December 10, 2019
Digital depiction of a Falcon 9 rocket’s upper stage. Credit: SpaceX
On Thursday, December 5th, SpaceX launched a Falcon 9 rocket from Cape Canaveral, Florida during SpaceX's 19th ressupply mission to the International Space Station (ISS), under their Commercial Resupply Cargo Services contract with NASA. They successfully deployed their Dragon spacecraft with over 5,700 pounds of cargo.
[Read: SpaceX Dragon arrived to the International Space Station this morning with over 5,700 pounds of cargo!]
The @SpaceX Dragon is holding at 30m from @Space_Station for some checks before beginning its final approach to the capture point. @AstroDrewMorgan and @Astro_Luca are standing by to capture it with the station's robotic arm. Watch: https://t.co/DxgojCBOHv— NASA (@NASA) December 8, 2019
Questions? Use #AskNASA pic.twitter.com/JWtyr3b0bs
SpaceX took advantage of this launch to conduct an extended demonstration mission for the Falcon 9 rocket’s upper stage which aimed to show SpaceX’s ability to perform long duration flights to take United States military payloads directly into higher altitudes in geosynchronous orbit.
On Friday during a meeting with reporters at SpaceX headquarters in Hawthorne, California, the SpaceX president and chief operating officer, Gwynne Shotwell, said Thursday's extended test was successful.
"This was our third long coast (demonstration). They’re still looking at the data, but I got a thumbs up this morning that it looked like it went really well."
During this extended test, the Falcon 9 rocket lifted off into space, upon arrival the rocket's second stage released the Dragon cargo to low Earth orbit less than 10 minutes after liftoff. Usually SpaceX preforms a short deorbit burn soon after releasing the Dragon spacecraft into orbit, but this time the rocket's upper stage continued moving, coasting around the planet for several orbits before igniting its Merlin engines again for a longer firing that lasted approximately 20.1 seconds. The director of Dragon mission management at SpaceX, Jessica Jensen, said:
"After Dragon is dropped off into orbit, the Falcon 9 second stage stage is going to continue on for a thermal demonstration. So it’s going to be a long six-hour coast that then results in a disposal burn."
The Falcon 9 rocket is powered by super cold kerosene and cryogenic liquid oxygen propellants, they also had to perform a thermal test of the upper stage to see if it can keep the fuel at optimal temperatures so that when the craft's engine's are restarted the fuel does not freeze during a long coasting period that can involve many hours. A well-balanced temperature is needed to ignite optimally and proceed moving. Engineers added baffles to the second stage tanks to help prevent liquid propellant from pooling on the tank walls and tested if the craft can keep its temperature balanced.
SpaceX successfully demonstrated that their craft is also capable of performing extended missions. These kind of mission can be used by the U.S military to place satellites on trajectories high over Earth, where the spacecraft can remain over the same geographic region at an altitude of more than 22,000 miles over the equator, some in circular geosynchronpous orbits. For example, SpaceX could be contracted by the military to take a United States government’s top secret spy satellite on a long duration ride into geosynchronous orbits. These type of missions could last over 5 hours, unlike regular Dragon missions to the ISS that typically reach their target deployment orbit in less than 10 minutes, or a commercial communications satellite deployment mission which is usually deployed around a half an hour after liftoff. Those are shorter trips compared to the duration needed for a future military mission.