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Posted by: tuvas May 26 2008, 02:31 AM

So, I think we can say now that we are in post-EDL operations, now that the solar panels have been verified. Still on the list of things to come:

1. Full panoramic from Phoenix, I would expect it to be coming in pieces over the next day, every hour and a half or so.
2. Imagery from HiRISE and possible Mars Express, which might show Phoenix while landing. The odds of success are slim, but it sure would be cool!
3. Imagery of HiRISE on it's landing spot. I find this unlikely to come by this Wednesday release, for a few reasons. First of all, it's likely due to a late parachute opening that Phoenix overshot it's landing a bit. If it overshot it far enough, then it would miss a HiRISE window (Remember, the FOV on HiRISE isn't that high...) Secondly, it takes about 4 advanced notice to change an image location, so the next opportunity won't be for a while. Given also the length of a downlink, I put a HiRISE image for the 4th of June.

Anyways, please post your topics on Sol 1 (Or is it 0) of Phoenix. I have a hunch we'll have to do a post for each of the first few days, but...

By the way, for those trying to see the Phoenix Images, and want to download the JPGs, look at http://phoenix.lpl.arizona.edu/ , and then click view images now, then the image you want, then look at the right. You will see an area to download the image now, in JPG format.

Posted by: DFinfrock May 26 2008, 02:39 AM

I believe they're calling this Sol 0.

Congratulations to NASA, JPL and the entire Phoenix team.

And congratulations also to Rui and his judges for choosing Doug's illustration as their contest winner. Doug nailed it, and Rui recognized it.

Posted by: climber May 26 2008, 02:43 AM

Most definitely
I have to leave to get a plane in a few minutes, kuddos to you all.
Whouuuuuuuuaaaa, we're on a NEW Mars again

Posted by: climber May 26 2008, 02:46 AM

The upper soil seams to be soft enough. Have you seen how "dirty" the foot is ?

Posted by: nprev May 26 2008, 02:47 AM

You know, I think one thing we've learned is that each landing from now on is in fact going to be a "new Mars". The Viking rocky desolate stereotype appears to have been broken decisively.

This place feels very, very different. It looks like a mine dump, but this place is not what it appears to be at first glance by any means. Our first alien tundra...

Posted by: Stu May 26 2008, 02:50 AM

Yeah? Go look at http://www.unmannedspaceflight.com/index.php?act=attach&type=post&id=14341on the other thread... it's stunning...!!

Posted by: nprev May 26 2008, 02:57 AM

Indeed it is! I was talking about big, huge freakin' rocks like there are around V1 & V2. (BTW, anybody ever sit back & think just how incredibly lucky we were for BOTH of those? Each lander came within mere meters of rocks big enough to destroy them, and to this day we don't know what sort of stony daggers are pointed against their bellies, nor how far away they are from vital areas...)

Others have commented on the weathered appearance of the rocks around Phoenix. Could repeated CO2 deposition/sublimation do this, or is the wind perhaps a little more constant in Vastitas Borealis? Sure looks like there's nothing to stop it...

Posted by: belleraphon1 May 26 2008, 03:01 AM

Truly beautiful..... I think Peter Smith will have a hard time deciding where to dig.... at small scales what a wonderful cornucopia to delve into....

Hard to believe how worried we were just a few hours ago.... now Phoenix is in it's element, to do what it is designed to do... congrats to that entire team....

Luv it!!!!!

Can't wait for the Sol 0 press briefings for tonight and into tomorrow...

Craig

Posted by: Ant103 May 26 2008, 03:04 AM

So, last pic, after, I will go to bed.
A mosaic from 4 pic (always very approximative in colors).

Posted by: nprev May 26 2008, 03:07 AM

Beautiful as always, Ant; thank you!

Anybody notice that rock about midway up the field in the near distance? It looks like an owl staring at Phoenix (shameless attempt to name a rock, here... )

Posted by: Greg Hullender May 26 2008, 03:19 AM

Exactly how much beer did you say you had?

--Greg :-)

Posted by: PDP8E May 26 2008, 03:19 AM

To all UMSFers,
What a great evening (east coast US)!
The pictures coming down are a wonderful surprise.
The colorized versions from you guys are amazing!
What a great community!
Thanks to JPL, UA, and all of you!

Posted by: nprev May 26 2008, 03:25 AM

Apparently somewhere between not enough & too much! No miniBigfoots in evidence, though...

Posted by: dvandorn May 26 2008, 03:29 AM

Whatever that light-colored "splinter" is in the one horizon view, in the mid-to-far field between us and a bump on the horizon, it's real. It casts a shadow that is plainly visible beyond it. And it really does appear to be as skinny as it looks.

My bet is that it's the heatshield, which sliced into the ground edge-on.

-the other Doug

Posted by: Sunspot May 26 2008, 03:36 AM

Is it my imagination or could one of the landing pod legs landed on a sheet/slab of ice?

http://www.nasa.gov/images/content/229920main_SS000EFF896228288_10C96L1M1.jpg

Posted by: nprev May 26 2008, 03:36 AM

Cool thought, oDoug! I'd been regarding it as an artifact; can hardly wait to see the second look!

