Astronomy Picture of the Day
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
2004 February 7 
Posted on 02/06/2004 9:31:51 PM PST by petuniasevan
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
2004 February 7
Explanation: This pretty planetary nebula, cataloged as NGC 6369, was discovered by 18th century astronomer William Herschel as he used a telescope to explore the medicinal constellation Ophiucus. Round and planet-shaped, the nebula is also relatively faint and has acquired the popular moniker of Little Ghost Nebula. Planetary nebulae in general are not at all related to planets, but instead are created at the end of a sun-like star's life as its outer layers expand into space while the star's core shrinks to become a white dwarf. The transformed white dwarf star, seen near the center, radiates strongly at ultraviolet wavelengths and powers the expanding nebula's glow. Surprisingly complex details and structures of NGC 6369 are revealed in this delightful color image composed from Hubble Space Telescope data. The nebula's main ring structure is about a light-year across and the glow from ionized oxygen, hydrogen, and nitrogen atoms are colored blue, green, and red respectively. Over 2,000 light-years away, the Little Ghost Nebula offers a glimpse of the fate of our Sun, which should produce its own pretty planetary nebula only about 5 billion years from now.
Spirit readies for long drive after rock cleaning, grinding
BY SPACEFLIGHT NOW
Posted: February 6, 2004
Whipping half-inch stainless steel bristles against a pyramid-shaped rock, the Spirit rover has performed "the greatest interplanetary brushing of all time," a scientist joked Friday with the unveiling the latest images from Mars.
 The brush on Spirit's instrument arm is shown in this image with Adirondack as backdrop. Credit: NASA/JPL/Cornell |
"I think I can say this morning, with as much certainty as we can say anything here, that our patient is healed. We are very excited about that!" mission manager Jennifer Trosper told reporters at Friday's rover status briefing.
On Wednesday, controllers spent about three hours erasing the flash memory and an hour reformatting and resetting the vehicle.
"All indications were that worked extremely well. Of course it was nerve-racking...In the end, the spacecraft did what we wanted it to do and it performed perfectly. It's in great health right now," Trosper said.
 This image taken by the panoramic camera shows the post-brushing view of Adirondack. The cleaned patch is clearly visible. Credit: NASA/JPL/Cornell Download a larger image here |
Scientists weren't expecting to see much change in the rock's appearance since it seemed clean. Instead, the brushing created a dark blotch on Adirondack.
"I didn't expect much of a difference. This is a big surprise," said Stephen Gorevan of Honeybee Robotics, lead scientist for the RATs. "Ladies and gentlemen, I present you the greatest interplanetary brushing of all time."
"To our surprise, there was quite a bit of dust on the surface," said Ken Herkenhoff, lead scientist for the rovers' Microscopic Imagers. "Remember, we selected this rock target because it looked relatively dust-free."
"The material on the surface posed literally no resistance," Gorevan said. "We saw almost no effort in the motor telemetry that said this material offered any resistance whatsoever."
The close-up images show "a bunch of details in here we are just beginning to understand," Herkenhoff said.
"We are seeing...mineral crystals on the rock surface. Of course as we continue to abrade the surface with the RAT, we are very excited to see what that will show us."
 This microscopic image shows a cleaned off portion of the rock dubbed Adirondack. The observed area is 3 centimeters (1.2 inches) across. Credit: NASA/JPL/Cornell/USGS Download a larger image here |
Once finished with Adirondack, Spirit could begin driving Saturday, bound for a large crater in the distance.
"We are kind of on the west-southwest side of the lander. We are going to drive around the lander and head northeast for Bonneville Crater. We do believe we will be able to get there," Trosper said.
"We're having strategy discussions now on how we would use the capabilities of the vehicle in terms of traversing and auto-navigation in order to get us there.
"Our initial thinking is we will start with being able to just designate traverses from the imaging. So we will tell the rover exactly were to drive, but at the end of that traverse we will turn on our auto-navigation software and allow the rover, for a meter or so just to check out the auto-navigation software, to determine how to get to the next way point."
As Spirit continues to journey across Gusev Crater, controllers expect to expand the distance it can travel in each increment.
"We will start in those baby steps and each sol (day) that we are driving, we will probably expand the numbers," Trosper said. "There is going to be a lot of driving on Spirit."
Over the course of the long trip, the rover will make a few extended stops to perform science investigations along the route.
"We have worked with the science team and we've talked about four or five different places that we might stop and do some specific science with the (arm) as we go. That's our plan, long-term."
Imagery indicates that there will be a path for the rover to actually reach the crater rim.
"Of course we will know that better as we move closer," Trosper said.
Driving up the inclined wall of the small crater the craft landed in, the Mars rover Opportunity was expected to arrive at the outer edge of bedrock outcropping early Saturday to begin its geologic work.
 This picture from the rear hazard-identification camera on Opportunity looks back at the tracks the rover has made. Credit: NASA/JPL |
Earlier this week, the Opportunity rover used its suite of instruments to examine a patch of soil in front of the rover. This is the spot where the craft drove to after rolling of its lander base last weekend.
"We've had a good number of productive days over the last few days. We completed exercising the instrument arm and the Mossbauer Spectrometer, APXS (Alpha Particle X-Ray Spectrometer) and MI (Microscopic Imager) at the site where we egressed to.
"Yesterday, we completed a drive of about three-and-a-half meters. The drive was composed of several arc turns to the left, followed by an arc turn to the right, a turn in place and then a small drive forward, all of which were designed to give us some additional confidence in the characterization of the mobility system and its performance at Meridiani in this crater.
"Today, we sequenced a drive to approach the right-hand side of the outcrop, a target that is named Snout. The drive was about a 1.6-meter drive. We executed the drive (but) we came up a little bit short on Snout. And so we will complete that approach tomorrow."
Opportunity has another 30 or 40 centimeters to go, Wallace said.
 A view from Opportunity's forward camera shows the outcrop. Credit: NASA/JPL |
As the rover climbs the crater wall, it is pitched nose-up by almost 13 degrees, he said.
Before finishing the drive Saturday, Opportunity's arm will be deployed to take microscopic images of it the soil of the current position before moving on.
"We'll drop the arm down towards the soil and take several more of these spectacular Microscopic Imager pictures of the soil so we can continue to catalogue the soil inside this crater. Then we will restow the arm and drive forward."
After reaching Snout, the rover's science devices will be employed Sunday to examine the exposed bedrock.
"From there, it's looking like the scientists are asking us to start an arc along the bottom of the outcrop area, stopping at several choice viewing locations and taking some additional pictures and potentially dropping the arm down and getting additional microscopic images as we go.
"So that's where we've been and that's where we're going.
"The spacecraft continues to operate nominally. She's healthy and happy and continuing to do the job she was sent to do."
are we going to be consumed by a giant jellyfish?
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