A Camera Drone for space

[biosehnsucht]

On the subject of transmitting the video to the Dragon for store and possibly forward...

What's the free-space range of some nearly off the shelf 802.11ad equipment? That can deliver up to 7Gbit/s. Officially it supports up to 10 meters with beam forming... might have to go with 802.11ac, which would limit you to a much slower rate... but still, assuming no interference (a big assumption), still in the ballpark of regular gigabit ethernet.

There's Li-Fi too, though that's actually slower, it would have potentially greater range perhaps. Or just slap some of the laser comms gear on it from CommX, though that may be too bulky ...

trying to return the entire camera drone via re-entry on it's own is certainly way too hard to do by comparison to simply sending the data...

[Jim]

Just out of interest, if you have two craft in formation, how do they currently know, automatically, where they were in relation to each other, without GPS.

Both would require INS and some sort of sensor suite like LIDAR, RADAR, or 3D cameras (multiple), etc

[Ludus]

I don't have much knowledge about how they do it but I have the impression that off the shelf drones now have quite a bit of sophistication about sensing and responding to their immediate environment independently of GPS or ultrasonics. I think some of this, like with autonomous vehicle tech, uses image processing. The ideal would be if more or less off the shelf Drone tech could be repurposed to do positioning and collision avoidance from video images and/or RF signal strength with this sort of drone.

[Ludus]

On the subject of transmitting the video to the Dragon for store and possibly forward...

What's the free-space range of some nearly off the shelf 802.11ad equipment? That can deliver up to 7Gbit/s. Officially it supports up to 10 meters with beam forming... might have to go with 802.11ac, which would limit you to a much slower rate... but still, assuming no interference (a big assumption), still in the ballpark of regular gigabit ethernet.

There's Li-Fi too, though that's actually slower, it would have potentially greater range perhaps. Or just slap some of the laser comms gear on it from CommX, though that may be too bulky ...

trying to return the entire camera drone via re-entry on it's own is certainly way too hard to do by comparison to simply sending the data...

802.11ac does 230' with gigabit/sec and is well tested and that seems like enough.

[Ludus]

Just out of interest, if you have two craft in formation, how do they currently know, automatically, where they were in relation to each other, without GPS.

Both would require INS and some sort of sensor suite like LIDAR, RADAR, or 3D cameras (multiple), etc

Because of all the effort going into those things for autonomous vehicles, I'd think any of those things could be an option. LIDAR and proximity RADAR is much cheaper. 3D imaging is very useful at less than 100m like this. Tesla folks may have more to contribute than SpaceX.

[Jim]

Because of all the effort going into those things for autonomous vehicles, I'd think any of those things could be an option. LIDAR and proximity RADAR is much cheaper. 3D imaging is very useful at less than 100m like this. Tesla folks may have more to contribute than SpaceX.

INS is needed regardless and it would need some type of star tracker

[envy887]

Because of all the effort going into those things for autonomous vehicles, I'd think any of those things could be an option. LIDAR and proximity RADAR is much cheaper. 3D imaging is very useful at less than 100m like this. Tesla folks may have more to contribute than SpaceX.

INS is needed regardless and it would need some type of star tracker

Both star tracking and INS can be done on a Raspberry-Pi sized board with off the shelf chips. Probably 3D imaging also, but that might require a longer baseline given rather low angular resolution cameras.

[starsilk]

I'd want to target human eye resolution, which is 150 - 200 urad/pixel.  Once you account for some overlap between sensors, the combined resolution of the camera ball will be over 400 megapixels.  At 60 fps, that's 24 gigapixels/second.  The moon flyby will last at least an hour, maybe two.

