* Astronomy

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RE: The Opportunity rover

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On a plain that stretches for miles in every direction, the panoramic camera on NASA's Mars rover Opportunity has caught a first glimpse on the horizon of the uplifted rim of the big crater that has been Opportunity's long-term destination for six months.
Opportunity's twin, Spirit, also has a challenging destination, and last week switched to a different route for making progress.
Endeavour Crater, 22 kilometres in diameter, is still 12 kilometres away from Opportunity as the crow flies, and at least 30 percent farther away on routes mapped for evading hazards on the plain. Opportunity has already driven about 3.2 kilometres since it climbed out of Victoria Crater last August after two years of studying Victoria, which is less than one-twentieth the size of Endeavour.

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The mysteries of Mars are slowly unravelling - one rover at a time.

At a talk Thursday evening held at the Peabody Museum of Natural History, Steven Squyres, professor of astronomy at Cornell University and the principal investigator of the Mars Exploration Rover Mission, offered an in-depth look into the construction and history of the Spirit and Opportunity robotic explorers.

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OPPORTUNITY UPDATE: Happy Anniversary! - sol 1770-1776, January 15-21, 2009:

Happy anniversary to both Spirit and Opportunity for completing five Earth-years exploring the surface of Mars!
Opportunity's goal this past week has been to put the pedal to the metal and acquire drive-by images of a crater dubbed "Ranger Crater."
Preliminary results from last week's shake of the mirror on the miniature thermal emission spectrometer on sol 1771 (Jan. 16, 2009) indicated that no dust was removed as engineers had hoped.
Opportunity is healthy, and all subsystems are performing as expected as of the downlink of information on sol 1776 (Jan. 21, 2009). Solar energy levels are at 613 watt-hours (slightly more than the amount of energy needed to light a 100-watt bulb for six hours). Tau, a measure of sunlight-blocking dust in the atmosphere, is 0.455. The dust factor, a measure of the proportion of sunlight penetrating dust on the solar arrays, is 0.6196.

Sol-by-sol summary:
In addition to monitoring daily dust-related changes in atmospheric clarity with the panoramic camera and relaying data to NASA's Mars Odyssey orbiter for transmission to Earth, Opportunity completed the following activities:

Sol 1770 (Jan. 15, 2009): Opportunity drove and acquired image mosaics with the navigation and panoramic cameras. The rover measured argon gas in the Martian atmosphere using the alpha-particle X-ray spectrometer and went into a mini-deep sleep.

Sol 1771: Opportunity completed a systematic foreground quarter survey using all 13 colour filters of the panoramic camera. The rover checked for drift (changes with time) in the miniature thermal emission spectrometer, conducted a utility test of the instrument, and completed a post-shake test calibration by looking at the ground and sky. Opportunity measured argon gas in the Martian atmosphere using the alpha-particle X-ray spectrometer and went into a mini-deep sleep.

Sol 1772: Opportunity surveyed the sky at low Sun with the panoramic camera and, after relaying data to Odyssey, measured argon gas in the Martian atmosphere using the alpha-particle X-ray spectrometer. The rover went into a mini-deep sleep.

Sol 1773: Opportunity took morning, thumbnail images of the sky with the panoramic camera and full-colour images, using all 13 filters of the panoramic camera, of a target dubbed "Thassos." The rover acquired a 6-by-1 panel of images of pavement textures using the panoramic camera. After measuring argon gas in the Martian atmosphere using the alpha-particle X-ray spectrometer, Opportunity went into a mini-deep sleep.

Sol 1774: Opportunity drove 115.36 metres and acquired new image mosaics with the navigation and panoramic cameras, including a 360-degree view with the navigation camera. After the day's activities, the rover went into a deep sleep.

Sol 1775: In the morning, Opportunity surveyed the sky at high Sun with the panoramic camera. The rover completed a systematic foreground quarter survey with all 13 colour filters of the panoramic camera. After relaying data to Odyssey, Opportunity measured argon gas in the Martian atmosphere using the alpha-particle X-ray spectrometer and went into a mini-deep sleep.

Sol 1776 (Jan. 21, 2009): In the morning, Opportunity took spot images of the sky with the panoramic camera for calibration purposes. Opportunity drove 29.90 metres to approach Ranger Crater and completed a quick get fine attitude to check the rover's precise location relative to the Sun. The rover acquired new image mosaics with the navigation and panoramic cameras and took a Tau measurement of atmospheric dust at sunset. Opportunity then went into a deep sleep. The following morning, Opportunity was to take spot images of the sky for calibration purposes with the panoramic camera, acquire time-lapse movie frames in search of clouds with the navigation camera, and monitor dust accumulation on the panoramic-camera mast assembly.

