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ESA Explores a fictional asteroid impact
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By European Space Agency
In 2022 NASA’s DART spacecraft made history, and changed the Solar System forever, by impacting the Dimorphos asteroid and measurably shifting its orbit around the larger Didymos asteroid. In the process a plume of debris was thrown out into space.
The latest modelling, available on the preprint server arXiv and accepted for publication in the September volume of The Planetary Science Journal, shows how small meteoroids from that debris could eventually reach both Mars and Earth – potentially in an observable (although quite safe) manner.
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By NASA
5 min read
NASA, ESA Missions Help Scientists Uncover How Solar Wind Gets Energy
Since the 1960s, astronomers have wondered how the Sun’s supersonic “solar wind,” a stream of energetic particles that flows out into the solar system, continues to receive energy once it leaves the Sun. Now, thanks to a lucky lineup of a NASA and an ESA (European Space Agency)/NASA spacecraft both currently studying the Sun, they may have discovered the answer — knowledge that is a crucial piece of the puzzle to help scientists better forecast solar activity between the Sun and Earth.
A paper published in the Aug. 30, 2024, issue of the journal Science provides persuasive evidence that the fastest solar winds are powered by magnetic “switchbacks,” or large kinks in the magnetic field, near the Sun.
“Our study addresses a huge open question about how the solar wind is energized and helps us understand how the Sun affects its environment and, ultimately, the Earth,” said Yeimy Rivera, co-leader of the study and a postdoctoral fellow at the Smithsonian Astrophysical Observatory, part of Center for Astrophysics | Harvard & Smithsonian. “If this process happens in our local star, it’s highly likely that this powers winds from other stars across the Milky Way galaxy and beyond and could have implications for the habitability of exoplanets.”
This artist’s concept shows switchbacks, or large kinks in the Sun’s magnetic field. NASA’s Goddard Space Flight Center/Conceptual Image Lab/Adriana Manrique Gutierrez Previously, NASA’s Parker Solar Probe found that these switchbacks were common throughout the solar wind. Parker, which became the first craft to enter the Sun’s magnetic atmosphere in 2021, allowed scientists to determine that switchbacks become more distinct and more powerful close to the Sun. Up to now, however, scientists lacked experimental evidence that this interesting phenomenon actually deposits enough energy to be important in the solar wind.
“About three years ago, I was giving a talk about how fascinating these waves are,” said co-author Mike Stevens, astrophysicist at the Center for Astrophysics. “At the end, an astronomy professor stood up and said, ‘that’s neat, but do they actually matter?’”
To answer this, the team of scientists had to use two different spacecraft. Parker is built to fly through the Sun’s atmosphere, or “corona.” ESA’s and NASA’s Solar Orbiter mission is also on an orbit that takes it relatively close to the Sun, and it measures solar wind at larger distances.
The discovery was made possible because of a coincidental alignment in February 2022 that allowed both Parker Solar Probe and Solar Orbiter to measure the same solar wind stream within two days of each other. Solar Orbiter was almost halfway to the Sun while Parker was skirting the edge of the Sun’s magnetic atmosphere.
This conceptual image shows Parker Solar Probe about to enter the solar corona. NASA/Johns Hopkins APL/Ben Smith An artist’s concept shows Solar Orbiter near the Sun. NASA’s Goddard Space Flight Center Conceptual Image Lab
“We didn’t initially realize that Parker and Solar Orbiter were measuring the same thing at all. Parker saw this slower plasma near the Sun that was full of switchback waves, and then Solar Orbiter recorded a fast stream which had received heat and with very little wave activity,” said Samuel Badman, astrophysicist at the Center for Astrophysics and the other co-lead of the study. “When we connected the two, that was a real eureka moment.”
Scientists have long known that energy is moved throughout the Sun‘s corona and the solar wind, at least in part, through what are known as “Alfvén waves.” These waves transport energy through a plasma, the superheated state of matter that makes up the solar wind.
However, how much the Alfvén waves evolve and interact with the solar wind between the Sun and Earth couldn’t be measured — until these two missions were sent closer to the Sun than ever before, at the same time. Now, scientists can directly determine how much energy is stored in the magnetic and velocity fluctuations of these waves near the corona, and how much less energy is carried by the waves farther from the Sun.
