Last Updated Apr 8, 2016 8:50 PM EDT
An upgraded SpaceX Falcon 9 rocket rocket boosted a Dragon cargo ship into orbit Friday, kicking off a two-day flight to the International Space Station to deliver 3.5 tons of cargo, including an innovative inflatable module that could pave the way to future deep space habitats and commercial space stations.
And in a notable first for the California rocket company, the booster's first stage flew itself to a picture-perfect touchdown on an off-shore barge, whimsically named the "Of Course I Still Love You," stationed about 185 miles northeast of Cape Canaveral.
Video from a company aircraft showed the 156-foot-tall stage descending vertically on the power of a single rocket engine and sticking the landing just a few feet from the center of the drone ship's deck, stable on its splayed landing legs as the ship rocked in slightly choppy seas.
"'Of Course I Still Love You,' we have a Falcon 9 on board," a SpaceX engineer triumphantly radioed about eight minutes and 35 seconds after launch.
It was the latest in a series of dramatic tests to perfect re-entry and landing techniques so spent rocket stages can be routinely recovered, refurbished and relaunched, a key element in SpaceX CEO Elon Musk's drive to lower the cost of spaceflight.
"I think this was a really good milestone for the future of spaceflight, I think it's another step toward the stars," Musk told reporters after the landing. "In order for us to really open up access to space, we've got to achieve full and rapid reusability.
"Being able to do that for the primary rocket booster is going to be a huge impact on costs," he said. "It'll obviously take us a few years to make that smooth and make it efficient, but I think it's proven that it can work."
SpaceX successfully landed a booster stage at the Cape Canaveral Air Force Station last December, but Friday's touchdown was the first on an off-shore barge after several near misses. The eventual payoff, Musk said, will be dramatically lower launch costs.
"The cost to refuel our rocket, it's mostly oxygen on board, is only $200,000 to $300,000, but the cost of the rocket is $60 million," he said. "Fully and rapidly reused, it's somewhere on the order of a hundred-fold cost reduction. You still have your fixed costs, but in marginal costs it's a hundred-fold reduction."
But the landing, however successful, was a strictly secondary objective. The primary goal of the company's eighth operational space station resupply flight is delivery of some 7,000 pounds of cargo and equipment to the lab complex.
The mission began when the Falcon 9s nine first-stage engines roared to life at 4:43 p.m. EDT (GMT-4), generating 1.5 million pounds of sea-level thrust and a ground-shaking roar as they pushed the 213-foot-tall rocket away from launch complex 40 at the Cape Canaveral Air Force Station.
Climbing directly into the plane of the space station's orbit, the Falcon 9 put on a spectacular afternoon sky show, trailing a brilliant jet of fiery exhaust as it smoothly accelerated away to the northeast to kick off a two-day rendezvous.
The first stage boosted the rocket out of the lower atmosphere, shutting down and falling away about two-and-a-half minutes after liftoff. The single Merlin 1D engine powering the Falcon 9's second stage then ignited to continue the climb to orbit.
The first stage, meanwhile, flipped around and restarted three of its engines to slow down and head back toward Florida. Another rocket firing slowed the craft still more for re-entry with a final "burn" to set down on the deck of the drone ship.
Company officials opted for a barge landing attempt Friday because of the relatively heavy weight of the loaded Dragon capsule and to gain more experience with off-shore recoveries. More than half of SpaceX's launchings overall will involve heavy payloads, making barge landings the only viable option for recovery.
And this time around, it worked like a charm. After draining residual propellants and welding the rocket's landing feet to the deck, the SpaceX drone ship will haul the booster back to Port Canaveral for off-loading and detailed post-flight inspections.
Musk said he hopes to re-launch the refurbished stage in the next few months to demonstrate its reusability. He did not identify the payload.
"We're going to do a series of test fires, we're hoping to do that at the Cape," Musk said. "Our thought is to fire it 10 times in a row on the ground and if things look good at that point, we feel it's qualified for reuse and launch. We're hoping to relaunch on an orbital mission probably around May or June. So pretty soon."
President Obama tweeted "congrats SpaceX on landing a rocket at sea. It's because of innovators like you & NASA that America continues to lead in space exploration."
Tweeted former space shuttle flight director and program manager Wayne Hale: "And they said it couldn't be done (at least no one has ever done it) until, of course, you did it."
While the first stage was flying back to Earth, the Falcon 9 second stage chalked up a flawless flight of its own, shutting down as planned 10 minutes after launch. The SpaceX Dragon cargo ship then separated to continue the station chase on its own, followed a few minutes later by deployment of its solar arrays.
If all goes well, the Dragon will pull up to within about 30 feet of the space station early Sunday and then stand by while British astronaut Timothy Peake, operating the lab's robot arm, locks onto a grapple fixture. Flight controllers in Houston then plan to take over arm operations, pulling the Dragon in to a berthing at the forward Harmony module's Earth-facing port.
The Dragon will be the third cargo ship to arrive at the space station in just 15 days, a record for the lab project, following the berthing of an Orbital ATK Cygnus supply ship March 26 and a Russian Progress freighter on April 2. Altogether, more than 12 tons of cargo and supplies will have reached the lab in a little more than two weeks.
