NASA and SpaceX are getting ready for tomorrow’s (June 1) launch of the SpaceX-11 (SpX-11) cargo mission to the International Space Station (ISS). The Dragon spacecraft will be packed full of supplies and equipment for the ISS crew as usual, but what makes this mission unique is that this Dragon has been to ISS before. Originally launched in 2014, SpaceX had to change out some of the components, but most of it took this ride on SpaceX-4. [UPDATE: The launch was successful on June 3, 2017, a 2-day delay after weather scrubbed the June 1 attempt. Dragon’s arrival at the ISS is scheduled for June 5. First stage landing at Landing Zone 1 on Cape Canaveral Air Force Station also was successful.]

During a press conference today, ISS program manager Kirk Shireman was asked if NASA got a discount for agreeing to use a second-hand spacecraft. Shireman explained that NASA has a fixed price contract with SpaceX for these launches so it does not quite work like that. Over the course of time, both sides need to make changes resulting in what he called “equitable adjustments” for each. He could not cite precisely what adjustment NASA may have received in this case.



NASA ISS Program Manager Kirk Shireman. Photo credit: NASA

Hans Koenigsmann, SpaceX’s Vice President for Mission Assurance, said the spacecraft’s hull and basic structure are unchanged, but some components — including the thrusters, batteries, some avionics, and heat shield — were replaced and the entire vehicle recertified.

Launch is scheduled for 5:55:51 ET from Launch Complex 39A (LC-39A) at Kennedy Space Center. The weather forecast is 70 percent favorable, with a risk of afternoon thunderstorms. The first stage will land 7 minutes and 27 seconds later at SpaceX’s Landing Zone 1 on the adjacent Cape Canaveral Air Force Station (CCAFS).

It is the fifth attempt to land on land; the other four were successful (Dec. 31, 2015; July 18, 2016; Feb. 18, 2017: and May 1, 2017). SpaceX has successfully landed another six first stages on drone ships out at sea. The launch vehicle’s trajectory determines whether the first stage is recovered on land or a drone ship. The first flight of a reused first stage took place earlier this year.

Reusability is SpaceX’s watchword. SpaceX founder, CEO and Lead Designer Elon Musk is convinced it is the key to lowering launch costs and enabling bold goals such as the settlement of Mars.

NASA’s space shuttle was the first reusable space transportation system. It never achieved the cost reductions promised at the beginning of the program because of the high costs of refurbishing the solid rocket boosters and shuttle orbiters after each flight (the large cylindrical External Tank was not reused). Consequently there are many skeptics about the true cost reductions that can result from reusability, but that has not deterred Musk.

Asked today about the cost savings for reused Falcon 9s, Koenigsmann demurred, saying one must think about it in the long term. First the company must recoup the money it spent on developing and testing Falcon 9 and its predecessor, Falcon 1, noting that three of the four Falcon 1 flights and two Falcon 9s failed. “Maybe the 10th flight, maybe the 20th flight, that’s when you finally could see some money saved.”

SpaceX does offer a price discount to its commercial customers for buying launches on previously flown Falcon 9s. SpaceX President Gwynne Shotwell said the discount is 10 percent.

NASA selected SpaceX not only for its commercial cargo program to resupply the ISS with equipment, experiments and other necessities, but for its commercial crew program to ferry astronauts back and forth. Koenigsmann said today that SpaceX is still targeting the first demonstration launch (Demo 1) of its Crew Dragon for the end of this year and the second, Demo 2, for the first quarter of 2018. Demo 1 will be unoccupied. Demo 2 will carry two crew members. Assuming all goes well, operational flights would begin thereafter.

SpaceX leases LC-39A at Kennedy Space Center from NASA. It has another launch site at CCAFS next door, Space Launch Complex-40 (SLC-40), which was badly damaged when a Falcon 9 exploded on September 1, 2016 during fueling for a pre-launch test. Work continues on repairing the launch pad and Koenigsmann said launches will resume in late summer or early fall. The company will use both LC-39A and SLC-40 as it tries to accelerate its launch rate and work off the backlog caused by the explosion and resulting investigation.

SpX-11 is delivering 4,500 pounds of research supplies and investigations according to Camille Alleyene, Associate Program Scientist for the ISS at NASA’s Johnson Space Center. Among the cargo are mice and fruitflies. The rodent experiments are investigating how to reduce bone loss and grow new bone. The fruitfly research is related to cardiovascular changes.

Dragon’s unpressurized trunk will be filled with three payloads: the Neutron Star Interior Composition Explorer (NICER) for astrophysics research; the Multiple User System for Earth Sensing (MUSES), a platform onto which up to four Earth-sensing instruments can be placed; and the Roll Out Solar Array (ROSA), to test a new type of solar array. NICER and MUSES will be installed onto the ISS. ROSA will be rolled out from its storage location in Dragon’s trunk and tested for 7 days. It then will be retracted into its housing in the trunk. The trunk is detached from Dragon as it reenters the atmosphere and destroyed by the heat of reentry while the main capsule continues to Earth and splashes down in the Pacific Ocean off the coast of California.

In total, Dragon is delivering approximately 6,000 pounds of experiments, equipment and supplies to the ISS. It is due to arrive at the ISS on Sunday, June 4, and remain there for about a month.

If the launch does not take place for any reason tomorrow, the next opportunity is Saturday, June 3, at 5:07 pm ET. The weather forecast for that day is 60 percent “go.”