb. 24, 2007 | 07:32 PST | 15:32 UTC
In just a couple of hours, Rosetta will turn to Mars to begin its science observations, heading toward its flyby at 01:54 UTC (17:54 PST). I'm posting below my blow-by-blow timetable of the events on Rosetta's flyby. Enjoy! Doug Ellison will shortly be in Darmstadt, ready to give you live updates on the exciting events as they happen. He's put together a nifty movie of the middle three hours of the flyby of Mars as seen from the spacecraft (3 MB, .mov format). And here's another one he made of the same event -- but from the opposite viewpoint. Neat.
Of course, New Horizons is already in the heat of its scientific activities on its Jupiter flyby. Two flybys in a week! Since this Rosetta post is very long, I'll put in a link here to the preceding post, which was an update from John Spencer on New Horizons, including some brand-new data from that spacecraft as well as Hubble.
Without further ado, here's what Rosetta is in for over the coming days:
Rosetta's lengthy cruise to comet Churyumov-Gerasimenko requires a total of three gravity assist flybys of Earth as well as one of Mars before it finally reaches the comet in 2014. The first flyby of Earth was successfully completed on March 5, 2005, and Rosetta is now approaching for the Mars flyby on February 25, 2007 at 01:45 UTC (February 24 at 17:45 PST). Rosetta will take advantage of the close approach by performing observations with most of its science instruments. Once the Mars flyby has ended, it will turn toward Jupiter to observe the planet in support of the science being conducted by New Horizons as that spacecraft flies by on February 28, 2007 at 05:45 UTC. Visit The Planetary Society Weblog for live reports from the European Space Operations Centre on February 24 and 25!
Space-
craft
Time
(UTC) | Event |
|---|
Jan 2
21:20 | OSIRIS measurement of light curve of asteroid 21 Lutetia
The observation lasts 16 hours. | Feb 8
20:11 | Trajectory correction maneuver (-16 days)
Rosetta will fire thrusters to maintain course. | Feb 17
20:05 | Trajectory correction maneuver (-7 days) | Feb 21
20:02 | Trajectory correction maneuver (-3 days) | Feb 22
23:55 | Standard Radiation Monitor (SREM) observations begin
SREM will measure the radiation environment around Mars continuously for 48 hours, until just before closest approach. | Feb 23
00:15 | Rosetta Plasma Consortium (RPC) observations begin
RPC includes six different sensors designed to measure the properties of charged particles and the magnetic field at the position of the spacecraft. It will operate continuously for 48 hours. | Feb 24
01:55 | Reaction wheel offload
Like all spacecraft that use reaction wheels to control spacecraft pointing, Rosetta's reaction wheels build up excess momentum over time, spinning faster and faster. Periodically, the spacecraft must spend time de-spinning the wheels. This "reaction wheel offload" will take 2 hours, during which time most of the instruments except SREM and RPC cannot be used. | | 17:11 | Begin Phobos occultation by Mars
Phobos' 7.65-hour orbit will carry it behind Mars as seen from Rosetta. | | 17:15 | Turn to Mars
Over 45 minutes, the spacecraft will turn or "slew" to point the optical remote sensing instruments (OSIRIS, VIRTIS, and ALICE) at Mars. |
Mars as seen from Rosetta, February 24 18:00 UTC OSIRIS wide-angle camera field of view Credit: NASA / JPL / Solar System Simulator |
| 18:00 | OSIRIS observations of Phobos
OSIRIS is Rosetta's sharpest-eyed camera system. It will watch Mars' limb to see Phobos emerge from behind the planet. Phobos will appear just a few pixels across. | | 18:07 | End Phobos occultation by Mars | | 18:11 | VIRTIS and ALICE scan across Mars
These instruments will perform spectroscopy on Mars and its atmosphere. | | 18:25 | ALICE observations of Mars dayglow (OSIRIS and VIRTIS ride along)