Posted by: PDP8E May 26 2008, 03:36 AM

The Other Doug,

It could be a flare effect that we see in many MER shots of very reflective objects, but I am in agreement with you that that is a man made object.
I can wait to get the calibrated (vs. JPG) images to play around with!

Posted by: djellison May 26 2008, 03:37 AM

Heatshield having done an opportunity I think. If it were the backshell, we'd have a parachute next to it.

Doug

Posted by: dvandorn May 26 2008, 03:38 AM

Yeah, that was my thought, Doug. I thought about lens flare and cosmic ray hit, too -- but the thing casts a shadow. Lens flares don't cast shadows.

-the other Doug

Posted by: edstrick May 26 2008, 03:41 AM

red/blue <whatever the real wavelengths are...> color, no balancing to get "natural".... just showing the most detail.

Posted by: PDP8E May 26 2008, 03:42 AM

Ed,

where are the filter numbers used in each image?

Posted by: Paolo May 26 2008, 05:54 AM

What a great way to start the day! It's about 8 AM here in Italy.

Posted by: Paolo May 26 2008, 06:16 AM

What happens next? I can't find a timetable for the next actions/communication opportunities

Posted by: Steve G May 26 2008, 06:46 AM

At closer look at the artifact near the horizon definately looks like it's an object, it's about 10 pixels in length. The flare reminds me of the shots we have of Opportunity's heat sheild that also caused a significant image flare from the CCD. Perhaps we can get some "super resolution" shots of it, as obviously, we're as close as we can get. I hope the parachute is a little closer.

Posted by: edstrick May 26 2008, 07:44 AM

Did NOT catch the filter numbers, it's pretty obvious which is longwave and which is shortwave. Green filter is a mindless average of "red" and "blue"

I see somebody else posted essentially the same pic. Only difference is I did a "sharpen" on my ver. to "crisp" things up. I have to compsite up the other color pairs. also. Very little in the way of reddish "dust", none of the fine "drifts" as seen at the Viking 2 site, where they were common in polygonal troughs (obviously much younger), though "protected" areas in low spots and between rocks do seem smoother and red, as though there's a thin dust coating in the area.

The surface is pervasively granular, as though 20% of the material was poorly sorted gravel. I'm NOT sure at all that a lot of that stuff is in fact rock, though much of it in the color pic I made up is bluer than the "soils" and clearly is not highly weatered reddish material.

No "duricrust" visible, but 1 frame out of a landing site ain't much.

Re the "object" on the horizon.. it looks too sharp, as though not imaged by the optics. I'm 90% convinced it's just a cosmic ray hit, like gadzillions of'm on the MER rovers.

Posted by: PhilCo126 May 26 2008, 08:26 AM

amazing terrain indeed, but remember we're near the Pole

Posted by: Tesheiner May 26 2008, 08:36 AM

Good morning everyone... is there anybody in there?
(Mmm, it looks like there was a party here a few hours ago and now everybody is sleeping.)

It was great to start the morning with such great news! I've just finished reading the threads here at UMSF from the point I left yesterday --yes, I was *sleeping* during EDL. It seems I'm against the mainstream.-- and will now continue on other sites.

Posted by: PhilCo126 May 26 2008, 08:51 AM

Two quick questions:

1. Did NASA already pinpoint the exact location of the Phoenix Lander?
( newsarticle stated: 68.2 North - 234 East )
2. How long before Mars Reconnaissance Orbiter will snatch a photo of the landing area?

Exciting times indeed

the other Phil

Posted by: ustrax May 26 2008, 09:00 AM

I managed to sleep three hours...
A hard working day ahead...

Posted by: Simon May 26 2008, 09:05 AM

Hi,

Here is another false colour knock up job.



Does anyone have a filter guide. I looked around the net for one - but could not find.

Also the images at LPL are not listing their filter numbers so you have to guess what they are with trial and error.

But this came out eventually and does the trick.

Will be interesting to see what the "real" colours are.

I'm guessing there should be color images available in a few hours.



Cheers,
Simon Mansfield
SpaceDaily.com

Posted by: SFJCody May 26 2008, 09:08 AM

Congratulations to the Phoenix team! This is certainly terrain for a static lander: homogeneous on scales larger than the polygons.

Half of all the spacecraft to have survived landing on Mars are still active!

Posted by: slinted May 26 2008, 09:16 AM

Filter characteristics and filename conventions : http://www.met.tamu.edu/mars/
As to the exact filenames, they can be found in http://www.nasa.gov/mission_pages/phoenix/images/raw/SSI/ssi_gallery_collection_archive_1.html at nasa.gov. The web addresses have the filename (eg ...http://www.nasa.gov/mission_pages/phoenix/images/raw/SSI/SS000EFF896228409_10CA8R8M1.html) In that example, it's an R8 filter image.

