* Astronomy

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RE: Mars Exploration Rover Spirit

Blobrana · L

SPIRIT UPDATE: Downhill Progress - sol 668-680, Dec 01, 2005:

Spirit is healthy and making good progress downhill. The short-term goal is to drive toward couple of interesting features dubbed "Comanche" and "Miami." A decision on which target to choose for close examination will be made after the drive images come down from sol 680 (Dec. 1, 2005).

Last weekend, Spirit used all four devices on its robotic arm -- the alpha particle X-ray spectrometer, the Mössbauer spectrometer, the microscopic imager, and the rock abrasion tool (the brush on the abrasion tool) -- to study an outcrop area called "Seminole.
The two targets for use of those tools on this outcrop were informally named "Abiaka" and "Osceola". The names refer to native American tribes in Florida. The investigations of the targets' composition identified abundant olivine and indicated that the outcrop is mafic (bearing a class of usually dark-coloured minerals rich in magnesium and iron).

As of sol 679 (Nov. 30, 2005), Spirit has driven 5,463 metres.

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This synthetic image of the Spirit Mars Exploration Rover in the "Columbia Hills" was produced using "Virtual Presence in Space" technology. Developed at NASA's Jet Propulsion Laboratory, Pasadena, California this technology combines visualisation and image-processing tools with Hollywood-style special effects.

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Image Note: Rover model by Dan Maas; synthetic image by Koji Kuramura, Zareh Gorjian, Mike Stetson and Eric M. De Jong.
Image credit: NASA/JPL-Caltech

The image was created using a photorealistic model of the rover and an image taken by the Spirit navigation camera during the rover's 438th Martian day, or sol ( March 27, 2005). The size of the rover in the image is approximately correct and was based on the size of the rover tracks in the navigation-camera image.

Because this synthesis provides viewers with a sense of their own "virtual presence" (as if they were there themselves), such views can be useful to mission teams in planning exploration by enhancing perspective and a sense of scale.

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Spirit Observing Meteor Shower - sol 660-667, Nov 18, 2005:

Spirit is healthy and making good progress downhill. The rover performed an extensive campaign with the tools on the robotic arm at an outcrop called "Larry's Bench" and made targeted observations with other instruments. The team has been taking advantage of every drive sol, averaging about 40 meters per sol.

Mars is currently passing through a debris trail of Halley's comet, and Spirit is attempting to observe resulting meteor showers with the panoramic camera at night.

Sol-by-sol summaries:

Sol 660 (Nov. 11, 2005): Spirit performed robotic-arm work on Larry's Bench. Spirit took pictures of Larry's Bench with the microscopic imager before and after the rock abrasion tool brushed the area. Spirit used the panoramic camera to take pictures of the eastern part of the hill and took images in the direction Spirit plans to drive. Spirit used the alpha particle X-ray spectrometer and attempted to observe the Odyssey orbiter at night.

Sol 661: Spirit performed a long integration with the Mössbauer spectrometer, targeted observations with the panoramic camera (pointed towards "Husband Hill" summit), and targeted stares with the miniature thermal emission spectrometer.

Sol 662: Spirit performed a long integration with the Mössbauer spectrometer, targeted observations with the panoramic camera, atmospheric science, and more stares with the miniature thermal emission spectrometer.

Sol 663: Spirit performed a long integration with the Mössbauer spectrometer, made targeted observations with the panoramic camera and miniature thermal emission spectrometer, and did a meteor search at night.

Sol 664: Spirit stowed the robotic arm, took panoramic-camera images of the arm's work area, and drove 38 meters downhill.

Sol 665: Spirit drove 42 meters downhill.

Sol 666: Spirit drove 40 meters downhill.

Sol 667: No scientifically outstanding targets for the robotic arm were seen near the rover's current location, so the team planned a long drive. The team does not have good images that show the view over the ridge, so the rover will use autonomous navigation and drive with a reduced tilt limit to traverse safely downhill.