"Dayglow" is the emission of ultraviolet light from the sunlit upper atmosphere of a planet. At Mars, dayglow occurs in the atmosphere between 100 and 200 kilometers above the surface. It is caused mostly by the release of photons associated with the excitation of carbon dioxide molecules by solar radiation. Studying Mars' dayglow reveals detailed information about the behavior of carbon dioxide, the main constituent of Mars' atmosphere, at these high altitudes. | | 19:50 | VIRTIS mapping of Mars (OSIRIS and ALICE ride along) | | 20:10 | Dust ring search
OSIRIS and ALICE will be pointed along Mars' equator and slightly off of Mars' disk (first 2.5 and then 7.5 degrees away) to search for a dusty ring around the planet. | | 21:05 | OSIRIS Mars map and Phobos transit (ALICE and VIRTIS ride along)
OSIRIS will snap images as Phobos crosses Mars' disk. Phobos will appear 0.01° in diameter (or about 10 OSIRIS pixels) and be nearly fully lit at 15° phase. | | 21:06 | Begin Phobos transit of Mars | | 21:50 | VIRTIS mapping of Mars (OSIRIS and ALICE ride along) | | 21:55 | End Phobos transit of Mars | | 22:10 | Prepare for eclipse
Over the next two hours, the spacecraft will prepare for its passage into Mars' shadow -- and the loss of solar power -- by shutting down all of the science instruments and rotating to the orientation at which it will resume science operations once the eclipse has ended. |
Mars as seen from Rosetta, February 24 22:10 UTC OSIRIS wide-angle camera field of view Credit: NASA / JPL / Solar System Simulator |
| 23:58 | Philae lander instruments powered on
Unlike the mother spacecraft, the Philae lander is designed to operate its science instruments on battery power alone, so it will be able to perform observations throughout closest approach, for a period of three hours. | Feb 25
00:40 | Begin Phobos occultation by Mars | | 01:44 | End Phobos occultation by Mars | | 01:53 | Begin occultation of Rosetta by Mars
Rosetta will pass behind Mars as seen from Earth, so communications with the spacecraft will be interrupted. | | 01:47 | Begin Deimos occultation by Mars
Deimos is half the size of Phobos and takes about four times as long to orbit Mars. Its tiny size and distance from Rosetta will prevent any dedicated observations. | | 01:54 | Mars closest approach
Rosetta will pass by Mars at an altitude of 250 kilometers. | | 01:55 | Begin eclipse
Rosetta will pass into Mars' shadow. | | 01:57 | End Deimos occultation by Mars | | 02:05 | Phobos closest approach
Rosetta will pass by Phobos at an altitude of 4,621 kilometers. Although it will not be able to perform observations at closest approach, the spacecraft is pointed in the right direction to be ready to observe Phobos just 15 minutes after it exits Mars' shadow | | 02:18 | Deimos closest approach
Rosetta will pass Deimos at a distance of 23,119 kilometers. | | 02:10 | End occultation | | 02:20 | End eclipse |
Phobos as seen from Rosetta, February 25, 2007 02:35 UTC OSIRIS narrow-angle camera field of view Credit: NASA / JPL / Solar System Simulator |
Feb 25
02:35 | OSIRIS Phobos spectrophotometry
As Rosetta recedes from Mars, science observations resume with high-phase (140°) spectral measurements of Phobos. During the 20-minute observation, Phobos will shrink from 0.07 to 0.03° (66 to 28 OSIRIS pixels) in apparent diameter. | | 02:40 | Standard Radiation Monitor (SREM) observations resume
SREM will measure the radiation environment around Mars continuously for 48 hours. | | 02:50 | Rosetta Plasma Consortium (RPC) observations begin
RPC includes six different sensors designed to measure the properties of charged particles and the magnetic field at the position of the spacecraft. It will operate continuously for 48 hours. |
