AVIATR - Titan Airplane Mission Concept, Proposed unmanned aerial exploration of Titan Options

[Juramike]

The AVIATR mission concept is an unmanned aerial vehicle that would fly over Titan’s surface. It’s nominal one year mission would enable detailed high-resolution images of Titan’s diverse landscapes for better comparison to Earth’s geological processes. Selected regions could be imaged at resolutions near 30 cm/pixel, equivalent to current HiRise imaging of Mars. In addition, atmospheric sampling would allow a profile of Titan’s thick lower atmosphere and how it relates to Earth’s atmospheric processes and weather systems.

Further details of the AVIATR mission concept were presented at the Lunar and Planetary Sciences Conference 2010 and at Titan Through Time 2010.
See: Barnes et al. LPSC 41 (2010) Abstract 2551. “AVIATR: Aerial Vehicle for In-situ and Airborne Titan Reconnaissance.”
Freely available here: http://www.lpi.usra.edu/meetings/lpsc2010/pdf/2551.pdf

And also: http://www.info.uidaho.edu/documents/2010%...18467&doc=1

[algorimancer]

I'm really bothered by the very low (2 Gb) projected data return. This just doesn't sound like a lot of return for a billion dollar investment. Even with compression, 2 Gb doesn't add up to a lot of images (try going on vacation with only a 2 Gb flash card for your digicam), and this mission has the potential to explore much of Titan. Also, the 30 cm/pixel maximum resolution of the surface is on par with what I would expect from an orbiter, not an aircraft. I'd be reasonably happy with 3 mm per pixel (presumably associated with occasional low passes over targets of interest), and I'd like to see data return increased by at least a factor of 10, preferably 100. Possibly the greater data return might be achieved by storing much of the data until near end of mission, then achieving an intact landing and then leisurely transmitting the remainder over a period of months or years; I could even envision adding a very lightweight parabolic antenna to be deployed post-landing to accelerate data return.

[Jason W Barnes]

I'm really bothered by the very low (2 Gb) projected data return. This just doesn't sound like a lot of return for a billion dollar investment.

That should be 2 gigabytes (GB) and not 2 gigabits as written.

While AVIATR certainly is not going to be like MRO blasting back terabytes and terabytes of data, let me take this opportunity to suggest that data is not knowledge. Put another way, more bits does not always mean more science.

At Mars there's been 40 years of exploration. In order to make new scientific discoveries from a orbiter taking pictures, you need to do more and better than the missions that have gone before you. Because HiRISE is following on a very capable, very successful imager on MGS, it needed to do better in order be able to do things that MOC was unable to do. In the planetary exploration business, the general rule of thumb is that you need to do about 10 times better than the previous mission in order to be compelling enough to fly. HiRISE's pixel scale is 3 times better than MOC, its swath width at least 5 times wider, and it can send back more images due to the greater bandwidth available on MRO. Hence it was deemed a compelling investigation.

Cassini's RADAR has a best pixel scale of about 300 meters per pixel. Since pixel scale is not resolution, the actual resolution of the RADAR images is more like 750 - 1000 meters due to inherent speckle noise in the RADAR data. The best VIMS data are 250 meters per pixel, but those noodles are only 13 pixels across. AVIATR would do 1000 times better than these in terms of spatial resolution.

A better comparison for AVIATR would be Huygens. Huygens returned mosaics from around its landing site of varying resolution. Obviously the picture from the surface had spatial resolution that we can't match from an airplane! But our image mosaics from sites of interest will resemble Huygens', but with better control, higher spatial resolution where desired, and better signal-to-noise since we're imaging in the infrared.

If you think that 2GB is too little for a mission, then would you fly a mission that would return a total of just 60 MB of data? That's all that we got from Huygens. AVIATR would return 30 times the total data that we got from from Huygens. The reason that 2GB is enough isn't because of the quantity of data -- its that we'll be returning images that can't be obtained any other way. AVIATR will have a huge science and exploration impact because we're looking where nobody's looked before.

It's not the number of bits that you have. Its how you use them

- Jason W. Barnes

[rlorenz]

Cassini's RADAR has a best pixel scale of about 300 meters per pixel. Since pixel scale is not resolution, the actual resolution of the RADAR images is more like 750 - 1000 meters due to inherent speckle noise in the RADAR data. The best VIMS data are 250 meters per pixel, but those noodles are only 13 pixels across. AVIATR would do 1000 times better than these in terms of spatial resolution.

Hoi! Misrepresentations like that will get you kicked from the team, pal.

The archive pixel scale (oversampled) is 175m/pixel. The formal range and azimuth resolutions vary throughout
a flyby, but are typically 300m (sometimes less) at closest approach - these resolution histories per flyby, and all
the other radar-voodoo parameters such as prf, bandwidth etc. are documented in the
sequence design memos (in the 'extras' directory on the PDS archive). Resolution (and thermal noise) are
separate consideration from speckle noise, which is a function of the number of looks.

Whether you consider the 'useful' resolution to be the same as the real resolution depends
on the application; some tasks require higher signal-to-noise than others. This is also true for VIMS data, which
does not always have the signal-to-noise to do what you'd like to do (and will be for AVIATR).

[Jason W Barnes]

Hoi! Misrepresentations like that will get you kicked from the team, pal.

The archive pixel scale (oversampled) is 175m/pixel.

I'm not impressed. That's like me saying that the VIMS data are 0.5 km/pixel because I've interpolated them that way. What's the actual Nyquist-sampled pixel scale? I don't think that I'm the one misrepresenting

- Jason

[rlorenz]

I'm not impressed. That's like me saying that the VIMS data are 0.5 km/pixel because I've interpolated them that way. What's the actual Nyquist-sampled pixel scale? I don't think that I'm the one misrepresenting

- Jason

No, that's why I said oversampled. (Since the resolution elements, defined by doppler bandwidth etc.
are not square, the archive product is oversampled so as not to lose information when the data are
projected onto a square grid.)
Like the post said, the real resolution can be 300-350m (and there are many good SAR tutorials on-line
to explain how we get that.)