Posted by: Stu May 26 2008, 09:20 AM

(rubs eyes) Morning everyone...

Wow, I had an AMAZING dream... I dreamed I sat by my computer for, like, 9 hours, jumping in and out of chat rooms and talking with dozens, hundreds of UMSFers and people all around the world, all sharing a love of science and discovery and exploration, all looking forward to, then celebrating, the arrival of a probe at Mars...! I dreamed I sat here, crunching peanuts and watching the expressions on the faces of people in Mission Control change from 'apprehension' to 'fear' and then 'joy'... I dreamed that I leapt into the air as images of a pebble-strewn polar martian plain appeared on my screen, one after the other, dizzyingly fast, to a soundtrack of whoops and cheers and yells of delight...

Anyone else have that dream..?

Posted by: PFK May 26 2008, 09:29 AM

Oh yes The two things that will linger in the memory are those mentioned above - the tension of the altitude countdown and its reflection in the faces of the team, and the first view. Wonderful stuff; just glad its a Bank Holiday here though I hope Phoenix aint expecting the day off...

Posted by: As old as Voyager May 26 2008, 09:48 AM

It was a great night and made all the better that we all enjoyed the tension and joy together.

That landscape looks so desolate but a mere centimetres below that surface lie such possibilities.

Posted by: kenny May 26 2008, 09:50 AM

Given the extremely flat terrain, without obstructions, I'm expecting to see the parachute and backshell lying on the ground when we get photos of the other side of the spacecraft...

The bright object in the distance I'm sure is the backshell inverted to expose the shiny interior, as happened on both Spirit and Opportunity.

Posted by: Skyrunner May 26 2008, 09:56 AM

I certainly hope it isn't any closer as that might spark another round of: "clearance fever". I hope the chute has pulled the backshell far away.

Posted by: Tesheiner May 26 2008, 10:11 AM

No luck on my attempts to stitch the pictures downlinked up to now.
I'm using autostitch and although it works very well with the rovers pictures, it's failing to match these ones here: http://phoenix.lpl.arizona.edu/images.php?gID=434&cID=8, http://phoenix.lpl.arizona.edu/images.php?gID=436&cID=8, http://phoenix.lpl.arizona.edu/images.php?gID=438&cID=8, http://phoenix.lpl.arizona.edu/images.php?gID=440&cID=8. Any help?

Posted by: Alex Chapman May 26 2008, 10:14 AM

I don't know if you have found the answers to your questions but in case you haven't I thought I would give them ago.

1. The red circle on the attached image (taken from Emily's blog) is Phoenix’s estimated location and the associated error margin. We were told there is a 90% or so chance of it being in the red circle. It’s calculated from the UHF signals and the inertial measurement units on Phoenix. So really they just have a good idea where it is not an exact fix. If you notice it’s to a large degree outside the blue landing ellipse, the parachute opened 7 seconds after its nominal time. The reason for which is still not known.

2. AS for MRO imaging they will be trying today based on the estimated position and they think they should have Phoenix imaged in just a few days.

Posted by: jaredGalen May 26 2008, 10:30 AM

What kind of downlink are we expecting in terms of images etc?

I'm so used to the Firehose photostreamTorrent from the rovers that my expectations are probably a bit too high

Congrats to all involved also, Mars is a busy place these days.

Posted by: Ant103 May 26 2008, 11:28 AM

What a wonderful night (do you ear the song ? ).

So, an other try with the 3 pointings made probably in red and blue filters. I have made a synthetic green layer to have the RVB trichromy.

Other pics (solar panels pan and anaglyph of pod) are here, a special page of my website : http://www.astrosurf.com/merimages/Images_de_phoenix.html

Posted by: tedstryk May 26 2008, 11:44 AM

This has been incredible. I was able to follow it on my phone and see the first pics when they were released. I tried to post here, not sure what happened to it. Congratulations to the Phoenix team!

Posted by: MichaelT May 26 2008, 11:48 AM

What a night! I also stayed up until the first pictures came down and went to bed around 4:30 am
That makes working today quite hard.
Thank you everybody for posting these fantastic pics! I am so excited about this new mission and hope to see the first Martian water ice soon!

I just found what seems to be a "true" color image of the horizon, on Spiegel Online:

Source: http://www.spiegel.de/wissenschaft/weltall/0,1518,555297,00.html
I could not find it on the NASA pages, however.

Edit: Now I did: http://www.nasa.gov/mission_pages/phoenix/images/press/false_color_postcard.html
It is an approximate-color image "inferred from two color filters, a violet, 450-nanometer filter and an infrared, 750-nanometer filter".

The colors are very close to what we already know from the two rovers, I think.

Congratulations to the Phoenix-Team! Outstanding job! Can't wait to see more!

Michael

Posted by: Leither May 26 2008, 11:52 AM

Ant

Your anaglyph of the pad is just great - is it just me or has Phoenix broken thro' a surface crust? Is that a bit of the ice crust poking up?

