Ascent & Flight Day 1: Far Field Phasing and Demonstrations
Flight Day 1 of the Dragon C2/3 Mission begins with Vehicle Power Up and Countdown Operations that include the final rounds of testing of the Falcon 9 Rocket and the Dragon Spacecraft. Also, the launch vehicle goes through the fueling process and Dragon is configured for Operations in Orbit. A detailed Countdown Timeline is available here.
10 Minutes before Liftoff, the Terminal Countdown Sequence is initiated during which final re-configurations of both vehicles will be made by computer commands. Three seconds before Blastoff, the nine Merlin 1C Engines of the Falcon 9 Rocket ignite and at T-0, the large Booster lifts off from Space Launch Complex 40 at Cape Canaveral Air Force Station, Florida. After completing a short vertical ascent, Falcon 9 will make a Roll and Pitch Maneuver to align itself with the proper flight trajectory. Leaving the Space Coast, the launch vehicle reaches Maximum Dynamic Pressure at T+84 seconds. Three Minutes into the Mission, the first stage shut down and separates from the vehicle five seconds later. Another 7 seconds after that, the Merlin Vacuum Engine of the Second Stage ignites. This burn will be 6 minutes and 2 seconds in duration. During the second stage burn, the Dragon Nose Cone separates to increase ascent performance - exposing the Spacecraft Docking System. The Nose Cone is used to protect the docking system and instruments of Dragon while the vehicle is waiting for launch under Florida Skies and during the initial ascent portion while the vehicle is flying through the dense portion of the atmosphere. 9 minutes and 14 seconds after lifting off, the vehicle shuts down is engine. 35 seconds later, the Dragon Spacecraft is released. To complete Orbital Insertion, Dragon will deploy its two solar arrays. Teams at Dragon Control in Hawthorne, California, will conduct a vehicle status checks to verify Dragon is in good condition and ready for on-orbit operations. Dragon Mission Control and ISS Flight Controllers in Houston, Texas, will be working closely together throughout the mission.
Inital Orbit Operations Timeline
The first day in space is dedicated to Far Field Phasing Maneuvers and several Test Objectives. As the mission progresses, Dragon has to complete a series of tests and meet a number of objectives in order to be allowed to Rendezvous with the International Space Station. Just an hour into the flight, Dragon will demonstrate its Absolute GPS Navigation Capability. For that, Dragon will use its GPS receiver to communicate with Navigation Satellites to determine its exact position in space. Just before passing the T+2.5-hour mark, Dragon will start deploying the GNC Bay Door to put required Rendezvous instruments in place. DragonEye, the Vehicle's Rendezvous and Navigation Instrument Suite, includes a LIDAR (Light Detection And Ranging) Imager and a thermal Instrument. Just after being deployed, both of these instruments will be activated and undergo thorough checkouts.
Flight Day 2: Far Field Phasing
On Flight Day 2, the Dragon Spacecraft will make several Engine Burns to adjust its Orbit to set the Stage for a Rendezvous with the Space Station on Flight Day 3. These Burns are known as Far Field Phasing or Height Adjust Burns and will increase Dragon's Orbital Altitude. The vehicle will target a point, 10 Kilometers beneath and behind the Space Station. During the entire Flight, the SpaceX Mission Control Team will be monitoring the vehicle as it orbits the Earth.
Flight Day 3: ISS Fly-Under
Once arriving at a point 10 Kilometers below and behind the Station (Red Arrow), teams at both Mission Control Centers will conduct a poll and allow Dragon to conduct its Fly-under Maneuver taking it to the R-Bar. The Vehicle will perform two burns called HA2 and CE2. Dragon will enter the 28-Kilometer Communications Zone of the Space Station in which it can directly communicate with ISS Systems. The Spacecraft will use a proximity communications link for Relative GPS Communication with ISS and the Commercial Orbital Transportation Services (COTS) Ultra High Frequency (UHF) Communication Unit (CUCU) aboard the Station will also be used to communicate with the Spacecraft. While making its close approach, Dragon will demonstrate the Relative GPS System. RGPS determines Dragon's Position relative to the Station. During the Test, the System will be assessed by comparing data obtained with RGPS with simultaneously acquired Absolute GPS Data. To test the CUCU, the Space Station Crew Members in charge of Dragon Operations, Andre Kuipers and Don Pettit, will send a Strobe Command, a test command, to Dragon. When receiving and executing the command, Dragon will activate a light for visual confirmation of successful CUCU Communications.
__Once Dragon has passed 2.5 Kilometers below the Station and all operations are complete, the Spacecraft will make a Trajectory Adjustment to retreat to a distance of 10 kilometers to begin the ISS Flyaround. For that, the vehicle will make several engine burns to cross the Station's V-Bar or Velocity Vector more than 200 Kilometers ahead of the Space Station flying to a point 7 Kilometers above the V-Bar before making another maneuver to reduce its velocity. Dragon will then pass over the Station making one more height Adjust Burn to increase the Distance between itself and ISS to 10 Kilometers. Once passing the 200 Kilometer mark, the vehicle will once again fire its engines to cross the V-Bar one more time targeting a point behind and below the Station. The entire process will take 22 to 24 hours and set the stage for re-rendezvous. The Data that was acquired during the Fly-Under will be carefully reviewed by SpaceX and NASA Teams. After assessments are complete, the Space Station Mission Management Team will make a GO/No GO decision for Rendezvous. Should data reviews take longer than planned, Dragon would remain in its position behind and below the station until a decision is made.
