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]

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),

Hi -- this is Jason Barnes. I'm proposing AVIATR as Principal Investigator. I appreciate the attention to AVIATR around here -- keep up the comments!

While 30cm/pixel is what HiRISE is getting at Mars, you're not ever going to get that from an orbiter at Titan. Here's why. Because Mars' atmosphere is so thin, and because its gravity is relatively high, you can orbit Mars at just 150 km altitude safely to take pictures. In contrast, Titan's atmosphere is super-thick and its gravity only 1/7 that of the Earth -- this means that if you're orbiting Titan, you need to be orbiting at 1500 km instead of 150 km. That's a degradation of a factor of 10 in spatial resolution. In addition, you're at 10AU from the Sun so you'd need to have a primary mirror 6 times the diameter of the equivalent for Mars, even with the lower resolution. Now take into account that HiRISE at Titan would see nothing but haze. You'll need to go out to 5 microns, where the atmosphere is nearly transparent, to do as well at Titan. But the Sun is much dimmer at 5-microns than it is in the visible. And this would mean super-cooled optics, and an infrared detection system.

The bottom line is that to do the equivalent of HiRISE at Titan would require something like a 10-meter JWST sent out to Saturn and burned into orbit around Titan. Not going to happen. Even TSSM was baselining 50-meters-per-pixel global imaging for the orbiter.

Taking high-resolution imagery for Titan's surface makes sense from an aerial platform. You can use all of that pesky air to your advantage, instead of fighting it with a giant orbiter. AVIATR would have 100 times better resolution than the TSSM orbiter. Resolution isn't everything, though, and we're going to great lengths in order to gather context imaging in order to be able to interpret our high-resolution postage stamps, too.

- Jason W. Barnes

[algorimancer]

While 30cm/pixel is what HiRISE is getting at Mars, you're not ever going to get that from an orbiter at Titan.
...
Taking high-resolution imagery for Titan's surface makes sense from an aerial platform.

My original post seems to have stirred a lot of discussion, and apparently it could have been more clearly written, as it seems to have spurred some misconceptions and overreactions. For the record, I am overall very impressed and even excited about the AVIATR proposal, but my perspective on its capabilities are shaded by experience with MER and MRO. I do realize that this is a small mission to a place orders of magnitude more remote than Mars. My fantasy mission would be something like AVIATR that lands periodically to provide both broad overview and local focus.

My critique of "30cm/pixel" was in the context of seeking a bit of that local focus which a landed vehicle would provide. Essentially I'm advocating that, for particularly interesting targets, that the aircraft fly closer to the ground such that millimeter-scale imagery can be acquired. This might be just a few times over the course of the mission, once the topography is better understood so as to avoid accidents, and would be the equivalent of sending multiple landed vehicles -- very cost-effective. Worst case, if engineering and environment provide a fundamental limit on how low the vehicle can fly and continue flying, this might be a single descent near the end of the mission. Beyond this, I'm really quite happy with 30cm/pixel -- this has worked beautifully with MRO -- but the benefit of an aircraft versus an orbiter is that an aircraft has the option to maneuver in altitude without much difficulty. Oh, I definitely agree that an aircraft is optimal for Titan, while an orbiter would border on a waste of time (possibly excepting an imaging radar mission).

The 2 GB limitation is less of an issue to me, but I feel that with a bit of creativity it is not out of the question that this might be expanded by a factor of 10. Potentially, if Cassini is still functioning, it might act as a local relay. Does AVIATR use a directional antenna? If not, might the dorsal surface be contoured to function as one, even perhaps only intermittently when the flight orientation is congruent with transmission to Earth, thus allowing higher rater transmission on those occasions? I realize that there would be a compromise between optimizing a surface for aerodynamics and as a directional antenna, but the low gravity and high density of Titan's atmosphere would seem to permit a fair amount of flexibility in this regard.

Overall, I would be ecstatic to see AVIATR fly as currently designed -- to me, Titan is in the top 3 of interesting places to visit in the solar system, and I've been itching to see another dedicated mission ever since those tantalizing images from Huygens.

Finally, I very much appreciate your taking the time and interest to discuss the mission here. I work in orthopedic research, and involvement with the public -- even educated semi-pro amateurs -- just doesn't happen in that world, so I don't have to deal with backseat drivers second guessing my research designs.