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Unmanned Spaceflight.com _ Messenger _ MESSENGER Primary Mission Phase

Posted by: nprev Apr 1 2011, 02:05 AM

Thought it was time to start a new thread, since MESSENGER has definitely arrived! Reserved for post-commissioning observations.

Posted by: Holder of the Two Leashes Apr 5 2011, 05:13 AM

Prime mission underway.

http://messenger.jhuapl.edu/news_room/details.php?id=166

Posted by: Phil Stooke Apr 5 2011, 02:53 PM

Astro0's mosaic from the end of the previous thread can be extended with this image:

http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?page=2&gallery_id=2&image_id=439

Phil



Posted by: Explorer1 Apr 5 2011, 09:29 PM

Just saw this:

http://www.pbs.org/newshour/updates/science/jan-june11/solarstorm.html

Would a direct hit have really ended the mission before it began? Scary if true!

Posted by: djellison Apr 5 2011, 09:40 PM

A bad enough hit could kill any spacecraft, especially in the inner solar system.

Posted by: Alan S Apr 11 2011, 04:18 AM

I see the probe is making passes over the north pole of the planet. When can we expect data regarding the composition of north pole. I'd really like to know it is has ice there.

Alan

Posted by: Phil Stooke Apr 11 2011, 12:02 PM

From:

http://www.scribd.com/doc/48850455/Messenger-Fact-Sheet-2001

polar cap volatiles– The gamma-ray and neutron spectrometer will determine if Mercury’s polar caps contain hydrogen in water ice, and the laser altimeter will map the caps’ topography and thickness. The particle and plasma and UV spectrometers will detect effluent from the frozen volatiles, even if the cap is formed of elemental sulfur.

Phil

Posted by: Holder of the Two Leashes Apr 26 2011, 10:10 PM

First laser track made from orbit has been released.

http://messenger.jhuapl.edu/soc/highlights.html

This is on a generic link for science highlights, so likely only to be there a few days.

They caught a radar bright crater on this very first pass.

Update: the link for the report on the laser has been archived http://messenger.jhuapl.edu/soc/hl_042611.html

Posted by: OWW Jun 2 2011, 11:25 PM

Announcement on the Messenger http://messenger.jhuapl.edu/index.php:

QUOTE
June 16, 2011, 1 pm
NASA Science Update: Early Science from Mercury Orbit

Hopefully some nice mosaics will be released at the same time... smile.gif

BTW, has anybody noticed, in the narrow angle images released thus far, many have a horrible "blocky" http://messenger.jhuapl.edu/gallery/sciencePhotos/pics/EN0212982520M_glassyregolith.map.png? What's up with that? Noise? Compression artefacts? Didn't see that in the flyby images.

Posted by: JohnVV Jun 2 2011, 11:50 PM

QUOTE
BTW, has anybody noticed, in the narrow angle images released thus far, many have a horrible "blocky" texture? What's up with that? Noise? Compression artefacts? Didn't see that in the flyby images.

looks like someone jpg it before the mapping

level1 and 2 in cub
export to jpg
import
level3
export to png ( indexed)
you can see the "graph " like lines
on a diagonal , same as the mapping
[attachment=24479:Screenshot_1.png]

Posted by: elakdawalla Jun 3 2011, 02:48 AM

The "JPEG" compression artifacts are likely due to the onboard wavelet compression, necessary because of limits of onboard memory and downlink bandwidth (remember that MESSENGER does not have a HGA because its pointing is so tightly constrained by the thermal environment; instead it has a steerable phase-array thingamabob that they call the "MGA"). From http://img.pds.nasa.gov/documentation/MDIS_CDR_RDRSIS.PDF:

QUOTE
2.1.3 MDIS Data Compression

The MESSENGER mission requires compression to meet its imaging objectives within the available downlink. Figure 2-5 summarizes the compression options available to MDIS at the instrument level using the DPU and the spacecraft main processor (MP). At the focal plane, 2×2 binning is available on-chip to reduce the 1024×1024 images to 512×512 format. In the DPU, 12-bit data number (DN) levels can be companded to 8 bits, and data can be compressed losslessly. The strategy for DPU image compression is to acquire all monochrome data in 8-bit mode, and color data in 12-bit mode, and to compress all data losslessly to conserve recorder space. After data are written to the recorder, they can be uncompressed and recompressed by the MP more aggressively using any of several options: additional pixel-binning, subframing, and lossy compression using an integer wavelet transform. The nominal strategy for MP compression is that all data except flyby color imaging will be wavelet compressed, typically 8:1 for monochrome data and to a lower ratio (≤ 4:1) for orbital color data. Color imaging but not monochrome imaging may be further pixel-binned. For the special case of optical navigation images, there is a “jailbar” option that saves selected lines of an image at a fixed interval for optical navigation images of Mercury during flyby approaches.