Odometry:
As of sol 1776 (Jan. 21, 2009), Opportunity's total odometry was 13,866.70 metres.

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Panorama of Meridiani Plain, Mars, taken by the Opportunity Rover on the 6th February, 2009 (Sol 1791).

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Credit NASA/JPL

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Opportunity's View After Long Drive on Sol 1770

full-circle view of the rover's surroundings

This view is presented as a cylindrical projection with geometric seam correction.
Credit: NASA/JPL-Caltech

NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this full-circle view of the rover's surroundings just after driving 104 metres on the 1,770th Martian day, or sol, of Opportunity's surface mission (January 15, 2009). North is at the center; south at both ends.
Tracks from the drive extend northward across dark-toned sand ripples and light-toned patches of exposed bedrock in the Meridiani Planum region of Mars. For scale, the distance between the parallel wheel tracks is about 1 metre.
Prior to the Sol 1770 drive, Opportunity had driven less than a meter since Sol 1713 (November 17, 2008), while it used the tools on its robotic arm first to examine a meteorite called "Santorini" during weeks of restricted communication while the sun was nearly in line between Mars and Earth, then to examine bedrock and soil targets near Santorini.
The rover's position after the Sol 1770 drive was about 1.1 kilometre south southwest of Victoria Crater. Cumulative odometry was 13.72 kilometres since landing in January 2004, including 1.94 kilometres since climbing out of Victoria Crater on the west side of the crater on Sol 1634 (August 28, 2008).

Source NASA

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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 minimising 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 Mössbauer 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 Mössbauer 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 Mössbauer 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 metres.

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"Santorini" Panorama from Opportunity
This 360-degree panorama shows the vista from the location where NASA's Mars Exploration Rover Opportunity spent five weeks in November and December 2008 while the sun was nearly directly in between Mars and Earth, limiting communications.
Opportunity is approaching the fifth Earth-year anniversary of its landing on Mars, continuing a surface mission that was initially scheduled to last three months. The rover landed on Jan. 24, 2004 (Pacific Standard Time; Jan. 25, 2004 Universal Time). When it reached the location from which its panoramic camera (Pancam) captured this view, it had driven a total of 13,616 metres since its landing.
The view combines 276 different exposures taken with Opportunity's panoramic camera (Pancam) -- 92 pointings, with three filters at each pointing. The component images were taken during the period from the rover's 1,716th Martian day, or sol, to the mission's Sol 1719 (Nov. 21 to 24, 2008).
Opportunity has driven 1.83 kilometres since it exited Victoria Crater on Sol 1634 (Aug. 28, 2008). It skirted the west rim of Victoria and, at the point from which this panorama was taken, had reached a position about a kilometre southwest of the south rim of the crater.
North is in the center of the panorama. Rover tracks are visible from the drive to the location from which the Pancam captured this view. For scale, the distance between the parallel wheel tracks is about one metre.

Full-Circle 'Santorini' Panorama from Opportunity

Full-Circle 'Santorini' Panorama from Opportunity

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Credit: NASA/JPL/Cornell University

Opportunity is on a 12-kilometre trek toward Endeavour crater, a crater more than 20 times the size of Victoria Crater, which Opportunity studied for about two years. On the way toward Endeavour the rover is pausing to examine selected loose rocks on the surface. At the location from which this panorama was taken, the rover used the spectrometers on its robotic arm to examine a cobble informally called "Santorini," a dark rock about 8 centimetres long, which the inspection indicates is probably a meteorite. The rock is too close to the rover to be visible in this panorama.
The lighter-toned patches of ground in this view are sulphate-rich bedrock. Darker patches are dark, windblown sand. The metal post in the foreground is the top of Opportunity's low-gain antenna.
Opportunity began driving again on Sol 1748 (Dec. 23, 2008).
This is an approximate true-colour, red-green-blue composite panorama generated from images taken through the Pancam's 750-nanometer, 530-nanometer and 430-nanometer filters. This "natural colour" view is the rover team's best estimate of what the scene would look like if we were there and able to see it with our own eyes.

Source NASA

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Image taken by the Opportunity rover on Sol 1713

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Credit NASA

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Panorama taken by the Opportunity rover on Sol 1671

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Credit NASA