My coordinates come from the Malin Space Science Systems website, where new MOC images of the three
'boxes' are being released each month.

Phil

'We will have a landing ellipse...however, because our landing site is in the high northern latitudes the geometry of the ellipse will be different than those for the MERs...ours will be longer and thinner.

I didn't tought about that; could be more difficult to find the right place.
On Earth, Northern latitudes have thiner air than equatorials; Do you know if it's the same on Mars and if so, if this could have an effect on the size of the elipse? Does somebody know the size and shape of MPL's elipse back in 1999 ? It shouldn't be much different to Phoenix's.

As I understand it - the pre-launch ellipse ( i.e. what they'll pick ) will be 'butterfly' shape becasue the geometry will change so much between the opening and closing of the launch window.

Now - as the ellipse moves from the opening to the closing position, it draws out quite a large area they have to 'certify' as suitable for landing....not easy.

More equatorial sites, the ellipse just moves around just a little.

http://sci.esa.int/science-e/www/object/do...fobjectid=36770 is quite interesting on the issue - not sure how up to date that is however. (attached - screenshot of interesting page)

http://www.lpi.usra.edu/meetings/lpsc2006/pdf/2341.pdf as well

The phrase 'butteryfly' gets mentioned, which I believe is the shape drawn by the opening and closing ellipse
http://www.msss.com/mars_images/moc/guest/...23_phoenix.html

Doug

Found out this:

http://planetary.chem.tufts.edu/Phoenix/la...e_selection.htm

There are also some cool Death Valley pictures in the site...

Hmmm, that link shows co-ordinates of 120 degrees West and 67 north. Is this a second landing site candidate (eg. Area A?), separate from the one Phil and Rodolfo describe?

I believe it is just an example...
The other candidates you indicate, the one referred by Doug Lombardi are all still under discussion...
Soon we'll know...

The site mentioned above (area D, adjacent to Area A) is only an illustration of a feasible site for pre-mission publication. It's not a new site and will certainly not be used.

Phil

Good reference. The resume of that article is that the selected landing site presents the following characteristics:

1. Low roghness values - approximately 1±0.6 m.
2. They found textures interpreted to be due to periglacial processes, including terrain they describe as having basketball-like, wrinkled-looking, and polygonally shaped features.
3. The slopes are gentle and easily within the slope constraint listed above.
4. The most likely obstacles to be encountered are rocks.
5. Thermal inertias computed from TES data show values of 230±48 J/(m2Kvs)— a range that indicates slightly indurated soillike material covers the surface, at least to depths of the diurnal skin depth of approximately several centimeters. Given the site average thermal inertia, the likelihood of landing on a high rock is very small.

However, it is not yet the final site landing but the decision on the final landing site will be through the NASA Associate Administrator for Space Sciences. They look for more community scientific input and suggestions.

Rodolfo

Not to mention HiRISE pictures of potential sites.

http://space.newscientist.com/article/dn10...nding-site.html

NASA's Mars Reconnaissance Orbiter (MRO) has started scanning the arctic plains of Mars for possible landing sites for the next spacecraft, the Phoenix Mars Lander.

Some of the first pictures returned to Earth have already dashed the hopes of scientists who wanted to land Phoenix at a place they call Region B. It turns out Region B is littered with boulders, which could make a landing very dangerous.

Perhaps Mars Polar Lander struck a boulder while landing ? If it made it to the surface that is.

I'm having deja vu all over again, as I recall the frantic search by the Viking 1 orbiter for a landing site for Viking 1, after landing site mapping images with 50 meter/pixel resolution of (I think Ares Valles outwash plain) showed rough erosional features and blew the planned July 4'th landing out of consideration.

Yes, it was the outwash area.

