Updates: August 2008 - October 2008
Flight 4 Launch Update
Posted October 7, 2008
A week spent reviewing data has confirmed that the flight went really well, including the coast and restart. The mood here at SpaceX is just ecstatic! This is the culmination of six years of hard work by a very talented team. It is also a great relief for me, who led the overall design of the rocket (not a role I expected to have when starting the company). I felt a little sheepish receiving the AIAA award for the most outstanding contribution to the field of space transportation two weeks before this flight.
Orbit was achieved with the first burn terminating at 330.5 km altitude and 8.99 degree inclination. The goal for initial insertion was a 330 km altitude and a 9.0 degree inclination, so this was right on target! Accuracy far exceeded our expectations, particularly given that this was the first time Falcon 1 reached orbit.
The primary purpose of the second burn was to test the restart capability and then burn as long as possible. The upper stage coasted for 43.5 minutes and then burned for 6.8 seconds, which is 4 seconds longer than needed to circularize. Most of the burn was actually done sideways to avoid creating a highly elliptical orbit, hence a change in inclination to 9.3 degrees. The final orbit, confirmed by US Space Command, was 621 km by 643 km.
As an added bonus, we picked up several minutes of video and data from the upper stage when it passed over Kwajalein one orbit later, which showed the stage to be in good condition. You will see some eerie footage of the upper stage drifting in zero g at the end of the video clip below.
Photo caption: After one complete orbit, the SpaceX Falcon 1 Flight 4 vehicle passes over its launch site at the Kwajalein Atoll, and returns a view of the Earth.
While Falcon 1 was the world's first privately developed liquid fuel rocket to reach orbit, I would like to acknowledge and express appreciation for the role of DARPA, the Air Force, the ORS Office of the Department of Defense and ATSB and the Malaysian government. They played an important role as early "beta" customers of Falcon 1. There are many individuals in those organizations, as well as in NASA, NRL, FAA, USAKA/RTS, other departments of the US government and the private sector to whom we owe gratitude for their support and advice. You didn't have to help, but you did, often at risk of career and credibility, so you have my deepest thanks.
The next flight of Falcon 1 is tentatively scheduled for March next year and will carry a Malaysian primary satellite, as well as US government secondary satellites, to near equatorial orbit. Flight 6 will probably be a Defense Department satellite in the summer and Flight 7 a commercial satellite mission in the fall. In 2010, I expect the launch cadence for Falcon 1 to step up to a mission every two to three months.
Below is a highlight reel of the Falcon 1 flight, including the restart and video footage from the upper stage when it does its first orbit back over Kwajalein. Some of this has not been shown before, so there is something new even if you watched the live webcast.
--Elon--
Photo caption: Liftoff of Falcon 1, Flight 4 from the Kwajalein Atoll on September 28, 2008 (UTC).
Click above image to view the highlight reel in the SpaceX Video Gallery.
Flight 4 Launch Update
Posted September 28, 2008
Post Launch Statement
Wow, this is a great day for SpaceX and the culmination of an enormous amount of work by a great team. The data shows we achieved a super precise orbit insertion — middle of the bullseye — and then went on to coast and restart the second stage, which was icing on the cake.
I will have a more complete post launch statement tomorrow, as right now I'm in a bit of a daze and need to go celebrate :)
--Elon--
A. Launch of the Falcon 1 Flight 4 vehicle from Omelek Island, in the Kwajalein Atoll, 2,500 miles southwest of Hawaii. Liftoff occurred Sunday 28 September 2008, at 4:15 PM (PDT), 23:15 (UTC).
B. The critical stage separation sequence began about 2 minutes and 37 seconds into flight with shutdown of the Merlin first stage engine, then separation of the first and second stages, followed by ignition of the Kestrel second stage engine.
C. A few seconds after second stage ignition, the fairing (nose cone) that covers the payload section separates from the vehicle and falls to Earth.
