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New NASA DART data prove viability of asteroid deflection as planetary defense strategy –



The last complete image of Dimorphos and its bouldery terrain, taken by the DRACO imager on the DART mission approximately 7 miles from the asteroid. Credit: NASA/Johns Hopkins APL.

NASA’s Double Asteroid Redirection Test (DART) was Earth’s first attempt at launching a spacecraft to intentionally collide with and deflect an asteroid as a planetary defense technique. On September 26, 2022, the DART spacecraft collided with a small asteroid moon called Dimorphos, which orbits a larger asteroid called Didymos. Neither asteroid posed a threat to Earth, but they represented similar celestial bodies that could one day approach and endanger the planet.

In four papers published in the journal Nature on March 1, 2023, the DART team—which includes University of Maryland astronomers—detailed DART’s successful impact, the possible physics behind the collision, observations of the resulting debris ejected from the asteroid and calculations of Dimorphos’ orbital changes. The findings confirm the feasibility of redirecting near-Earth objects like asteroids as a planetary defense measure.


“We can’t stop hurricanes or earthquakes yet, but we ultimately learned that we can prevent an with sufficient time, warning and resources,” said Derek Richardson, a professor of astronomy at UMD and a DART investigation working group lead. “With sufficient time, a relatively small change in an asteroid’s orbit would cause it to miss the Earth, preventing large-scale destruction from occurring on our planet.”

DART mission more successful than expected

Richardson and his UMD Department of Astronomy colleagues Professor Jessica Sunshine and Principal Research Scientist Tony Farnham played critical roles in studying the effectiveness of the DART mission to deflect an asteroid from an Earth-bound path.

Farnham was instrumental in computing the geometrical conditions and dimensions needed to interpret observations of the event accurately. Using data from engineers and from the Didymos Reconnaissance and Asteroid Camera for Optical Navigation (DRACO), Farnham helped determine what the DART spacecraft was looking at as it approached Dimorphos.

“When dealing with observations from a spacecraft, we need to understand where in space the spacecraft is located with respect to the asteroid, the sun and Earth and where it’s facing at any given time,” Farnham explained. “With this information, we have the context to make our conjectures and evaluate our work.”

Thanks to Farnham’s work, the DART team gained important information about the general timeline of the impact, the location and nature of the impact site, and the size and shape of Dimorphos. To the team’s surprise, they found the small asteroid to be an oblate spheroid, or a slightly squashed sphere-like body, instead of a more elongated shape expected from theoretical predictions.

“Both Didymos and Dimorphos are more squishy in shape—looking more like peanut butter M&Ms and less like peanut M&Ms—than we expected,” Sunshine said. “This shape also challenges some of our preconceptions about how such asteroids form and complicates the physics behind DART because it prompts us to rethink our current models of binary asteroids.”

In addition to Dimorphos’ irregular shape, the scientists also noticed that the asteroid’s surface was noticeably bouldery and blocky. This geomorphic quality likely influenced crater formation, the amount and physical properties of ejecta (debris expelled from impacts), and the momentum of a DART-like impact.

Sunshine, who previously served as the deputy principal investigator for the UMD-led NASA Deep Impact mission, observed that these different textural qualities led to different impact outcomes—critical in evaluating how successfully the DART spacecraft redirected Dimorphos from its original orbit.

“The Deep Impact mission collided with a comet whose surface is made up of small, mostly uniform grains,” Sunshine explained. “Deep Impact resulted in a more uniform fan of debris than the filamentary structures seen after DART’s impact into bouldery terrain. As it turns out, the movement of DART-caused ejecta really had a profound effect on the success of DART’s mission.”

New NASA DART data prove viability of asteroid deflection as planetary defense strategy
Dimorphos (pictured left), a small asteroid moon, orbits a larger asteroid called Didymos (right). Credit: NASA/Johns Hopkins APL.

Extra push from impact debris shortened Dimorphos’ orbit

The DART spacecraft was not the sole provider of momentum in the impact with Dimorphos; an additional shove was caused by violent spews of debris when the spacecraft slammed into the diminutive asteroid moon.

“There was so much debris ejected from the impact that Dimorphos was pushed approximately 3.5 times more effectively compared to being hit by the DART spacecraft alone,” explained Richardson, who helped compute and verify the momentum transferred between the DART spacecraft and Dimorphos.

According to Farnham, who calculated the direction of the asteroid’s ejecta, this finding was confirmed when the team measured the asteroid’s orbit had changed more than the team’s more conservative expectations. The difference in orbital periods, or the length of time it takes for a celestial object to complete one rotation around another object, indicates that the orbit of Dimorphos around Didymos had changed.

