# How often has the ISS been physically vacant (un-manned)?

Currently six great folks are working in the International Space Station (ISS). I am wondering if it is ever vacant and if there's a rule of thumb (magnitude of order of days, an average or anything) that it might be so.

On a high level estimation, how frequently - if ever - is the ISS not manned on board?

• Please kindly note that I can't find the answer to whether it has happened (nobody inside the ISS) or not, so that's the odd tone of the question. Nov 27, 2016 at 9:51

According to wikipedia, the ISS has been manned ever since the first crew of Expedition 1 entered on November 2nd 2000.

EDIT: As @Tristan pointed out the ISS was technically unmanned for a couple of times so far when there was just one crew on board which had to relocate the soyuz to another docking port, see comments below.

• There have been brief excursions (only a few minutes) where nobody was technically on board. These occurred between the departure of one increment crew and the launch of its replacement, where the crew was only at 3. In these instances, they needed to move their Soyuz from one docking port to another. All three were in the Soyuz during that transfer, with nobody on board the ISS. Nov 29, 2016 at 21:23
• Do you have an example of that happening? Nov 29, 2016 at 21:25
• October 10, 2006, with Soyuz TMA-9; November 18, 2005, with Soyuz TMA-7; March 20, 2006, with Soyuz TMA-7; July 19, 2005, with Soyuz TMA-6; November 29, 2004, with Soyuz TMA-5; April 18, 2001, with Soyuz TM-31; February 24, 2001, also with Soyuz TM-31 Nov 30, 2016 at 16:01
• Pulled from Wikipedia to find all Soyuz flights that involved a relocation, then crosschecked ISS expedition information and other Soyuz and shuttle flights to make sure nobody else was there at the time. Nov 30, 2016 at 23:20
• The reason for that is in case there is a problem and that person cannot redock the soyuz, the others would be left without a way to get back to earth. (see here) They actually prepare everything as if they'd leave the spacestation to go back to earth whenever they perform a relocatio maneuver. Apr 15, 2017 at 16:29

Expedition-1 docked to ISS November 2, 2000. Since then ISS has been continuously occupied... except for brief periods when the crew undocked in order to relocate their Soyuz return vehicle from one docking port to another. Per the thread below on collectSPACE, ISS was left unoccupied for the following durations [mm:ss]:

Soyuz TM-31 ... 02/24/2001 ... [29:04]
Soyuz TM-31 ... 04/18/2001 ... [20:30]
Soyuz TM-32 ... 10/19/2001 ... [16:00]
Soyuz TM-33 ... 04/20/2002 ... [21:35]
Soyuz TMA-5 ... 11/29/2004 ... [20:48]
Soyuz TMA-6 ... 07/19/2005 ... [29:49]
Soyuz TMA-7 ... 11/18/2005 ... [19:38]
Soyuz TMA-7 ... 03/20/2006 ... [22:01]
Soyuz TMA-9 ... 10/10/2006 ... [20:10]
Soyuz TMA-9 ... 03/29/2007 ... [24:31]
Soyuz TMA-10 .. 09/27/2007 ... [27:10]


Since then the ISS crew size has been expanded. There have been subsequent Soyuz port relocations (and will be future port relocations of Crew Dragon and Starliner) but none have left/will leave the station completely unoccupied. So the "true" start of permanent occupation of ISS was 9/27/2007.