Flight Day 4: Rendezvous and Capture
Dragon will start out at a point 10 Kilometers below and behind the Station when Rendezvous operations are re-initiated. Using AGPS, Dragon will make the HA2/CE2 Burn to reach a position 2.5 Kilometers below and behind the station. By that time, Integrated Operations between SpaceX and NASA Mission Control Centers will be underway with Visiting Vehicle Officers and other Flight Controllers making direct communications in order to stay up to date on Vehicle and Rendezvous statuses. At 2.5 Kilometers, the Control Teams are polled for the HA3/CE3 Burn before Dragon is allowed to fire its engines again taking it closer to ISS. At that point, Dragon switches to the Relative GPS Navigation System for Proximity Operations. Approach Initiation occurs at 1.4 Kilometers to ISS. Aboard the Space Station, the Crew begins monitoring Dragon at a Distance of 1000 meters ready to take action if necessary. The HA4 Burn is performed to take Dragon right on the R-Bar. The Vehicle is expected to acquire the R-Bar at a distance of 350 Meters to the Station. After approaching 100 more Meters, Dragon will automatically enter a period of Stationkeeping. At the 250-Meter Hold a series of Demonstrations and Maneuvers will be made. Dragon has to complete all the requirements to be allowed to enter the Keep Out Zone around the Station which is an imaginary 200-meter circle around the Station that is a zone of highest safety and restrictions. Only after successfully demonstrating its capabilities, Dragon will be allowed to get closer to ISS.
At the 250-Meter Hold, several systems will be checked. Both Rendezvous Navigation Systems, LIDAR and the Thermal Instrument will be tested to demonstrate DragonEye's Capabilities. Mission Controllers will confirm that Dragon's position and velocity is accurate by comparing AGPS, RGPS, LIDAR and Thermal Imagers.
After Mission Control has verified that Dragon is receiving correct navigation data and is in good shape, the Approach will be re-started and Dragon will make short engine pulses to re-initiate the Rendezvous. Once reaching 220 meters on the R-Bar, the Station Crew will send a Retreat Command to demonstrate one of Dragon's Rendezvous Abort Capabilities. Dragon will then fire its engines to go back to the 250 Hold Point which it would do from any point in the Approach when the Retreat Command is sent. While Dragon completes the retreat operation, Mission Control will assess whether the spacecraft maintains accurate range to ISS, expected acceleration and braking performance. Also, the vehicle has to hold at its pre-determined point 250 Meters from Station using the RGPS System.
__When all that is verified, Dragon will re-initiate the approach. Demonstrating the second Abort Scenario, the Crew will issue a Hold Command which initiates an immediate period of Stationkeeping at 220 Meters. Mission Controllers will again verify that Dragon's breaking performance is nominal and the vehicle stays within the expected range. Only when all these objectives are met, Mission Control will give a Go for Close Approach. Then, Dragon will fire its engines again and close in on the Station, entering the Keep Out Zone. At that point, the ISS Crew will be monitoring the vehicle to make sure there are no problems during the approach. When reaching the 30-meter mark, Dragon will make another hold to give the two Mission Control Centers the opportunity to check the vehicle's status and conduct another GO/No GO Poll before allowing Dragon to proceed. Initiating the final approach, Dragon will move to ISS at a very gentle speed and stop its approach at 10 Meters - known as the Capture Point. When is is verified that Dragon is in the proper position, Free Drift will be initiated disabling all of Dragon's Thrusters. The Space Station Robotic Arm will then be used under the control of Don Pettit with assistance from Andre Kuipers. SSRMS will capture Dragon and start a delicate maneuver to place the vehicle above its desired berthing position at the Earth-facing (nadir) Common Berthing Mechanism on the Harmony Module. Four Ready to Latch Indicators will be used to verify that the Spacecraft is in the correct position and ready for berthing. Procedures will begin to perform first stage capture of the Vehicle and allow the SSRMS to go limp. Afterwards, second stage capture will be performed and Dragon will be secured in place forming a hard-mate between Station and the Spacecraft marking the official start of docked operations. The Robotic Arm will return to its pre-grapple position to finish the day's work. The entire Rendezvous up to Capture and Berthing will take about 8 hours making it a long day for the Crew aboard the Station and personnel inside the two Mission Control Centers.
