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By NASA
5 Min Read Reinventing the Clock: NASA’s New Tech for Space Timekeeping
The Optical Atomic Strontium Ion Clock is a higher-precision atomic clock that is small enough to fit on a spacecraft. Credits: NASA/Matthew Kaufman Here on Earth, it might not matter if your wristwatch runs a few seconds slow. But crucial spacecraft functions need accuracy down to one billionth of a second or less. Navigating with GPS, for example, relies on precise timing signals from satellites to pinpoint locations. Three teams at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, are at work to push timekeeping for space exploration to new levels of precision.
One team develops highly precise quantum clock synchronization techniques to aid essential spacecraft communication and navigation. Another Goddard team is working to employ the technique of clock synchronization in space-based platforms to enable telescopes to function as one enormous observatory. The third team is developing an atomic clock for spacecraft based on strontium, a metallic chemical element, to enable scientific observations not possible with current technology. The need for increasingly accurate timekeeping is why these teams at NASA Goddard, supported by the center’s Internal Research and Development program, hone clock precision and synchronization with innovative technologies like quantum and optical communications.
Syncing Up Across the Solar System
“Society requires clock synchronization for many crucial functions like power grid management, stock market openings, financial transactions, and much more,” said Alejandro Rodriguez Perez, a NASA Goddard researcher. “NASA uses clock synchronization to determine the position of spacecraft and set navigation parameters.”
If you line up two clocks and sync them together, you might expect that they will tick at the same rate forever. In reality, the more time passes, the more out of sync the clocks become, especially if those clocks are on spacecraft traveling at tens of thousands of miles per hour. Rodriguez Perez seeks to develop a new way of precisely synchronizing such clocks and keeping them synced using quantum technology.
Work on the quantum clock synchronization protocol takes place in this lab at NASA’s Goddard Space Flight Center in Greenbelt, Md.NASA/Matthew Kaufman In quantum physics, two particles are entangled when they behave like a single object and occupy two states at once. For clocks, applying quantum protocols to entangled photons could allow for a precise and secure way to sync clocks across long distances.
The heart of the synchronization protocol is called spontaneous parametric down conversion, which is when one photon breaks apart and two new photons form. Two detectors will each analyze when the new photons appear, and the devices will apply mathematical functions to determine the offset in time between the two photons, thus synchronizing the clocks.
While clock synchronization is currently done using GPS, this protocol could make it possible to precisely synchronize clocks in places where GPS access is limited, like the Moon or deep space.
Syncing Clocks, Linking Telescopes to See More than Ever Before
When it comes to astronomy, the usual rule of thumb is the bigger the telescope, the better its imagery.
“If we could hypothetically have a telescope as big as Earth, we would have incredibly high-resolution images of space, but that’s obviously not practical,” said Guan Yang, an optical physicist at NASA Goddard. “What we can do, however, is have multiple telescopes in various locations and have each telescope record the signal with high time precision. Then we can stich their observations together and produce an ultra-high-res image.”
The idea of linking together the observations of a network of smaller telescopes to affect the power of a larger one is called very long baseline interferometry, or VLBI.
For VLBI to produce a whole greater than the sum of its parts, the telescopes need high-precision clocks. The telescopes record data alongside timestamps of when the data was recorded. High-powered computers assemble all the data together into one complete observation with greater detail than any one of the telescopes could achieve on its own. This technique is what allowed the Event Horizon Telescope’s network of observatories to produce the first image of a black hole at the center of our galaxy.
The Event Horizon Telescope (EHT) — a planet-scale array of eight ground-based radio telescopes forged through international collaboration — was designed to capture images of a black hole. Although the telescopes making up the EHT are not physically connected, they are able to synchronize their recorded data with atomic clocks.EHT Collaboration Yang’s team is developing a clock technology that could be useful for missions looking to take the technique from Earth into space which could unlock many more discoveries.
An Optical Atomic Clock Built for Space Travel
Spacecraft navigation systems currently rely on onboard atomic clocks to obtain the most accurate time possible. Holly Leopardi, a physicist at NASA Goddard, is researching optical atomic clocks, a more precise type of atomic clock.
While optical atomic clocks exist in laboratory settings, Leopardi and her team seek to develop a spacecraft-ready version that will provide more precision.
