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KNaCK LIDAR Technology Demonstration at 5th Joint EVA Test Team (JETT5) Field Compaign, Flagstaff, Arizona
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By Space Force
A group of 18 personnel from the 4th Space Operations Squadron, a component of Delta 8, headquartered at Peterson Space Force Base, Colorado, recently traveled to Joint Base Pearl Harbor Hickam, Hawaii for a contingency operations exercise to test a highly technical piece of equipment known as a Mobile Constellation Control Station.
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By NASA
5 min read
Voyager 1 Team Accomplishes Tricky Thruster Swap
A model of NASA’s Voyager spacecraft. The twin Voyagers have been flying since 1977 and are exploring the outer regions of our solar system. NASA/JPL-Caltech The spacecraft uses its thrusters to stay pointed at Earth, but after 47 years in space some of the fuel tubes have become clogged.
Engineers working on NASA’s Voyager 1 probe have successfully mitigated an issue with the spacecraft’s thrusters, which keep the distant explorer pointed at Earth so that it can receive commands, send engineering data, and provide the unique science data it is gathering.
After 47 years, a fuel tube inside the thrusters has become clogged with silicon dioxide, a byproduct that appears with age from a rubber diaphragm in the spacecraft’s fuel tank. The clogging reduces how efficiently the thrusters can generate force. After weeks of careful planning, the team switched the spacecraft to a different set of thrusters.
The thrusters are fueled by liquid hydrazine, which is turned into gases and released in tens-of-milliseconds-long puffs to gently tilt the spacecraft’s antenna toward Earth. If the clogged thruster were healthy it would need to conduct about 40 of these short pulses per day.
Both Voyager probes feature three sets, or branches, of thrusters: two sets of attitude propulsion thrusters and one set of trajectory correction maneuver thrusters. During the mission’s planetary flybys, both types of thrusters were used for different purposes. But as Voyager 1 travels on an unchanging path out of the solar system, its thruster needs are simpler, and either thruster branch can be used to point the spacecraft at Earth.
In 2002 the mission’s engineering team, based at NASA’s Jet Propulsion Laboratory in Southern California, noticed some fuel tubes in the attitude propulsion thruster branch being used for pointing were clogging, so the team switched to the second branch. When that branch showed signs of clogging in 2018, the team switched to the trajectory correction maneuver thrusters and have been using that branch since then.
Now those trajectory correction thruster tubes are even more clogged than the original branches were when the team swapped them in 2018. The clogged tubes are located inside the thrusters and direct fuel to the catalyst beds, where it is turned into gases. (These are different than the fuel tubes that send hydrazine to the thrusters.) Where the tube opening was originally only 0.01 inches (0.25 millimeters) in diameter, the clogging has reduced it to 0.0015 inches (0.035 mm), or about half the width of a human hair. As a result, the team needed to switch back to one of the attitude propulsion thruster branches.
Warming Up the Thrusters
Switching to different thrusters would have been a relatively simple operation for the mission in 1980 or even 2002. But the spacecraft’s age has introduced new challenges, primarily related to power supply and temperature. The mission has turned off all non-essential onboard systems, including some heaters, on both spacecraft to conserve their gradually shrinking electrical power supply, which is generated by decaying plutonium.
While those steps have worked to reduce power, they have also led to the spacecraft growing colder, an effect compounded by the loss of other non-essential systems that produced heat. Consequently, the attitude propulsion thruster branches have grown cold, and turning them on in that state could damage them, making the thrusters unusable.
The team determined that the best option would be to warm the thrusters before the switch by turning on what had been deemed non-essential heaters. However, as with so many challenges the Voyager team has faced, this presented a puzzle: The spacecraft’s power supply is so low that turning on non-essential heaters would require the mission to turn off something else to provide the heaters adequate electricity, and everything that’s currently operating is considered essential.
Studying the issue, they ruled out turning off one of the still-operating science instruments for a limited time because there’s a risk that the instrument would not come back online. After additional study and planning, the engineering team determined they could safely turn off one of the spacecraft’s main heaters for up to an hour, freeing up enough power to turn on the thruster heaters.
It worked. On Aug. 27, they confirmed that the needed thruster branch was back in action, helping point Voyager 1 toward Earth.
“All the decisions we will have to make going forward are going to require a lot more analysis and caution than they once did,” said Suzanne Dodd, Voyager’s project manager at the Jet Propulsion Laboratory which manages Voyager for NASA.
The spacecraft are exploring interstellar space, the region outside the bubble of particles and magnetic fields created by the Sun, where no other spacecraft are likely to visit for a long time. The mission science team is working to keep the Voyagers going for as long as possible, so they can continue to reveal what the interstellar environment is like.
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Calla Cofield
Jet Propulsion Laboratory, Pasadena, Calif.
