ESA Rosetta, news, updates and discussion Options

[helvick]

I love the "relatively slow speed of about 9kilometres per second" note for editors. You know you're spending too much time in space when 40,000 kph is relatively slow.

[ustrax]

Here's a Steins animation.

[cndwrld]

Information on Rosetta's Earth Fly-By 2

Someone was asking for information on the Rosetta fly-by of Earth in November 2007. I asked the Rosetta science ops people for some info.

The closest approach (CA) will take place on November 13 (DOY317). At the moment of closest approach, the altitude of Rosetta will be 5330 km above the Earth surface, at sub-surface position: 63°46' S, 74°35' W (local time 16:17). A glance at Google Earth shows the closest approach is above the Magellen Strait, between South America and Antarctica. Not the spot I would have picked, but that's why I don't work in Flight Dynamics.

The Earth solar elongation around closest approach shows a very unfavorable configuration for observing the Earth during the ESB2 event. The solar angle from +Z, towards +X, must not exceed 140 degrees for thermal reasons. We assume a minimum observing angle of 10° and a maximum angle of 140°. For solar elongation angles between 20 and 95 degrees, the duration of the attitude is not constrained; for larger angles (but smaller than the hard upper limit 140 degrees at 1 AU) the maximum attitude period is 4 hours. Attitudes with SEA smaller than 20 degrees would violate several instrument constraints.

Power and data rate are not expected to present any constraints, since we are at 1 AU.

Some of the ideas being explored for instrument operations are shown below.

ALICE (AL): UV spectrometer observations:
• decontamination) and dark exposures)
• 1 Earth pointing spectral calibration and flatfield using Earth Airglow)
• 3 Moon pointing observatoins with absolute flux calibration and flatfield using Moon’s limb, slit in N-S direction)
• 1 stellar pointing for calibrations with preferentially Vega

MIRO (MR): Microwave Instrument for the Rosetta Orbiter Observations:
• 2 Earth pointings to stare at Earth during approach and recession for detector linearity calibrations.
• 2 Moon pointings to stare at Moon during approach and recession for detector linearity calibrations.
• 1 Asteroid Mode sequence test run at closest approach

OSIRIS (SR): Science camera SR Observations:
• 3 Moon pointings for science – spectrophotometry of lunar disk), Moon Na/OH tail, also straylight calibration)
• 2 Stellar pointings for calibrations on Vega and 16 Cyg
• 1 Earth pointing for calibration and imaging, Spectroscopy and straylight
• 3 imaging observations

VIRTIS (VR): Visible and Infrared Mapping Spectrometer Observations:
• 1 stare to Earth terminator, repeated several times before CA
• 2 scans from Earth limb to terminator, repeated several times before CA
• 1 raster mosaic

PHILAE (LZ): Rosetta Lander Observations:
• continuous RoLand Magnetometer and Plasma Monitor (ROMAP) measurements 6 days before and 1 day after CA
• 1 imaging of different CIVA images during CA

Magnetometer (RP) Observation: continuous magnetometer science observation 7 days around the CA

Radio Science (RS) Observation: one ground station configuration for radio science anomalous acceleration measurement

SREM (SE): Radiation Monitor Observations: continuous science observation with increased sampling of 24 hours around CA

So to summarize what I take away from this, the trajectory is not great for observations due to observation constraints. We come in on the dark side, close to the terminator, which means we have the highest relative speeds with the worst observing conditions when we are closest. Still, the early planning has a lot going on. They'll try to catch more images with the Lander camera, like they did at Mars, but they are not certain what the orientation will be so it isn't at all certain yet. During the long cruise phase, the teams are not in place to do experiments. So the fly-by and the time around it will be used for a number of calibrations, which are important if not overlly exciting. Should be able to get some decent images as we sail away on the light side.

The ESA page on the Rosetta mission is at: http://www.esa.int/SPECIALS/Rosetta/index.html.
Rosetta Science page: http://www.esa.int/esaSC/120389_index_0_m.html

Hope that helps.

-Don

[tedstryk]

Any idea how close the lunar approach will be? I remember it being quite distant last time.


Ted

[Rakhir]

Rosetta and New Horizons watch Jupiter in joint campaign

http://www.esa.int/esaCP/SEMHFHT4LZE_index_0.html

[ugordan]

More like "Rosetta and New Horizons watched Jupiter in joint campaign".

[centsworth_II]

More like "Rosetta and New Horizons watched Jupiter in joint campaign".

From the article:

"Rosetta’s observations are set to continue until 8 May, and when complete,
will include some 400 hours worth of observations."

[ugordan]

Yeah, but I was adressing the fact the joint part of the observations is over. Probably has been for quite a while now.

[centsworth_II]

The flyby portion of the joint study is over, but joint observations do continue.

From: http://www.planetary.org/blog/article/00000875/

"Feb 28
03:00 Turn to Jupiter for New Horizons flyby support
[activity descriptions removed -- CW_II]
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"

[ugordan]

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,

Hm... didn't the article mention NH's ALICE can't turn back to Jupiter due to a very high phase angle? Is this phase angle going to significantly drop to allow distant NH ALICE measurements or am I not seeing something?

EDIT: Just checked the Solar System Simulator, phase angle will remain a whopping 174 degrees until the end of april and only drop to 170 at end of june. That seems too dangerous for comfort.

[centsworth_II]

Hm... didn't the article mention NH's ALICE can't turn back to Jupiter due to a very high phase angle?

I'm REALLY not familliar with the program, but I'm guessing that NH is looking at the
magnetotail now and not Jupiter itself, so the instrument does not have to point at Jupiter.

edit: But come to think of it, how does a spectrometer look at a magnetotail?

edit #2: Or maybe NH is not using its Alice at this point, studying the magnetotail
with other instruments while Rosetta uses its Alice.

[centsworth_II]

From: http://www.physorg.com/news92058084.html

"We couldn't pass up this opportunity to study Jupiter's meteorology, rings, aurorae, satellites, and magnetosphere," says Alan Stern, Southwest Research Institute, Colorado, and New Horizon's Principal Investigator....

The idea for the joint observations came from Stern. As well as leading New Horizons, he is also the principal investigator for Rosetta's ALICE instrument.

ALICE is the ultraviolet imaging spectrometer. Designed to analyse gases being given off by Rosetta's target comet....

Rosetta will study Jupiter for between 6 and 8 days in total, spread over the next few weeks. Each time Rosetta opens its eyes to look at Jupiter, it will do so for several hours at a time, collecting as much light from the faraway planet as possible. "Rosetta will give us the big picture context in which to see the up-close data from New Horizons," says Stern. During this time, New Horizons will be riding the long tail of magnetism that stretches out behind Jupiter and funnels charged particles away.

Rosetta's ALICE was the prototype for the ultraviolet imaging instrument flying on New Horizons.....

[Guest_AlexBlackwell_*]

Note the newly posted (with temporary free online access) special issue of Space Science Reviews (Numbers 1-4/February, 2007) - Rosetta: Mission to Comet 67P/Churyumov-Gerasimenko, which contains 33 articles.

[CAP-Team]

Any idea how close the lunar approach will be? I remember it being quite distant last time.
Ted

I ran some simulations using xplanet with the latest spice kernels from the NAIF site, and according to this, closest approach will be on november 13, 11 pm UTC at a distance of 380.000 km

With a narrow angle camera view of 2.35 degrees and a camera resolution of 2048x2048 this would look like this:



(camera specs found here

[tedstryk]

It's a shame the perspective is so, well, earthlike.