Wrapping up a two-day transit from a launch pad in Florida, a SpaceX Dragon capsule autonomously linked up with the International Space Station Saturday with more than 7,300 pounds of cargo, including new solar arrays, crew supplies, and experiments looking at how spaceflight affects the biology of tardigrades and baby squid.
The tardigrades and squid are part of scientific investigations to examine biological changes caused by microgravity might affect humans. The two solar array wings will augment the space station’s aging electrical grid.
After a smooth rendezvous, the Cargo Dragon spaceship docked with the upper port of the space station’s Harmony module at 5:08 a.m. EDT (0908 GMT) as the orbiting complex soared 258 miles (415 kilometers) over the South Pacific Ocean.
Astronauts Shane Kimbrough and Megan McArthur monitored the Dragon spacecraft’s automated final approach from a position inside the space station.
A few minutes after the initial docking, the Dragon capsule retracted its docking ring, and 12 hooks drove closed to create firm mechanical connection with the space station.
“Hard capture is complete, and it’s a great day seeing another Dragon on the ISS,” radioed Leslie Ringo, spacecraft communicator at NASA’s mission control in Houston.
“It was a great approach, and it was awesome watching it come on in, and we’re glad it’s here,” Kimbrough replied. “Looking forward all the science and other goodies it brought up, along with the EVA solar arrays, so it’s going to be a great few weeks as we get into Dragon and get things out. So thanks to the team for everything. Looking forward to working with everything on-board.”
Here’s the moment the Cargo Dragon spacecraft linked up with the International Space Station, delivering fresh food, experiments, and new solar arrays.
— Spaceflight Now (@SpaceflightNow) June 5, 2021
Kimbrough and crewmate Thomas Pesquet are scheduled to head outside the space station for a pair of spacewalks, or EVAs, June 16 and June 20 to connect the two new solar array wings to the far left, or port, side of the lab’s huge power truss.
The Cargo Dragon capsule launched at 1:29 p.m. EDT (1729 GMT) Thursday aboard a Falcon 9 rocket from NASA’s Kennedy Space Center in Florida.
While astronauts open hatches and unpack the Dragon’s pressurized compartment, the space station’s Canadian-built robotic arm will reach into the capsule’s unpressurized trunk and remove the two solar array wings. The arm will transfer the solar arrays to a mounting bracket on the space station’s power truss, which stretches as long as a football field.
The International Space Station Roll-Out Solar Array, or iROSA, units are spooled on cylindrical canisters. They are designed to roll out like a yoga mat. Conventional solar panels used on most spacecraft unfold like an accordion, and are heavier and take up more volume than the iROSA wings.
Kimbrough and Pesquet will install and configure the iROSA canisters before the wings deploy over top of a pair of existing solar arrays. The iROSA wings will be canted at an angle of about 10 degrees relative to the station’s current solar panels.
“They come up rolled up,” said Joel Montalbano, NASA’s space station program manager at the Johnson Space Center in Houston. “Think of it like a Tootsie Roll, and they expand and then deploy.”
The roll-out arrays come with more efficient solar cells than the 20-year-old solar panels they will replace. Developed by Deployable Space Systems, a manufacturer recently acquired by the space infrastructure company Redwire, the roll-out arrays are half the size of the space station’s existing solar panels, but they generate roughly the same amount of electricity.
The space station’s eight original solar panels launched in pairs on four space shuttle missions in 2000, 2006, 2007, and 2009. The old arrays will remain on the station, but six will be partially covered by the new roll-out wings.
“Over time, the solar arrays on-board have degraded,” Montalbano said. “We celebrated 20 years of continuous human presence last year, and over time, just like any large home, you have to do upgrades and repairs.”
The upgraded arrays, coupled with residual power output from the old solar panels, will give the space station about 215 kilowatts of electrical power.
“These new solar arrays will put us at a power generation equal to when we first flew arrays on-board the International Space Station,” Montalbano said.
The added power generation capability will allow the space station to welcome a new commercial module developed by Axiom Space, and keep the complex running until at least 2030, officials said.
Four more iROSA wings are scheduled to launch on two Dragon cargo flights in 2022. Similar roll-out solar arrays are in development for use on the planned Gateway mini-space station in orbit around the moon, part of NASA’s Artemis program to return astronauts to the lunar surface.
