Update 9:02 p.m. EDT: The Cygnus spacecraft lost two burns following spacecraft separation; there is hope for capture and docking Tuesday morning, according to NASA.
While the weather proved challenging ahead of Sunday's launch attempt for the Northrop Grumman Cargo Resupply-21 (NG-21) mission, SpaceX received a good enough margin to be able to launch NASA's mission to the International Space Station.
Lifting off on its Falcon 9 rocket at 11:02 a.m. EDT (1502 UTC), Northrop Grumman's Cygnus spacecraft began its roughly 40-hour journey to the orbiting outpost. It deployed its two circular solar arrays at 2:21 a.m. EDT (1821 UTC) to begin charging its batteries.
However, before that could happen, at 11:44 a.m. EDT (1544 UTC), NASA said that Cygnus did not conduct its first planned burn. In a statement posted to a NASA blog shortly after 5 p.m. EDT, NASA claimed the reason was “due to a late entry into the burn sequence,” but did not provide additional clarification on what exactly this means.
“Known as the directed altitude burn, or TB1, it was rescheduled for 12:34 p.m., but the maneuver was canceled shortly after the engine ignited due to a slightly low initial pressure state,” NASA wrote. “There is no indication that the engine itself is experiencing any issues at this time.”
Astronauts aboard the International Space Station were notified of the failed burns shortly after the second burn occurred. During an unrelated communication between Mission Control in Houston and NASA astronaut Mike Barratt around 2:30 p.m. EDT, Barratt inquired about the status of Cygnus.
He was told a new burn plan was still being worked on, but engineers were still working on a capture plan Tuesday. CAPCOM said they “probably won't have it by the time you go to sleep, so by the time you wake up, we'll know what the plan is.”
“Cygnus is at a safe altitude and Northrop Grumman engineers are working on a new burn and trajectory plan,” NASA wrote on its blog. “The team is aiming to meet the spacecraft’s original capture time at the station, which is currently scheduled for 3:10 a.m. on Tuesday, Aug. 6.”
Following the deployment of Northrop Grumman's Cygnus spacecraft this morning to begin the NG-21 mission, Mission Control in Houston notified the Expedition 71 crew aboard the space station that “the first two burns were not performed by Cygnus, so they are re-evaluating which one is best.” image.twitter.com/8Lm5h5nHKK
— Spaceflight Now (@SpaceflightNow) August 4, 2024
The mission marks the second of three planned Cygnus launches on a Falcon 9 rocket as Northrop Grumman and Firefly Aerospace work to build the Antares 330 rocket, with the first launch planned for 2025.
NG-21 successfully lifted off from the Cape Canaveral Space Station as Tropical Storm Debby headed toward the Sunshine State. Prior to Sunday's launch attempt, the 45th Weather Squadron predicted a 10 percent chance of favorable weather conditions for liftoff.
As the countdown progressed, however, conditions eventually improved to 40 percent favorable, enough to give SpaceX, NASA and Northrop Grumman the confidence to proceed with the launch.
“We’re not within the cone of the center. However, tropical cyclone impacts extend far from the center,” Melody Lovin, launch weather officer for the 45th Weather Squadron, said during a prelaunch teleconference Friday. “So Sunday looks like an incredibly challenging time for us if we need to utilize that backup launch window.”
Shortly before 8 a.m. EDT Sunday, the National Hurricane Center issued its eighth advisory on Tropical Storm Debby, noting that it was “expected to strengthen rapidly prior to landfall in the Big Bend region of Florida.”
“We're expecting a steady 25 to 30 mph from the southeast on Sunday morning,” Lovin said. “Sunday looks pretty tricky, so my team will do everything we can to find the hole in the clouds tomorrow and get the liftoff done on time.”
SpaceX’s Falcon 9 rocket, B1080 of the SpaceX fleet supporting this mission, launched for the 10th time. It previously launched the Ax-2 and Ax-3 private astronaut missions for Axiom Space; the European Space Agency’s Euclid observatory; and a Cargo Dragon spacecraft on SpaceX’s Commercial Resupply Services-30 (CRS-30) mission.