626-808-2469
calla.e.cofield@jpl.nasa.gov
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Last Updated Sep 10, 2024 Related Terms
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By NASA
On Sept. 9, 1994, space shuttle Discovery took to the skies on its 19th trip into space. During their 11-day mission, the STS-64 crew of Commander Richard “Dick” N. Richards, Pilot L. Blaine Hammond, and Mission Specialists Jerry M. Linenger, Susan J. Helms, Carl J. Meade, and Mark C. Lee demonstrated many of the space shuttle’s capabilities. They used a laser instrument to observe the Earth’s atmosphere, deployed and retrieved a science satellite, and used the shuttle’s robotic arm for a variety of tasks, including studying the orbiter itself. During a spacewalk, Lee and Meade tested a new device to rescue astronauts who found themselves detached from the vehicle. Astronauts today use the device routinely for spacewalks from the International Space Station.
Left: The STS-64 crew patch. Middle: Official photo of the STS-64 crew of L. Blaine Hammond, front row left, Richard “Dick” N. Richards, and Susan J. Helms; Mark C. Lee, back row left, Jerry M. Linenger, and Carl J. Meade. Right: The patch for the Lidar In-space Technology Experiment.
In November 1993, NASA announced the five-person all-veteran STS-64 crew. Richards, selected as an astronaut in 1980, had made three previous spaceflights, STS-28, STS-41, and STS-50. Lee, a member of the astronaut class of 1984, had two flights to his credit, STS-30 and STS-47, as did Meade, selected in 1985 and a veteran of STS-38 and STS-50. Each making their second trip into space, Hammond, selected in 1984 had flown on STS-39, and Helms, from the class of 1990 had flown on STS-54. In February 1994, NASA added first time space flyer Linenger to the crew, partly to make him eligible for a flight to Mir. He holds the distinction as the first member of his astronaut class of 1992 to fly in space.
Left: Workers tow Discovery from the Orbiter Processing Facility to the Vehicle Assembly Building at NASA’s Kennedy Space Center (KSC) in Florida. Middle: Space shuttle Discovery arrives at Launch Pad 39B, left, with space shuttle Endeavour still on Launch Pad 39A. Right: The STS-64 crew exits crew quarters at KSC on their way to the launch.
Discovery returned to NASA’s Kennedy Space Center (KSC) in Florida following its previous flight, the STS-60 mission, in February 1994. Workers in KSC’s Orbiter Processing Facility (OPF) removed the previous payload and began to service the orbiter. On May 26, workers moved Discovery into the Vehicle Assembly Building for temporary storage to make room in the OPF for Atlantis, just returned from Palmdale, California, where it underwent modifications to enable extended duration flights and dockings with space stations. Discovery returned to the OPF for payload installation in July, and rolled back to the VAB on Aug. 11 for mating with its external tank and solid rocket boosters. Discovery rolled out to Launch Pad 39B on Aug. 19, with its sister ship Endeavour still on Launch Pad 39A following the previous day’s launch abort. The six-person crew traveled to KSC to participate in the Terminal Countdown Demonstration Test, essentially a dress rehearsal for the launch countdown, on Aug. 24.
Liftoff of Discovery on the STS-64 mission.
On Sept. 9, 1994, after a more than two-hour delay caused by inclement weather, Discovery thundered into the sky to begin the STS-64 mission. Eight and a half minutes later, the orbiter and its crew reached space, and with a firing of the shuttle’s Orbiter Maneuvering System (OMS) engines they entered a 160-mile orbit inclined 57 degrees to the equator, ideal for Earth and atmospheric observations. The crew opened the payload bay doors, deploying the shuttle’s radiators, and removed their bulky launch and entry suits, stowing them for the remainder of the flight. They began to convert their vehicle into a science platform.
Left: LIDAR (light detection and ranging) In-space Technology Experiment (LITE) telescope in Discovery’s payload bay. Middle: Schematic of LITE data acquisition. Right: Image created from LITE data of clouds over southeast Asia.
One of the primary payloads on STS-64, the LIDAR (light detection and ranging) In-space Technology Experiment (LITE), mounted in Discovery’s forward payload bay, made the first use of a laser to study Earth’s atmosphere, cloud cover, and airborne dust from space. Lee, with help from Richards and Meade, activated LITE, built at NASA’s Langley Research Center in Hampton, Virginia, on the flight’s first day. The experiment operated for 53 hours during the mission, gathering 43 hours of high-rate data shared with 65 groups in 20 countries.
Left: View of the shuttle’s Remote Manipulator System, or robotic arm, holding the 33-foot long Shuttle Plume Impingement Flight Experiment (SPIFEX). Middle: Closeup view of SPIFEX. Right: A video camera view of Discovery from SPIFEX.