Posted by: pechisbeque May 26 2008, 12:06 PM

Hey people,

I'm one of the hundreds of people that have been lurking here yesterday!

For my first post I have a question: does anyone know what was the event that triggered the parachute deploy? I'm wondering if it was a specific altitude, speed, density, or something else. If it's something like that, then the Martian atmosphere models will have to be recalculated. The 7 seconds delay of the parachute deploy at that speed caused a significant deviation from the center of the landing ellipse.

Posted by: PFK May 26 2008, 12:16 PM

Folks
Forgive my inorance, or inattention if its already been pointed out, but is it possible to hazard a guess as to the scale involved in the nearby features above ie what is the approx width of the closest of the polygons?

Posted by: remcook May 26 2008, 12:45 PM

"Smith said such pithy things as: "I know it looks a little like a parking lot, but that's a safe place to land. That makes it exactly where we want to be. Underneath this surface, I guarantee there's ice. You can see lots of pebbles, and soil, and all these troughs you see in between the polygons. These are probably about 15 feet [5 meters] across."

"This is probably the cutest polygon that I have ever seen...." "

(from Emily's blog)

So, when's the next batch coming?

Posted by: PFK May 26 2008, 12:53 PM

Excellent, thank you. That makes the front square just about the same size as the patch of lawn I see right now if I look out of my window - really does help to (quite literally!) bring home the magnitude of what has been acheived.

Posted by: MichaelT May 26 2008, 12:55 PM

If you go to this page http://fawkes3.lpl.arizona.edu/images.php?gID=440&cID=8 and mouse over an image, the pointing elevation of the camera is shown. From that and the fact that the cameras are situated about 2 m above the surface, plus the knowledge of the field of view of the camera (14°, see here: http://www.lpi.usra.edu/meetings/lpsc2008/pdf/2156.pdf), you can calculate the distances and the scales of the objects (assuming that the lander is level and the ground, too, which it pretty much is).

Distance of the center of the image from the camera:
d_c = h / sin(a)

Top
d_t = h / sin(-b/2 - a)

Bottom
d_b = h / sin(b/2 - a)

Where a is the pointing angle (eg. a = -27.1185° for the lowest part of the mosaic), b the field of fiew (b = 14°) and h is the camera height (h = 2 m).

So the center of the lowest frame (see below) has a distance from the camera of about 4 m.

The width of the frame at center is:

w_c = 2 d tan(b/2) = 2 h tan(b/2) / sin(a)

So the width of the field is about 1 m and so is the polygon in the lower part of the mosaic. The larger pebbles to the left (image below) are about 5-8 cm in diameter.

I hope I got the maths approximately right. It seems the polygon is a little smaller than said by Smith?

Michael

Posted by: Ulysses May 26 2008, 01:12 PM

Great landing, awesome pics, congrats to all involved. Still a bit of a shame to be at the pole without skis!

Posted by: rlorenz May 26 2008, 01:36 PM

For lots of background you can read Ball et al, 'Planetary Landers and Entry Probes'

Usually the specification on the parachute is for deployment in an allowed dynamic pressure range
(i.e. not too high density*speed^2 or you shred the thing when it deploys) and a Mach number
range for probe/parachute stability (typically Mach 1.4 - as you get to the transonic regime, the
sphere-cone entry configuration can start to tumble, so you deploy before you slow down to this
point)

But, you cant measure Mach directly. So for a range of plausible models you calculate the entry
deceleration history, and it turns out that there is typically a function of the form

Right_Time_to_deploy = time_g_falls_below_X + the_time_between_g_rising_above_y_and_falling_below_X
(with maybe an extra offset term or something)

This can be implemented with simple logic and g-switches (literally microswitches with weights on springs)
or more typically an accelerometer (both Huygens and Galileo used this approach - for Huygens the accels
were prime, with g-switches as a backup). I think in Phoenix's case it was probably a full-up IMU (i.e.
accels integrated to derive speed)

Interestingly (see Harland and Lorenz 'Space System Failures') on Galileo the two switches were
miswired, and the parachute was deployed late (meaning the descent data only began from
lower down than desired).

I think for Phoenix the hardware and software is rather more sophisticated, so a simple miswiring like
this is unlikely to explain the late chute for Phoenix - it may be as you say an atmospheric profile issue, but
it's too early to know.

Posted by: vikingmars May 26 2008, 01:42 PM

Recreating a synthetic green + filter corrections, here is my interpretation of the Mars REAL colors at the Phoenix landing site as they should be seen...
Congrats to trhe whole Phoenix team + especially to Mark Lemmon the SSI designer !
Enjoy !

Posted by: pechisbeque May 26 2008, 01:49 PM

Thanks for the clarification, very informative. I will try to get my hands on those two books.

Posted by: algorimancer May 26 2008, 01:54 PM

MichaelT's response will have to do for now.

