Every day you learn something new! Thanks for your input.BTW, that does makes it interesting to think if a wider body Progress couldn't position the tanks to improve the control authority due to c/g problems.

Progress M-16M will perform a fast-rendezvous profile with four maneuvers on orbits 1-3 and five-six maneuvers on orbits 3-4 for docking on orbit 4.

Quote from: anik on 07/01/2012 08:26 pm Progress M-16M will perform a fast-rendezvous profile with four maneuvers on orbits 1-3 and five-six maneuvers on orbits 3-4 for docking on orbit 4.

This Progress will be taking a short cut to Station, cutting the arrival time down from the traditional two days, to just four orbits, potentially laying the foundations for a much shorter mission timeline prior to docking for future Soyuz astronauts.

From the recent NSF article on Soyuz TMA-05M:QuoteThis Progress will be taking a short cut to Station, cutting the arrival time down from the traditional two days, to just four orbits, potentially laying the foundations for a much shorter mission timeline prior to docking for future Soyuz astronauts.Can someone explain why didn't they do this many years ago, what changed? I thought the approach to ISS took two days because the vehicle didn't have enough thrust or propellant to do a faster approach and the rocket couldn't put it in a high enough initial orbit. But I don't see any mention of this progress having new engines, more fuel or launching on a new version of Soyuz.

AFAIK, about every 6 months or so, the ISS will fly over a launch site so that a vehicle launched from that site can rendezvous with the station if launch is made at a very precise time. If that time is missed, it would be another 6 months before another quick rendezvous can be made.However, the 2 or 3 day rendezvous approach allows for launch to the ISS every day.