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By European Space Agency
Week in images: 21-25 April 2025
Discover our week through the lens
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By NASA
The asteroid Donaldjohanson as seen by the Lucy Long-Range Reconnaissance Imager (L’LORRI). This is one of the most detailed images returned by NASA’s Lucy spacecraft during its flyby. This image was taken at 1:51 p.m. EDT (17:51 UTC), April 20, 2025, near closest approach, from a range of approximately 660 miles (1,100 km). The spacecraft’s closest approach distance was 600 miles (960 km), but the image shown was taken approximately 40 seconds beforehand. The image has been sharpened and processed to enhance contrast.NASA/Goddard/SwRI/Johns Hopkins APL/NOIRLab NASA’s Lucy spacecraft took this image of the main belt asteroid Donaldjohanson during its flyby on April 20, 2025, showing the elongated contact binary (an object formed when two smaller bodies collide). This was Lucy’s second flyby in the spacecraft’s 12-year mission.
Launched on Oct. 16, 2021, Lucy is the first space mission sent to explore a diverse population of small bodies known as the Jupiter Trojan asteroids. These remnants of our early solar system are trapped on stable orbits associated with – but not close to – the giant planet Jupiter. Lucy will explore a record-breaking number of asteroids, flying by three asteroids in the solar system’s main asteroid belt, and by eight Trojan asteroids that share an orbit around the Sun with Jupiter. April 20, 2025 marked Lucy’s second flyby. The spacecraft’s next target is Trojan asteroid Eurybates and its satellite Queta in Aug. 2027.
Lucy is named for a fossilized skeleton of a prehuman ancestor. This flyby marked the first time NASA sent a spacecraft to a planetary body named after a living person. Asteroid Donaldjohanson was unnamed before becoming a target. The name Donaldjohanson was chosen in honor of the paleoanthropologist who discovered the Lucy fossil, Dr. Donald Johanson.
Learn more about Lucy’s flyby of asteroid Donaldjohanson.
Image credit: NASA/Goddard/SwRI/Johns Hopkins APL/NOIRLab
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By NASA
3 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
As associate administrator for NASA’s Space Operations Mission Directorate Ken Bowersox puts it, “nothing happens without communications.”
And effective communications require the use of radio waves.
None of NASA’s exciting science and engineering endeavors would be possible without the use of radio waves to send data, communications, and commands between researchers or flight controllers and their flight platforms or instruments.
Reflecting on his time as a pilot, commander, and mission specialist during the Space Shuttle Program, Bowersox says, “If you’re not there physically, you can’t be a part of the team. But if you’re getting the data, whether it’s video, telemetry data with states of switches, or individual parameters on temperatures or pressures, then you can act on it and provide information to the spacecraft team so they can do the right thing in their operation.”
These vital data and communications functions, as well as the gathering of valuable scientific data through remote sensing applications, all use radio frequencies (RF) within the electromagnetic spectrum. NASA centers and facilities also use the RF spectrum to support their everyday operations, including the walkie-talkies used by security guards, air traffic control systems around airfields, and even office Wi-Fi routers and wireless keyboards.
Nothing happens without communications.
Ken Bowersox
NASA Astronaut & Associate Administrator for NASA's Space Operations Mission Directorate
All of NASA’s uses of the RF spectrum are shared, with different radio services supporting other kinds of uses. Service allocation is a fundamental concept in spectrum regulation and defines how the spectrum is shared between different types of applications. A service allocation defines ranges, or bands, of radio frequencies that can be used by a particular type of radio service. For example, a television broadcasting satellite operates in frequency bands allocated to the broadcasting satellite service, terrestrial cellular services operate in bands allocated for the mobile service, and the communications antennas on the International Space Station (ISS) operate in bands allocated to space operations service.
However, an allocation is not a license to operate — it does not authorize a specific system or operator to use particular frequencies. Such authority is granted through domestic and international regulatory processes.
Most frequency bands of the RF spectrum are shared, and each frequency band typically has two or more radio services allocated to it. Careful spectrum regulation, planning, and management aim to identify mutually compatible services to share frequency bands while limiting its negative impacts.
NASA’s Most Notable Spectrum Uses
Many of NASA’s most notable uses of spectrum rely on the following service allocations:
Earth exploration-satellite service Space research service Space operations service Inter-satellite service Note that allocations in the Earth exploration-satellite service and the space research service are designated either for communications links in the Earth-to-space, space-to-Earth, or space-to-space directions or designated for active or passive sensing of Earth or celestial objects (respectively) to differentiate the types of uses within the service and afford the requisite protections.
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Watch the video to learn more about how each kind of system uses the radio frequency spectrumNASA Learn how NASA manages its use of the RF spectrum. Learn about who NASA collaborates with to inform the spectrum regulations of the future. Learn about the scientific principles of the electromagnetic spectrum, including radio waves. Share
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Last Updated Apr 23, 2025 Related Terms
General Communicating and Navigating with Missions Keep Exploring Discover Related Topics
Missions
Humans in Space
Climate Change
Solar System
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By NASA
4 min read
NASA’s Lucy Spacecraft Images Asteroid Donaldjohanson
In its second asteroid encounter, NASA’s Lucy spacecraft obtained a close look at a uniquely shaped fragment of an asteroid that formed about 150 million years ago. The spacecraft has begun returning images that were collected as it flew approximately 600 miles (960 km) from the asteroid Donaldjohanson on April 20, 2025.