I've been fixing some last minute bugs in my rangefinder application as updated for Phoenix. Just at the moment I only see only one stereo image pair (of the landing pad). I've got two camera models for Phoenix, one (official) which is giving me some clearly incorrect values, and another (less official) which seems more consistent but seems to show the pad is rather closer than I would have expected. Does anyone know the actual diameter of those landing pads? Does something near 30 centimeters sound correct? Sounds big to me.

Posted by: Steve G May 26 2008, 01:59 PM

A pity Madame Curie couldn't have hitched a ride. Perfect terrain for her!

Posted by: Zvezdichko May 26 2008, 01:59 PM

Here's a simple mosaic of 3 images, created by me. It's not very good, I know.

Posted by: nprev May 26 2008, 02:06 PM

VERY interesting, Ralph; I need to get these books, too.

Question: On Phoenix, was the descent radar turned on prior to parachute deployment? Everything happened so rapidly that I lost track. Reason I ask is that I can see a combination of IMU deceleration data & ground proximity to cue chute deployment. The only other thing I can think of if the radar was NOT on is that they were relying on IMU data alone, which would include a Martian "geoid" model for surface reference (assuming that ambient atmospheric pressure was not used as a reference, and can't see why it would be based on the highly variable density of the upper atmosphere). Or did they do it all based just on deceleration data, which seems quite risky?

Posted by: ugordan May 26 2008, 02:10 PM

Radar was enabled after parachute deployment and heatshield jettison. I believe the parachute timing was made using IMU delta-V integration.

BTW, it was great to wake up in the morning and already see a 3 frame color mosaic. Looking at that color release, even though it's false color (in the sense that natural color was inferred from it), it's the probably the best first color image from a lander on Mars I've seen. It actually looks natural color straight-off, no funky blue skies or accidental IR instead of red filters

The whole thing up until now seems to be so perfect in fact that it's got me worried. It's almost too good to be true!

Posted by: Mogster May 26 2008, 02:15 PM

Looks like perfect terrain for a static lander to me, the same flat tundra stretching for miles. I don't see the advantage of a small rover.

looking at that first pic Phoenix seems ideal. Mobility would always be better but on this terrain for the extra cost how much would be gained?

Posted by: imipak May 26 2008, 02:16 PM

That analglyph view is a really nice composition, with the leg pulling the eye into the surface. I'm probably seeing things, but it almost looks to me as if there's a dish-like depression around the pad, and if it didn't so much touchdown as "squishdown". It's almost like a crater rim...

Is the ice crust poking up that you refer to the bit just to the right of the triangular hole on the shadow?

Posted by: gpurcell May 26 2008, 02:31 PM

I agree with this. The first picture has done a lot to assuage my fears we would be frustrated by tantalizing targets just out of reach of the lander.

Posted by: Zvezdichko May 26 2008, 02:32 PM

there may be some interesting targets in the area that is not yet seen

Posted by: Stu May 26 2008, 02:46 PM

Very true... who knows what interesting things are waiting to be seen to Phoenix's sides, or behind it? I wonder if we'll be treated to any new images at the media briefing later today? (7pm British Summer Time)

http://journals.aol.com/stuartatk/Cumbrian-Sky/entries/2008/05/26/phoenix-oh-what-a-night.../3688, thanks to everyone who made it so special. Special "Thanks, and well done!"s to Doug and Emily for all their hard work. Very proud of you both. And a huge night for UMSF too. Welcome to all our new members!

Posted by: Tesheiner May 26 2008, 02:52 PM

When the SSI mast is/was expected to be extended?

Posted by: elakdawalla May 26 2008, 02:57 PM

Yes, that's what they said last night. IMU = Inertial Measurement Unit.

It was either Barry Goldstein or Ed Sedivy who remarked that it seemed that the radar came on late but when he checked back with the guys at LockMart, they said it was within the normal range -- it was just time stretching out in their excitement

Thanks all for your kind words and for sticking with me through the various attacks on the website and ustream channel!

--Emily

Posted by: vikingmars May 26 2008, 02:57 PM

Just before the opening of RA's Biobarrier

Posted by: Zvezdichko May 26 2008, 03:05 PM

Whendo we expect to see the LIDAR in action?

Posted by: nasaman58 May 26 2008, 03:07 PM

I'd have to echo Emily's words from her blog: please consider joining the Planetary Society!

Posted by: Stu May 26 2008, 03:11 PM

Just wondering about something, thoughts appreciated...

In her excellent report on last night, Emily advises that http://hirise.lpl.arizona.edu/PSP_002249_2485is, apparrently, dead centre on the landing zone...

I've just been looking at it with IAS Viewer and found this at 1:1 scale...

... which looks like this if you zoom in on it x2...



Could that be a jagged rock we're mistaking for the backshell..?

Posted by: surreyguy May 26 2008, 03:12 PM

Hi, all. First post here, though I've been following the site for a few months now.

Thank you to everyone who made last night such a great time - all good fun switching between Mars Live, Nasa TV, and Emily's TV.

I do have one question about the image showing the horizon: given that Phoenix is tilted at a quarter degree, doesn't that mean it's sitting on a hill? The horizon looks to be tilted by several degrees there.

