SpaceX’s long-awaited “Flight Six” of its Falcon 9 rocket—the first in the new “v1.1″ configuration, powered by uprated Merlin-1D engines—must wait a little longer, having been stalled by an issue which arose during Thursday’s “hot fire” test at Space Launch Complex (SLC)-4 East at Vandenberg Air Force Base, Calif. At the time of writing, SpaceX CEO Elon Musk has remained characteristically quiet about what occurred during the hot fire test, noting on Twitter: “Full thrust achieved on 2 sec static fire” and adding “Some anomalies to be investigated, so launch date TBD.”
The mission will be SpaceX’s first flight from Space Launch Complex (SLC)-4 East at Vandenberg Air Force Base, Calif., and the first Falcon 9 to launch over the Pacific Ocean. It will also trial the uprated Merlin-1D engines for the first time, will attempt a risky propulsive-return-over-water test after first-stage separation, and will showcase a payload fairing to encapsulate its primary cargo: Canada’s 800-pound CASSIOPE communications and science satellite.
CASSIOPE was developed by the Canadian Space Agency (CSA), with project leadership from the University of Calgary’s Institute for Space Research. The spacecraft has been built and integrated by MacDonald Dettwiller & Associates, Inc. (MDA) of Richmond, British Columbia. CASSIOPE carries the Cascade secure digital store-and-forward communications system and the enhanced Polar Outflow Probe (ePOP) atmospheric and solar science experiment. Together, these have produced the impressive “CASSIOPE” acronym, which stands for “Cascade, SmallSat, and IOnospheric Polar Explorer.” The hexagonal satellite measures 71 inches corner-to-corner and about 50 inches tall and will be injected into a highly-elliptical low-Earth orbit, with a “high point” (or “apogee”) of 930 miles and a “low point” (or “perigee”) of 200 miles.
SpaceX’s customer for the mission, MDA, have opted to not allow media representatives to attend the CASSIOPE launch. SpaceX has announced that it will not host media for this launch, nor allow for the setup of remote cameras at SLC-4 East. Instead, the U.S. Air Force will host the media and conducted remote camera setup outside SpaceX’s area of control (despite this not being a USAF launch). This is in stark contrast to how every other launch in the continental United States is conducted by every other launch service provider currently in existence. As noted by AmericaSpace yesterday, SpaceX representative Christina Ra identified the wishes of MDA and SpaceX’s “less-developed” facilities at Vandenberg as pivotal factors in the decision.
During Thursday’s hot fire test—which evaluated the performance of the SLC-4 East fueling equipment and was tasked with demonstrating the nominal start-up of the Falcon 9 v1.1′s nine Merlin-1D first-stage engines—two aborts were experienced, ahead of success on a third attempt. The anomalies which arose during this attempt led to Musk’s clipped announcement of a new launch date “To Be Determined,” which was yesterday (Friday) confirmed by the Canadian Space Agency (CSA). “The launch of Canadian satellite CASSIOPE,” CSA tweeted, “previously scheduled on September 15th is delayed to a later date.” According to NASASpaceflight.com, the anomalies may produce a launch delay of between 1-2 weeks.
The long-awaited “Flight Six” of the 227-foot-tall, two-stage Falcon 9 marks a clear break with convention. For starters, the five previous missions have all flown from Space Launch Complex (SLC)-40 at Cape Canaveral Air Force Station, Fla., delivering either full-scale test articles into orbit or actual Dragon cargo craft to the International Space Station. CASSIOPE represents SpaceX’s first Falcon 9 mission on which a commercial satellite forms the primary payload and, as such, this flight will also showcase a new payload fairing. This 43-foot-long jettisonable fairing was extensively tested in the Reverberant Acoustic Test Facility at NASA’s Plum Brook Station in Sandusky, Ohio, part of the space agency’s Cleveland-based Glenn Research Center. It will protect the 800-pound CASSIOPE spacecraft during its violent climb to orbit.
The launch will also trial the uprated Merlin-1D engines—nine of which will power the rocket’s first stage and one Vacuum variant will propel the second stage—which generate about 56 percent increased sea-level thrust than their Merlin-1C predecessors on the Falcon 9 v1.0. At the “business end” of the first stage, the Merlin-1Ds are configured in an octagonal pattern, with a circle of eight engines and a ninth in the center. This is somewhat different from the “tic-tac-toe” layout of the Merlin-1C engines on the v1.0. The first stage is significantly longer than its predecessor, to account for the larger propellant tanks. When the liftoff command is issued, the first stage engines will generate 1.3 million pounds of thrust—about 200,000 pounds greater than the v1.0—and will push the vehicle uphill for 180 seconds, their propulsive yield gradually rising to 1.5 million pounds in the rarefied high atmosphere.
“Unlike airplanes, a rocket’s thrust actually increases with altitude,” noted SpaceX. “Falcon 9 generates 1.3 million pounds of thrust at sea level, but gets up to 1.5 million pounds of thrust in the vacuum of space. The first-stage engines are gradually throttled near the end of first-stage flight to limit launch vehicle acceleration as the rocket’s mass decelerates with the burning of fuel.” With the nine Merlin-1Ds of the first stage having completed their role and separated, the turn will come of the second stage, which is powered by a single Merlin-1D Vacuum engine. This will burn for about 345 seconds, with a thrust of 180,000 pounds, to insert CASSIOPE into its highly-elliptical low-Earth orbit.
After separation, the first stage will attempt a propulsive water landing in the Pacific Ocean, part of efforts to eventually make the Falcon 9 reusable and capable of touching down back at its launch site. “The initial recovery attempts will be from a water landing,” Musk explained after the CRS-2 Dragon splashdown in March 2013. “The first-stage booster will, after separation, continue in a ballistic arc and execute a velocity-reduction burn in the atmosphere to lessen the impact.” This burn should slow the first stage from about Mach 10 (7,600 mph) to a more controllable descent velocity, after which a second burn will occur just before it impacts the Pacific Ocean to simulate a vertical landing. “I want to emphasize that we don’t expect success in the first several attempts,” Musk cautioned. “Hopefully, next year, with a lot more experience and data, we should be able to return the first stage to the launch site, deploy its landing legs and then do a propulsive landing on land back at the launch site. This year, our efforts will be focused on recovering the first stage … from an ocean landing and then next year it will be about the return to launch site with the landing gear deployed.”
Elon Musk has stressed on Twitter that the large amount of new technology on the first Falcon 9 v1.1 mission raises the risk factor and “the probability of failure is significant.” This will be the first high-altitude, high-velocity test of SpaceX’s strategy to ultimately bring both the first and second stages of the Falcon 9 v1.1 back to the launch site for refurbishment and reuse. It is Musk’s expectation that these attempts will continue on each Falcon 9 mission until a successful return-to-launch-site is achieved. Last month, the company’s Grasshopper VTVL technology demonstrator ascended to an altitude of about 820 feet and conducted a 330-foot lateral (horizontal) maneuver, before alighting back onto its launch pad. Earlier this summer, a Grasshopper rose to a record altitude of 1,066 feet above SpaceX’s test facility in McGregor, Texas, and landed safely.