Capture and Berthing Animation
Flight Day 5: Leak Checks and Hatch Opening
After being berthed the day before, Dragon will already be hard-mated to ISS when the Crew's Day on Flight Day 5 starts. Before starting FD5 Operations, the crew will take care of any open items from Flight Day 4. Teams could elect to detach the Robotic Arm from Dragon on Flight Day 5 should the Rendezvous run longer than planned. The vestibule between the hatches of Harmony and Dragon will be pressurized and a series of leak checks will be completed to make sure the seal between ISS and the Spacecraft is tight. When leak checks are complete, Mission Control will give a go for Hatch Opening. Once the Harmony Hatch is open, the Crew Members will start the Vestibule Outfitting Task which involves the installation of ducts and the removal of equipment that was needed to bolt Dragon in Place. Control Panel Assemblies will be removed before Dragon's Hatch is opened. Once both Hatches are open, the crew will perform Air Sampling as part of initial ingress operations. The team will assess the air inside Dragon before Mission Control gives a GO for Dragon ingress. At that point, the cargo transfer portion of the mission can get underway.
Flight Day 6-9: Cargo Operations
During the docked phase of the Mission, the crew aboard the International Space Station will perform about 25 hours of Cargo Operations. Cargo items delivered on Dragon will be offloaded and placed aboard the Space Station. Afterwards, the crew will load cargo on board the Dragon Spacecraft that will return to Earth inside the capsule. On this test flight, Dragon will transport 460 kilograms of cargo and will return 620 kilograms. The full Cargo Manifest of the Dragon C2 Mission is available here.
Flight Day 9/10: Egress
After cargo operations are complete, the Dragon Spacecraft will be closed out and its hatch will be closed. Afterwards, the vestibule will be outfitted for unberthing. Ducts will be removed and the Control Panel Assemblies needed to drive bolts will be re-installed. Once Harmony's hatch is closed once again, the leak check process will be repeated to make sure that the hatches are closed and latched properly. Once leak checks are complete, the vestibule between the two spacecraft will be depressurized to prepare for the unberthing of Dragon.
Flight Day 10: Unberthing, Release, Entry and Landing
The Space Station Robotic Arm will be used to grapple Dragon before bolts are driven to release the Spacecraft. Once Dragon is free, the Robotic Arm will maneuver it to its Release Position 10 Meters from the Space Station. Dragon and ISS will be in Free Drift Mode at that point with all Thruster Systems being inhibited. At that point, Dragon's Navigation Instruments will undergo checkouts to make sure the vehicle is getting correct navigation data. Once all checks are complete and both Mission Control Centers have given the GO for release, the Dragon vehicle will be ungrappled and the SSRMS will retreat. Dragon will re-activate its thrusters and recover from Free Drift. Three Engine Burns will be performed by the Vehicle to leave the vicinity of the Space Station. Mission Control Houston will verify that the Vehicle is on a safe path away from ISS.
While moving away from the Station, Dragon will close its Guidance Navigation and Control Bay Door to protect the instruments inside from the Re-Entry Environment. Four hours after release, Dragon will be at a safe distance to the Station to fire its engines and make the Deorbit Burn taking it on a trajectory to re-enter Earth's Atmosphere. The Deorbit Burn will have a duration of about 6 minutes slowing the vehicle down just enough to place its on a path to intercept the atmosphere. 20 Minutes after the conclusion of the Deorbit Burn, Dragon hits Entry Interface and starts to feel the effects of the dense portion of Earth's Atmosphere. During the Re-Entry Process, Dragon's PICA-X Heat Shield has to withstand temperatures of up to 1,600°C. PICA-X is derived from NASA’s phenolic impregnated carbon ablator heat shield, also called PICA. This heat shield has a substantial flight heritage. The PICA-X version is expected to be re-usable many times without showing a high degree of degradation. This design also provides high flexibility in the nature of a mission as it can also support re-entries at velocities exceeding typical speeds of Low Earth Orbit Missions. During the Entry Phase, Dragon uses its Draco Thrusters to stabilize its position and control its lift to precisely target the desired landing location. About 10 minutes before Splashdown, at an altitude of 13.7 Kilometers, Dragon opens its dual Drogue Chutes slowing the vehicle down. Full deployment of the Drogues triggers the Main Chute Opening Command. This occurs at an altitude of 3 Kilometers. Flying under the Main Chutes, Dragon is slowed to its landing speed of 17 to 20 Kilometers per Hour. The vehicle will make a splashdown landing about 450 Kilometers off the coast of California. The Dragon Spacecraft will be recovered by a Barge that is equipped with a crane to pull it out of the Water. On board will be approximately 12 SpaceX engineers and technicians as well as a 4-person dive team. It will be returned to land shortly after landing.
May 31 - Unberthing/Return Timeline
Final Orbit & Splashdown Zone
|1||May 22||Countdown Operations|
|Solar Array Deployment|
|Absolute GPS Demonstration|
|Free Drift Demonstration|
|2||May 23||Far Field Phasing|
|3||May 24||Space Station Fly-Under|
|Relative GPS Demonstration|
|CUCU (UHF Communications) Demonstration|
|LIDAR and Thermal Imager Demonstration|
|First&Second Stage Capture|
|5||May 26||Leak Checks|
|6-9||May 27-30||Cargo Operations|