The team works on OASIC, which stands for Optical Atomic Strontium Ion Clock. While current spacecraft utilize microwave frequencies, OASIC uses optical frequencies.
The Optical Atomic Strontium Ion Clock is a higher-precision atomic clock that is small enough to fit on a spacecraft.NASA/Matthew Kaufman “Optical frequencies oscillate much faster than microwave frequencies, so we can have a much finer resolution of counts and more precise timekeeping,” Leopardi said.
The OASIC technology is about 100 times more precise than the previous state-of-the-art in spacecraft atomic clocks. The enhanced accuracy could enable new types of science that were not previously possible.
“When you use these ultra-high precision clocks, you can start looking at the fundamental physics changes that occur in space,” Leopardi said, “and that can help us better understand the mechanisms of our universe.”
The timekeeping technologies unlocked by these teams, could enable new discoveries in our solar system and beyond.
More on cutting-edge technology development at NASA Goddard By Matthew Kaufman, with additional contributions from Avery Truman
NASA’s Goddard Space Flight Center, Greenbelt, Md.
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Last Updated Sep 18, 2024 EditorRob GarnerContactRob Garnerrob.garner@nasa.govLocationGoddard Space Flight Center Related Terms
Goddard Technology Communicating and Navigating with Missions Goddard Space Flight Center Technology View the full article
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By NASA
Podcast art for Universo curioso de la NASA, the agency’s first podcast in Spanish, which returns for a second season in September 2024. Credits: NASA / Krystofer Kim Lee este comunicado de prensa en español aquí.
In celebration of Hispanic Heritage Month, NASA is releasing new content for Universo curioso de la NASA, the agency’s first Spanish-language podcast, now in its second season. A five-week season starts Tuesday with new episodes released weekly.
Listen to the preview of the second season of Universo curioso de la NASA.
In each episode, Universo curioso highlights the contributions of NASA’s Hispanic and Latino workforce to the agency’s work in Earth and space exploration for the benefit of all.
“Through the Universo curioso de la NASA podcast, we are thrilled to tell the story of NASA’s efforts to open space to more people from across the world,” said Tonya McNair, deputy associate administrator for NASA’s Space Operations Mission Directorate in Washington. “In the second season, you’ll hear from NASA’s Hispanic and Latino workforce, like flight director Diana Trujillo and astronaut Marcos Berríos, helping lead some of the agency’s most vital space exploration missions and inspiring the world through discovery.”
Episodes focus on some of NASA’s top missions, bringing the wonder of exploration, space technology, and scientific discoveries to Spanish-speaking audiences around the world.
“This podcast highlights NASA’s dedication to making knowledge available to all, regardless of their native language,” said Shahra Lambert, NASA senior advisor for engagement. “By sharing the excitement of NASA’s missions in the second most spoken language in the U.S. and around the world, we are amplifying our outreach and possibly paving the way for a more diverse STEM workforce in the future.”
The first episode of Universo curioso ran in 2021, as part of the agency’s Spanish coverage of the launch of its James Webb Space Telescope. In 2023, the show was selected as a “Podcast We Love” by Apple Podcasts Latin America.
Hosted by Noelia González, communications specialist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, listeners are invited to go on a journey to one of Jupiter’s icy moons, hear about the first two years of discoveries of the James Webb Space Telescope, as well as learn about an astronaut from Puerto Rico’s and a Colombian flight director’s path to NASA.
Episodes will cover the upcoming launch of Europa Clipper in October 2024, a mission that aims to determine whether there are places below the surface of Jupiter’s icy moon, Europa, that could support life.
A complete list of the new episodes, as well as their release dates, is as follows:
Tuesday, Sept. 17: Introducing the Second Season Tuesday, Sept. 24 Diana Trujillo: From Cali to the Moon and Mars Tuesday, Oct. 1 Europa Clipper: A Poetic Journey to Jupiter’s Moon Tuesday, Oct. 8 Marcos Berríos: How to Become a NASA Astronaut Tuesday, Oct. 15: Exploring Cosmos with Webb Universo curioso de la NASA is a joint initiative of the agency’s Spanish-language communications and audio programs. The new season, as well as previous episodes, are available on Apple Podcasts, Spotify, and NASA’s website.
