Falcon 1 Flight 3 : Department of Defense ORS Office, ATSB and NASA
Statement by Elon Musk: CEO and CTO, SpaceX
August 6, 2008
Timing is Everything
On August 2 nd, Falcon 1 executed a picture perfect first stage flight, ultimately reaching an altitude of 217 km, but encountered a problem just after stage separation that prevented the second stage from reaching orbit. At this point, we are certain as to the origin of the problem. Four methods of analysis – vehicle inertial measurement, chamber pressure, onboard video and a simple physics free body calculation – all give the same answer.
The problem arose due to the longer thrust decay transient of our new Merlin 1C regeneratively cooled engine, as compared to the prior flight that used our old Merlin 1A ablatively cooled engine. Unlike the ablative engine, the regen engine had unburned fuel in the cooling channels and manifold that combined with a small amount of residual oxygen to produce a small thrust that was just enough to overcome the stage separation pusher impulse.
We were aware of and had allowed for a thrust transient, but did not expect it to last that long. As it turned out, a very small increase in the time between commanding main engine shutdown and stage separation would have been enough to save the mission.
The question then is why didn't we catch this issue? Unfortunately, the engine chamber pressure is so low for this transient thrust -- only about 10 psi -- that it barely registered on our ground test stand in Texas where ambient pressure is 14.5 psi. However, in vacuum that 10 psi chamber pressure produced enough thrust to cause the first stage to recontact the second stage.
It looks like we may have flight four on the launch pad as soon as next month. The long gap between flight two and three was mainly due to the Merlin 1C regen engine development, but there are no technology upgrades between flight three and four.
Good Things About This Flight
- Merlin 1C and overall first stage performance was excellent
- The stage separation system worked properly, in that all bolts fired and the pneumatic pushers delivered the correct impulse
- Second stage ignited and achieved nominal chamber pressure
- Fairing separated correctly
- We discovered this transient problem on Falcon 1 rather than Falcon 9
- Rocket stages were integrated, rolled out and launched in seven days
- Neither the near miss potential failures of flight two nor any new ones were present
The only untested portion of flight is whether or not we have solved the main problem of flight two, where the control system coupled with the slosh modes of the liquid oxygen tank. Given the addition of slosh baffles and significant improvements to the control logic, I feel confident that this will not be an issue for the upcoming flight four.
The third Falcon 1 launch is scheduled for August 2, 2008. The lift-off will take place from SpaceX's Falcon 1 launch site at the Kwajalein Atoll, approximately 2500 miles southwest of Hawaii. The Falcon 1 launch facilities are situated on Omelek Island, part of the Ronald Reagan Ballistic Missile Defense Test Site (RTS) at United States Army Kwajalein Atoll (USAKA).
This launch will carry the Department of Defense Operationally Responsive Space (ORS) Office's first Jumpstart mission payload. The Jumpstart mission aims to establish a preliminary framework for responsive contracting, and to demonstrate the ability to rapidly integrate and execute a mission, from initial call-up to launch. SpaceDev's Trailblazer bus was selected as the primary payload by the ORS Office after the Jumpstart Pre-shipment Review, conducted on May 20, 2008 (Press Release).
In line with the Jumpstart mission philosophy of responsive contracting, ATSB of Malaysia will fly a RideShare Adapter (RSA), which enables multi-payload manifesting and promotes contract-to-launch times of less than one year. (ATSB will be the primary payload provider on the fourth flight of Falcon 1, scheduled later in 2008.) SpaceX will also fly technology onboard that offers the potential to greatly lower the cost of mission operations. Additional payloads include two cube satellites from NASA, a memorial flight from Space Services, Inc and digital images of artwork from over 400 students in McGregor, TX, where SpaceX owns and operates an engine and structural test facility.
The Flight 3 Webcast will provide live coverage of launch activities. The webcast will be accessible via a link on the SpaceX home page at www.SpaceX.com.
Click the links below to access the following resources:
All media inquiries should be directed to Diane Murphy, VP, Marketing and Communications at 310.363.6714 or email@example.com.
The latest pictures and information leading up to launch will be posted here, with the most recent at the top.
Falcon 1 on the launch pad.
Final payload installation and Quality Assurance checks (L) and Encapsulation (R) have been completed.
Falcon 1 First and Second Stages on the tracks in the SpaceX hanger on Omelek Island.
Falcon 1 First Stage arrives in Guam.
Falcon 1 First Stage (development hardware) during recovery training operations in the San Diego harbor.
The Falcon 1 First Stage, bound for Kwajalein (via Guam), is loaded on a ship in Long Beach, California.
The Falcon 1 First Stage is loaded on a truck bound for Long Beach, California.
The Falcon 1 First Stage is shrink-wrapped in SpaceX's Hawthorne, California headquarters to protect it during shipment to Kwajalein.
The Falcon 1 First Stage awaits final preparations in SpaceX's Hawthorne, California headquarters prior to shipment to Kwajalein.
*Continental United States (CONUS) date