Pretty cool, though it will take a while before PLT could be used for interplanetary missions. The demonstrated thrust is in micro newtons, and requires phenomenal precision between the spacecraft, so would only be useful over at most a few kilometers. The net thrust is experienced between the launching and launched spacecraft, so the practical ejecta mass is the launching part that is left behind.

If I assume a few orders of magnitude improvement in range and thrust over the current design, I could postulate a 1 Milli newton thrust, and a maximum practical range of 100km. If I take ESA's figures of a ~60 tonne habitat for a manned mars mission, and I assume that the launching platform...

Pretty cool, though it will take a while before PLT could be used for interplanetary missions. The demonstrated thrust is in micro newtons, and requires phenomenal precision between the spacecraft, so would only be useful over at most a few kilometers. The net thrust is experienced between the launching and launched spacecraft, so the practical ejecta mass is the launching part that is left behind.

If I assume a few orders of magnitude improvement in range and thrust over the current design, I could postulate a 1 Milli newton thrust, and a maximum practical range of 100km. If I take ESA's figures of a ~60 tonne habitat for a manned mars mission, and I assume that the launching platform offsets it's reaction acceleration using Solar Electric Propulsion or chemical rockets, I get a figure of about 3.5 megaseconds to achieve 100km separation distance at a relative velocity of 59 mm/s.

If I scale up the thrust another 1000 times, and reduce the payload to 1 tonne (assuming a robotic mission) then the time and speed are slightly more useful, at ~14000 seconds (under 5 hours) at a final relative velocity ~14 m/s. Escape from Earth orbit requires ~3500 meters from LEO, then another 1400 or so (depending on launch window) for a transfer orbit to Mars. 14m/s is not enough to matter in this case.

To allow a launch to Mars from LEO, I have to tweek the figures another several orders of magnitude until the acceleration is ~1 gee (10m/s/s) and extend the functional range to ~1300km.

This PLT seems only useful for precision formation flight, and I think that the "journalists" that reported a potential interplanetary option are irresponsible and at best, innumerate.