As of the end of sol 667, (Nov. 18, 2005), Spirit has driven 5,392 meters.

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The Mars Exploration Rover Spirit continues to take advantage of favourable solar power conditions to conduct occasional nighttime astronomical observations from the summit region of "Husband Hill."

Spirit has been observing the Martian moons Phobos and Deimos to learn more about their orbits and surface properties. This has included observing eclipses. On Earth, a solar eclipse occurs when the Moon's orbit takes it exactly between the Sun and Earth, casting parts of Earth into shadow. A lunar eclipse occurs when the Earth is exactly between the Sun and the Moon, casting the Moon into shadow and often giving it a ghostly orange-reddish colour. This colour is created by sunlight reflected through Earth's atmosphere into the shadowed region. The primary difference between terrestrial and Martian eclipses is that Mars' moons are too small to completely block the Sun from view during solar eclipses.

Recently, Spirit observed a "lunar" eclipse on Mars. Phobos, the larger of the two Martian moons, was photographed while slipping into the shadow of Mars. Jim Bell, the astronomer in charge of the rover's panoramic camera (Pancam), suggested calling it a "Phobal" eclipse rather than a lunar eclipse as a way of identifying which of the dozens of moons in our solar system was being cast into shadow.

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Image credit: NASA/JPL-Caltech/Cornell

With the help of the Jet Propulsion Laboratory's navigation team, the Pancam team planned instructions to Spirit for acquiring the views shown here of Phobos as it entered into a lunar eclipse on the evening of the rover's 639th Martian day, or sol (Oct. 20, 2005) on Mars. This image is a time-lapse composite of eight Pancam images of Phobos moving across the Martian sky. The entire eclipse lasted more than 26 minutes, but Spirit was able to observe only in the first 15 minutes. During the time closest to the shadow crossing, Spirit's cameras were programmed to take images every 10 seconds.

In the first three images, Phobos was in sunlight, moving toward the upper right. After a 100-second delay while Spirit's computer processed the first three images, the rover then took the fourth image, showing Phobos just starting to enter the darkness of the Martian shadow. At that point, an observer sitting on Phobos and looking back toward the Sun would have seen a spectacular sunset! In the fifth image, Phobos appeared like a crescent, almost completely shrouded in darkness.

In the last three images, Phobos had slipped entirely into the shadow of Mars. However, as with our own Moon during lunar eclipses on Earth, it was not entirely dark. The small amount of light still visible from Phobos is a kind of "Mars-shine" -- sunlight reflected through Mars' atmosphere and into the shadowed region.

Rover scientists took some images later in the sequence to try to figure out if this "Mars-shine" made Phobos colourful while in eclipse, but they'll need more time to complete the analysis because the signal levels are so low. Meanwhile, they will use the information on the timing of the eclipse to refine the orbital path of Phobos. The precise position of Phobos will be important to any future spacecraft taking detailed pictures of the moon or landing on its surface. In the near future it might be possible for one of the rovers to take images of a "Deimal" eclipse to learn more about Mars' other enigmatic satellite, Deimos, as well.

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The Mars Exploration rover Spirit continues to descend along the East Side of the "Columbia Hills," taking panoramic views of surrounding terrain at the end of each day of driving. This helps members of the science team get a sense of place before proceeding, kind of the way a hiker pauses now and then to view the scenery. Scientists and engineers use panoramas like this to select interesting rocks and soils for further study and to plan a safe path for the rover.

In this image mosaic, Spirit is pausing to take a good look around while descending due east toward a ridge nicknamed "Haskin Ridge." Before driving the rest of the way down, Spirit will take a panoramic image of the large, deep basin to the left of the ridge, labelled "East Basin," which was not visible from the summit.
A longer-term destination is the prominent, round, platform-like feature labelled "Home Plate."

