Color 'Pancam' images now expected overnight
Posted: January 5, 2004

Four of the Spirit rovers critical scientific instruments sailed through initial checkout operations and a fifth will be tested late this evening, officials said today. A 3D panorama shot by Spirit's low-resolution navigation cameras was unveiled today and a full-resolution, color mosaic showing the terrain immediately in front of the rover is scheduled for downlink early Tuesday.

Looking further ahead, chief scientist Steve Squyres said a nearby depression, a possible impact crater nicknamed "Sleepy Hollow," may be Spirit's first major scientific target after the robot rolls onto the surface next week.

"The thing the science team has been focusing on very much is where to go after we egress," Squyres said. "And I would say that we have pretty much come to a consensus now, on the basis of the data that we have so far. ... If we had to choose today where we would go, it would be that circular depression that you see right there."

Turning to face one of the 3D panoramas, Squyres was pointing toward a 30-foot-wide depression located about 50 to 60 feet due north of the lander. Reporters looked on, wearing cardboard red-and-blue 3D "glasses" provided by NASA. "We've had a lot of discussion on our team as to what this is. In fact, there are a lot of these things."

A 3D view from Spirit showing the depression near the lander. Credit: NASA/JPL
He described it as "a hole in the ground" that provides "a window into the interior of Mars."

"We think this may have been an impact crater that's been largely filled in with dust," he said. "If it is, it would have dug down a number of meters, blown stuff out onto the surface. You can see on the far wall of it that there is rock exposed there. That may be a chance to see what the rock looks like in the upper layers in this site. It's a very, very exciting feature for us. It's probably where we are going to go, unless we find something even better."

See the full image 3D here.

The depression may be what geologists call a secondary impact crater. Two dark areas in the lighter-colored dust filling in the depression may, in fact, by bounce marks caused by Spirit's landing bags as the spacecraft rolled to a stop Saturday.

"When you have an impact take place, some big rock comes hurtling in from space (and) hits the ground, throws a bunch of stuff in the air, it comes back down again, these chunks of stuff fall out of the sky and they make more craters," Squyres said. "And those secondary craters, the ones that come subsequently, are typically characterized by being fairly shallow, not having very high rims, being sort of in clusters. And we may actually be in a secondary crater field here. That's a hypothesis, but boy, there are a lot of these things."

But before Spirit can begin its three-month tour across the floor of Gusev Crater, engineers first must complete a complex series of steps to check out and activate various systems, elevate the rover, unfold two of its six wheels and release numerous restraints that now hold the robot to its landing platform.

An artist's concept of Spirit in its current crouched state. Credit: NASA/JPL
Two of three bundles of data and/or cooling lines and cables must be cut - the first was severed earlier - by sharp blades driven by small explosive charges. The second cable bundle will be cut this evening and the third, shortly before Spirit's roll off next week. Roll off currently is targeted for Jan. 13.

In addition, four restraint cables attached to the four corners of the rover's body must be cut, along with cables securing each of the robot's six wheels. Other charges will be fired to release the rover's robot arm, which was firmly locked down for launch and landing.

Spirit's undercarriage currently is collapsed, or folded down, with the body of the rover flush against the lander's upper surface. Later this week, a screw lift on the lander will turn, pushing the rover upward and allowing the undercarriage to drop down and unfold. When the screw lift retracts, the appendages of the undercarriage will lock in place, completing Spirit's so-called "stand up." The two forward wheels, folded against the front of the rover for launch and landing, will be extended and the two back wheels will slip aft slightly to increase the robot's wheel base.

For all of that to happen, the cables now securing Spirit to the lander must be successfully severed. The cable cutters are not redundant and they must work. But engineers say they are extremely reliable and dozens have already worked properly. In fact, Spirit entered the martian atmosphere Saturday with 60 such pyrotechnic devices on board.

"If for some reason, heaven forbid, we couldn't fire a cable cutter, we'd turn from a rover mission into a lander mission," Squyres said. "We'd never be able to do any science with any of the instruments on the arm. We can Pancam and mini-TES (thermal emission spectrometer) until the cows come home, but the scenery's never going to change. So we're looking forward to getting that cables cut. And we intend to do it."

An artist's concept of Spirit driving off its lander. Credit: NASA/JPL
A major objective of today's work is to retract partially collapsed airbags that could obstruct Spirit's exit route off the lander. Overnight, engineers downlinked more pictures of the airbags to determine what effect temperature changes might have on the gas trapped inside.

"You have no doubt seen that there are some areas where the airbags are puffed up," said mission manager Matt Wallace. "One of the things we're trying to do is determine, first of all, whether or not we're looking at airbags or whether we might be looking at some rocks. And we have confirmed positively that in fact those puffed up areas are, in fact, airbags.

"And so the next question is, are there rocks underneath those airbags in those areas? So we're going to spend a little time (today), retracting the airbags a little bit farther, in particular the base petal airbag."

The base petal is the one Spirit is sitting on. The other three unfolded to the sides.

"We have tendons that go from our airbag retraction actuator mechanism that fan out to the airbags," Wallace said. "So when we retract those airbags, we roll those tendons back up. During the nominal critical deployment activities, we stop at a certain point. We're going to go ahead and continue that activity and roll them back up another three revolutions and see if that helps us out, in particular with those two protrusions in front of the rover."

On the science front, Squyres said Spirit's panoramic camera, or pancam, will take images for a 90-degree full-resolution mosaic late today, as will the thermal emission spectrometer. The data will be stored in the rover's memory until engineers have time to downlink them to Earth. A 12-frame pancam "postcard" was recorded yesterday and will be downlinked this evening if all goes well. The mosaic will be the sharpest view ever seen of the martian surface.

Reporters had hoped to see the postcard mosaic today, but Squyres said engineering data took priority.

"The focus right now is on the engineering activities and getting this vehicle safely off the lander," he said. "The science stuff is going to have to wait a little bit."

But he was particularly excited about the success of yesterday's instrument check out, including confirmation, via thumbnail images of the pancam postcard mosaic, that Spirit's main visible-light camera is working properly.

"Well, the good news just keeps on coming," he said. "We had a fantastic day yesterday for the science team and by far the best day yet for the science payload. The focus of yesterday's activities from a science perspective was health checks. These are checks to verify that there is scientific instruments have survived the shock of landing with airbags on the martian surface. And I am thrilled to be able to tell you that the Microscopic Imager and the APXS (alpha particle X-ray spectrometer) and the Mossbauer Spectrometer have all checked out beautifully."

"Now I've got to confess I was scared about the Mossbauer," he said. "This is an instrument that malfunctioned on us during cruise (to Mars). ... Over a period of several months, we managed to find a way to change the way in which we operate the instrument, get it so it was working OK. But anytime you have an instrument that undergoes some kind of mechanical damage, which seems like what was going on here - this thing had gone through some substantial shaking as the rocket was launched - it scared the living daylights out of us. I didn't know what we were going to see after we hit the ground.

"And you should have seen the scene in the Mossbauer (control) room yesterday when the data came down," Squyres said. "You guys have all seen the video in the (main) control room the night we landed and everybody was jumping up and down and cheering and hugging and tears? It was the same thing, only in German. It was just wonderful."

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