I was able to get fairly decent signal using a GPS dongle with integrated LNA, modified by removing the GPS filter, bridging the contacts. It didn't have to be pointed right at the satellite. It was about 3 dB down in SNR form the Outernet patch antenna. That's a lot, but depending on the initial signal strength and location, say, out in the middle of the ocean, it may not be a problem. In any case, it would greatly simplify aiming to only have to get within 20 degrees or so of the satellite.
What about an array of cheap GPS antennas, say, maybe three, set on a mount at 120 degree angles from each other, and combined to one signal.... OR, just a multiple element flat array, with a good LNA.
There seems to be some adjacent satellite traffic around 1539.8725, but nothing right on that frequency.