Not on everywhere but particular areas, shouldn't be too hard to get routes of these gliders. My primary concern was animals.Too large of sea area. And plenty sea creature around here are larger than those glider
Set NOTAM for military exercises and switch jamming region daily. Hostility? This will be done in territorial waters.Bad idea (diplomatic & legal) to jam any RNSS signal without prior open hostility
Computers in these machines are really simple, i doubt if these use advanced encryption, the processors are rather low-energy ones and storing raw data to maximize operational time. Especially GNSS module of processor would keep a portion of the offline data. Also, the data do not have any value worth to encrypt except of the satellite modem which in most cases are the commercial one.Modern cryptanalysis is one aspect that the entire Indonesia establishment severely lack of (And I'm already softening my wording here)
too much of ocean-sea data is available on open scientific communities, temperature, salinity, o2, clarity are major parameters either constantly being collected or surveyed in researches. Especially thermocline is used for sea-ocean current modelling and heat carriage for accurate meteorological forecast models, so these are pretty much avaliable.What worrisome about this glider finding is, the location of their finding in Makassar Strait mean in the most likely case, the glider was mapping thermocline
Just yesterday got an e-mail from fellow researcher offering a terabytes of raw data to be processed by whom might be interested, literally there is excessive amount of data waiting to be processed.
I am aware of other methods to detect such systems but i don't think Indonesia has resources to install hydrophone arrays and comint buoys in great extends. Diver detection sonar could help but it would need a good network and commitment,in terms of financial and operation. Also would perform better at shallow waters.
It is nearly impossible to detect these through passive methods. Primary source of noise is the oil pump which is used to elevate the glider (revealing its acoustic signature nearly to 5 km), but nowadays for extra a few thousand bucks people can get a silent pump and avoid detection by that. weight shifter(pitch control) and roll control motor has typical noises in high bands which is absorbed-damped in first hundred meters below the background noise.