David

Posted by: Alex Chapman May 26 2008, 03:16 PM

full inline quote removed

I take it thats pre-landing HiRISE imaging Stu?

Posted by: elakdawalla May 26 2008, 03:18 PM

Just want to comment here that it was slinted who identified that image. (Thanks, slinted, for all the helpful links in the chat channel.)

--Emily

Posted by: Stu May 26 2008, 03:19 PM

Yep, no post-landing HiRISE images have been released yet, as far as I know...

Posted by: nprev May 26 2008, 03:25 PM

Gordan, thanks for the illumination, and Emily, thanks for the confirmation.

Hate to critique something that worked...great!!!...but given the extreme variability of the density of the upper atmosphere of Mars it seems that this technique could be refined a bit better. One approach that might be cost-effective and not incur a mass penalty or add additional physical complexity would be to add a reference Martian geoid (basically a mathematical model of Mars' 'sea level' surface if it were spherical/slightly oblate and featureless) to the navigation system as a model for estimated absolute altitude based on IMU data, which can also provide distance & vector relative to such a geoid traveled since entry. An "and-gate" approach to parachute cueing might provide better targeting accuracy, provided that the inputs have the required redundancy.

Posted by: djellison May 26 2008, 03:34 PM

I pulled out a pre-launch test mosaic that Mark put onto the pre-landing blog and the SSI webpage - and then put our pieces onto it from last night - gives it all a bit of context.

Posted by: Tesheiner May 26 2008, 03:36 PM

Not "several degrees" but 1.5º if I did my math correctly. In any case, it's not a quarter of a degree so I have the same question.

Posted by: centsworth_II May 26 2008, 03:37 PM

Were those really attacks and not just the result of heavy traffic? I can't understand attacks. It does not compute.

Posted by: elakdawalla May 26 2008, 03:48 PM

Thanks Doug -- that one went straight into the blog

And yes, there were attacks. Our site handles high traffic just fine; it's managed by a company whose clients are mostly major motion picture studios whose websites have to stream movie trailers, so bandwidth is the least of our problems (though not always the least of our expenses ) Fortunately the team was on duty last night and was really able to recover from the attacks very quickly -- it just seemed to take forever from my perspective, as it happened, of course, right during the landing!

We seem to be all better this morning though.

--Emily

Posted by: ElkGroveDan May 26 2008, 03:50 PM

Emily are the press conferences still going to be coming from JPL today? Or has it all moved out to Arizona now that science has taken over?

Posted by: nprev May 26 2008, 03:54 PM

Attacks during the landing...incredible. I don't think a swear jar large enough to absorb the financial penalties incurred by me describing the fully accurate obscene attributes and activities of such alleged people could ever be built...

Thanks for persevering, Emily; you were beyond great!

Posted by: elakdawalla May 26 2008, 04:01 PM

I am certain that at least Monday and Tuesday there will be briefings at JPL. I'm a bit confused as to the rest of the week -- one pre-landing schedule I saw had them returning to UA on Wednesday, but JPL had press briefings all week on their calendar. I'll get clarification when I go there today. I believe Peter Smith has already returned to Tucson.

--Emily

Posted by: Leither May 26 2008, 04:12 PM

30cm is a bit big. A caption on Phoenix image gallery says -
"Each footpad is about the size of a large dinner plate, measuring 11.5 inches from rim to rim. The base of the footpad is shaped like the bottom of a shallow bowl to provide stability."

Posted by: Stu May 26 2008, 04:14 PM

My idle, sleep-deprived speculation continues...

Still wondering about this "rock"... feel free to jump in, anyone... I've even found a way to line up the lander's POV with the "sharp rock" and two vague mounds/humps on the horizon and features on the HiRISE image.

Probably nothing, but I'd appreciate input from more informed members.

Posted by: ugordan May 26 2008, 04:18 PM

Nick, it's not the altitude that triggers the parachute (and really it shouldn't even be, as Ralph pointed out), it's parachute dynamic pressure margin (don't go too fast!) on one side and not too slow a speed on the other side. Both of these can be perfectly well accomodated by a good IMU that integrates from a known initial velocity. All you need to do is make sure there's plenty of altitude left for the parachute to do its job and Phoenix did this. IIRC, the chute was opened at around 12 km and the majority of remaining velocity was lost soon thereafter. It was a more gentle descent after that.

To cope with varying atmospheric density, an active entry of some kind might be envisioned that adjusts lift/drag effects on the heatshield to compensate for modeled/measured deceleration profile. That's just arm-waving on my side, though.

Posted by: ElkGroveDan May 26 2008, 04:18 PM

Paging Phil Stooke... Mr. Stooke please pick up the white courtesy phone.

Posted by: glennwsmith May 26 2008, 04:19 PM

I am still stunned by the correspondence between the planned mission objectives and the first views of the landing site -- looks (to my fevered imagination!) exactly like the type of heaving terrain beneath which one would expect to find ice!