The asteroid Donaldjohanson as seen by the Lucy Long-Range Reconnaissance Imager (L’LORRI) on NASA’s Lucy spacecraft during its flyby. This timelapse shows images captured approximately every 2 seconds beginning at 1:50 p.m. EDT (17:50 UTC), April 20, 2025. The asteroid rotates very slowly; its apparent rotation here is due to the spacecraft’s motion as it flies by Donaldjohanson at a distance of 1,000 to 660 miles (1,600 to 1,100 km). The spacecraft’s closest approach distance was 600 miles (960 km), but the images shown were taken approximately 40 seconds beforehand, the nearest ones at a distance of 660 miles (1100 km). NASA/Goddard/SwRI/Johns Hopkins APL The asteroid was previously observed to have large brightness variations over a 10-day period, so some of Lucy team members’ expectations were confirmed when the first images showed what appeared to be an elongated contact binary (an object formed when two smaller bodies collide). However, the team was surprised by the odd shape of the narrow neck connecting the two lobes, which looks like two nested ice cream cones.
“Asteroid Donaldjohanson has strikingly complicated geology,” says Hal Levison, principal investigator for Lucy at Southwest Research Institute, Boulder, Colorado. “As we study the complex structures in detail, they will reveal important information about the building blocks and collisional processes that formed the planets in our Solar System.”
From a preliminary analysis of the first available images collected by the spacecraft’s L’LORRI imager, the asteroid appears to be larger than originally estimated, about 5 miles (8 km) long and 2 miles (3.5 km) wide at the widest point. In this first set of high-resolution images returned from the spacecraft, the full asteroid is not visible as the asteroid is larger than the imager’s field of view. It will take up to a week for the team to downlink the remainder of the encounter data from the spacecraft; this dataset will give a more complete picture of the asteroid’s overall shape.
Like Lucy’s first asteroid flyby target, Dinkinesh, Donaldjohanson is not a primary science target of the Lucy mission. As planned, the Dinkinesh flyby was a system’s test for the mission, while this encounter was a full dress rehearsal, in which the team conducted a series of dense observations to maximize data collection. Data collected by Lucy’s other scientific instruments, the L’Ralph color imager and infrared spectrometer and the L’TES thermal infrared spectrometer, will be retrieved and analyzed over the next few weeks.
The Lucy spacecraft will spend most of the remainder of 2025 travelling through the main asteroid belt. Lucy will encounter the mission’s first main target, the Jupiter Trojan asteroid Eurybates, in August 2027.
“These early images of Donaldjohanson are again showing the tremendous capabilities of the Lucy spacecraft as an engine of discovery,” said Tom Statler, program scientist for the Lucy mission at NASA Headquarters in Washington. “The potential to really open a new window into the history of our solar system when Lucy gets to the Trojan asteroids is immense.”
The asteroid Donaldjohanson as seen by the Lucy Long-Range Reconnaissance Imager (L’LORRI). This is one of the most detailed images returned by NASA’s Lucy spacecraft during its flyby. This image was taken at 1:51 p.m. EDT (17:51 UTC), April 20, 2025, near closest approach, from a range of approximately 660 miles (1,100 km). The spacecraft’s closest approach distance was 600 miles (960 km), but the image shown was taken approximately 40 seconds beforehand. The image has been sharpened and processed to enhance contrast. NASA/Goddard/SwRI/Johns Hopkins APL/NOIRLab NASA’s Goddard Space Flight Center in Greenbelt, Maryland, provides overall mission management, systems engineering and the safety and mission assurance for Lucy, as well as the designing and building the L’Ralph instrument. Hal Levison of the Boulder, Colorado, office of SwRI is the principal investigator. SwRI is headquartered in San Antonio and also leads the mission’s science team, science observation planning, and data processing. NASA’s Goddard Space Flight Center in Greenbelt, Maryland, provides overall mission management, systems engineering, and the safety and mission assurance for Lucy, as well as the L’Ralph instrument. Lockheed Martin Space in Littleton, Colorado, built the spacecraft, designed the orbital trajectory, and provides flight operations. Goddard and KinetX Aerospace are responsible for navigating the Lucy spacecraft. The Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, designed and built the L’LORRI (Lucy Long Range Reconnaissance Imager) instrument. Arizona State University designed and built the L’TES (Lucy Thermal Emission Spectrometer). Lucy is the thirteenth mission in NASA’s Discovery Program, which is managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama.
By Katherine Kretke
Southwest Research Institute
Media Contact:
Karen Fox / Molly Wasser
Headquarters, Washington
202-358-1600
karen.c.fox@nasa.gov / molly.l.wasser@nasa.gov
Nancy N. Jones
NASA’s Goddard Space Flight Center, Greenbelt, Md.
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Last Updated Apr 21, 2025 Editor Jamie Adkins Contact Molly Wasser molly.l.wasser@nasa.gov Related Terms
Lucy Asteroids Goddard Space Flight Center View the full article
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