“Pre-impact, we expected the impact to shorten Dimorphos’ orbit by only about 10 minutes,” Farnham said. “But after the impact, we learned that the orbital period was shortened even more, reducing an ordinarily 12-hour orbit by slightly more than 30 minutes. In other words, the ejected material acted as a jet to push the moon even further out of its original orbit.”

Following up with Hera mission

The DART mission represents a major first step to developing appropriate planetary defense strategies against near-Earth objects like asteroids.

The DART team anticipates that the upcoming European Space Agency Hera mission launching in October 2024 will unravel more information about the DART impact site. By 2026-27, the Hera spacecraft will revisit the binary asteroid system containing Dimorphos and Didymos and assess the internal properties of both asteroids for the first time, providing a more detailed analysis of the DART impact’s effects on the system and the geophysics behind solar system formation.

“We still don’t know a lot about Dimorphos and Didymos because we have only seen the outsides,” Sunshine said. “What is their internal structure like? Are there differences in porosity between the two? Those are the types of questions we need to answer to really see how effective our deflections are and how celestial bodies like those asteroids form and evolve.”

While the Hera mission is still in the construction phase, research from both DART and its predecessors like Deep Impact still offer a wealth of information on how humans can develop additional ways to defend Earth from approaching asteroids and comets. Thanks to a legacy of kinetic impact testing initiatives and planetary defense research led by the late Distinguished University Professor of Astronomy Mike A’Hearn, UMD astronomers are uniquely equipped to evaluate and advance planetary scale impact experimentation. Richardson, Sunshine, Farnham and their colleagues hope to honor the work that led up to DART by continuing to help pioneer new methods of asteroid threat mitigation.

“These papers are simply the very first results about the DART mission to be published,” Farnham said. “But there are dozens of studies currently underway that will help us further our understanding of the impact and implications for planetary defense while uncovering more interesting phenomena.”

More information:
Andrew F. Cheng et al, Momentum Transfer from the DART Mission Kinetic Impact on Asteroid Dimorphos, Nature (2023). DOI: 10.1038/s41586-023-05878-z

New NASA DART data prove viability of asteroid deflection as planetary defense strategy (2023, March 1)
retrieved 1 March 2023

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James Webb spots swirling, gritty clouds on remote planet



This illustration conceptualizes the swirling clouds identified by the James Webb Space Telescope in the atmosphere of exoplanet VHS 1256 b. The planet is about 40 light-years away and orbits two stars that are locked in their own tight rotation. Its clouds, which are filled with silicate dust, are constantly rising, mixing, and moving during its 22-hour day. Credit: NASA, ESA, CSA, Joseph Olmsted (STScI)

Researchers observing with NASA’s James Webb Space Telescope have pinpointed silicate cloud features in a distant planet’s atmosphere. The atmosphere is constantly rising, mixing, and moving during its 22-hour day, bringing hotter material up and pushing colder material down.

The resulting brightness changes are so dramatic that it is the most variable planetary-mass object known to date. The team, led by Brittany Miles of the University of Arizona, also made extraordinarily clear detections of water, and carbon monoxide with Webb’s data, and found evidence of carbon dioxide. This is the largest number of molecules ever identified all at once on a planet outside our solar system.

Cataloged as VHS 1256 b, the planet is about 40 light-years away and orbits not one, but two stars over a 10,000-year period. “VHS 1256 b is about four times farther from its stars than Pluto is from our sun, which makes it a great target for Webb,” Miles said. “That means the planet’s light is not mixed with light from its stars.”

Higher up in its atmosphere, where the silicate clouds are churning, temperatures reach a scorching 1,500 degrees Fahrenheit (815 degrees Celsius).


Within those clouds, Webb detected both larger and smaller silicate dust grains, which are shown on a spectrum. “The finer silicate grains in its atmosphere may be more like tiny particles in smoke,” noted co-author Beth Biller of the University of Edinburgh in Scotland. “The larger grains might be more like very hot, very small sand particles.”

VHS 1256 b has compared to more massive brown dwarfs, which means that its silicate clouds can appear and remain higher in its atmosphere where Webb can detect them. Another reason its skies are so turbulent is the planet’s age. In astronomical terms, it’s quite young. Only 150 million years have passed since it formed—and it will continue to change and cool over billions of years.

