Table of Contents

STS-121 Mission Timeline

If there are only 2 spacewalks

If there are 3 spacewalks
Flight days 1 to 7 would remain the same, but activities on the following days would change.

Flight Day 1

• Launch of Space Shuttle Discovery at 2:38 p.m., EDT
• Payload bay door is opened
• KU band antenna is deployed
• The crew powers up Canadarm
• The crew plays back handheld launch video of the external tank and loads digital photos of the tank and data from Discovery's wing leading edge sensors into a laptop computer for downlink.
• Overnight, Mission Control downlink data from the wing leading edge sensors for analysis by engineers looking for sites of potential debris impact during launch.

Flight Day 2

• The Shuttle crew completes checkout of Canadarm, if necessary, and installs the centerline camera in the orbiter docking system
• The crew grapples and unberths the Canadian-built orbiter boom and sensor system (OBSS) to conduct a survey of Discovery's leading wing edges and nose cap using Canadarm
• The crew begins a checkout of the rendezvous tools
• Orbiter docking system is extended
• The crew performs system checks on the extravehicular mobility unit spacesuits and tools in preparation for upcoming spacewalks.
• The crew berths the orbiter boom.
• The crew surveys Discovery's upper surfaces and the crew cabin using Canadarm.

Flight Day 3

• The crew begins the final stage of rendezvous operations as Discovery closes in for docking with the International Space Station (ISS)
• Discovery performs the rendezvous pitch Manoeuvre, enabling the ISS crew to photograph the Shuttle's thermal protection systems
• Discovery docks with the ISS
• The Shuttle and ISS crews open the hatches and shake hands
• European Space Agency Astronaut Thomas Reiter, who launched with the STS-121 crew, is now a member of the ISS crew. This brings the station crew back to 3 members.
• The crews begin transferring cargo from Discovery to the Station
• The crew uses the Canadarm2 on the ISS to grapple the Boom and hand it off to the Shuttle's Canadarm
• The crew manoeuvres Canadarm2 to use cameras to inspect the common berthing mechanism on the Unity module, which will be used the next day for the multi-purpose logistics module installation.

Flight Day 4

• The crew grapples the Leonardo multi-purpose logistics module with Canadarm2, unberths the module from Discovery and installs it on the Unity module's common berthing mechanism
• Canadarm2 detaches from the module and walks-off to the mobile base System (MBS) to support a survey of the Shuttle tiles
• The crew activates the multi-purpose logistics module and ingresses
• The crew uses the Shuttle's Canadarm and the OBSS to conduct a survey of the Shuttle's heat-protection tiles
• Canadarm2 grapples onto Destiny. It remains with one end on Destiny and one on the MBS overnight

Flight Day 5

• Final preparations begin for the first spacewalk
• Canadarm2 ungrapples from the MBS
• Piers Sellers and Michael Fossum begin the first spacewalk (EVA 1)
• The spacewalkers replace a cable cutter placed on the top, or zenith side, of the mobile transporter
• The spacewalkers perform load tests using Canadarm and the OBSS (Detailed Test Objective 849) in Discovery's payload bay
• Transfer of supplies and other items between multi-purpose logistics module and the ISS begins

Flight Day 6

• Transfers continue between multi-purpose logistics module and the ISS
• The crew reviews procedures for the second spacewalk
• The crew participates in a joint crew news conference

