A minor nitpick but it's not relativity (as in Einstein's relativity,) it's just relative velocity.
The launch imparts velocity on the satellite but that velocity difference doesn't mean it flies in formation with the ISS a few hundred meters or a few kilometers apart. If they were launched in the direction the ISS is going (positive delta-v), that extra velocity means a higher orbit; if they're launched backwards (negative delta-v), it'll be a lower orbit. If it's launched sideways, it's either higher, lower, or same depending on delta-v but a different inclination (angle to the equator.) I couldn't quickly find where exactly the deployer is located but I'm guessing it's aft because it's the same module the ISS launches it's trash out of now (the Bishop airlock,) and I'm guessing they wouldn't launch anything in a fast decaying slightly higher orbit just to get hit by it a few cycles later.
The whole thing it's pretty cool, and it's quite new, it was installed only 3 months ago.
Are we assuming that the satellite is going to stay in the same orbit? The atmo drag will constantly be applying pressure on the cubesat so that its orbit will always being decaying.
I don't think atmospheric drag at 400km is large enough to decay the orbit by half the vertical height of the ISS in half a cycle, though. The ISS itself with it's comparatively huge surface area does orbital reboosts only about once a month or so.[1] Also, my original comment was quite simplistic - a launch with a negative delta-v with no other course correction would result in an elliptic orbit with the same apogee but a lower perigee (and the other way around with a positive delta-v.) Orbits are tricky that way.
I assume the two confounding factors are (a) the satellite should be moving relative to the ISS at the speed it was launched, so it is going to take a while to come back around and (b) when it does come back around, it should only be going as fast as you launched it, so it shouldn't be nearly as dangerous as the typical orbital collision.
[Huh, if the cubesats are launched at 90 mph from the ISS (the speed of a fastball), it only takes ~12 days for them to come back around; that's quite a bit faster than I would have guessed, but still probably long enough for orbital decay and ISS adjustments to put them out of line.]
The launch imparts velocity on the satellite but that velocity difference doesn't mean it flies in formation with the ISS a few hundred meters or a few kilometers apart. If they were launched in the direction the ISS is going (positive delta-v), that extra velocity means a higher orbit; if they're launched backwards (negative delta-v), it'll be a lower orbit. If it's launched sideways, it's either higher, lower, or same depending on delta-v but a different inclination (angle to the equator.) I couldn't quickly find where exactly the deployer is located but I'm guessing it's aft because it's the same module the ISS launches it's trash out of now (the Bishop airlock,) and I'm guessing they wouldn't launch anything in a fast decaying slightly higher orbit just to get hit by it a few cycles later.
The whole thing it's pretty cool, and it's quite new, it was installed only 3 months ago.