SpaceX engineers made final preparations Monday for the planned Tuesday launch of a Falcon 9 rocket carrying a Dragon cargo ship loaded with more than 5,200 pounds of supplies, equipment and science gear bound for the International Space Station. The company also will attempt to land the booster’s first stage on an off-shore barge, a key element in founder Elon Musk‘s long-range plans to lower costs by recovering, refurbishing and re-flying rocket hardware.
“We are extremely interested in the success of this flight in terms of getting cargo to the ISS,” station Program Manager Mike Suffredini told reporters. “But as an agency, we’re also extremely proud of our affiliation with SpaceX and very excited about the steps they take to further spaceflight in general and reduce the cost.”
Hans Koenigsmann, vice president of mission assurance for SpaceX, stressed that while the landing test was an important goal for the company’s long-range plans, “the main mission is absolutely to get cargo to the station and to make sure the station’s supply (chain) is steady and stable and reliable.”
Running three weeks late because of now-resolved problems encountered during an engine test firing last month, the 208-foot-tall Falcon 9 was scheduled for liftoff from complex 40 at the Cape Canaveral Air Force Station at 6:20:29 a.m. EST (GMT-5) Tuesday, roughly the moment Earth’s rotation moves the booster into the plane of the space station’s orbit. Forecasters predicted a 70 percent chance of acceptable weather.
It will be the company’s fifth operational resupply mission under a $1.6 billion contract with NASA calling for 12 flights. It will be the first U.S. station supply flight since an Orbital Sciences Antares booster exploded seconds after liftoff Oct. 28, destroying a Cygnus cargo ship making the company’s third flight under a separate $1.9 billion contract.
Orbital’s Antares rocket is now grounded pending a switch to different engines, leaving SpaceX as NASA’s only provider of U.S.-based resupply services. The Russians also launch supplies using unmanned Progress cargo ships and larger Japanese HTV supply ships fly once every year or so. Three Progress launches are planned between now and early August, along with an HTV launch on Aug. 17.
But with Orbital out of action in the near term, the SpaceX flights are critical for sustaining the station’s six-person crews. Suffredini said a SpaceX failure, depending on its severity and the steps needed to recover, could force NASA to reduce the station’s crew from six to three or, in a worst-case scenario, to briefly abandon the laboratory.
Before the loss of the Orbital Sciences cargo ship, NASA and its partners were trying to keep about six months of supplies on board the station at all times. Given the failure, that margin is expected to be reduced to four or five months.
“So if something happened to SpaceX, we’d have to figure out where we were and how quickly they could return to flight and we would react accordingly,” Suffredini said. “The crew has enough supplies, including research, to continue to work for somewhere between four and six months. So the decision we’d have to make is, how quickly can SpaceX get back up? And then what can we do with our Russian colleagues with regard to any support they might supply?
“Then we’d have to look together about what are the right steps to take, do we go ahead and let everybody go home until we’re ready to resupply again, or do we step down to three crew? And I suspect that’s what we’d do if we had to, we’d step down to three crew first.”
But given the supplies that are constantly stockpiled on board, mission planners would have “quite a bit of time” to work through launch problems if they occur.
“In all cases, we have plenty of time to decide what to do next, figure out what we’re really dealing with and then figure out how we want to react to it,” he said.
While station resupply is the primary goal of the SpaceX mission, the company hopes to achieve another milestone with an attempt to land the first stage on a remotely operated barge stationed some 200 miles east of Jacksonville. If it works, the company’s long-range goal of routinely recovering and re-flying booster stages, dramatically lowering the cost of access to space, will move a step closer to reality.
“Reusability is the critical breakthrough needed in rocketry to take things to the next level,” Musk said during the MIT AeroAstro Centennial Symposium in October. “We’ve been able to soft land the rocket booster in the ocean twice so far.
“So what we need to do is be able to either land on a floating platform or ideally boost back to the launch site and land back at the launch site. But before we boost back to the launch site and try to land there, we need to show that we can land with precision over and over again, otherwise something bad could happen.”
He gave the initial landing attempt a 50 percent chance of success.
“If we land on (the barge), I think we’ll be able to refly that booster,” Musk said. “But it’s probably, maybe not more than a 50 percent chance, or less, of landing it on the platform for the first time. But there are … at least a dozen launches that will occur over the next year, and I think it’s quite likely, probably 80-to-90 percent likely, that one of those flights will be able to land and refly. So I think we’re quite close.”
Joan Johnson-Freese, professor of national security affairs at the U.S. Naval War College, said “being able to do a soft-landing recovery of rocket boosters saves launch companies time — and time is money.”
“If commercial spaceflight is ever going to be anything like a ‘normal’ industry, fast turnaround and (relatively) low costs are imperative,” she told CBS News in an email exchange last month. “Airplanes land ready to use again — not requiring months of hanger time between flights. The analogy with recoverable rocket boosters isn’t perfect, but it’s close.”
The Falcon 9 will launch into the plane of the station’s orbit on a northeasterly trajectory. The first stage’s nine SpaceX Merlin 1D engines will fire for about two minutes and 37 seconds to boost the Dragon capsule and Falcon 9 second stage out of the dense lower atmosphere to an altitude of around 50 miles and a velocity of 10 times the speed of sound.