The Shuttle Plume Impingement Flight Experiment (SPIFEX), built at NASA’s Johnson Space Center (JSC) in Houston, consisted of a package of instruments positioned on the end of a 33-foot boom, to characterize the behavior of the shuttle’s Reaction Control System (RCS) thrusters. On the flight’s second day, Helms used the shuttle’s Remote Manipulator System (RMS), or robotic arm, to pick up SPIFEX. Over the course of the mission, she, Lee, and Hammond took turns operating the arm to obtain 100 test points during various thruster firings. A video camera on SPIFEX returned images of Discovery from several unusual angles.
Left: Astronaut Susan J. Helms lifts the Shuttle Pointed Autonomous Research Tool for Astronomy-201 (SPARTAN-201) out of Discovery’s payload bay prior to its release. Middle: Discovery approaches SPARTAN during the rendezvous. Right: Astronaut Susan J. Helms operating the Shuttle’s Remote Manipulator System prepares to grapple SPARTAN.
On the mission’s fifth day, Helms used the RMS to lift the Shuttle Pointed Autonomous Research Tool for Astronomy-201 (SPARTAN-201) satellite out of the payload bay and released it. Two and a half minutes later, SPARTAN activated itself, and Richards maneuvered Discovery away from the satellite so it could begin its science mission. On flight day seven, Discovery began its rendezvous with SPARTAN, and Hammond flew the shuttle close enough for Helms to grapple it with the arm and place it back in the payload bay. During its two-day free flight, SPARTAN’s two telescopes studied the acceleration and velocity of the solar wind and measured aspects of the Sun’s corona or outer atmosphere.
Left: Patch for the Simplified Aid for EVA (Extravehicular Activity) Rescue (SAFER). Middle: Astronauts Mark C. Lee, left, and Carl J. Meade during the 15-minute prebreathe prior to their spacewalk. Right: Lee, left, tests the SAFER while Meade works on other tasks in the payload bay.
On flight day seven, in preparation for the following day’s spacewalk, the astronauts lowered the pressure in the shuttle from 14.7 pounds per square inch (psi) to 10.2 psi to reduce the likelihood of the spacewalkers, Lee and Meade, from developing decompression sickness, also known as the bends. As an added measure, the two spent 15 minutes breathing pure oxygen before donning their spacesuits and exiting the shuttle’s airlock.
Left: Astronaut Mark C. Lee tests the Simplified Aid for EVA (Extravehicular Activity) Rescue (SAFER) during an untethered spacewalk. Middle: Astronaut Carl J. Meade tests the SAFER during an untethered spacewalk. Right: Meade, left, tests the ability of the SAFER to stop his spinning as Lee looks on.
The main tasks of the spacewalk involved testing the Simplified Aid for EVA (Extravehicular Activity) Rescue (SAFER), a device designed at JSC that attaches to the spacesuit’s Portable Life Support System backpack. The SAFER contains nitrogen jets that an astronaut can use, should he or she become untethered, to fly back to the vehicle, either the space shuttle or the space station. The two put the SAFER through a series of tests, including a familiarization, a system engineering evaluation, a crew rescue evaluation, and a precision flight evaluation. During the tests, Lee and Meade remained untethered from the shuttle, the first untethered spacewalk since STS-51A in November 1984. Lee and Meade successfully completed all the tests and gave the SAFER high marks. Astronauts conducting spacewalks from the space station use the SAFER as a standard safety device. Following the 6-hour 51-minute spacewalk, the astronauts raised the shuttle’s atmosphere back to 14.7 psi.
A selection of STS-64 crew Earth observation photographs. Left: Mt. St. Helens in Washington State. Middle left: Cleveland, Ohio. Middle right: Rabaul Volcano, Papua New Guinea. Right: Banks Peninsula, New Zealand.
Like on all space missions, the STS-64 astronauts spent their spare time looking out the window. They took numerous photographs of the Earth, their high inclination orbit allowing them views of parts of the planet not seen during typical shuttle missions.
Left: The Solid Surface Combustion Experiment middeck payload. Middle: Jerry M. Linenger gets in a workout while also evaluating the treadmill. Right: Inflight photograph of the STS-64 crew.
In addition to their primary tasks, the STS-64 crew also conducted a series of middeck experiments and tested hardware for future use on the space shuttle and space station.
Left: Commander Richard “Dick” Richards suited up for reentry. Middle: Pilot L. Blaine Hammond, left, and Mission Specialists Carl J. Meade and Susan J. Helms prepare for reentry. Right: Hammond fully suited for entry and landing.
Mission managers had extended the original flight duration by one day for additional data collection for the various payloads. On the planned reentry day, Sept. 19, bad weather at KSC forced the crew to spend an additional day in space. The next day, continuing inclement weather caused them to wave off the first two landing attempts at KSC and diverted to Edwards Air Force Base (AFB) in California.