NASA’s Webb Spots Swirling, Gritty Clouds on Remote Planet
A research team led by Brittany Miles of the University of Arizona used two instruments known as spectrographs aboard the James Webb Space Telescope, one on its Near Infrared Spectrograph (NIRSpec) and another on its Mid-Infrared Instrument (MIRI) to observe a vast section of near- to mid-infrared light emitted by planet VHS 1256 b. They plotted the light on the spectrum, identifying signatures of silicate clouds, water, methane and carbon monoxide. They also found evidence of carbon dioxide. Credit: Image: NASA, ESA, CSA, J. Olmsted (STScI); Science: Brittany Miles (University of Arizona), Sasha Hinkley (University of Exeter), Beth Biller (University of Edinburgh), Andrew Skemer (University of California, Santa Cruz)

In many ways, the team considers these findings to be the first “coins” pulled out of a spectrum that researchers view as a treasure chest of data. In many ways, they’ve only begun identifying its contents. “We’ve identified silicates, but better understanding which grain sizes and shapes match specific types of clouds is going to take a lot of additional work,” Miles said. “This is not the final word on this planet—it is the beginning of a large-scale modeling effort to fit Webb’s complex data.”

Although all of the features the team observed have been spotted on other planets elsewhere in the Milky Way by other telescopes, other research teams typically identified only one at a time. “No other telescope has identified so many features at once for a single target,” said co-author Andrew Skemer of the University of California, Santa Cruz. “We’re seeing a lot of molecules in a single spectrum from Webb that detail the planet’s dynamic cloud and weather systems.”

The team came to these conclusions by analyzing data known as spectra gathered by two instruments aboard Webb, the Near-Infrared Spectrograph (NIRSpec) and the Mid-Infrared Instrument (MIRI). Since the planet orbits at such a great distance from its stars, the researchers were able to observe it directly, rather than using the transit technique or a coronagraph to take this data.

There will be plenty more to learn about VHS 1256 b in the months and years to come as this team—and others—continue to sift through Webb’s high-resolution infrared data. “There’s a huge return on a very modest amount of telescope time,” Biller added. “With only a few hours of observations, we have what feels like unending potential for additional discoveries.”

What might become of this planet billions of years from now? Since it’s so far from its stars, it will become colder over time, and its skies may transition from cloudy to clear.

The researchers observed VHS 1256 b as part of Webb’s Early Release Science program, which is designed to help transform the astronomical community’s ability to characterize planets and the disks where they form.

The team’s paper, entitled “The JWST Early Release Science Program for Direct Observations of Exoplanetary Systems II: A 1 to 20 Micron Spectrum of the Planetary-Mass Companion VHS 1256-1257 b,” will be published in The Astrophysical Journal Letters.

The work is currently published on the arXiv preprint server.

More information:
Brittany E. Miles et al, The JWST Early Release Science Program for Direct Observations of Exoplanetary Systems II: A 1 to 20 Micron Spectrum of the Planetary-Mass Companion VHS 1256-1257 b, arXiv (2022). DOI: 10.48550/arxiv.2209.00620

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James Webb spots swirling, gritty clouds on remote planet (2023, March 22)
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Parade of planets: Jupiter, Mercury, Venus, Uranus and Mars alignment



Sky-gazers will be treated to a parade of planets near the end of month when Jupiter, Mercury, Venus, Uranus and Mars will appear together in the night sky.

On March 28, a large planetary alignment will take place when the five planets appear just after sunset, all within a 50-degree sector of the sky, according to sky tracking site Starwalk.

Jupiter and Mercury will appear near the horizon, in the constellation Pisces, while Venus will be visible higher in the sky on the constellation Aries, the sky-tracking site noted.

Next, Uranus will line up nearby but a pair of binoculars may be required to get a glimpse of the planet. Finally, Mars will appear higher in the sky, near the moon, to complete the five-planet alignment.


“Although March 28 is the best day for observation, the alignment will be visible several days before and after that date,” the website explained.

If the weather isn’t in your favour next week, there will be other opportunities to catch a planetary alignment this year, including another five-planet alignment on June 17. Mercury, Uranus, Jupiter, Neptune, and Saturn will be on parade that evening.


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'Astronomical lightshow' – Gazette



Next year, 2024, is Solar Eclipse Year.

A bird's eye view of a map of Mexico-U.S.-Canada with a line through it indicating the viewing path of the 2024 solar eclipse


On April 8, 2024, a total solar eclipse will be visible from the south Pacific Ocean, northern Mexico, across the U.S. and through the Atlantic provinces of Canada.

More importantly, the total solar eclipse will be visible from southwestern Newfoundland, in the areas of Stephenville and across central Newfoundland through Terra Nova Park and Gander.

A partial eclipse will be visible across the province, with St. John’s and Corner Brook just outside the range of a total eclipse, an 80 per cent eclipse in Labrador City and a 70 per cent eclipse in Nain.

