I've split this Dawn thread in three: pre_launch (this one), launch and cruise.

Great words USTRAX, you put how I feel in much better words than i could ever manage.

I'm in awe about the achievements of the last 50 years from a small nitrogen filled sphere to the sophisticated probes scattered throughout the solar system and a permanent manned presence in orbit.

Apollo was way ahead of it's time, IMO. I guess, as I wasn't around back then it didn't give me an impression of what to expect and the disappointment when it turned out to be false.

If we can make as much progress over the next 50 years as the last, I'll be a happy 80 year old.

Onwards...

Yeah, but look at how many threads are in each of those forums, too many for me to count!

Once the threads start mounting then a case for keeping them all together in a sub-forum can be made, but that time isn't now.

James

You need to do a bit of both (and the amount is dependent on the amount of stretching).

James

4) Three cameras all in landscape with elevations +15, -20 and -55 degrees. 76% 99%



5) Three cameras all in portrait, two side by side (35 degrees) with one underneath (-45 degrees) 72% 96%



So in conclusion, if we can stretch to three cameras I'd go for option 4 (even with just 10 images per camera I still get 94% coverage of the ground hemisphere in this simulation). This one also has the added benefit of being a bit Huygens like.

James

Your wish is my command...

In each of these I've used the same orientations of the gondola when each picture is taken to make them somewhat comparable. In each case there are 15 images from each camera. Also included is the coverage after one shot from each camera and two percentages indicating the total coverage and the coverage in the lower hemisphere (as the upper one should be mostly black sky ). Of course this is very biased as a lot of pixels near nadir represent very little solid angle in this projection but hopefully it tells us something. The cameras are arranged so they have about the same amount of overlap between the images (5 degrees or so).

1) Similar to before two cameras, upper in landscape, lower in portrait and pointed down at 40 degrees. 61% 86%



2) Both cameras in portrait one pointed down at 45 degrees. 65% 91%



3) Both cameras in landscape one pointed down at 35 degrees. 54% 71%



Sims using three cameras to follow.

OK a few simulations of camera coverage.

Two cameras, one landscape pointed horizontally, one portrait, pointed 45 degrees down both normal 35mm field of view. Take one image with each and here is the coverage on a 360x180 degree equirectangular projection.



Rotate and swing to the payload, 30 degrees looks about right from a lot of images I've seen from other attempts.
Take 25 images per camera (one every 15 seconds for ~6 minutes say) and you'd be unlucky not to get a 360 and most terrain should be covered twice.



Coverage tends to improve (less likely to get that jagged line of missing data) if you don't have the cameras going off simultaneously (which should also be easier to implement )

Wow. Take a look at the latest MI images. Are those vugs?

I don't think controlling the rotation is going to be possible, certainly not to the level required to guarantee that we get 100% coverage.

iirc Huygens was designed to spin just to make sure all the images didn't point in the same direction, not to have a controlled sweep to pan the camera. Looking at images from other balloons it doesn't look like forcing the balloon/parachute to rotate will be a necessary, it looks like quite a wild ride.

Lets just concentrate on taking as many shots as possible, it looks to me that we won't have to be too lucky to get good 360 coverage and we have plenty of talent here to fill in any small gaps in the data.

James

Well I've already re-invented the wheel as best I can, but this would still be most welcome. Applying this step to the stretched jpegs is not ideal, having JPL do it first would work much better.

James

One more stitching test using the SABLE-3 images. These images are fully 6 minutes and 6,400ft apart and still stitch nicely. With two cameras taking pictures 15 seconds apart and we could have 50 images within this time frame, nice.



James

EDIT: just came across this page of records for this sort of thing - http://showcase.netins.net/web/wallio/ARHABrecords.htm

Hopefully even with just one camera some nice panoramas will be possible.

Some quick tests:

Nova - images taken 15 seconds apart - altitude change 300ft - altitude 100,000ft


Even at low altitudes and with large time intervals this can still be done.
SABLE-3 - images taken 1 minute apart - altitude change 800ft - altitude (above ground) 10,000ft


If we had two cameras I'd vote for one pointing horizontally and one pointed down at 45 degrees and turned 90 degrees 'portrait', which should give maximum coverage.

It may take a while to sort through the images but with a couple of cameras like this firing quite frequently some pretty spectacular stuff should be possible.

James

Great info AndyG.

Looking at some of the other folk who have done stuff like this, 30 - 35km seems to be reasonable.

Surely we've got to be aiming for the 32km 'Mars surface pressure' mark.

J

If you look at the route map Stu you'll see we're right over the other side of HP from Mackey at the moment.

James

Quite a good article from the BBC about this today.

Oppy moved again tosol (1305). Here is what is in front of us at the new site.



The right side of this image is the same patch of ground as at the top-left of my sol 1302 image, near where CR was pointing to interesting stuff.

James

I do almost exactly the same as oDoug, including the reading order: inner solar system first, then up from the bottom, finishing with Mars. I read every post, but sometimes skim reading those that I'm not so interested in.

After the big morning read I then use the 'View New Posts' link to get the latest during the day.

My take on it was that 'column' refered to the two frames being one above each other, i.e in one column.

I don't think there has been any improvement in the left pancam - same dust model used here.

Sol 1302 two frame L257 'work volume':



James

I'm really loving this image looking back up, with the tracks through the rim ripple/dune on the horizon.

Nice view of the 'dog's breakfast' as well. The nice layers in front of us do look like a much more tempting target, I can see why we skipped straight down.

James

Congrats. Great work, well done.

Now get on with the drinking and celebrating!

Cheers,

James

Split Sputnik 50th posts into a new thread.

J

Quick stitch of the sol 1298 drive direction mosaic in L2 (L5 & L7 still to come)



James

Of course the ballon could go a LONG way in 24 hours and could make recovery quite a lot more difficult. I quite like the quick up and down mission profile.

James

Ah but Tesh, the update Fredk quoted talked about a full 13 filter image being taken so it must be the 'dumpling_fracture' which is pointed near the bottom centre of this navcam

James