I've been looking at the Phoenix site planning:

Phoenix potential landing areas

Step 1: select areas (D and E: rejected)
A 65º to 72º N 250º to 270º E
B 65º to 72º N 120º to 140º E
C 65º to 72º N 65º to 85º E
D 65º to 72º N 230º to 250º E
E 65º to 72º N 300º to 320º E
Step 2 : Examine preferred box in each area
Area A box 68º N 260º E
Area B box 67.5º N 130º E
Area C box 70º N 80º E
Step 3 :Seek preferred boxes in the best area
Area B, box 1 67.5º N 130º E
Area B, box 2 66º N 136º E
Area B, box 3 70.5º N 136º E

The MRO images of "northern plains" are mostly in these areas.
orbit 828 is in B-1
orbit 841 is in B-2
orbit 848 is in B-3
orbit 856 is near C
orbit 861 is in B-2
orbit 881 is in B-1

Phil

Unless ice/frost/soil processes heaved buried boulders to the surface in a slow peri-glacial "churning process", I just UTTERLY don't understand the boulder populations on the northern plains. The VL2 site barely helps, since the boulder field MAY be ejecta from the large and quite reasonably fresh (remarkably little degraded) Mie crater to the east.

I agree, it's puzzling. To me it says "lag deposit", but I still don't see exactly what's happened here.

There are less blocky patches between the clusters of rocks. I suppose the next year will be spent trying to find one relatively block-free patch big enough to fit a "butterfly" (post 53 above) in.

Phil

We have a humongously widespread plains deposit -- it ain't called Vastitas Borealis for nothing -- in which 100 km craters are obliterated, apparently buried, showing up as topographic ghost craters: rimless crater"ish" depressions visible only in the MOLA topography.

We have a surface that appears mantled, so that the ghost craters appear to be visible only by the "sagging" or compression of the mantling overburden, which is burying those 100'ish km diameter craters to depths of many tens to hundreds of meters. (that's my interpretation)

Yet large concentrations of boulders, some very large, that should utterly be buried beneath this mantle show up on the surface, concentrating on -- or seemingly over -- the rims of more or less buried, massively subdued small sub-kilometer or few kilometers diameter craters that seem to be mantled, or blurred beyind recognition of any original topographic form.

In the words of a Robot I learned to loathe quite some decades ago: IT DOES NOT COMPUTE!

Aren't you assuming simple scenarios here? Namely, that the event which buried the craters ought also to have buried the boulders as well?

But what if the reality is that multiple events have happened at such sites, no doubt separated by millions or hundreds of millions of years? For example, one event buried the craters, a subsequent event (or sequence of events) transported & deposited the boulders on top & buried them in another layer, and a third event eroded the topmost later and uncovered the boulders again.

Just a thought.

======
Stephen

The thing is that the muted terrain implies mantling to a depth of tens of meters, somewhat less on mantled crater rims. And the boulder fields seem associated with the craters.. .. TELEPORTED !?! up from underneath? Yeah... RIGHT!. They're not impact ejecta from distant craters, or we'd see lots of the same at Meridian, other than Bounce rock and a few meteorites.

I'm starting to think that the muted look of the terrain means the craters aren't just mantled, but the surface ice+dust+sand+boulders has done a periglacial churning and brought the boulders to the surface the way things happen on Earth.

For anyone struggling with the large images there is a nice manageable image of some of these 'boulders' in Emily's Planetary Society blog. I agree they look very strange. For a start far too many of them are about the same size. Although I can't imagine one yet I suppose an upward extrusion process of some kind might achieve a degree of size sorting.

Frost heave? Seems like a perfectly plausible explanation especially given the latitude and expected presence of water ice.

Just noticed this is also being discussed in 'November 22 MRO' thread.

Phoenix Mars Lander: The Search For A Safe Haven
By Leonard David
Senior Space Writer, Space.com
posted: 10 January 2007
06:38 am ET

I got to go to a little of the landing site meeting yesterday and am working up a Web article. Could I get a little help from those of you who are slavering over the MRO images? I've got the center coordinates of the three landing sites under consideration. (Does anyone know offhand how large the boxes are supposed to be around those center coordinates?) I'd like to know which of those dozens of "Northern Plains" images are closest to these locations.