Posted by: imipak May 26 2008, 04:21 PM

Infestations of trolls, etc, in the chat channel were unfortunate but not too surprising, alas. But an attack against TPS really boggles me, both as a TPS member and professionally speaking, as someone who works in security. It wasn't a normal "DoS" attack where a site's swamped with spurious, but otherwise normal, requests, because Emily referred to rebooting the server to bring the site back. I don't know of any public "crash your server" exploits in the wild that work against Apache 2.0.59 as used on planetary.org . There's no money to be made from such an attack, which suggest sociopathic types ("script kiddies") with too much time on their hands... Although come to think of it, there's a thriving industry in DoS for blackmail purposes, especially around one-off events with high traffic peaks (hitting betting sites on the day of a huge sporting event was a favourite tactic a year or two back.)

Well, anyway, last night saw some of the absolute best the Internet can offer, as well as a couple of glimpses of the worst. (The Internet, plus dedicated, unbelievably knowledgeable people like Emily and Doug of course!) It bears repetition: enormous kudos to Emily, Doug and the Selsey crew, and all the UMSFers out there, as well as of course to the project team. So many memorable moments... and what a fabulous atmosphere, from Sir Patrick Moore's shirt and monocle, to the banter in the chat rooms (especially as the beers went down!) I'd love to see some traffic stats from umsf as well - did you pick up many new user registrations?

PS Next press briefing is 7pm BST / 1800 UTC on NASA TV I think?

PPS 11.5 inches == 29.21 cm

Posted by: fredk May 26 2008, 04:22 PM

I noticed that as well - I also get 1.5 degrees. Could it be the SSI mast is tilted a degree or so from vertical?

Posted by: nprev May 26 2008, 04:26 PM

Gotcha; thanks, man! I'm overthinking this; too used to INS as applied to military airdrop systems, I guess.

Posted by: DEChengst May 26 2008, 04:32 PM

That was quite a night. I actually decided to sleep through the event as I had to hack some application into submission at work this morning so I couldn't take the day off and needed to be focussed. Somehow my internal timer managed to boot my brain exactly 10 minutes before touchdown ERT. After taking a look at the clock it dawned on me what time it was. I quickly rolled out of bed, put on some clothes, ran to the living room and turned on the TV. Just in time to hear that atmospheric entry was confirmed. Back in bed 5 minutes after touch down. Deep sleep failed but mission accomplished

Posted by: Stu May 26 2008, 04:33 PM

I wasn't that surprised by the trolls and the attacks, as the internet is no different to real life: there are always going to be pathetic little people with pathetic little lives who are drawn to the brighter, richer lives of people better than themselves, just as moths are drawn to a flame. They can't stand to see people enjoying themselves, so they bang on community hall windows when people are having meetings, uproot flower displays, type abuse and worse in chat rooms, etc. Last night some low life somewhere saw that a group of people had come together to experience something fantastic, something unique, something they had no chance of grasping the significance of, so they decided to spoil it, just because they could. It's sad but it's not rocket science.

But compare that with the goodwill found in the chat rooms, the sheer delight on Emily's face when she was in her element at JPL, and the joy on the Phoenix team's faces during the press briefing and, well, we know who won, don't we?

Posted by: Leither May 26 2008, 04:36 PM

- I agree that's what I see in that anaglyth



I was thinking more the big bit at 10:00ish, but that bit to the right of the shadow looks good as well.

PPPS 0.79 cm is a bit!!

Posted by: nprev May 26 2008, 04:36 PM

It was a terrific afternoon/evening when it's all said and done; best time I've had ever during an EDL!

Would add one note: Some clown asked Emily what I, at least, felt was an intrusive and highly personal question when she was beginning her first 'cast, and I called him on it. He wasn't ejected, and behaved himself from then on. Since Emily has intimated that she'd like to do more live 'casts, I think it is incumbent upon us all to ensure that she is allowed to do so without having to put up with that sort of nonsense, and of course this should be the rule for all people who are kind enough to provide their time and expertise for our collective enlightenment.

Posted by: belleraphon1 May 26 2008, 04:38 PM

Stu... right on!!! I had the same dream and it was a late night for me ..... HAD to stay up for those pics.

Yes, can hardly wait for the full panorama.....

And I would also like to comment on what a fantastic community we have here with UMSF.... what a joy it is to know that
out there are all you wonderful folks who love space exploration as deeply as I do. What an added joy it gave last night as the Phoneix team made history.

Doug and Emily continue to do an awesome job.... as do so many of you poets and image mages!!!!

Now a mission op questions.... since we really do not KNOW how deep the ice is, are they going to dig a rehersal trench just to give them that benchmark and then dig an adjacent sampling trench? They only have so many chambers to use for soil/ice analysis. Any one know the answer... or is this a stupid question? Still a bit whumped from last night's late night excitement.

