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Concerning the wintering over of Spirit:<br />I hope they address this during the press briefing tomorrow (7/16). I have several questions.<br /><br />Will a point be reached where there is only enough energy being collected by the solar panels to keep the battery alive, with no rover activity possible? When would this wintering period have to begin? Will the rover be parked for an extended period? I so, any north-facing slope not shaded by Husband Hill will do. Perhaps at the top of the West Spur or in the area of Lookout Point, depending on how soon the parking period would have to begin.<br /><br />I don't know if the possibliity exists for continued exploration through the winter if Spirit explores an expansive north-facing slope area. This requirement is only met by the north slope of Husband Hill, but so far I have seen no interest on the part of NASA in heading either up Husband Hill or to the north, as opposed to heading south to Lookout Point.<br /><br />Hopefully more light will be shed on the subject at the briefing. <div class="Discussion_UserSignature"> </div>
Here's the basic news on Spirit from the press briefing:<br /><ul type="square"><li>A fourth full-colour stereo panorama was released, taken at the midpoint of the traverse to Columbia Hills.<li>The wheel heating has reduced the current draw by 25%, but not as much as hoped.<li>Testing shows 5 wheel operation is feasible, but dependent on terrain. Six wheel operation will be saved for when it is needed. Driving in reverse is preferable, and Spirit will be mostly going backwards from now on. Driving with four wheels was also found to be possible. Losing one or two wheels just makes the rover slower.<li>Spirit is currently driving over an exposed layered outcrop, with apparently fine layers, which will soon be investigated. The plan is then to drive up West Spur, by first driving north and then swiching back south onto the spur. This is longer than the direct route, but has slope and solar energy benefits. <li>The target on the spur is a massive outcrop, which does not appear so far to have many thin layers.<li>Activities will slowly decline as winter approaches, but it didn't sound like Spirit would completely stop moving, except for the period of superior conjunction. The lowest temperatures expected for midwinter (-100C) are only a few degrees colder than the rover experiences now.<li>There was no mention of where the rover would go after West Spur.</li></li></li></li></li></li></li></ul><br /><br />Should be a great view from the top of the spur!
Some of my questions answered: <br /><br />I get the feeling from the 7/16 briefing that there will not be the need for a lengthy hibernation for the rover. The way it was described, there will definately be less rover activity than usual. Perhaps a sol or a few sols will be devoted entirely to battery recharging from time to time, but otherwise there will be continued activity through the winter. <br /><br />The longest period of inactivity will be due to communications interruption by solar conjunction (the sun blocking Mars from Earth) which will last from about 9/10 to 9/20. Coincidentally, the winter midpoint is 9/20. I'm sure we'll all be holding our breaths and crossing our fingers waiting for the first signals showing that the rovers have made it through that long wait. <div class="Discussion_UserSignature"> </div>
Good summary, redgryphon, I just have one addition to make concerning: <i>"Spirit is currently driving over an exposed layered outcrop, with apparently fine layers, which will soon be investigated."</i><br /><br />The scientist discussing this outcrop refused to commit on whether the apparent layering was real or the result of weathering processes giving a layered <i>appearence</i> to the rock. Hopefully the pending investigation will clear this up. <div class="Discussion_UserSignature"> </div>
To help you (and others) orient I have placed orientation points on these 3 images. These are approximations but should give everyone an idea of relationships. In the bottom image, I believe due north is straight up. As usual I was unable to catch the press briefing today. Once we get to the north-facing slopes of West Spur the power situation will improve dramatically. We will not be able to negate the effect of season completely, we can potentially drive the mid-day angle down to a mere 10 degrees or so.
Thanks for the summary guys, I missed the brief <img src="/images/icons/frown.gif" /><br /><br />Nothing was mentioned of the bright easily-crushed material on Gusev ?<br />No spectra were taken of it ? <div class="Discussion_UserSignature"> <em>I feel better than James Brown.</em> </div>
<i>"Nothing was mentioned of the bright easily-crushed material on Gusev ?"</i><br /><br />I can't believe I forgot about that! No, nothing was mentioned. Now, that's going to bother me. <div class="Discussion_UserSignature"> </div>
Thanks, fangsheath, those images do help me orient. According to the press briefing, Spirit is currently heading for the north slope of West Spur (the magenta dot in your image). It will climb that slope to investigate the outcrops in the area of your red dot. After that, they didn't say and I don't know. <br /><br /> Although there are north-facing slopes in the area of Lookout Point, the drive to get there is not optimal from a sun catching perspective. <br /><br />I see the advantage of staying on the north side of Husband Hill but I wonder if the energy used in climbing that slope would use up any additional energy gathered because of the optimal orientation of the solar panels to the sun. At least the drive to Lookout Point is downhill or flat until reaching the northwest face of Lookout Point. They seemed to be eager to get to the Inner Basin on the other side of Lookout point (when they were talking about it a month ago). But I <i>really</i> don't see the rover driving around in that Inner Basin until the sun is much higher in the sky.<br /><br />By the way, the rover is spending a lot of time driving in reverse. This was found to work better with the front right wheel turned off. I can see a lot of people being confused when looking at the forward and rear hazcam images from now on! <div class="Discussion_UserSignature"> </div>
I think the decision about whether to continue up the ridgetop toward the peak of Husband Hill or veer off to the south before that will depend on how much time is spent on West Spur. I think there will be plenty of interesting targets on West Spur and I could easily see the rover spending the next 4 months there. By the time the decision needs to be made, illumination may have improved so much that the rover will be directed southward toward Lookout Point. I think this is the most likely scenario, assuming the vehicle survives that long. I would certainly like to at least get a look at what lies on the other side of Lookout Point. On the other hand, as they traverse up the ridegetop they may start to resolve outcrops up near the peak that are too interesting to pass up. Meanwhile, I think we will get plenty of fascinating science from West Spur.
