Juno development, launch, and cruise, Including Earth flyby imaging Oct 9 2013 Options

[mcaplinger]

I'll take that as there will be no such flyby. Unfortunate.

It's not obvious to me that the Juno payload would really provide much useful data from any plausible asteroid flyby; at least Junocam is not well-suited for such an encounter.

I'll note that neither Cassini nor New Horizons returned any asteroid images that were anything but dots IIRC, and they were far more capable of flyby science.

[0101Morpheus]

I understand that Cassini or NH did not preform any asteroid flybys and I assume that is just due to poor processioning because space is really big. If it wastes too much fuel to try to get close to an asteroid then it should be avoided. That fuel can be better spent in a gas giant system.

However I understand that Juno has a visual camera of some sort? I believe that the Pioneer probes showed that the public demands a camera on planetary missions. Juno's camera was made to watch Jupiter's clouds, and I look foreword to that footage since that was something Galileo failed to deliver.

Speaking of Galileo, it visited two asteroids on its way to Jupiter because it needed to save fuel by slingshoting around the inner solar system. Yet its twin Cassini, built similarly and used the same method to save fuel visited no asteroids? This can be termed bad luck I guess but I hope it doesn't mean that the lesser bodies of the solar system are being ignored. I am aware that Galileo was originally supposed to visit Vesta but do to certain setbacks it had to visit the minor asteroid Gaspra instead. At the time there was a lot of disappointment that Gaspra would have little to offer, yet the visit changed a lot of what we knew about how small bodies in the solar system work.

So in conclusion, I am perfectly fine with us not visiting asteroids due to poor luck, but if the opportunity is there, why not? We'll learn something new.

[Explorer1]

Actually Cassini flew by asteroid Masursky in January 2000. Here's what it looked like at 'only 1.6' million kilometers away:
http://photojournal.jpl.nasa.gov/catalog/PIA02449

Space is big, so don't expect anything more impressive from Juno until 2016!

[0101Morpheus]

Better than Hubble would have done I suppose.

[Gerald]

Junocam is a wide-angle camera, so the resolution will be low for asteroids.
Identifying pointlike objects fainter than about magnitude 3 is going to get difficult, even with TDI 60. I'll later (in a few weeks or so) try to provide a preliminary statistics about how likely it is to find an object of a given magnitude. It also depends on the jpg compression. To get maximum sensitivity uncompressed data are needed. That needs much bandwidth, if the rotation phase isn't known.

[mcaplinger]

if the opportunity is there, why not?

Because it costs money, and in a world of finite resources, there has to be cost-benefit analysis.

The Masursky images count as dots as far as I'm concerned.

[mcaplinger]

Junocam is a wide-angle camera, so the resolution will be low for asteroids.

We have no plans to do anything with Junocam with regard to asteroids.

[Gerald]

"News from Juno's Earth Flyby
Dec. 10, 2013, 10:30 a.m. PT (1830 UTC)"
scheduled to be accessible via NASA JPL Live.

[mcaplinger]

The Juno EFB press conference is at http://www.youtube.com/watch?v=gtvsiRPzcXU

The first image, a triplet of EFB10, 11, and 12 produced at MSSS, was apparently not deemed worthy of Planetary Photojournal, nor is it on missionjuno, so here it is. Still not perfect, but not too bad.

My original draft caption:

These three Junocam images of Earth were taken during Juno's close flyby on October 9, 2013. The leftmost was taken at 19:08 UT at a altitude of 5741 km; the center was taken at 19:11, 4001 km, and the right at 19:12, 3197 km. The center image was taken using Junocam's narrowband methane filter; the other two are combinations of the instrument's red, green, and blue filters and approximate natural color. Each image is a mosaic of 82 individual frames taken as the spacecraft spun; these have been composited and remapped by ground processing.

The first shows the southern two-thirds of South America. As the spacecraft moves eastward, the Chilean coast and the snowy line of the Andes mountains recedes toward the limb. The third image has a good view of the Argentinean coastline with specular highlights off the Rio Negro north of Golfo San Matias, as well as cloud formations over the continent of Antarctica.

[Paolo]

there is an interesting post in NASAspaceflight by one of the Danish guys working on the magnetometers and their star camera. http://forum.nasaspaceflight.com/index.php?topic=26357.75
turns out it will be used to search for asteroids, to study the zodiacal light, Jovian ring (and I suppose also the smaller sats). It should also make another approach video, of Jupiter this time!

[Gerald]

Just to keep you up to date, here an excerpt of a still ugly-looking intermediate calibration step for EFB15:
Data-reduced EFB15 ,
Simulated BSC5p, visual magnitude < 5 ,
Combined for RANSAC .

This 0th approximation, the above images are an excerpt of, inferes 4 parameters (3 rotational and 1 optical) automatically by a RANSAC-like algorithm with nested hill-climbing, actually any 2 of the 10 brightest reduced EFB15 spots are identified with any 2 of the 15 brightest BSC5p stars. The above simulated image is number 17 of 34 combinations within "reasonable" constraints of a total of roughly 10,000 tries. Other parameters are inferred manually from images or are intentionally guessed or set to defaults.
They will be pinned down in consecutive optimization steps.

Used BSC5p data:  bsc5p_equatorial_less_vmag5_sortby_vmag.txt ( 112.93K ) Number of downloads: 482

Simulated BSC5p positions of this run:  BSC5_SpotTab_Match00017_Simulated.txt ( 44.91K ) Number of downloads: 500

Intermediate BSC5p star assignments to EFB15 spots (RANSAC consensus set) as a result of this run:  BSC5_SpotTab_Match00017_Actual.txt ( 16.98K ) Number of downloads: 331
(contains cumulative data of the first 17 "reasonable" runs)

Data source for stars:
Bright Star Catalog, 5th Edition, preliminary
J2000.0

[stevesliva]

there is an interesting post in NASAspaceflight by one of the Danish guys working on the magnetometers and their star camera.
...
turns out it will be used to search for asteroids, to study the zodiacal light, Jovian ring (and I suppose also the smaller sats). It should also make another approach video, of Jupiter this time!

Thanks! This should be a very direct link... Jonas' posts are definitely worth reading.

[Gerald]

I'm curious, to which magnitude we can go with JunoCam. But from the images so far, I'd think, objects of magnitude 7-9 will be out of reach, even with less straylight from the sun or Earth. Although, there is no uncompressed TDI-60 JunoCam image available yet for a final assessment, at least not from Earth flyby.

[mcaplinger]

I'm curious, to which magnitude we can go with JunoCam.

I'd have guessed no dimmer than mag 5 or 6 on the basis of nothing in particular. We have no real requirement to image stars at all, and the only reason I'm interested is to help constrain the accuracy of camera pointing and optical distortion knowledge.

We didn't do any lossless high-TDI imaging during EFB; only EFB17 (which is full of particle hits from the Van Allen belts) was taken lossless. But we have lots of lossless cruise imaging that I could make available.

[Gerald]

In the next months I'm also mainly interested in pinning down geometric properties. I'll probably need about two more months to fully exploit the efb images from the geometric point of view. But then with additional images of the star background, especially with uncompressed data, statistical errors should shrink with the inverse of the square root of the number of samples. That's roughly the same principle as applied in the algorithm used for the Gaia data: Calibration parameters and measurements of stars are comprised in one big overdetermined system of unknowns.

So I'm almost sure, that additional uncompressed images would be helpful for camera calibration over the next months.

After geometric calibration, radiometric/colorimetric calibration will also work better with more reference data (images of stars) available.

Sensitivity determination for faint objects is a by-product.

EFB17 is highly challenging, but good to know, that it's uncompressed.