The 2024 solar eclipse will be the first eclipse crossing the province since 1970 and the only one until 2079.

For many, this is a once-in-a-lifetime event to see a total solar eclipse in Newfoundland and Labrador.

“Solar eclipses are special events in many cultures and have allowed scientists to make great discoveries.”

We are fortunate to even be able to observe a solar eclipse.

The Earth is the only place in our solar system where there is a moon that is about the same size in the sky (0.5 degree) as the sun.

Solar eclipses are special events in many cultures and have allowed scientists to make great discoveries.

When the moon passes in front of the sun, most of the light is blocked and we can see the sun’s corona (more about the corona below).

A note: make sure to wear appropriate eye protection during an eclipse to look at the sun.

A composite image of the sun during a solar eclipse, showing the sun from left to right with a partial block of light all the way through a complete block of light and then continuing to a clear view.
This composite image of 13 photographs shows the progression of a total solar eclipse, from right to left, at Madras High School in Madras, Oregon on Monday, Aug. 21, 2017.

Photo: NASA/Aubrey Gemignani

The late Dr. Jay Pasachoff, an American astronomer, was so inspired by solar eclipses that he chased them around the world to experience more than 70 eclipses in about 50 years.

In a New York Times 2010 op-ed, he wrote: “There’s also the primal thrill this astronomical lightshow always brings the perfect alignment, in solemn darkness, of the celestial bodies that mean most to us.”

There is the thrill of observing solar eclipses and there is the thrilling science of them, too.

Thanks to solar eclipses, we learn about the sun’s corona, a thin layer of plasma that is just above the sun’s surface.

We normally can’t see it because it is so thin and has such a small density, but the temperature of the corona is about one million degrees Celsius.

It is believed that the corona is related to the sun’s magnetic field and to things like solar flares and mass ejections.

These flares and mass ejections impact the Earth through space weather and the aurorae — phenomena that those of us in the Northern Hemisphere recognize as the Northern Lights.

Scientific discovery

And it’s not just the sun.

Solar eclipses were important to provide some of the early evidence of Albert Einstein’s Theory of General Relativity.

Einstein predicted that light is bent by the gravity of stars.

So, if we can see stars behind the sun, they will appear to be in a slightly different location in the sky relative to each other than when we see them normally.

In 1919 scientists observed stars behind the sun that became visible during a solar eclipse and found that, indeed, their observations agreed with Einstein’s theory.

Town of Gander a major partner

Solar eclipses are fantastic events that connect humans to nature, celestial bodies and to the universe.

Next year’s celebration is an opportunity to celebrate science, nature and humanity.

Thanks to the enthusiasm and excitement of its staff and council, Prof. Svetlana Barkanova, Department of Physics, Grenfell Campus, and I are partnering with the Town of Gander to host a solar eclipse viewing party on April 8, 2024, and a science festival in the days before the eclipse.

The sun is shown in black with a sliver of light showing on the top right side during a solar eclipse.
Some prominences are seen as the moon begins to move off the sun during the total solar eclipse on Monday, Aug. 21, 2017 above Madras, Oregon.

Photo: NASA/Aubrey Gemignani

The town is excited to be a major partner bringing people from across Newfoundland and Labrador to learn, discover and experience a total solar eclipse together.

The town has pledged to develop a budget to assist with the costs of this unique science festival, along with providing facilities, viewing sites and in-kind assistance.

The event is being planned in collaboration with a continuing science and community outreach program led by Prof. Barkanova and her team.

They deliver a large-scale scientific and cultural outreach program for youth in our province, especially rural youth, girls and Indigenous students, and is currently developing in-person and online seminars and workshops leading up to the solar eclipse.

“It is an ideal chance for us at Memorial to do what we do best — share what is great about our fields.”

This is a call to faculty, students and staff at Memorial University across all campuses to join in the celebration and help it grow and expand.

Not only will we have the opportunity to experience an amazing celestial event, it is a chance to come together in central Newfoundland and share the stories of what we do at Memorial from how we understand the sun and moon in astrophysics, in cultures, in literatures, in humanities and so on.

This is a call to action for your involvement; more participating colleagues means more public talks, Science on Tap events, outreach in schools and more.

It is an ideal chance for us at Memorial to do what we do best — share what is great about our fields and do so around this rare event in Newfoundland and Labrador.

Come join in for Solar Eclipse Year 2024 in Gander. Contact me via email.

Co-authored by Dr. Svetlana Barkanova, Department of Physics, Grenfell Campus, and Brian Williams, tourism development officer, Town of Gander.

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