I think you've got it right. They may find things to do on the sunny top and side of West Spur until the sun is higher in the sky. I just wish I knew what they were talking about in their back rooms. Are they planning to make a decision when they get to the top of West Spur about staying there for the winter or, if it's not as interesting as they had hoped, moving to Lookout Point?<br /><br />They may even stop to investigate the layered-looking rocks that we have seen peeking up from the sand. One of the scientists at the 7/16 briefing regreted not having done so already, but said that images -- including orbiter images -- indicated that that rock mass was extensive and they would probably run across a good spot to study it on the way to the north face of West Spur. He's the same scientist that said those rocks looked layered but it could be a weathering effect, not true layering. But he'd sure like to find out! <div class="Discussion_UserSignature"> </div>
I have a few questions regarding the up coming moutaineering expedition Spirits about to tackle.<br /><br />Firstly, how high up are the first three objectives on West Spur and also Lookout Point?<br /><br />I seem to remember reading somewhere that there is quite a significant temperature variation, even just a couple of meters off the ground.<br />Would there be a big temperature difference between where Spirit is at the base compared to Lookout Point?<br /><br />Just found the page below, not sure how accurate it is but it shows up to a 20C difference within .75 meters from the surface.<br /> As Spirit climbs and uses Deep Sleep mode then I guess the mini-TES is doomed. Or Is it?<br /><br /><br />http://www-k12.atmos.washington.edu/k12/resources/mars_data-information/temperature_overview.html
I think what is being observed here is a ground-warming effect, NOT an altitude effect. The dirt is acting as a solar collector in daytime, and radiates infrared energy, increasing temperatures within a few inches of the ground. Yes the top of the ridge will probably be cooler, but not 20 degrees cooler than the plain.<br /><br />As a rock-******, I say this with no authority.
Here is a site showing the first ever ground-to-space temperature profile of the martian atmosphere (made possible by the MER mini-tes instrument): http://photojournal.jpl.nasa.gov/catalog/PIA05559<br /><br />It shows temperatures dropping very slowly in the first 100m above the ground. At about 100m the temperature drop is about 10 degrees centigrade. The maximum height of Columbia Hills is about 100m. The height of West Spur, which is as high as the rover has plans to go, is about 30m.<br /><br />Bushuser is correct in pointing out that the great temperature drop in the first meter above the ground is due to the rapid loss of ground heat in the thin atmosphere. And remember, no matter how high the rover climbs, it is still resting on the ground.<br /><br /> <div class="Discussion_UserSignature"> </div>
These are good questions. It is important to get a sense of scale because it is difficult to gain this from the Pancam images. The distance from where we are to the peak of Husband Hill is less than a third of that from Bonneville Crater to our present position. West Spur is a mere 70 feet or so above the plain, Lookout Point less than that. The peak of Husband Hill is about 300 feet high.<br /><br />Of course temperature decreases with altitude. The top graph shows that the temperature 30 m above the landing site is often 2-6 degrees lower than that near the ground. 100 m above the ground, the temperature may be 8-10 degrees less. But the bottom graph shows that near the ground, temperature fluctuations are dramatic. At one point, IN LESS THAN 30 SECONDS, the temperature dropped at least 5 degrees 30 m above the ground. Closer to the ground fluctuation is even greater.<br /><br />The "outcrop" touted on the JPL website was driven over rather unceremoniously. There will be far better ones to come. But we need to get those panels tilted northward.<br /><br />With the backwards driving, using the right front wheel only 10% of the time, we see just one example of the JPL engineers at their finest. They are nothing if not adaptable, and it is a pleasure to watch them overcome these difficulties. I think we will see more of this in the months to come.
So what would cause such rapid temp fluctuations near the ground? Could these be caused by martian wind gusts? Or some other fluctuation in barometric pressure? Do the rovers have anemometers? I know the Viking landers did.
There is definitely a lot of convection going on near the surface during the day. This should come as no surprise given the fact that Mars produces dust devils that dwarf any seen on our planet. This graph shows pockets of warm air moving over the rover, some possibly developing riight over it and rising.<br /><br />These rovers have no means of measuring wind speed directly.
Thanks for all that great info. <br /><br />Is all the atmospheric data like daily temperatures readings and stuff available to the general public, i.e. me?<br />If so could you point me towards it?<br />Just curious to see what the rover puts up with and how the mini-TES is lasting with respect to the predicted -50 to -60 degree failure point. <br />Two months ago at meridiani thermal models for the time predicted a nightime temp of -48C, so I'd like to see how things are going without having to clog up the board with polite requests for weather bulletins. <img src="/images/icons/smile.gif" /><br /><br />Thanks again<br />
Check out the millimeter-scale lamination. This may turn out to be the beginning of a crescendo of evidence pointing to water-mediated sedimentation at Gusev Crater.<br /><br />I have cranked up the contrast a bit.
If I understood the flight director report correctly, the panels are now tilted 4 degrees northward. Although this is a small amount of tilt (the sun is about 38 degrees off the zenith at mid-day lately), they have confirmed that it does help the power generation. Our outcrop is scheduled to be RATed very soon.