Compression performance was extensively modeled prior to launch. The 12-to-8 bit look-up tables have been designed to preferentially retain information at low, medium, or high 12-bit DN values, for a nominal detector bias or for one that has decreased with time (Figure 2-6). Compression ratios to be used for flight have been based on a study of the magnitude and spatial coherence of compression artifacts using NEAR images. For expected loading of the main processor, simulations have shown that the MP can compress the equivalent of 82 full 1024×1024 images per day (or 330 512×512 images per day). The actual number of images has also been simulated, based on orbital trajectory simulations and the imaging plan described below. The MP image compression capabilities are consistent with the mission-average number of images per day. However, on days when lighting is favorable for global mapping, a peak of ~260 images per day may be expected, requiring on-chip binning of most of the data on peak days. The full implications for average imaging resolution are still being assessed.

Posted by: tanjent Jun 3 2011, 11:07 AM

It looks comparable in quality to what the Surveyor landers sent back as they approached the moon, except I think those contained white framing marks.

Posted by: JGodbaz Jun 3 2011, 11:25 AM

Does anyone have any idea where to find the description of the compression algorithm? Apparently it is in a document called:
MDIS Compression Description, Pat Murphy
(Which doesn't appear to be available anywhere on the internet.)

Posted by: Holder of the Two Leashes Jun 7 2011, 05:47 AM

NASA is going to have a science update June 16th on early results from MESSENGER. It will be at 1pm (presumably Eastern Time). No other details as yet.

Posted by: Paolo Jun 7 2011, 05:18 PM

that looks like a press briefing just before publication in Science the next day...

Posted by: nprev Jun 7 2011, 10:47 PM

Based on the surprisingly large variety of small-scale albedo features, I think that even early minerology results may prove VERY interesting. Fingers crossed...

Posted by: Holder of the Two Leashes Jun 16 2011, 04:52 PM

Initial results are being announced today, some of which are already on the MESSENGER website.

http://messenger.jhuapl.edu/news_room/details.php?id=174

Multimedia for the upcoming press conference (due to start in just five minutes) are now available too.

http://messenger.jhuapl.edu/news_room/presscon_multi9.html

Edit at ten minutes past the hour: News conference underway on NASA TV. Huge volcanic deposit at north pole.

Half past the hour: High level of potassium and sulfur, much higher amounts of volatiles than thought. Not so much iron and titanium as was thought from the flybys. Magnetic field way offset toward the north.

Posted by: elakdawalla Jun 16 2011, 05:26 PM

I had to answer my door and missed what Sean Solomon said about water ice at the poles. Did anybody hear?

Posted by: jasedm Jun 16 2011, 05:32 PM

Missing raw image access on this mission - I think we've been spoilt by the MER's and Cassini.

Posted by: Hungry4info Jun 16 2011, 05:52 PM

QUOTE (elakdawalla @ Jun 16 2011, 11:26 AM) *
Did anybody hear?

They used altimetry to produce a model of one of the craters, then modelled sunlight around the crater to see where the permanantly shaded areas are, and found that they do coincide with the radar-reflective areas - consistent with the ice interpretation.

Posted by: Holder of the Two Leashes Jun 16 2011, 05:55 PM

Solomon also repeated his statements at the end, in reply to a question, and said that if the radar bright deposits are mostly water (the jury is still out), then Mercury likely has more water than the moon.

Posted by: elakdawalla Jun 16 2011, 06:03 PM

Oooh. Cool. Thanks for the summary.

There's a hilarious conversation going on on Twitter right now about the MESSENGER scientists' remarks about "Mercury is not dead like the Moon."

Posted by: Phil Stooke Jun 16 2011, 06:09 PM

I love the pictures of the small volcanic vents. It's interesting to compare them with Ina (AKA D-Caldera) and the cluster of smaller features inside Hyginus on the Moon.

Phil

Posted by: ElkGroveDan Jun 16 2011, 07:08 PM

Anyone know if there is a link to a video replay of this? I searched but I'm not finding anything.

EDIT: I see it's being replayed at 4:00 my local time.

Posted by: Oersted Jun 18 2011, 12:54 AM

Here you go:

http://www.space-multimedia.nl.eu.org/index.php?option=com_content&view=article&id=6875:nasa-messenger-science-news-conference&catid=1:latest

http://www.space-multimedia.nl.eu.org rocks!

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