Before a new launch vehicle is cleared for liftoff from Cape Canaveral, federal regulators and Air Force officials meticulously go over the rocket's safety systems to verify the mission will pose no danger to the public.
The process is in motion again as SpaceX prepares to launch its first Falcon 9 rocket, a thoroughly-tested but unproven launcher that could blast off as early as next month.
The Air Force 45th Space Wing and the Federal Aviation Administration are still reviewing paperwork on the new rocket, which is currently on the launch pad at Cape Canaveral for several days of ground tests.
Because of the continuing safety checks, SpaceX founder and CEO Elon Musk says the earliest launch could occur is around March 22, although the 154-foot-tall rocket could be ready before then.
"The rocket itself should be ready to launch by early March," Musk told Spaceflight Now. "We are still working through the schedule for finishing the qualification tests of the flight termination system and receiving final range approval. SpaceX only has limited control over that schedule, so it is difficult to estimate the completion date accurately."
Musk said launch may not occur until April or May.
The flight termination system, or FTS, would destroy the rocket if problems developed causing the fuel-laden booster to veer off course.
The Falcon 9's destruct system features linear-shaped charges along two sides of the rocket, according to SpaceX officials.
"A way to get through the range safety process fast is to use most of the traditional equipment," said Tim Buzza, the Falcon 9 launch director. "It's in their experience base, and you're not trying to get too many new ideas on the table."
Company officials say there are some unique components in the Falcon 9 flight termination system, including new parts vendors, but the launcher carries a standard command receiver and pyrotechnic charges. The rocket has an auto destruct feature and can receive commands from a range safety officer on the ground, senior officials told Spaceflight Now.
Workers won't make final connections of the ordnance charges on the Falcon 9 until it completes fueling and engine tests in the coming days.
SpaceX's smaller Falcon 1 rocket, a predecessor to the medium-class Falcon 9, has launched five times from a diminutive island at Kwajalein Atoll in the central Pacific Ocean. The launch site's remote location away from civilians and valuable property means the Falcon 1's flight termination system carries no ordnance, instead ordering the rocket's engines to shut down if problems develop.
The so-called thrust termination technique is widely used on Russian rockets, but the Air Force requires a more robust system for launches in the continental United States.
New rockets often undergo closer scrutiny, and the Falcon 9 is no different, Air Force and FAA officials told Spaceflight Now.
Before previous inaugural flights, the Air Force has approved the safety systems of new rockets just days before launch.
The Air Force Eastern Range oversees launch operations at Cape Canaveral Air Force Station, providing tracking, communications and safety services for all missions originating from the Space Coast. Headquartered at Patrick Air Force Base just south of Cape Canaveral, the 45th Space Wing manages the range operations.
"Based on [the] status of documentation provided by SpaceX to date, Wing Safety reviews are approximately two-thirds complete," said Col. Loretta Kelemen, the 45th Space Wing's chief of safety. "We are still waiting on a significant amount of data from testing currently being performed by SpaceX and their suppliers as well as some final flight termination system design documentation and final launch site operating procedures."
Air Force officials say their primary interest is the safety of the public, base personnel and nearby launch facilities.
"The Wing's red line in the sand is safety. We can't take a great risk in this area and must ensure compliance with all safety requirements," Kelemen said in a reponse to written questions.
The Falcon 9 launch site is at Complex 40, situated halfway between other operational pads supporting Atlas 5 and Delta 4 rockets. NASA's space shuttle launch pads are also a few miles north of Complex 40.
Because the Falcon 9 is a commercial rocket, the FAA also has jurisdiction in granting a launch license after conducting its own review of the booster's safety systems, according to Ken Wong, manager of the FAA's commercial space licensing and safety division.
The FAA's analysis also accounts for policy, environmental and financial implications, while the Air Force's focus is on safety.
"There are certain differences, but in general, the objective is to have common launch safety requirements [with the Air Force]," Wong said.
"I would say the major part that we really focus on is the safety review," Wong said in an interview. "What that entails is the applicant, in the their licensing application to us, they need to demonstrate that they can safely conduct their proposed launch."
Wong said the FAA is "actively evaluating" SpaceX's license application. By statute, the FAA has 180 days to rule on a license application, according to Wong.
"It's still in the evaluation process within the FAA," Wong said. "At this time, we don't see any major issues, but the determination hasn't been made yet."
Although Wong declined to reveal details of the status of the Falcon 9 application, he said the destruct system is receiving the most attention.
"Every time there's an application, we review the flight safety critical systems, especially for the newer vehicles," Wong said. "A major flight safety critical system is the flight termination system. If the vehicle were to go off course, you definitely want the flight termination system to be functioning."
"For certain companies that have been flying a long time, perhaps the review of the flight termination system may not need to be as in-depth as someone who has flown a lot before or has received a license from us before," Wong said.
The Air Force did not clear the flight termination system on NASA's Ares 1-X test rocket until four days before the first launch attempt last October, according to Kelemen.
Range approvals for the inaugural launches of the Air Force-supported Atlas 5 and Delta 4 rockets came 13 days and 16 days before liftoff, respectively, Kelemen said. Both vehicles entered service in 2002.
All three boosters ultimately flew successfully, and the flight termination system was not activated on those missions.
"The way we treat SpaceX is no different than other applicants in the past," Wong said.
According to Kelemen, Air Force policies require reviews of documentation to be completed within 45 days after they are submitted. But range officials have typically been reviewing SpaceX's documentation within one or two weeks, Kelemen said.
The Air Force must first approve the design of "hazardous and safety critical systems" through documentation provided by the launch operator. Once the designs are approved, the systems including the FTS must face performance margin testing and be installed to meet Air Force guidelines, according to Kelemen.
Range officials are also responsible for verifying the flight termination system is functioning properly during the final countdown.
"Wing Safety expects to provide a rapid response when the required data is provided," Kelemen wrote. "We are committed to doing whatever we can to help SpaceX and all our range customers succeed."
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