Four seconds after engine shutdown, the first stage will fall away and and eight seconds later, the second stage’s single Merlin 1D engine will ignite to continue the push toward orbit. If all goes well, the Dragon capsule will be released to fly on its own about 10 minutes after launch.
The first stage, meanwhile, will attempt a powered descent to the remotely operated ship some 200 miles east of Jacksonville, extending four landing legs a few moments before touchdown just before the Dragon capsule is released into orbit. The barge, modified for use as a landing platform, features a deck measuring 300 feet long and 170 feet wide and thrusters to maintain its position to within a few feet. SpaceX calls it an “autonomous spaceport drone ship.”
“Returning anything from space is a challenge, but returning a Falcon 9 first stage for a precision landing presents a number of additional hurdles,” SpaceX said in a blog post last month. “At 14 stories tall and traveling upwards of 1300 m/s (meters per second, or 2,900 mph), stabilizing the Falcon 9 first stage for re-entry is like trying to balance a rubber broomstick on your hand in the middle of a wind storm.
“To help stabilize the stage and to reduce its speed, SpaceX relights the engines for a series of three burns. The first burn — the boostback burn — adjusts the impact point of the vehicle and is followed by the supersonic retro propulsion burn that, along with the drag of the atmosphere, slows the vehicle’s speed from 1300 m/s to about 250 m/s (560 mph). The final burn is the landing burn, during which the legs deploy and the vehicle’s speed is further reduced to around 2 m/s (4.5 mph).”
The Falcon 9 first stage features four deployable fins mounted around the upper end of the booster. The fins can be repositioned in flight to help control the rocket’s lift and orientation. The use of the fins, along with steering by the first stage engines, “will allow for precision landing — first on the autonomous spaceport drone ship, and eventually on land,” the company said in its blog post.
Assuming a successful touchdown, Koenigsmann said SpaceX engineers standing by on a nearby support ship will wait one to two hours while residual liquid oxygen boils away and vents overboard. Then they will move in to lock the landing legs to the drone ship’s deck and secure the booster for the long haul back to Jacksonville.
But the landing attempt, while important to SpaceX, is a strictly secondary objective. The primary goal of the flight is to deliver cargo to the space Station. The Dragon capsule is loaded with more than 4,000 pounds of cargo in the ship’s pressurized hold, along with a 1,000-pound atmospheric research instrument mounted in an unpressurized trunk section accessible by the lab’s robot arm.
The Cloud Aerosol Transport System, or CATS, instrument will be extracted from the trunk later and mounted on a platform attached to the Japanese Kibo lab module.
“CATS is a spectacular opportunity to utilize the International Space Station to achieve important Earth-science measurements at a modest cost,” said Matthew McGill, the principal investigator. “The goal of CATS is to measure and characterize the global distribution of clouds and tiny airborne particles, or aerosols, in the Earth’s atmosphere.”
About the size of a refrigerator, CATS features a compact telescope, a pair of lasers and sensitive detectors. Together, they make up a sophisticated LIDAR system that works “by sending discrete pulses of laser light into the Earth’s atmosphere and detecting the tiny, tiny fraction of that light that scatters straight back toward our collecting telescope,” McGill said.
Studying clouds and aerosols from low-Earth orbit will allow researchers to monitor the effects of transient events like volcanic eruptions in near realtime, to monitor the effects of natural and human-generated pollutants and to study the factors contributing to climate change.
“Clouds are one of the largest uncertainties right now in predicting climate change because clouds are the key determiner of the planet’s average temperature,” McGill said. “But in create more accurate climate models, we need more accurate representations of clouds to put in the models. That is information CATS can provide.”
Cargo packed into the Dragon capsule’s pressurized compartment includes food, clothing and personal items for the station’s six-member crew, research equipment and spare parts along with high-priority items intended to replace cargo lost in the Antares launch failure in October, including a variety of student experiments.
Among the science gear is a fruit fly lab for studies of the immune system, a flatworm regeneration experiment to learn more about how the organisms regenerate and replace damaged cells and an investigation to learn how proteins clump together in fibrous plaques like the amyloids that play a role in Alzheimer’s disease.
If all goes well, the Dragon cargo ship will fly a complex rendezvous to catch up with the station Thursday around 6:25 a.m., pulling up to within about 30 feet and then standing by while Expedition 42 commander Barry “Butch” Wilmore, operating the lab’s robot arm, locks onto a grapple fixture.
Ground controllers then will take over, remotely operating the arm to move the Dragon capsule into position for berthing at the Earth-facing port of the forward Harmony module. Wilmore, assisted by European Space Agency astronaut Samantha Cristoforetti, will operate the common berthing mechanism, driving home motorized bolts to lock the spacecraft in place.
The Dragon is expected to remain attached to the station for about a month. As the astronauts unload the capsule, they will repack it with some 3,600 pounds of no-long-needed equipment, trash and experiment samples. Wilmore and company will use the station’s robot arm to detach the capsule, releasing it for a fiery nighttime descent to Earth. Splashdown in the Pacific Ocean southwest of Sand Diego is expected around 8:30 p.m. on Feb. 7.