Flight Day 7

• Prior to the start of the second spacewalk, the mobile transporter (carrying the MBS) will translate from its current location at Worksite 4 to Worksite5. This translation gives the spacewalkers room to replace the trailing umbilical system (TUS) cable. The TUS cable was inadvertently cut in December 2005.
• Piers Sellers and Michael Fossum begin the second spacewalk (EVA 2)
• The spacewalkers remove a pump module from the payload bay which is grappled by Canadarm2. The pump module is a spare part for the station's thermal control system.
• Canadarm2 manoeuvres the pump module to the external stowage platform-2 (ESP-2), which was installed on Quest during STS-114, and the spacewalkers install it there
• Canadarm2 then manoeuvres to the TUS location on the S0 truss and a spacewalker carrying the failed TUS rides Canadarm2 back to the Shuttle payload bay
• The spacewalkers swap the failed TUS for a new one in the payload bay
• Canadarm2 manoeuvres the spacewalker with the new TUS back up to the S0 truss
• The spacewalkers install the new TUS restoring full capability to the Mobile Transporter and MBS
• The Flight Controllers on the ground perform checkouts of new TUS cable
• Second spacewalk ends with crew ingress
• Transfers continue between multi-purpose logistics module and the ISS

Flight Day 8

If there are only 2 spacewalks

• Transfers continue between multi-purpose logistics module and the ISS

If there are 3 spacewalks

• Transfers continue between multi-purpose logistics module and the ISS
• The crew is off-duty 

Flight Day 9

If there are only 2 spacewalks

• The crew is off-duty today
• Mobile transporter with MBS translates from Worksite 5 to Worksite 4

If there are 3 spacewalks

• The third spacewalk begins (EVA 3).
• Canadarm2 supports a spacewalker while tile repair methods are tested and pictures taken using an infrared camera
• Mobile transporter with MBS translates from Worksite 5 to Worksite 4.

Flight Day 10

If there are only 2 spacewalks

• Final transfers occur between multi-purpose logistics module (Leonardo) and the ISS
• The crew egresses and deactivates Leonardo
• Canadarm2 grapples and uninstalls Leonardo from Unity
• Canadarm2 berths Leonardo in Discovery's payload bay
• Canadarm2 walks off to the MBS to support inspection of the Shuttle tiles by the Shuttle's Canadarm

If there are 3 spacewalks

• Transfers continue between multi-purpose logistics module and the ISS
• Discovery's crew begins deorbit preparations
• Payload bay door is closed
• The crew is off-duty

Flight Day 11

If there are only 2 spacewalks

• Discovery and ISS crews bid farewell and close their hatches
• Centerline camera is reinstalled
• Discovery undocks and separates from the Station
• The Shuttle crew completes inspection of Shuttle tiles using Canadarm and the OBSS.
• The crew is off-duty 

If there are 3 spacewalks

• Final transfers occur between Leonardo and the ISS.
• The crew egresses and deactivates Leonardo 
• Canadarm2 grapples and uninstalls Leonardo from Unity.
• Canadarm2 berths Leonardo in Discovery's payload bay.
• Canadarm2 walks off to the Mobile Remote Servicer Base System to support inspection of the Shuttle tiles by the Shuttle's Canadarm.

Flight Day 12

If there are only 2 spacewalks

• Discovery crew performs flight control system checkout and begins cabin stowage in preparation for tomorrow's landing.
• The crew performs reaction control system hot fire and reviews tomorrow's deorbit timeline.
• KU band antenna is stowed.

If there are 3 spacewalks

• Discovery and Station crews bid farewell and close their hatches.
• Centerline camera is reinstalled.
• Discovery undocks and separates from the Station.
• The Shuttle crew completes inspection of Shuttle tiles using Canadarm and the Orbiter Boom.

Flight Day 13

If there are only 2 spacewalks

• Discovery's crew begins deorbit preparations.
• Payload bay door is closed for entry.
• Deorbit burn occurs.
• Landing occurs at Kennedy Space Center.

If there are 3 spacewalks

• Discovery crew performs flight control system checkout and begins cabin stowage in preparation for tomorrow's landing.
• The crew performs reaction control system hot fire and reviews tomorrow's deorbit timeline.
• KU Band antenna is stowed.

Flight Day 14

If there are 3 spacewalks

• Deorbit burn occurs.
• Landing occurs at Kennedy Space Centre.

CSA has prepared this document from the overview of the mission in the NASA press kit