Other payloads aboard the Cargo Dragon spacecraft include biological experiments, technology demonstration hardware, spare part, food, and other provisions for the space station’s crew.
“This particular flight is going to bring up 37 investigations, and that is going to be a complement to the hundreds that we do every year on the ISS,” said Jennifer Buchli, NASA’s deputy chief scientist for the space station program.
One of the experiments delivered tardigrades, or water bears, to the space station to allow researchers to examine how the tiny animals withstand the stresses of spaceflight. Scientists have already shown tardigrades can survive extreme temperatures, pressures, radiation, and even in the vacuum of space.
The tardigrades will help scientists identify the genes involved in their adaptation and survival in high-stress environments, according to NASA. The resilient animals will return to Earth for scientists to study. Researchers hope the results could aid in the understanding of the stress factors affecting humans in space, NASA said.
“We’re using these animals because they’re some of the toughest animals we know of,” said Thomas Boothby, a professor of molecular biology at the University of Wyoming, and chief scientist on the tardigrade investigation.
Another research payload will focus on how spaceflight impacts interactions between biologically beneficial microbes and their animal hosts.
“Beneficial microbes play a significant role in the normal development of animal tissues and in maintaining human health, but gravity’s role in shaping these interactions is not well understood,” NASA said in a press kit for the Cargo Dragon mission. “This experiment could support the development of measures to preserve astronaut health and identify ways to protect and enhance these relationships for better wellbeing on Earth.”
The experiment, named UMAMI, will examine the relationship between young bobtail squid specimens and symbiotic bacteria, which will be introduced to the squid once in space.
Other experiments on the Cargo Dragon capsule include a payload to study the growth of cotton plant roots in microgravity, which could lead to development of cotton varieties on Earth that require less water and fewer pesticides, according to NASA.
The Cargo Dragon also hauled a catalytic reactor for the space station’s water generation system, hardware for an emergency breathing system for the station astronauts, and an electronics unit for a Russian remote-control docking system for visiting Progress cargo spacecraft.
The SpaceX supply ship also delivered two CubeSats that will be released into orbit outside the space station from a Nanoracks deployer. One of the CubeSats, built by middle school students in Tennessee, was sponsored by a NASA education program, and the other CubeSat is the first satellite from Mauritius to travel into space.
This mission is SpaceX’s 22nd cargo resupply flight to the space station under contract to NASA, and the second to use a new generation of Dragon cargo freighters derived from SpaceX’s human-rated Crew Dragon spacecraft.
The cargo load adds up to 7,337 pounds (3,328 kilograms). That makes it the heaviest supply shipment SpaceX has ever sent to the space station. Northrop Grumman’s Cygnus supply freighters, which are designed for one flight each, can accommodate slightly heavier and more voluminous cargo.
Here’s a breakdown of the cargo on the SpaceX CRS-22 resupply mission:
- ISS Roll-Out Solar Arrays: 3,042 pounds (1,380 kilograms)
- Science Investigations: 2,028 pounds (920 kilograms)
- Vehicle Hardware: 760 pounds (345 kilograms)
- Crew Supplies: 751 pounds (341 kilograms)
- Computer Resources: 129 pounds (58 kilograms)
- Spacewalk Equipment: 115 pounds (52 kilograms)
The new Cargo Dragon spacecraft design, which debuted with SpaceX’s previous resupply mission in December, can haul about 20 percent more cargo volume than previous Dragon cargo ships. The new cargo vehicle can stay at the space station for up to 75 days, more than twice as long as the first-generation Dragon spacecraft.
The Cargo Dragon, which splashes down off the coast of Florida at the end of each mission, can be used up to five times. That’s an improvement over the three-flight design of the first-generation Dragon cargo capsule. The new spacecraft can autonomously dock with the space station. Past Dragon cargo missions had to be captured by astronauts using the space station’s Canadian robot arm.
That change reduces the workload on the space station crew and makes the Cargo Dragon’s rendezvous profile nearly identical to the Crew Dragon, but the docking port used by the new Cargo Dragon has a narrower passageway than the connection used by the berthing system on the first-generation Dragon cargo capsule.
The first upgraded Cargo Dragon spaceship launched to the space station in December and returned to Earth in January. It’s now being refurbished for a future resupply mission. The capsule that docked with the space station Saturday is on its first voyage into space and is scheduled to depart the station and return to Earth in July.
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