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Image credit: NASA/JPL-Caltech/NMMNH
This mosaic of images shows a sweeping horizontal panorama in black and white from "Husband Hill" on the right to a basin, labelled the "East Basin" on the left. In between them are "Haskin Ridge," another basin labelled the "Inner Basin," "McCool Hill," and "Home Plate," a raised circular platform in the distance. On the left, beyond "East Basin," is the floor of Gusev Crater and a relatively flat horizon.

This 360-degree panorama was assembled from images Spirit took with its navigation camera on the 651st Martian day, or sol (Nov. 2, 2005), of its exploration of Gusev Crater on Mars.
The view is presented in a cylindrical projection with geometric seam correction.

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SPIRIT UPDATE: Spirit Coordinating with Hubble - sol 655-659, Nov 11, 2005:

Spirit is healthy. The rover is out of restricted sols and has been making excellent progress. On sol 655, Spirit drove 94.5 meters! The total drive distance from sol 655 to sol 659 was 126 meters. Spirit also took a large panoramic camera mosaic looking back at the "East Basin" for a long-baseline stereo observation. Spirit made other observations with the panoramic camera for coordinated science with the Hubble Space Telescope.

Sol-by-sol summaries:

Sol 655 (Nov. 5, 2005): Spirit drove 94.5 meters southeast down onto "Lower Haskin Ridge." The maximum uphill slip was 10 percent at the beginning of the drive. The maximum downhill slip was three percent.
Sol 656: Spirit performed untargeted remote sensing and began observations in coordination with Hubble Space Telescope. The observations included a sky survey, an atmospheric opacity reading, calibration target readings and a horizon survey.
Sol 657: Spirit took a targeted panoramic camera mosaic back at East Basin for the second observation of the long-baseline stereo view. Spirit also performed targeted stares with the miniature thermal emission spectrometer.
Sol 658: Spirit drove 24 meters at a heading of 180 degrees, with an average slip of three percent.
Sol 659: Spirit drove back 8 meters to an outcrop of interest for inspecting with tools on the robotic arm.

As of the end of sol 659, (Nov. 10, 2005), Spirit has driven 5,273 meters.

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Spirit took three days, sols 620 to 622 (Oct. 1 to Oct. 3, 2005), to acquire all the images that were combined into this mosaic, called the "Everest Panorama," looking outward in every direction from the true summit of "Husband Hill." During that period, the sky changed in colour and brightness due to atmospheric dust variations, as shown in contrasting sections of this mosaic. Haze occasionally obscured the view of the hills on the distant rim of Gusev Crater 80 kilometres away. As dust devils swooped across the horizon in the upper right portion of the panorama, the robotic explorer changed the filters on the camera from red to green to blue, making the dust devils appear red, green, and blue.
In reality, the dust devils are similar in colour to the reddish-brown soils of Mars. No attempt was made to "smooth" the sky in this mosaic, as has been done in other panoramic-camera mosaics to simulate the view one would get by taking in the landscape all at once. The result is a sweeping vista that allows viewers to observe weather changes on Mars.

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The summit of Husband Hill is a broad plateau of rock outcrops and windblown drifts about 100 meters higher than the surrounding plains of Gusev Crater. In the distance, near the centre of the mosaic, is the "South Basin," the destination for the downhill travel Spirit began after exploring the summit region.

This panorama spans 360 degrees and consists of images obtained during 81 individual pointings of the panoramic camera. Four filters were used at each pointing. Images through three of the filters, for wavelengths of 750 nanometers, 530 nanometers and 430 nanometers, were combined for this approximately true-colour rendering.

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This image shows a rough-edged boulder several inches high with multiple cracks and tiny holes in its surface. Below that, framing the bottom of the image, are the two front, metal wheels and the leading edge of the rover.
Between the rover and the outcrop is a rock-strewn, sandy surface. Beyond the rock outcrop, taking up approximately the top two-thirds of the image, is a clear Martian sky.
Spirit took these images with its front hazard-avoidance camera on Martian day, or sol, 625 (Oct. 6, 2005).

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Image credit: NASA/JPL-Caltech

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Spirit