Mars as seen from Rosetta, February 25, 2007 03:00 UTC OSIRIS wide-angle camera field of view Credit: NASA / JPL / Solar System Simulator |
Feb 25
03:00 | ALICE observations of Mars nightglow (OSIRIS rides along)
"Nightglow" is the emission of ultraviolet light from the nightside upper atmosphere of a planet. It was first detected at Mars by Mars Express in 2005. It is believed that, during the day, solar radiation dissociates some nitric oxide in Mars' upper atmosphere into its constituent nitrogen and oxygen atoms. At night, these atoms recombine into nitric oxide and emit ultraviolet radiation. ALICE will be searching for this as well as other possible nightglow emissions from different sources. | | 03:30 | VIRTIS scanning of Mars terminator (ALICE, OSIRIS ride along)
The "terminator" is the day-night boundary. | | 04:05 | ALICE observations of Mars nightglow (OSIRIS, VIRTIS ride along) | | 04:20 | OSIRIS Phobos
OSIRIS will watch as Phobos travels behind Mars' limb. | | 04:32 | Begin Phobos occultation by Mars | | 04:45 | VIRTIS scanning of Mars terminator (ALICE, OSIRIS ride along) | | 05:27 | End Phobos occultation by Mars | | 06:10 | VIRTIS, OSIRIS, ALICE scan across Mars
Over a period of almost 8 hours, VIRTIS will map Mas as ALICE studies the nightglow and OSIRIS studies the nightside atmospheric emission. | | 07:08 | Begin Deimos transit of Mars | | 07:44 | End Deimos transit of Mars | | 08:21 | Begin Phobos transit of Mars | | 09:08 | End Phobos transit of Mars | | 12:12 | Begin Phobos occultation by Mars | | 13:03 | End Phobos occultation by Mars | | 13:55 | Reaction wheel offload
During this two-hour period, all the optical remote sensing instruments will be powered off. | | 15:59 | Begin Phobos transit of Mars | | 16:10 | OSIRIS Mars spectrophotometry / nightside atmospheric emission
This observation lasts more than 16 hours as Rosetta recedes from Mars. | | 16:40 | ALICE Mars nightglow aeronomy
This observation also lasts 16 hours. | | 16:48 | End Phobos transit of Mars |
Mars as seen from Rosetta, February 25, 2007 16:48 UTC OSIRIS wide-angle camera field of view Credit: NASA / JPL / Solar System Simulator |
Feb 27
06:45 | End Mars observation period | Feb 28
03:00 | Turn to Jupiter for New Horizons flyby support
It will take Rosetta 60 minutes to rotate toward Jupiter. The observations are designed to support New Horizons, which will fly by Jupiter at 05:45. Rosetta and New Horizons carry two very similar ultraviolet imaging spectrometers, both called ALICE, and both will be able to observe Jupiter and its surroundings simultaneously. |
Jupiter as seen from Rosetta, February 18, 2007 04:00 UTC OSIRIS narrow-angle camera field of view Credit: NASA / JPL / Solar System Simulator |
| 04:00 | ALICE observations of Io plasma torus (OSIRIS rides along)
Io, with its active volcanoes, orbits Jupiter well within the planet's powerful magnetic field; gases it spews into space are ionized, forming a doughnut-shaped body of plasma surrounding Io's orbit called the plasma torus. The planet will appear about 12 pixels across to the OSIRIS narrow-angle camera. This observation block lasts about three and a half hours. | | 07:30 | VIRTIS Jupiter scan | | 08:00 | End New Horizons Jupiter flyby support | Mar 1
19:30 | ALICE observations of Jupiter begin
Following its flyby, New Horizons will exit the Jupiter system by flying down Jupiter's magnetotail. Rosetta will be able to study the Jupiter system using its ALICE instrument from outside the magnetic field at the same time that New Horizons studies it with its own ALICE instrument form inside the magnetic field. The observations will take place in a total of 22 blocks over the next two months, each block lasting anywhere from an hour to nearly four days. | May 9
17:30 | ALICE observations of Jupiter end |
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