About seven and a half minutes after liftoff, the rocket touched down at Landing Zone 1 (LZ-1) at Cape Canaveral, followed quickly by a sonic boom. This was the 42nd landing at that site and the 335th landing of a SpaceX rocket to date.
On Friday afternoon, SpaceX and Northrop Grumman teams completed the late loading of some of the most time-sensitive items onto the spacecraft.
“This is a complex, integrated operation where we’ve deployed a mobile clean room and attached it to the underside of the fairing and allowed access to lift the payload up to the fairing and load it directly onto the Cygnus spacecraft,” said Jared Metter, SpaceX’s director of flight reliability.
“We are leveraging the same operations we used on the Cygnus flight performed by SpaceX earlier this year, so the team is very confident in executing these complex, integrated operations.”
Cygnus is scheduled to arrive at the ISS on Tuesday, August 6, and will be captured and docked using the Canadarm. Once docked, it will remain at the space station until January, when it will burn up in Earth's atmosphere.
Cygnus separation confirmed image.twitter.com/0Z3WF03nGx
— SpaceX (@SpaceX) August 4, 2024
Fire simulations, 3D printed liver, CubeSats and more
Onboard the Cygnus spacecraft are more than 800 kg (1,763 lb) of scientific experiments, including a variety of studies. Several of them are sponsored by the International Space Station National Laboratory and the U.S. National Science Foundation.
One of them is an experiment that will study the spread of flames to better understand the complex mechanisms behind wildfires. That research is led by James Urban, an adjunct professor in the Department of Fire Protection Engineering at Worcester Polytechnic Institute (WPI).
Urban did his doctoral thesis on how wildfires originate from glowing metal particles, such as those found inside power lines, as seen in several large fires in California in recent years. He has also been indirectly affected by wildfires, such as when he was a college student in California and some of his classes were canceled due to wildfire smoke.
“I've come to appreciate the huge impact this issue can have, not only for the people directly involved, but also across broad geographic areas around the fire,” Urban said.
Urban’s experiment will study unsteady flame behaviors, which he describes as “a complex interaction between the hot gases produced by burning all that vegetation that rises up and the wind that creates these unsteady behaviors that play a very important role in how the flames spread through the fuel.”
Astronauts aboard the ISS will work with the Combustion Integrated Rack to conduct the experiment, which involves about 26 combustion samples, with each combustion test lasting between one and two minutes. The combustion samples will not be sent back to Earth, but Urban and his colleagues will receive a video of the experiment.
“In a lot of flammability research, the video footage that you get from the testing is like the gold, the treasure. You can get a lot of very useful information out of that video,” Urban said. “There are other sensors that can do that as well, but the video itself is very, very powerful and allows us to do a lot of things.”
Another experiment being launched is the Zero-Gravity Vascularized Liver Tissue Maturation (MVP Cell-07), developed by Redwire Space in collaboration with the Wake Forest Institute for Regenerative Medicine. The experiment is designed to improve microgravity bioprinting processes for research on Earth, as well as to create implantable tissue in the future.
“In this investigation, researchers determine whether bioprinted liver tissue scaffolds with blood vessels mature and behave the same way in space, where microgravity causes changes in cell shape, size, volume, and adhesion properties,” according to NASA’s description of the experiment. “The team aims to determine whether liver cells form proper tissue structures in microgravity and maintain their functionality. The team also assesses whether vascular cells properly form a lining on the walls of blood vessels within the liver scaffold.”
Two CubeSats will also join the NG-21 mission as part of NASA’s CubeSat Launch Initiative: Iowa State University’s CySat-1 and Arizona State University’s Deployable Optical Receiver Aperture (DORA). The former will measure soil moisture using a software-defined radiometer, according to NASA.
DORA is a partnership between ASU and NASA's Jet Propulsion Laboratory (JPL) in Southern California that will test new CubeSat technology.
“The technology will demonstrate novel optical communications without precision pointing and will use a solid-state photon detector to collect high data rates using wide-field optical receivers,” NASA wrote in a blog post. “To test the detector’s performance, DORA will measure background light from reflected sunlight, moonlight, and city lights as it is deployed from the space station to low-Earth orbit.”
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