[meteorite-list] Mars Exploration Rover Update: November 20 - December 17, 2008

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Mon, 26 Jan 2009 12:05:30 -0800 (PST)
Message-ID: <200901262005.MAA29400_at_zagami.jpl.nasa.gov>

http://marsrovers.jpl.nasa.gov/mission/status.html#opportunity

OPPORTUNITY UPDATE: Post-Solar Conjunction Hangover - sol 1716-1742,
November 20 - December 17, 2008:

As soon as Opportunity came out of solar conjunction - a period when the
Sun passes between Earth and Mars and prohibits communication -
engineers discovered that the rover's computer memory was a bit too full
for comfort. They spent the first two days after conjunction minimizing
data generation on Mars and planned to spend another two days doing the
same. The purpose of the slowdown was to give Opportunity a chance to
empty out some of the large number of "sent" data products.

In this case, the memory situation involved the data product limit, not
the data volume limit. In the event of an excess of data volume, the
rover automatically deletes data. An excess number of data products, on
the other hand, can cause a rover fault. Such a fault occurred on
Spirit, Opportunity's twin on the opposite side of Mars, shortly after
landing. The potential for such a fault becomes a concern whenever the
number of on-board data products is greater than 6,000. After solar
conjunction, on sol 1740 (Dec. 15, 2008), the number of data products in
Opportunity's computer memory was 6,448.

To prevent a potential fault, engineers postponed more scientific
studies and adopted a plan to minimize data products. These plans
permitted only one measurement per sol of atmospheric opacity or "tau"
(atmospheric darkness caused by dust) and an overnight measurement of
atmospheric argon. The rover science team expects a pending deletion of
about 3,000 "sent" data products on sol 1743 (Dec. 18, 2008) to
alleviate the memory overload.

As soon as engineers confirm deletion of a sufficient number of data
products from the rover's flash memory, Opportunity will resume studying
the cobble nicknamed "Santorini." The name Santorini comes from a Greek
isle once known as Thera that 3,600 years ago was the site of one of the
most powerful volcanic eruptions ever seen. Remaining observations will
include taking microscopic images and measuring elemental composition
with the alpha-particle X-ray spectrometer.

Opportunity is healthy and all subsystems are performing as expected as
of the downlink of data on sol 1742 (Dec. 17, 2008). Energy was around
594 watt-hours (almost enough to light a 100-watt bulb for six hours).
Tau, a measure of the amount of sunlight blocked by dust in the
atmosphere, was 0.622, and the dust factor, a measure of the amount of
sunlight penetrating dust on the solar arrays, was 0.6536.

Sol-by-sol summary

Before, during, and after solar conjunction, Opportunity completed the
following activities:

Sols 1716-1720: With only a few days left before solar conjunction,
Opportunity scrambled to get as much interactive work done as possible.
Having successfully placed the robotic arm on Santorini, Opportunity
began studying the mineralogy of Santorini with the Moessbauer
spectrometer and acquired images of the rock with the panoramic camera.
Opportunity also used the panoramic camera to acquire a 360-degree
panorama, take images of the rover's tracks, and monitor dust-related
changes in the atmosphere. In addition, the rover surveyed the horizon,
acquired time-lapse movie frames of the sky in search of clouds with the
navigation camera, and measured argon gas in the atmosphere with the
alpha-particle X-ray spectrometer.

Sols 1721-1722: Opportunity switched over to the master sequence of
commands to be followed during the two weeks of solar conjunction. Plans
called for Opportunity to study the mineralogy of Santorini using the
Moessbauer spectrometer on all but two Martian days - sols 1726 (Dec. 1,
2008) and 1736 (Dec. 11, 2008) - when the rover was to measure argon gas
in the atmosphere with the alpha-particle X-ray spectrometer. During
conjunction, Opportunity was also to complete a photon-transfer
measurement on each of the rover's cameras.

Sols 1723-1740 (Nov. 28-Dec. 15, 2008): While out of contact with Earth,
Opportunity studied Santorini's mineralogy with the Moessbauer
spectrometer, measured argon gas in the atmosphere with the
alpha-particle X-ray spectrometer, and made remote-sensing observations.
On sol 1725 (Nov. 30, 2008), approximately 0.93 megabits of data
transmitted to Earth was lost to solar interference. The following day,
sol 1726 (Dec. 1, 2008), at least a third of the expected data volume
from Mars was lost. After that, virtually all data was lost while the
Sun blocked communications.

Sol 1741 (Dec. 16, 2008): Opportunity relayed data to Earth via NASA's
Mars Odyssey orbiter, measured dust-related changes in atmospheric
clarity with the panoramic camera, and measured argon gas in the
atmosphere using the alpha-particle X-ray spectrometer.

Sol 1742 (Dec. 17, 2008): Opportunity measured dust-related changes in
atmospheric clarity with the panoramic camera and recharged the batteries.

Odometry

As of sol 1742 (Dec. 17, 2008), Opportunity's total odometry was
13,616.47 meters (8.46 miles).
Received on Mon 26 Jan 2009 03:05:30 PM PST