NASA, SpaceX to launch Dragon to ISS on CRS-26 mission


SpaceX’s newest Cargo Dragon 2 spacecraft, C211, will launch atop a Falcon 9 rocket at 3:54 PM EST (20:54 UTC) on Nov. 22 from Launch Complex 39A at NASA’s Kennedy Space Center (KSC). Cargo Dragon will later rendezvous and dock with the forward port on the Harmony module of the International Space Station (ISS). Docking is scheduled for 5:57 AM EST (10:57 UTC) on Nov. 23.

There is a backup launch opportunity scheduled for Saturday, Nov. 26 at 2:20 PM EST if the attempt on Nov. 22 is forgone for any reason.

The spacecraft will resupply the Expedition 68 crew aboard the Station and will carry a second pair of ISS Roll Out Solar Arrays or iROSAs inside the unpressurized trunk of the spacecraft. The two iROSAs will eventually be installed on the exterior of the ISS during spacewalks currently scheduled for late November and early December.

The Falcon 9 booster supporting this mission is B1076-1, which is launching on its first flight. Following the launch, it will attempt to land on the Autonomous Spaceport Drone Ship named Just Read the Instructions downrange of KSC in the Atlantic Ocean.

The booster is different from other SpaceX boosters as it features fewer SpaceX logos and no Falcon 9 markings (which is normal for Falcon Heavy side cores), which is a departure from the standard Falcon 9 livery. B1076 will be used as a Falcon Heavy side booster core later on.

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The launch on Nov. 22 at LC-39A comes a week to the day after NASA’s Space Launch System launched on its maiden flight from LC-39B on the Artemis 1 mission. This marks the closest back-to-back launches from both pads combined at Launch Complex 39.

The closest back-to-back launch from the complex occurred in 1973, when the Skylab space station launched atop the final Saturn V rocket from LC-39A on May 14, 1973. The first crew of Skylab then launched atop a Saturn 1B rocket at LC-39B 11 days later on May 25, 1973.

The closest Space Shuttle launches to occur from KSC was the launch of STS-71 on June 27, 1995, from LC-39B with Atlantis and the launch of STS-70 15 days later on Discovery from LC-39A. This marked the shortest time between flights (six days) during NASA’s Space Shuttle program.

The launch was originally scheduled for Nov. 21; however, this date was pushed back to Nov. 22 to address a leak that occurred in the thermal control system in the cabin onboard Dragon.

On Nov. 20, the drone ship Just Read the Instructions departed Port Canaveral, Florida, while under tow from the SpaceX recovery ship named Bob. The duo traveled into the Atlantic Ocean to the first stage recovery zone off the coast of the Carolinas.

On Nov. 21, Falcon 9 rolled out from the Horizontal Integration Facility (HIF) at LC-39A. Before this, the Cargo Dragon spacecraft was integrated with the launch vehicle after being fueled with hypergolic propellant at a different location.

The SpaceX Cargo Dragon 2 for the CRS-25 mission is seen during rollout from the HIF at LC-39A. (Credit: SpaceX)

The rocket was rolled out from the HIF on the Transport Erector, or T/E. Before the launch campaign for SpaceX’s CRS-26, Falcon Heavy launched from LC-39A, which required changes on the T/E. Between missions, the T/E and the pad itself had to be converted back to the Falcon 9 and Dragon configuration.

The Falcon 9 rocket was then rotated from horizontal to vertical on the launch pad. Before launch, cargo loading inside of Dragon occurred. This activity utilizes the crew access arm on the Shuttle-era Fixed Service Structure or FSS.

After the cargo loading was completed aboard Cargo Dragon, the arm was retracted on the FSS.

The main portion of the countdown will begin at the T-35 minute mark with the beginning of the launch autosequence, which means that the countdown will be commanded by Falcon 9’s onboard computers.

At around the same point in the countdown, fueling operations will commence on the launch vehicle. The fueling starts at this point with the loading of RP-1 kerosene on both the first and second stages of Falcon 9.

At around the same time that RP-1 is beginning to flow into the launch vehicle, liquid oxygen, or LOX, will also begin flowing into the first stage.

At the T-20 minute mark before launch, RP-1 loading will be complete on the Falcon 9 second stage. At the same time, a large vent emanating from the T/E will occur, showing that SpaceX and Falcon 9 are progressing toward the business end of the countdown.

LOX loading on the second stage will begin at the T-16 minute mark. Before launch, the T/E will retract to the launch position.

Falcon 9 launches from LC-39A carrying the CRS-25 Cargo Dragon to the ISS. (Credit: SpaceX)

Soon after this, Falcon 9 will enter what is called “startup.”

Three seconds before launch, the nine Merlin 1D engines on the first stage of the Falcon 9 will ignite. The ignition of these engines occurs with ignitor fluid called TEA-TEB and appears as a bright green flash.

At T0, the hold-down clamps on the reaction frame on the launch pad will release Falcon 9 and Dragon as they ascend into the sky. At the same time, the T/E will retract further to protect it from the launch vehicle.

Falcon 9 will next roll to the proper launch azimuth to take it to a 51.6-degree inclined orbit, enabling it to rendezvous with the ISS. The vehicle will then pitch downrange of KSC as it heads over the Atlantic Ocean.

At the end of the first stage flight, the nine Merlin 1D engines will shut down and the second stage will separate. Following this, the single Merlin MVac engine on the second stage will ignite as Dragon continues to ascend to orbit.

The first stage will then conduct a flip maneuver using cold gas thrusters to flip the stage 180 degrees. Four grid fins on the booster will then deploy.

Next, B1076 will conduct a boostback burn to slow the stage down. Soon after, the stage will conduct the entry burn to protect it from the heat of reentry and to slow the stage down.

As it heads into the denser part of the atmosphere, the grid fins on B1076 will activate to steer the vehicle. Next, B1076 will ignite its engine once again for the landing burn in an attempt to land itself on Just Read the Instructions.

At about the same time, the single MVac engine on the second stage will shut down, inserting Dragon into orbit. Soon after, Dragon will separate and continue on its own on its way to the ISS.

(Lead image: A pair of Falcon 9s at SLC-40 (left) and LC-39A (right) before their respective launch attempts on Nov.22. Credit: Ben Cooper)

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