The new research shows that the Alfvén waves in the form of switchbacks provide enough energy to account for the heating and acceleration documented in the faster stream of the solar wind as it flows away from the Sun.
“It took over half a century to confirm that Alfvenic wave acceleration and heating are important processes, and they happen in approximately the way we think they do,” said John Belcher, emeritus professor from the Massachusetts Institute of Technology who co-discovered Alfvén waves in the solar wind but was not involved in this study.
In addition to helping scientists better forecast solar activity and space weather, such information helps us understand mysteries of the universe elsewhere and how Sun-like stars and stellar winds operate everywhere.
“This discovery is one of the key puzzle pieces to answer the 50-year-old question of how the solar wind is accelerated and heated in the innermost portions of the heliosphere, bringing us closer to closure to one of the main science objectives of the Parker Solar Probe mission,” said Adam Szabo, Parker Solar Probe mission science lead at NASA.
By Megan Watzke
Center for Astrophysics | Harvard & Smithsonian
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Last Updated Aug 30, 2024 Related Terms
Goddard Space Flight Center Heliophysics Heliophysics Division Parker Solar Probe (PSP) Science & Research Science Mission Directorate Solar Flares Solar Orbiter Solar Science Solar Wind Space Weather The Sun The Sun & Solar Physics Explore More
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By NASA
6 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
A mirror that was later installed inside the telescope for NASA’s Near-Earth Object Surveyor shows a reflection of principal optical engineer Brian Monacelli during an inspection of the mirror’s surface at the agency’s Jet Propulsion Laboratory on July 17.NASA/JPL-Caltech A technician operates articulating equipment to rotate NEO Surveyor’s aluminum optical bench — part of the spacecraft’s telescope — in a clean room at NASA’s Jet Propulsion Laboratory in Southern California on July 17.NASA/JPL-Caltech The mirrors for NASA’s Near-Earth Object Surveyor space telescope are being installed and aligned, and work on other spacecraft components is accelerating.
NASA’s new asteroid-hunting spacecraft is taking shape at NASA’s Jet Propulsion Laboratory in Southern California. Called NEO Surveyor (Near-Earth Object Surveyor), this cutting-edge infrared space telescope will seek out the hardest-to-find asteroids and comets that might pose a hazard to our planet. In fact, it is the agency’s first space telescope designed specifically for planetary defense.
Targeting launch in late 2027, the spacecraft will travel a million miles to a region of gravitational stability — called the L1 Lagrange point — between Earth and the Sun. From there, its large sunshade will block the glare and heat of sunlight, allowing the mission to discover and track near-Earth objects as they approach Earth from the direction of the Sun, which is difficult for other observatories to do. The space telescope also may reveal asteroids called Earth Trojans, which lead and trail our planet’s orbit and are difficult to see from the ground or from Earth orbit.
NEO Surveyor relies on cutting-edge detectors that observe two bands of infrared light, which is invisible to the human eye. Near-Earth objects, no matter how dark, glow brightly in infrared as the Sun heats them. Because of this, the telescope will be able to find dark asteroids and comets, which don’t reflect much visible light. It also will measure those objects, a challenging task for visible-light telescopes that have a hard time distinguishing between small, highly reflective objects and large, dark ones.
This artist’s concept depicts NASA’s NEO Surveyor in deep space. The black-paneled angular structure in the belly of the spacecraft is the instrument enclosure that is being built at JPL. The mission’s infrared telescope will be installed inside the enclosure.NASA/JPL-Caltech “NEO Surveyor is optimized to help us to do one specific thing: enable humanity to find the most hazardous asteroids and comets far enough in advance so we can do something about them,” said Amy Mainzer, principal investigator for NEO Surveyor and a professor at the University of California, Los Angeles. “We aim to build a spacecraft that can find, track, and characterize the objects with the greatest chance of hitting Earth. In the process, we will learn a lot about their origins and evolution.”
Coming Into Focus
The spacecraft’s only instrument is its telescope. About the size of a washer-and-dryer set, the telescope’s blocky aluminum body, called the optical bench, was built in a JPL clean room. Known as a three-mirror anastigmat telescope, it will rely on curved mirrors to focus light onto its infrared detectors in such a way that minimizes optical aberrations.