Listen to the podcast at:
https://www.nasa.gov/universo-curioso-de-la-nasa
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María José Viñas / Cheryl Warner
Headquarters, Washington
240-458-0248 / 202-358-1600
maria-jose.vinasgarcia@nasa.gov / cheryl.m.warner@nasa.gov
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By Space Force
During CSO Gen. Chance Saltzman’s keynote address at the Air, Space and Cyber Conference, he explained how the service will transform to thrive in a new environment optimized for Great Power Competition.
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By NASA
Figure 1. An artist’s concept of the Van Allen belts with a cutaway section of the giant donuts of radiation that surround Earth. Image Credit: NASA Goddard Space Flight Center/Scientific Visualization Studio A new instrument is using advanced detection techniques and leveraging an orbit with specific characteristics to increase our understanding of the Van Allen belts—regions surrounding Earth that contain energetic particles that can endanger both robotic and human space missions. Recently, the instrument provided a unique view of changes to this region that were brought on by an intense magnetic storm in May 2024.
The discovery of the Van Allen radiation belts by the U.S. Explorer 1 mission in 1958 marked a prominent milestone in space physics and demonstrated that Earth’s magnetosphere efficiently accelerates and traps energetic particles. The inner belt contains protons in the MeV (million electric volt) to GeV (109 electric volt) range, and even higher concentrations of energetic electrons of 100s of keV (1000 electric volt) to MeV are found in both the inner belt and the outer belt.
The energetic electrons in these belts—also referred to as “killer electrons”—can have detrimental effects on spacecraft subsystems and are harmful to astronauts performing extravehicular activities. Understanding the source, loss, and varying concentrations of these electrons has been a longstanding research objective. High-energy resolution and clean measurements of these energetic electrons in space are required to further our understanding of their properties and enable more reliable prediction of their intensity.
Overcoming the challenges of measuring relativistic electrons in the inner belt
Measuring energetic electrons cleanly and accurately has been a challenge, especially in the inner belt, where MeV to GeV energy protons also exist. NASA’s Van Allen Probes, which operated from 2012 to 2019 in low inclination, geo-transfer-like orbits, showed that instruments traversing the heart of the inner radiation belt are subject to penetration by the highly energetic protons located in that region. The Relativistic Electron Proton Telescope (REPT) and the Magnetic Electron and Ion Spectrometer (MagEIS) instruments onboard the Van Allen Probes were heavily shielded but were still subject to inner-belt proton contamination.
To attempt to minimize these negative effects, a University of Colorado Boulder team led by Dr. Xinlin Li, designed the Relativistic Electron Proton Telescope integrated little experiment (REPTile)—a simplified and miniaturized version of REPT—to fly onboard the Colorado Student Space Weather Experiment (CSSWE). An effort supported by the National Science Foundation, the 3-Unit CSSWE CubeSat operated in a highly inclined low Earth orbit (LEO) from 2012 to 2014. In this highly inclined orbit, the spacecraft and the instruments it carried were only exposed to the inner-belt protons in the South Atlantic Anomaly (SAA) region where the Earth’s magnetic field is weaker, which greatly reduced the time that protons impacted the measurement of electrons.
REPTile’s success motivated a team, also led by Dr. Xinlin Li, to design REPTile-2—an advanced version of REPTile—to be hosted on the Colorado Inner Radiation Belt Experiment (CIRBE) mission. Like CSSWE, CIRBE operates in a highly inclined low-Earth orbit to ensure the exposure to damaging inner-belt protons is minimized. The team based the REPTile-2 design on REPTile but incorporated two additional technologies—guard rings and Pulse Height Analysis—to enable clean, high-energy-resolution measurements of energetic electrons, especially in the inner belt.
Figure 2: PI observing two engineers testing the interface between the CIRBE bus and REPTile-2 on September 29, 2021. Image Credit: Xinlin Li, University of Colorado Boulder As shown on the left in Figure 3, the field of view (FOV) of REPTile-2 is 51o. Electrons and protons enter the FOV and are measured when they reach a stack of silicon detectors where they deposit their energies. However, very energetic protons (energy greater than 60 MeV) could penetrate through the instrument’s tungsten and aluminum shielding and masquerade as valid particles, thus contaminating the intended measurements. To mitigate this contamination, the team designed guard rings that surround each detector. These guard rings are electronically separated from the inner active area of each detector and are connected by a separate electric channel. When the guard rings are triggered (i.e., hit by particles coming outside of the FOV), the coincident measurements are considered invalid and are discarded. This anti-coincidence technique enables cleaner measurements of particles coming through the FOV.
