"Dragonfly" Titan explorer drone, NASA funds Johns Hopkins University Applied Physics Laboratory (APL) Options

[vjkane]

Yes it was, slide 12.

Reading with my eyes closed. Mentally skipped that slide. Thank you.

From the craft dimensions published on the Dragonfly website "Dragonfly will be about 12.5 feet (3.85 meters) long, 12.5 feet (3.85 meters) wide and more than 5.5 feet (1.75 meters) tall". Not specified what is included (nose tip to end of MMRTG enclosure? width of rotorblades?) it looks like the forward and side cameras might be ~4 feet (1.2 m) above the ground, but that is a lot of eyeballing.

[mcaplinger]

It looks like 3 downward, two side, and two forward facing science cameras, plus one line for what appear to be 2 navigation cameras.

For additional kremlinology, you can try to guess the FOVs of the cameras from the sizes of the external housings in the side view.

"PRELIMINARY DESIGN OF THE DRAGONFLY NAVIGATION FILTER" https://arxiv.org/pdf/2307.13513v2 has a lot of detail about how navigation works, but it doesn't give the FOV of the Navcam explicitly. FWIW, LCAM on M2020 had an FOV of 90x113 degrees per https://www.msss.com/files/LCAM.pdf and that file also lists some other FOV options for our standard lenses.

[vjkane]

For additional kremlinology, you can try to guess the FOVs of the cameras from the sizes of the external housings in the side view.

"PRELIMINARY DESIGN OF THE DRAGONFLY NAVIGATION FILTER" https://arxiv.org/pdf/2307.13513v2 has a lot of detail about how navigation works, but it doesn't give the FOV of the Navcam explicitly. FWIW, LCAM on M2020 had an FOV of 90x113 degrees per https://www.msss.com/files/LCAM.pdf and that file also lists some other FOV options for our standard lenses.

The attached image from the current Dragonfly website shows the location of the cameras (in blue).

The science cameras appear to have smaller housings than the navigation camera; maybe a clue to krelionologists.

I was initially surprised that there was a single fixture for the navigation camera(s). I had expected two, maximally spaced apart for stereo imaging.

It could be that the housing is wide enough for spacing of two cameras for stereo imaging (the nav cameras on the turret of the Mars rovers are not that far apart). However, the forward motion of the craft also allows for overlapping imaging and photogrammetry with much wider spacing between images. The detailed image seems to show just one navigation camera.

The forward and side science cameras appear to have a downward angle, suggesting prioritizing the nearer surface over a horizontal view to capture a more panoramic view. This would allow them to also look down toward the terrain in flight.

I suspect that the downward facing science cameras in the rear will be used to build detailed 3D imaging of the each landing site as the craft descends to land.

Attached thumbnail(s)

 

[rlorenz]

Looking through the June OPAG presentation on the Dragonfly mission. The slide showing the current design suggests that the high-gain antenna design has evolved. In original designs, it could tilt to face the horizon and carried cameras for panoramic imaging. The new design appears to limit the HGA to pointing skyward and has lost the cameras.

Anyone know if Dragonfly will have one or more cameras that will be able to look out across landing sites when the craft is on the ground? Or will all imaging be from aerial perspectives looking down?

I appreciate Mike's discretion, I can chime in. There's nothing really secret, but a few features of the lander are still being adjusted so we have tended not to put out too many quantitative details yet.

But big picture, there are 2 down-looking Navigation cameras - these are plumbed directly into the mobility system for rapid on-board optical velocimetry and correlation-based navigation. There are two for redundancy (hence no need for separation for stereo).

The 2 down-looking science cameras are separated, indeed to get stereo of the area under the vehicle (e.g. to assess whether the ground is flat enough to deploy the seismometer).

The forward- and side-looking science cameras will survey the landing site from the ground (and there will be aerial imaging during flights from the down- and forward cameras). These cameras basically together pick up the landed horizontal survey function from the cameras formerly mounted on the High Gain antenna (which actually still tilts to the horizon, you are interpreting the picture incorrectly). Moving them from the HGA allowed the mass of the gimbal to be reduced substantially and simplifies the thermal management of camera operation considerably, at the cost of some pointing flexibility.

There is also a 'microscopic imager' which looks down-ish at the drill site when landed, to look at the surface material at the sand-grain scale. There are LEDs for color illumination of that spot (only red/near-IR sunlight gets down to Titan's surface). The LEDs also include UV to pick up organic fluorescence at night. https://www.hou.usra.edu/meetings/dunes2017/pdf/3018.pdf

(So, 7 science cameras, plus two navigation cameras)

Ralph

[mcaplinger]

But big picture, there are 2 down-looking Navigation cameras - these are plumbed directly into the mobility system for rapid on-board optical velocimetry and correlation-based navigation. There are two for redundancy (hence no need for separation for stereo).

Thanks, Ralph. To put it slightly differently, unlike the near-field navigation on the Mars rovers, there's no need for stereo to navigate Dragonfly in flight (at least, not two-camera stereo.) Read the navigation paper linked upthread for details.

AFAIK, there are no plans to run both Navcams at the same time.

As for size, compare our P50 camera https://www.msss.com/files/ECAM-P50_N50.pdf with the LCAM and you can probably guess what's going on.

[vjkane]

Thanks to mcaplinger and rlorenz for the information on the cameras.

This will be an awesome mission. Look forward to the images it returns. Unfortunately, given the distance and lack of relay, it won't be the bounty of images from the Mars rovers. However, the project team will have a process to select the best.