Box 1 68.35 N, 233. E
Box 2 66.75 N, 247.6 E
Box 3 71.2 N, 253 E
(lat/lons are Areocentric)

One is in region A, the other two are in region D, which was actually the region that Peter Smith first proposed to send Phoenix to based upon high water content in GRS maps, and which they had to return to when they had to throw out region B because of all those boulders.

--Emily

Emily, I think the boxes are 150 km E-W, 75 km N-S - I will confirm that for you shortly. These new locations are very useful for me - thanks.

edit - yes, this is confirmed.

Phil

I don't know but for some reason I'm reminded of Tom Sawyer Whitewashing the Fence.

I'm just joking, of course. At least you give credit, Emily, unlike, for example, Jim Oberg, who was (and probably still is) pretty effective at Tomsawyering his acolytes on Usenet. Typically, he started out with something like, "Hey, I'm working on a story about X and I need answers to the following fifteen questions. Thanks in advance, you guys are the greatest!"

65, 235 - http://hiroc.lpl.arizona.edu/images/PSP/PSP_001484_2455/
68, 265 - http://hiroc.lpl.arizona.edu/images/PSP/PSP_001496_2485/
68, 241 - http://hiroc.lpl.arizona.edu/images/PSP/PSP_001497_2480/
68, 223 - http://hiroc.lpl.arizona.edu/images/PSP/PSP_001392_2490/
69, 254 - http://hiroc.lpl.arizona.edu/images/PSP/PSP_001404_2490/
71, 260 - http://hiroc.lpl.arizona.edu/images/PSP/PSP_001417_2510/
69, 234 - http://hiroc.lpl.arizona.edu/images/PSP/PSP_001418_2495/
67, 266 - http://hiroc.lpl.arizona.edu/images/PSP/PSP_001430_2470/
65, 240 - http://hiroc.lpl.arizona.edu/images/PSP/PSP_001431_2460/
68, 260 - http://hiroc.lpl.arizona.edu/images/PSP/PSP_001431_2460/
69, 260 - http://hiroc.lpl.arizona.edu/images/PSP/PSP_001351_2490/

The best I can do running thru the Hi-Bucket.

Guilty I'm sure it's pretty obvious to everybody how much I depend upon the loyal denizens of UMSF as a resource! I do try to ask people to do work for me only if I think they'll actually enjoy it and if their answer will be of interest to everyone in the forum anyway. Most of the time I can't use everything that gets generated here as a result of a question I have -- but I think UMSFers enjoy the "extended data" being available here.

--Emily

Here's a list of a few that seem to be fairly close to the sites, along with their release number.

PSP_001351_2490 5
PSP_001418_2495 6
PSP_001404_2490 6
PSP_001392_2490 6
PSP_001431_2460 6
PSP_001417_2510 6

I'll look for a few more, hope this helps!

Wow, I was busy whitewashing away with my little toothbrush (i.e., looking up each image individually), then I see that Doug got the job done because he was using a spray gun!

Emily has a really good story at TPS, as well as a new blog entry.

Thanks for "being there," Emily.

Minor correction to the blog entry: The Robotic Arm's reach is eight feet, not eight meters!

Go, MRO!!! Man, that mission is really paving the way for the future of Mars surface exploration...incredible imagery.

Those 'polygons' seem to be, well, rather bumpy. Boulder hazard aside, how much tilt can Phoenix withstand & still function (to say nothing of land) nominally? Just eyeballing this without stereo, it looks like some of those bumps might have incident slopes on the order of 20 deg or more.

It's good that Emily could go to the meeting, because the process has not been as open as MER or MSL (for those of us who are into these things).

Phil

I've re-tweaked my sim of Phoenix. I wish I could get the right ammount of detail to show - still not quite there, it's a bit too sharp...I'll get it right eventually.

Also - the orig test image of the model - it's basically a VRML I found of MPL, + different arrays. I know the deck has changed shape, but at 33cm/pixel it's about right

Doug

The one that landed in the 3:00 position looks like it might have some "issues" with a small boulder.

In that cold and without TV Phoenix could only multiply herself...