Craig

Posted by: Steve G May 26 2008, 04:48 PM

I'm surprised by the amount of material inside the landing pad. A lot more than the Vikings and with the ground "frozen solid" as we expected tells me the top layer is quite loose and dry. I could be dead wrong, of course, but that's my impression. As for my earlier comment about wanting to land close to the parachute, it would be interesting to see a human made object interacting theith the martian environment over the lifetime of the lander. Will it ever flutter in the breeze, moved to a different direction? It would be a usefull passive experiment. I was dissapointed when Oppy didn't travers over to its chute which wasn't that far away.

Posted by: Sunspot May 26 2008, 04:53 PM

I think I remember someone asking about that shortly after Oppy landed.... and I think that they were concerned about the rover becoming tangled in the tethers attaching the parachute to the backshell should it move in the wind for instance.

Posted by: Steve G May 26 2008, 04:55 PM

I was amzed at Emily's knowledge. She always had an immediate answer to every question!

Posted by: Deimos May 26 2008, 05:21 PM

The images were taken to the NNW. Landing position shows Heimdall to NE. The sol 2 part of the initial low-resolution site pan could show something on the horizon.

Mark

Posted by: Deimos May 26 2008, 05:25 PM

I think you'll be very sorry if you miss the briefing. Should be a fantastic new goody.

Posted by: fredk May 26 2008, 05:28 PM

Interesting thought, Deimos.

Does anyone know why they wanted to land with the solar arrays aligned E-W? If they are horizontal, their azimuth shouldn't make any difference to power levels. Perhaps they were thinking about shadowing of the masts onto the arrays?

Posted by: ugordan May 26 2008, 05:32 PM

Via Twitter: a wonderful new picture to be unveiled at the press briefing

HiRISE?

Posted by: Norm Hartnett May 26 2008, 05:33 PM

Oh sure, with a half hour to wait you tease us. Could it have something to do with the increasing number of panoramic pieces showing up in the galleries? Or is it really a polar bear?

Posted by: ElkGroveDan May 26 2008, 05:34 PM

I'm going to guess HIRISE too - maybe the descent image from yesterday that they were going to try for.

Posted by: um3k May 26 2008, 05:38 PM

For those interested, here's a high bitrate (1200 kbps) version of NASA TV: http://playlist.yahoo.com/makeplaylist.dll?id=1368163

Only for fast connections, of course.

Posted by: ugordan May 26 2008, 05:40 PM

That would be about the only image cooler than seeing a lander footpad pressing into alien soil. There's just something about footpads. Airbags just don't come near in coolness factor.

Posted by: djellison May 26 2008, 05:41 PM

With it going so long on chute deploy - I'd be rather more expectant of an image of Phoenix on the ground rather than the under-the-chute image.

Doug

Posted by: remcook May 26 2008, 05:42 PM

i'll be tuning in for the press briefing in a few minutes for the first time. for me, the mission will really start now

Posted by: Skyrunner May 26 2008, 05:42 PM

The atmospheric variability at 12km is only about +/-5% from nominal density (+/- 10% @ 2km). Vertical wind variability isn't that large either (horizontal wind speeds may vary over 30m/s). All said I believe the total uncertainty in drag coefficient was up to +/-20% although I don't know anymore were that number came from.

Deployable/inflatable aerodynamic structures reduce ballistic coefficient increase the possible landed mass as well. As we are getting to do aerocapture we need to actively control the drag coefficients. Then the technology/hardware is in place to do it during the less harsh EDL. At the moment a large portion of the problems are due to errors in IMU initialization before entry. Better IMU's, improved orbital navigation (optical systems, spacecraft-to-spacecraft tracking), and improving the mars atmospheric model might do the trick.

If you hadn't had the heat shield you could use radar/lidar

Posted by: Deimos May 26 2008, 05:48 PM

The robotic arm workspace is to the north, and is shadowed at the warmest time of day. Once ice is exposed, that maximizes its lifetime against sublimation as material is accumulated for delivery.

Mark

Posted by: djellison May 26 2008, 05:58 PM

It will also minimise shadowing of the arrays during the best time of day for solar power by the deployed hardware such as MET and SSI.

Posted by: remcook May 26 2008, 06:03 PM

now where did you put that swear pot doug??

Posted by: imipak May 26 2008, 06:03 PM

The HiRISE image is incredible, I am just laughing out loud at the thing. Holey moley! More engineering images please!

Posted by: Adam May 26 2008, 06:03 PM

Whooah! Incredible!

Posted by: elakdawalla May 26 2008, 06:06 PM

What I said in the blog: Ohmygod, they are showing a photo of the parachute and lander and you can even see the parachute lines and stripes on the chute taken by HiRISE as Phoenix fell toward the ground. Ohymygod this is totally frikkin' awesome!!! I'm sitting next to Mars Reconnaissance Orbiter project manager Jim Erickson and he couldn't be prouder.

--Emily

Posted by: Bjorn Jonsson May 26 2008, 06:09 PM

"I know you don't like our engineering images" - Barry Goldstein

An *amazing* image.

Posted by: ElkGroveDan May 26 2008, 06:09 PM

I just can't wait for that final enhanced image. I'm going to want a poster for my office wall.