Good video compression will get that down to 0.1 bits/pixel, so 1-2 terabytes.  Transmitted over the course of 4 days, that's 23-46 Mb/s.  That's a very, very fast link.  Maybe you could use WiFi to transmit from the drone to the Dragon, and let the Dragon bring the data home, but that link would have to stay up for four days over ever-increasing range, or more likely run at very, very high data rates for many hours.  I agree that this is also a reasonable direction to go in, but I don't like it for a couple of reasons.

many of the cameras will be pointing at open space. they will essentially be recording 'black' with a few pinpricks of starlight. any reasonable video codec will collapse the stream from those cameras down to nearly nothing.

I'd expect the cameras that ARE pointing at something to compress pretty well too - dragon will be essentially static, the moon will be moving, but slowly, and very predictably, and no low level noise to filter out from atmospheric effects.

[smfarmer11]

Attitude control could be done by reaction wheels, for finer control than gas thrusters.

[Bubbinski]

I remember the Aercam Sprint drone flying on the STS-87 mission, flying around Columbia and getting pics of the payload bay. Would be a great idea for in space inspections and images of Dragon, CST-100 etc. But if I were an astronaut aboard a reentering spacecraft a camera drone reentering alongside would give me the heebie jeebies due to risk of collision, quite apart from the plasma sheath mentioned by Jim. I would think if live coverage of reentry were desired, coverage from a camera on an orbiting photo satelite or ISS, or a telescopic camera on a Learjet flying at FL 450 under the reentry path would be a lot more practical.

[IainMcClatchie]

many of the cameras will be pointing at open space. they will essentially be recording 'black' with a few pinpricks of starlight. any reasonable video codec will collapse the stream from those cameras down to nearly nothing.

Yes, a starfield should be very compressible.

I'd expect the cameras that ARE pointing at something to compress pretty well too - dragon will be essentially static, the moon will be moving, but slowly, and very predictably, and no low level noise to filter out from atmospheric effects.

What are the atmospheric effects that produce low level noise?  Most of the image noise that I've run across is photon shot noise, which is a quantum mechanical thing not having to do with the atmosphere.  The rest, significant only in low SNR images, is readout noise from the electronics on the sensor.

[smfarmer11]

There was a similar fly-about drone used to take images of the Tiangong-2 space station and Shenzhou vehicle while docked. It was called Banxing-2 and used an Ammonia gas based thruster system, had a 25 megapixel camera and had a mass of 47kg. Importantly it was capable of free-flying and was able to stay near the station for some time. Something similar could probably be put in Dragon's trunk for deployment during the lunar flyby.

[starsilk]

many of the cameras will be pointing at open space. they will essentially be recording 'black' with a few pinpricks of starlight. any reasonable video codec will collapse the stream from those cameras down to nearly nothing.

Yes, a starfield should be very compressible.

I'd expect the cameras that ARE pointing at something to compress pretty well too - dragon will be essentially static, the moon will be moving, but slowly, and very predictably, and no low level noise to filter out from atmospheric effects.

What are the atmospheric effects that produce low level noise?  Most of the image noise that I've run across is photon shot noise, which is a quantum mechanical thing not having to do with the atmosphere.  The rest, significant only in low SNR images, is readout noise from the electronics on the sensor.

wind, trees, grass, clouds, ocean movement etc. all things that are entirely nonexistent in space, so the pictures will be very 'static', or as I said previously, moving in very predictable ways.

[JamesH65]

many of the cameras will be pointing at open space. they will essentially be recording 'black' with a few pinpricks of starlight. any reasonable video codec will collapse the stream from those cameras down to nearly nothing.

Yes, a starfield should be very compressible.

I'd expect the cameras that ARE pointing at something to compress pretty well too - dragon will be essentially static, the moon will be moving, but slowly, and very predictably, and no low level noise to filter out from atmospheric effects.

What are the atmospheric effects that produce low level noise?  Most of the image noise that I've run across is photon shot noise, which is a quantum mechanical thing not having to do with the atmosphere.  The rest, significant only in low SNR images, is readout noise from the electronics on the sensor.

You would be getting rid of a lot of low level noise prior to compression anyway. It would be interesting however, to know what the extra noise sources are in space, if there are any, and what the characteristics are to tune the denoise algorithm.