Expedition 21

{{Use British English|date=August 2010}}

{{Use dmy dates|date=January 2024}}

{{Infobox spaceflight

| name = Expedition 21

| image = Expedition 21 Star Trek crew poster.jpg

| image_caption = Promotional Poster

| insignia = ISS Expedition 21 Patch.svg

| insignia_caption = Expedition 21 mission patch

| mission_type = Long-duration expedition

| mission_duration =

| orbits_completed =

| crew_size = 6 (to November)
5 (from November)

| crew_members = Expedition 20/21:
Frank De Winne
Roman Romanenko
Robert Brent Thirsk
Nicole P. Stott (to November)

Expedition 21/22:
Jeffrey N. Williams
Maksim Surayev

| crew_EVAs =

| crew_EVA_duration =

| crew_photo = Expedition 21 crew portrait.jpg

| crew_photo_caption = from left to right: Maksim Surayev, Nicole Stott, Jeffrey Williams, Frank De Winne (commander), Robert Thirsk, Roman Romanenko

| space_station = International Space Station

| start_date = {{start date text|11 October 2009}}

| end_date = {{end date text|1 December 2009}}

| arrival_craft = Soyuz TMA-15
Soyuz TMA-16
Stott: STS-128
{{OV|103}}

| departure_craft = Soyuz TMA-15
Soyuz TMA-16
Stott: STS-129
{{OV|104}}

| previous_mission = Expedition 20

| next_mission = Expedition 22

| programme = ISS expeditions

}}

File:Expedition 21 Lifts Off.jpg

Expedition 21 was the 21st long-duration mission to the International Space Station (ISS). The expedition began on 11 October 2009, with Frank de Winne becoming the first ESA astronaut to command a space mission.

The handover between Expedition 20 and Expedition 21 required three Soyuz vehicles being docked to the station at the same time, the first time this has occurred.

Soyuz TMA-16 brought the final members of Expedition 21 to the ISS, along with space tourist Guy Laliberté. Laliberté returned to Earth on Soyuz TMA-14 with two members of Expedition 20 on 11 October 2009.

Nicole P. Stott was the last ISS expedition crew member to fly on the Space Shuttle. She returned to Earth aboard STS-129 in November 2009.