“We have been carefully managing the fabrication of the spacecraft’s telescope mirrors, all of which were received in the JPL clean room by July,” said Brian Monacelli, principal optical engineer at JPL. “Its mirrors were shaped and polished from solid aluminum using a diamond-turning machine. Each exceeds the mission’s performance requirements.”
Monacelli inspected the mirror surfaces for debris and damage, then JPL’s team of optomechanical technicians and engineers attached the mirrors to the telescope’s optical bench in August. Next, they will measure the telescope’s performance and align its mirrors.
Complementing the mirror assembly are the telescope’s mercury-cadmium-telluride detectors, which are similar to the detectors used by NASA’s recently retired NEOWISE (short for Near-Earth Object Wide-field Infrared Survey Explorer) mission. An advantage of these detectors is that they don’t necessarily require cryogenic coolers or cryogens to lower their operational temperatures in order to detect infrared wavelengths. Cryocoolers and cryogens can limit the lifespan of a spacecraft. NEO Surveyor will instead keep its cool by using its large sunshade to block sunlight from heating the telescope and by occupying an orbit beyond that of the Moon, minimizing heating from Earth.
The telescope will eventually be installed inside the spacecraft’s instrument enclosure, which is being assembled in JPL’s historic High Bay 1 clean room where NASA missions such as Voyager, Cassini, and Perseverance were constructed. Fabricated from dark composite material that allows heat to escape, the enclosure will help keep the telescope cool and prevent its own heat from obscuring observations.
Once it is completed in coming weeks, the enclosure will be tested to make sure it can withstand the rigors of space exploration. Then it will be mounted on the back of the sunshade and atop the electronic systems that will power and control the spacecraft.
“The entire team has been working hard for a long time to get to this point, and we are excited to see the hardware coming together with contributions from our institutional and industrial collaborators from across the country,” said Tom Hoffman, NEO Surveyor’s project manager at JPL. “From the panels and cables for the instrument enclosure to the detectors and mirrors for the telescope — as well as components to build the spacecraft — hardware is being fabricated, delivered, and assembled to build this incredible observatory.”
Assembly of NEO Surveyor can be viewed 24 hours a day, seven days a week, via JPL’s live cam.
More About NEO Surveyor
The NEO Surveyor mission marks a major step for NASA toward reaching its U.S. Congress-mandated goal to discover and characterize at least 90% of the near-Earth objects more than 460 feet (140 meters) across that come within 30 million miles (48 million kilometers) of our planet’s orbit. Objects of this size can cause significant regional damage, or worse, should they impact the Earth.
The mission is tasked by NASA’s Planetary Science Division within the Science Mission Directorate; program oversight is provided by the Planetary Defense Coordination Office, which was established in 2016 to manage the agency’s ongoing efforts in planetary defense. NASA’s Planetary Missions Program Office at the agency’s Marshall Space Flight Center provides program management for NEO Surveyor.
The project is being developed by JPL and is led by principal investigator Amy Mainzer at UCLA. Established aerospace and engineering companies have been contracted to build the spacecraft and its instrumentation, including BAE Systems, Space Dynamics Laboratory, and Teledyne. The Laboratory for Atmospheric and Space Physics at the University of Colorado, Boulder will support operations, and IPAC-Caltech in Pasadena, California, is responsible for processing survey data and producing the mission’s data products. Caltech manages JPL for NASA.
More information about NEO Surveyor is available at:
https://science.nasa.gov/mission/neo-surveyor
News Media Contacts
Ian J. O’Neill
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-2649
ian.j.oneill@jpl.nasa.gov
Karen Fox / Alana Johnson
NASA Headquarters, Washington
202-358-1600 / 202-358-1501
karen.c.fox@nasa.gov / alana.r.johnson@nasa.gov
2024-114
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Last Updated Aug 28, 2024 Related Terms
NEO Surveyor (Near-Earth Object Surveyor Space Telescope) Comets Jet Propulsion Laboratory Near-Earth Asteroid (NEA) Planetary Defense Planetary Defense Coordination Office Explore More
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