Progress M-56

Progress M-56 approaching the ISS.
Mission type	ISS resupply
Operator	Roskosmos
COSPAR ID	2006-013A
SATCAT no.	29057
Mission duration	148 days
Spacecraft properties
Spacecraft type	Progress-M s/n 356
Manufacturer	RKK Energia
Start of mission
Launch date	24 April 2006, 16:03:25 UTC
Rocket	Soyuz-U
Launch site	Baikonur, Site 1/5
End of mission
Disposal	Deorbited
Decay date	19 September 2006, 04:14:40 UTC
Orbital parameters
Reference system	Geocentric
Regime	Low Earth
Perigee altitude	337 km
Apogee altitude	348 km
Inclination	51.6°
Period	91.4 minutes
Epoch	24 April 2006
Docking with ISS
Docking port	Zvezda aft
Docking date	26 April 2006, 17:41:31 UTC
Undocking date	19 September 2006, 00:28:17 UTC
Time docked	146 days
Cargo
Mass	2600 kg
Progress ISS Resupply ← Progress M-55 Progress M-57 →

Progress M-56 (Russian: Прогресс М-56), identified by NASA as Progress 21P, was a Progress spacecraft used to resupply the International Space Station. It was a Progress-M 11F615A55 spacecraft, with the serial number 356.^[1]

Progress M-56 was launched by a Soyuz-U carrier rocket from Site 1/5 at the Baikonur Cosmodrome. Launch occurred at 16:03:25 UTC on 24 April 2006.^[1] Also carried to the ISS was an experimental MIT students-built picosatellite, named SPHERE, that will float inside the station, strictly maintaining its location inside.

The spacecraft docked with the aft port of the Zvezda module at 17:41:31 UTC on 26 April 2006.^[2][3] It remained docked for 146 days before undocking at 00:28:17 UTC on 19 September 2006^[2] to make way for Soyuz TMA-9.^[4] It was deorbited at 03:28 UTC on 19 September 2006.^[2] The spacecraft burned up in the atmosphere over the Pacific Ocean, with any remaining debris landing in the ocean at around 04:14:40 UTC.^[2][5]

Progress M-56 carried supplies to the International Space Station, including food, water and oxygen for the crew and equipment for conducting scientific research.

• List of Progress flights
• Uncrewed spaceflights to the International Space Station