Left: Richard Richards brings Discovery home at California’s Edwards Air Force Base. Middle: Workers at Edwards safe Discovery after its return from STS-64. Right: Discovery takes off from Edwards atop a Shuttle Carrier Aircraft for the ferry flight to NASA’s Kennedy Space Center in Florida.
On Sept. 20, they closed Discovery’s payload bay doors, donned their launch and entry suits, and strapped themselves into their seats for entry and landing. They fired Discover’s OMS engines to drop them out of orbit. Richards piloted Discovery to a smooth landing at Edwards, ending the 10-day 22-hour 50-minute flight. The crew had orbited the Earth 176 times. Workers at Edwards safed the vehicle and placed it atop a Shuttle Carrier Aircraft for the ferry flight back to KSC. The duo left Edwards on Sept. 26, and after an overnight stop at Kelly AFB in San Antonio, arrived at KSC the next day. Workers there began preparing Discovery for its next flight, the STS-63 Mir rendezvous mission, in February 1995.
Enjoy the crew narrate a video about the STS-64 mission. Read Richards’ recollections of the mission in his oral history with the JSC History Office.
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By NASA
The four-person crew of the Polaris Dawn mission pictured wearing their SpaceX extravehicular activity suits.Credit: SpaceX NASA researchers will soon benefit from a suite of experiments flying aboard a new fully-commercial human spaceflight mission, strengthening future agency science as we venture to the Moon, Mars and beyond.
The experiments are flying as part of the Polaris Dawn mission which launched aboard a SpaceX Dragon spacecraft and Falcon 9 rocket earlier today.
The four-person Polaris Dawn crew of Jared Isaacman, Scott “Kidd” Poteet, Sarah Gillis, and Anna Menon will conduct science during the mission including essential health and human performance research for NASA’s Human Research Program. The research will help NASA scientists better understand how exposure to space conditions affects the human body. The crew will test new medical approaches and technology on telemedicine capabilities, gather data on space motion sickness, and better characterize flight-associated injury risks.
“Each mission, whether the crew is comprised of commercial or NASA astronauts, provides a key opportunity to expand our knowledge about how spaceflight affects human health,” said Jancy McPhee, associate chief scientist for human research at NASA. “Information gathered from Polaris Dawn will give us critical insights to help NASA plan for deeper space travel to the Moon and Mars.”
The crew will test drive, a commercial device that can collect and integrate measurements of health, including blood pressure, heart rate, respiration rate, and temperature. The technology also provides ultrasound imaging and larynx and throat-focused video camera capabilities, and includes an experimental telemedicine feature that could help diagnose crew members in near-real time.
To test this technology during the mission, crew members will compare vital sign collection from the device with data gathered from standard periodic health status exams. The technology’s telemedicine feature, which relies on SpaceX’s Starlink communications system to connect with doctors and specialists on Earth, will also be tested during a simulation. During the test, the device will attempt to offer an appropriate diagnosis based on crew inputs and available documentation.
“Crew members will need to be more self-reliant during lengthy missions, and we hope that telemedicine can provide crews with assistance,” said McPhee.
Another research project aims to better understand and prevent the motion sickness symptoms that many astronauts experience in space. Participating crew members will describe their motion sickness symptoms, what interventions they tried to alleviate their symptoms, and whether any approaches helped.
A separate NASA-based research project will survey crew members after their mission to see whether they experienced any injuries or discomfort during re-entry to Earth.
“Our team will take the crew’s survey data and combine it with information gathered from sensors on the spacecraft. This will allow us to link crews’ reported experiences and health outcomes with the spacecraft’s dynamics and landing loads,” said Preston Greenhalgh, an injury biomechanist at NASA who is leading this work.
Crew members also will participate in a variety of other health studies on behalf of the NASA-funded TRISH (Translational Research Institute for Health), a consortium with various academic institutions. As part of that work, the Polaris Dawn mission will set a new baseline for collecting standard health data on commercial spaceflights, creating a complement to the datasets routinely collected from NASA astronauts and missions.
Polaris Dawn crew members participating in these TRISH studies will provide data about how spaceflight affects mental and physical health through a rigorous set of medical tests and scans completed before, after, and during the mission. The work will include assessments of behavior, sleep, bone density, eye health, cognitive function, and other factors, as well as analysis of blood, urine, and respiration.
“We’re so grateful to the crew members who volunteer to be part of NASA’s work. The insights that we gain from each study may trigger breakthroughs that will help ensure future mission success,” said McPhee.
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NASA’s Human Research Program pursues the best methods and technologies to support safe, productive human space travel. Through science conducted in laboratories, ground-based analogs, commercial missions, and the International Space Station, the program scrutinizes how spaceflight affects human bodies and behaviors. Such research continues to drive NASA’s mission to innovate ways that keep astronauts healthy and mission-ready as space exploration expands to the Moon, Mars, and beyond.
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