Figure 3. Left (adapted from Figure 1 of Khoo et al., 2022): Illustration of REPTile-2 front end with key features labeled; Right: REPTile-2 front end integrated with electronic boards and structures, a computer-aided design (CAD) model, and a photo of integrated REPTile-2. Image Credit: Xinlin Li, University of Colorado Boulder To achieve high energy resolution, the team also applied full Pulse Height Analysis (PHA) on REPTile-2. In PHA, the magnitude of measured charge in the detector is directly proportional to the energy deposited from the incident electrons. Unlike REPTile, which employed a simpler energy threshold discrimination method yielding three channels for the electrons, REPTile-2 offers enhanced precision with 60 energy channels for electron energies ranging from 0.25 – 6 MeV. The REPT instrument onboard the Van Allen Probes also employed PHA but while REPT worked very well in the outer belt, yielding fine energy resolution, it did not function as well in the inner belt since the instrument was fully exposed to penetrating energetic protons because it did not have the guard rings implemented.
Figure 4: The CIRBE team after a successful “plugs-out” test of the CIRBE spacecraft on July 21, 2022. During this test the CIRBE spacecraft successfully received commands from ground stations and completed various performance tests, including data transmission back to ground stations at LASP. Image Credit: Xinlin Li, University of Colorado Boulder CIRBE and REPTile-2 Results
CIRBE’s launch, secured through the NASA CubeSat Launch Initiative (CSLI), took place aboard SpaceX’s Falcon 9 rocket as part of the Transporter-7 mission on April 15, 2023. REPTile-2, activated on April 19, 2023, has been performing well, delivering valuable data about Earth’s radiation belt electrons. Many features of the energetic electrons in the Van Allen belts have been revealed for the first time, thanks to the high-resolution energy and time measurements REPTile-2 has provided.
Figure 5 shows a sample of CIRBE/REPTile-2 measurements from April 2024, and illustrates the intricate drift echoes or “zebra stripes” of energetic electrons, swirling around Earth in distinct bunches. These observations span a vast range across the inner and outer belts, encompassing a wide spectrum of energies and electron fluxes extending over six orders of magnitude. By leveraging advanced guard rings, Pulse Height Analysis (PHA), and a highly inclined LEO orbit, REPTile-2 is delivering unprecedented observations of radiation belt electrons.
Figure 5: Color-coded electron fluxes detrended between REPTile-2 measurements for a pass over the South Atlantic Anomaly region on April 24, 2023, and their average, i.e., the smoothed electron fluxes using a moving average window of ±19% in energy; Black curves plotted on top of the color-coded electron fluxes are contours of electron drift period in hr. The second horizontal-axis, L, represents the magnetic field line, which CIRBE crosses. The two radiation belts and a slot region in between are indicated by the red lines and arrow, respectively. Image Credit: Xinlin Li, University of Colorado Boulder In fact, the team recently announced that measurements from CIRBE/REPTile-2 have revealed a new temporary third radiation belt composed of electrons and sandwiched between the two permanent belts. This belt formed during the magnetic storm in May 2024, which was the largest in two decades. While such temporary belts have been seen after big storms previously, the data from CIRBE/REPTile-2 are providing a new viewpoint with higher energy resolution data than before. Scientists are currently studying the data to better understand the belt and how long it might stick around — which could be many months.
PROJECT LEAD
Dr. Xinlin Li, University of Colorado Laboratory for Atmospheric and Space Physics and Department of Aerospace Engineering Sciences.
SPONSORING ORGANIZATIONS
Heliophysics Flight Opportunities for Research & Technology (H-FORT) program, National Science Foundation
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Last Updated Sep 17, 2024 Related Terms
Heliophysics Heliophysics Division Science-enabling Technology Explore More
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By European Space Agency
The European Galileo satellite navigation system Galileo keeps growing: a new pair of satellites has joined the constellation after a journey on a Falcon 9 rocket, launched from the Kennedy Space Center in Florida on 18 September at 00:50 CEST (17 September 18:50 local time).
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