The Dragon is loaded with 1,410 pounds of science gear, 1,205 pounds of crew supplies, 674 pounds of station hardware, 26 pounds of spacewalk equipment, 238 pounds of computer gear and 72 pounds of Russian equipment.
Also on board: 20 mice that are part of an Eli Lilly experiment to learn more about muscle atrophy and bone loss in space. Other experiments are focused on plant growth, fungi in space, the growth of microbes on the station and student research on genetics and immune system changes in orbit.
A wide variety of other research also is on board, along with 25 student experiments to replace those lost in the June launch failure.
Equally important to NASA, the Dragon will bring back biological samples that have been stored aboard the station when the supply ship returns to Earth around May 11, including blood and saliva samples collected from Scott Kelly during his nearly one-year stay in orbit.
But the clear centerpiece of the Dragon's cargo is the 3,100-pound Bigelow Expandable Activity Module, or BEAM, a collapsed compartment that will be pulled out of the Dragon's lower unpressurized trunk section and attached to the station's Tranquility module on April 16.
Around May 26, the module will be inflated, or "expanded," using station air and internal tanks, pressurized to match the lab's cabin atmosphere. Fully expanded, BEAM will measure 13 feet long and 10.5 feet wide. Internal volume will be about 565 cubic feet, or about the size of a small bedroom. It is not equipped with lights or any other crew amenities.
During a two-year test period, sensors will record temperature, pressure and radiation levels to characterize the module's performance. Because the technology is untried, station astronauts will leave the BEAM hatch closed most of the time, entering a few times each year to download recorded sensor data. At the end of its test period, the compartment will be detached to burn up in the atmosphere.
"We want to understand the structural integrity, the radiation performance of (the module) and the temperature controls in order to help inform our choices for deep space habitats," said Jason Crusan, director of NASA's Advanced Exploration Systems Division. "So we're going to do that over these two years."
Expandable modules offer a significant advantage over traditional solid-body compartments, taking up much less room atop a launch vehicle and allowing much roomier, lighter-weight modules to be launched than could otherwise be accommodated atop current rockets.
Billionaire Robert Bigelow, whose company Bigelow Aerospace of Las Vegas built the BEAM expandable under a $17.8 million contract with NASA, sees his module as a stepping stone to the future, an attempt to prove the technology works as advertised in the real-world space environment.
Bigelow hopes to launch much larger compartments with three times the volume of a typical station module around the end of the decade to form the core of a commercial space station. Similar modules may prove attractive to NASA as habitats for astronauts heading to Mars or other deep space destinations.
"We would operate these on behalf of nations that have astronaut corps and others that aspire to have them," Bigelow said Thursday. "Right now, the frequency of the opportunity to fly is not often. Other than for the United States and Russia, it's about once every three years. Some countries, maybe never, or very, very seldom. So there is a substantial appetite out there we've discovered, and so we think that's a market."
He said corporations, university researchers and users from other nations are "absolutely mainstream in our thinking, we would very much want to house those folks."
The value of a commercial space station is "a combination of everything, from what you could manufacture product-wise and send down, it could be information you're sending down," he said. "It can change the image of a country overnight to have that kind of facility. ... Naturally, NASA could be a very important customer to that kind of an industry."
As for transportation to and from his proposed space station, Bigelow showed a graphic with commercial crew ferry ships now being built by Boeing and SpaceX docked at the outpost.
NASA began development of an expandable module known as Transhab in the 1990s. But funding eventually was cut off and Bigelow Aerospace took over the technology. The company launched two small expandables on Russian rockets, but BEAM will be the first involving interaction with astronauts in space.
"It is the future," said Kirk Shireman, manager of the International Space Station program at the Johnson Space Center in Houston. "Humans will be using these kinds of modules as we move farther and farther off the planet and as we inhabit low-Earth orbit. So I think it really is the next logical step in humans getting off the planet."
Given the ever-present threat of impacts with space debris micrometeoroids, an inflatable "soft goods" module with fabric walls might seem counterintuitive. But BEAM meets or exceeds space station shielding requirements, making the module as tough or tougher than traditional solid-body compartments.
"There's a reason bullet-proof vests are made out of soft goods, not rigid materials, and it's a strength of materials and stopping power," said Crusan.
And the compartment features an internal framework. Even if a puncture occurred, the module would not collapse and it would be relatively easy to repair.
"I'm afraid I can't share too much because it's proprietary," a company engineer said of the fabric making up the module's skin. "It's a Vectran-like material that creates the outer structure, it's a load bearing structure, and it's covered by MMOD (micrometeoroid) shield protection. That's also our own proprietary materials, but it's been proven to perform up to the standards of ISS, and we look forward to demonstrating that."
Friday's launching was the 23rd of a Falcon 9 rocket since the booster debuted in 2010, the third flight in four months of an upgraded, more powerful version of the booster and the fourth since a catastrophic second stage failure last June that destroyed the previous station-bound Dragon cargo ship.
After replacing suspect internal struts and implementing the planned upgrades, SpaceX successfully launched two commercial satellite missions in December and March and a NASA science satellite in February, using a less-powerful version of the rocket, to clear the way for Friday's resumption of station delivery missions.