D. About nine and a half minutes after launch, the second stage engine shuts down, and the Falcon 1 becomes the first privately developed liquid fuel rocket to orbit the Earth.
Flight 4 Launch Update
Posted September 27, 2008
Flight 4 of Falcon 1
Falcon 1 is currently cleared for liftoff sometime between 4 p.m. and 9 p.m. (California time) tomorrow, Sunday September 28th. Of course, if we see anything that requires investigation, the launch will be postponed, but we'll let you know as soon as we know. As with prior flights, you can access the webcast from the SpaceX site: www.spacex.com
--Elon--
Photo caption: Falcon 1 Flight 4 vehicle on the launch pad at Omelek island, Kwajalein Atoll.
Flight 4 Launch Update
Posted September 23, 2008
Flight 4 of Falcon 1
The static fire took place on Saturday [20 Sep 2008, CA time], as expected, and no major issues came up. However, after a detailed analysis of data, we decided to replace a component in the 2nd stage engine LOX supply line. There is a good chance we would be ok flying as is, but we are being extremely cautious.
This adds a few extra days to the schedule, so the updated launch window estimate is now Sept 28th through Oct 1st [CA time].
--Elon--
Flight 4 of Falcon 1
Posted September 19, 2008
Flight 4 of Falcon 1
As mentioned in my update last month, we do expect to conduct a launch countdown in late September — as scheduled.
Having said that, it is still possible that we encounter an issue that needs to be investigated, which would delay launch until the next available window in late October. If preparations go smoothly, we will conduct a static fire on Saturday and launch sometime between Tuesday and Thursday (California time).
The SpaceX team worked hard to make this launch window, but we also took the time to review data from Flight 3 in detail. In addition to us reviewing the data, we had several outside experts check the data and conclusions. No flight critical problems were found apart from the thrust transient issue.
Flight 5 production is well underway with an expected January completion date, Flight 6 parts are on order and Flight 7 production will begin early next year. We are now in steady state production of Falcon 1 at a rate of one vehicle every four months, which we will probably step up to one vehicle every two to three months in 2010.
--Elon--
Expedited delivery — SpaceX purchased a C-17 flight from the USAF to fly the Falcon 1 Flight 4 vehicle from Los Angeles International to the Kwajalein Atoll.
SpaceX's Falcon 1 Flight 4 on the launch pad at Omelek Island in the Kwajalein Atoll of the Marshall Islands (19 Sep 2008).
Falcon 1, Flight 3 Mission Summary
Posted August 6, 2008
Timing is Everything
On August 2nd, 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.
--Elon--
Liftoff of Falcon 1, Flight 3 from the Kwajalein Atoll on August 2, 2008 (CONUS).
Click above image to play streaming video in Windows Media Player.
Plan Going Forward
Posted August 2, 2008
Plan Going Forward
It was obviously a big disappointment not to reach orbit on this flight [Falcon 1, Flight 3]. On the plus side, the flight of our first stage, with the new Merlin 1C engine that will be used in Falcon 9, was picture perfect. Unfortunately, a problem occurred with stage separation, causing the stages to be held together. This is under investigation and I will send out a note as soon as we understand exactly what happened.
The most important message I’d like to send right now is that SpaceX will not skip a beat in execution going forward. We have flight four of Falcon 1 almost ready for flight and flight five right behind that. I have also given the go ahead to begin fabrication of flight six. Falcon 9 development will also continue unabated, taking into account the lessons learned with Falcon 1. We have made great progress this past week with the successful nine engine firing.
As a precautionary measure to guard against the possibility of flight 3 not reaching orbit, SpaceX recently accepted a significant investment. Combined with our existing cash reserves, that ensures we will have more than sufficient funding on hand to continue launching Falcon 1 and develop Falcon 9 and Dragon. There should be absolutely zero question that SpaceX will prevail in reaching orbit and demonstrating reliable space transport. For my part, I will never give up and I mean never.
Thanks for your hard work and now on to flight four.
--Elon--
(In a message to Employees, August 2, 2008)