I now have a mental picture of Phoenix, with a broken transmitter after the long winter - waking up in 2011, and using the arm to fashion the local terrain into a replica of the ATLO facility.

Doug

I can see her building a CO2 snow fort during the winter in order to stave off further encroachment...

Still a bit worried about the uneven terrain, though. Other places we've landed have pretty uniform slopes with respect to the lander's scale, albeit usually studded with rocks; the polar areas (esp. region D) seem to have these hummocks much like terrestrial permafrost mounds...fairly treacherous.

I think people are much more concerned about the rocks than they are about meter-scale slopes. I wonder if these areas look more treacherous than they are because of the low angle of illumination that prevails at polar latitudes -- that would emphasize topography and make things look bumpier than they really are.

Unfortunately I missed the talks on meter-scale slopes at the meeting so I don't know what kinds of slopes they're finding in these terrains.

--Emily

Great update, Emily! Hopefully there'll be nothing to downgrade Green Valley as Phoenix approaches next next May

Emily, just curious, which HiRISE image did you end up using for your report? Thanks!

I should probably write that in the caption...anyway, I rarely change the filenames of images as I work with them, so it's still on there in the image in the post. Just save picture as and you'll see it: PSP_001497_2480_RED

I got an interesting email from Mark Lemmon, which I'll blog next week as I've done enough for today, but I thought y'all would enjoy it here:

I asked for more from him on why that orientation -- I'll post Monday.

And I did fix that 8-meter mistake (stupid Imperial units...)

--Emily

Emily wrote "which will align the solar panels roughly E-W."
May be I'm too impatient but as I see how important it's for Spirit to get her panel in the right orientation I may be understand why the "slope issue" (of having slopes less than a few degree) is as important as the "boulder issue"

Tried again - 33cm/pixel ( it just seems better at that res ) - with all the landers pointing with arms going north...makes it harder to see with a 30 degree high Sun off to the west - as the shadow falls more under the lander and less onto the ground beside it. Thanks for the pointers Mark

Doug

You'd have had real fun on the flight from LA to Dulles with all the JPL's EDL guys playing around altogether to get Phoenix OK on the ground

Landing site update from Peter Smith's LPSC poster. Of the three boxes considered in Regions D and A, Box 1 has been selected as the final 'box' (2.5 degrees north to south, 9 degrees east-west, which is about 150 km square). This is in the 'green valley' area, about 80 km west of a 10 km crater on the south edge of the valley. The ellipse can still move around a bit within the box.

Phil

Cool. Nice to know Phoenix's future home on the Red Planet has been selected

http://www.nature.com/news/2007/070312/full/070312-5.html

Update from LPSC on the Phoenix site.

This is the region of the landing site:

Click to view attachment

and this is the site itself with three landing ellipses oriented according to different arrival dates. The intersection of the ellipses is the preferred location.

Click to view attachment

Phil

I am on dial-up. I will not be downloading any Hirise size files, so I saved your graphics to a newly created Phoenix directory. Good basic material for following the future mission. However I have one question -

Edit
Forget the question. It can be answered by comparing both images.

Original question
Is the geometry of that image accurate? All the craters are extremely squashed ovals - wildly stretched east and west. Is it caused by projecting parallel longitude lines?

.

Yes, the first one is a simple cylindrical projection, which is why everything is so stretched out in longitude. 1 degree of longitude does not equal one degree of latitude this far north, not even close! Map projections are actually a real problem for this mission. Phil, of course, would be the correct authority on what projection they SHOULD be using for their maps...

Phil, where did you find that update? I couldn't find it on the Phoenix site. Can you post a link?

--Emily

The geometry is perfectly accurate - for that map projection. Simple Cylindrical does that to craters. The second image is part of the same thing, but stretched vertically to give a better idea of shape.

Emily - a polar sterographic or a conic projection at that latitude would be better for shape. I used the Simple Cylindrical because that's how we can now get all this good stuff straight off the Themis site:

http://jmars.asu.edu/data/

As for the update... Ah, Em, you shoulda been there! I took it from Peter Smith's LPSC talk and poster.

Phil