Looks like this is just data from the GPS receiver, mostly about where the rocket thinks it is at the moment. This doesn't strike me as particularly sensitive. Data from, say, sensors embedded in the engines would be much more interesting.
And if amateur astronomers can do it, a well-funded national space agency can do it even better. I'm 100% sure that any launch is picked up via radar and sattelites and the like when they happen, and various properties extracted and extrapolated to determine their target orbit.
That said, I wouldn't be surprised if some known launches also contained some unknown payloads. Stealth technology on a satellite would probably thwart detection in space well enough.
> Stealth technology on a satellite would probably thwart detection in space well enough.
Stealth is great for radar, but even the B-2 can be spotted pretty easily via the Mk 1 eyeball. Satellites also have to have radiators, which limits what you can manage.
>> but even the B-2 can be spotted pretty easily via the Mk 1 eyeball.
It has a visual cloaking device too. It isn't terribly complicated. The bottom of the aircraft is a particular color. If you fly at an altitude that the sky above is the same color as the bottom of your plane, people on the ground cannot see you. So a tiny camera pointed up can be used to calibrate the altitude to best hide.
Also see counterillumination, a trick used by many sea creatures to hide from things below them. I doubt the B2 uses this but the military has studied it as an option in the past.
The article would seem to indicate it helps, but certainly doesn't get you all the way there.
> Modern stealth aircraft, such as the F-117 Nighthawk attack jet and B-2 Spirit bomber, are painted in matte black or dark grey and are flown at night to limit their visual signature.
Can't really do that in space; you've got a day/night cycle ever 90 minutes or so.
Space is black. Even in daylight, the background behind an object in space is always black (except when passing in front of the sun). A black plane against a blue sky stands out. A black satellite against the black of space does not. Or a blue plane against a blue background.
The F117 is black and only flew at night, at lower levels. The bottom of the B2 isn't actually black, more a dark grey with a bit of blue in it. And the top of the aircraft is more sea blue than black at most angles. Someone thought long and hard about those colors, about not just painting it all black like the F117.
> A black satellite against the black of space does not.
It sure heats up fast, though. Radiating enough heat not to roast the electronics is already an issue for satellites with shiny coatings to keep heat from the sun out.
The ISS is way bigger than a highly classified satellite, but I'd guess a lot of nation states have way better capability than some guy with a telescope in his back yard in New Zealand.
I really want to upgrade to Mk 2 eyeballs, maybe with some new receptors to see extra colours, infrared and ultraviolet. Maybe the capability to see polarised light too.
> Stealth technology on a satellite would probably thwart detection in space well enough.
I bet you could make a satellite look like a stray screw or fleck of paint with enough effort. Careful geometry and surface design can reduce the radar cross section to a tiny fraction; some ultrablack coating and judicious heat rejection could make it look effectively invisible to optical and IR. Power with an RTG to avoid glints and radar scatter from solar panels.
And I'm sort of geeking out thinking about how you could misdirect observers about the payload's path— release a very shiny dummy payload, and then release the real thing some time before or after. Or pull a Millennium Falcon gambit and release the actual payload from a disposed fairing or stage when no one's looking...
Maybe it's possible to detect radio echoes off the rocket exhaust trail (passively) like it is possible to do with meteors [0][1] and roughly tell where the second stage is (just for the sake of doing it this way).
I can't speak to SpaceX's decision, but in FCC rulings, they have proposed encryption when commanding vehicles, not for telemetry or tracking comms (satellites, specifically, although I'd assume similar guidance for vehicles, with the only command you're going to send to the vehicle would be boom for range safety).
For historical purposes, range safety on SpaceX vehicles has been autonomous and onboard since 2017. Vehicles emit telemetry, but do not receive commands.
Those final gasps of data while a vehicle is breaking up could be critical for understanding what went wrong with it. I can definitely see how missing out on the final milliseconds of telemetry because some encryption buffer wasn't full enough to trigger a frame or something would be unacceptable.
I think this is the true reason that telemetry is as raw as possible.
The happy-path telemetry tells you very little you didn't already know, but when something goes wrong, those last few bits before the transmitter went silent can make or break your analysis. Sitting on bits until you have enough to run a block through the cipher seems like a terrible idea, even if that's only a few microseconds.
Things happen mighty fast when you're trying to get data that might represent the structural collapse or propagation of a blast wave through the body of a hypersonic vehicle.
I think this is a very plausible reason. After a F9 blew up in 2016 or so, the NASA accident review even threw a little bit of shade because the telemetry right before the explosion was lost to bufferbloat
How much would that affect the ability to recover a partially-corrupted stream, though? I feel like that's part of this too— where the last few seconds might have an increasing amount of the content scrambled, and encryption would render that completely unusable, whereas having it in plaintext would still permit some degree of inference about the fragments you do have.
Might be some truth here. Although at this point automatically interpreting plain text data would fail as well. In both cases, you could add separating symbols in the raw data stream.
Also, timing should help here. Sure there can be gaps, but at a given data rate the receiving end should be able to compensate for it, as long as velocity doesn't have large unexpected changes (doppler). Even then it should be decodable afterwards.
There are a lot of ways you can compensate for any of these issues. That said, of course plain text is going to be the easiest option for a human to decode when everything else fails.
I have been curious on what it would take to do a Contact like signal fake. Would it be possible for a satellite to be launched into a direction in space that for all intensive purpose make it look like it is coming from somewhere else further away? Would it be easy to tell that it is originating much closer than what it is simulating? How far would it need to be away from earth before it was believable, and then would the fact the signal's source is constantly moving futher away be discernible from the signal itself? Basically, think along the lines of a fanfic premise told from Michael Kitz' perspective.
>> Would it be possible for a satellite to be launched into a direction in space that for all intensive purpose make it look like it is coming from somewhere else further away?
Anything is possible but it would be very hard. You would have to fake the doppler shifts. With massive scrutiny you might even have to fake some absorption lines. Then, if the signal was longer than a few days/weeks, you would need to place the emitter far enough away that parallax, relative motion against the stellar background, was undetectable. That distance is probably measured in light-years.
