Jay McMahon News

CU Boulder leading $5 million multi-university project to advance the space economy

Anonymous — Tue, 03 Oct 2023 17:37:18 +0000

CU Boulder leading $5 million multi-university project to advance the space economy Anonymous (not verified) Tue, 10/03/2023 - 11:37

Jeff Zehnder

The space economy is booming, and the �ֲ��ý Boulder is at the forefront of a major federal funding initiative aimed at expanding science and engineering knowledge and workforce development for projects centered on operations Beyond Geostationary Orbit (xGEO) and Space Domain Awareness (SDA).

Leading this endeavor is Marcus Holzinger, a J. Negler Endowed Professor in the Ann and H.J. Smead Department of Aerospace Engineering Sciences. He is heading a new, $5 million, up to five-year research award with an option for an additional $1 million and further follow on funding.

The grant will go toward an array of diverse activities, including lunar-focused astrodynamics and sensing research, conflict simulation, and expanding workforce pathways related to the space workforce.

It may sound like science fiction, but NASA, the U.S. Space Force (USSF), and a rapidly growing number of private businesses envision significant potential for economic development on and around the Moon.

“There is a massive growth forecast in the space economy over the next 10-15 years; it’s going to double and then double again,” said Holzinger.

Called STARLIT, the grant brings together an array of leading aerospace universities, including CU Boulder, Purdue, Georgia Tech, Texas A&M, University of Texas Austin, and the University at Buffalo as well as an industry advisory board of 11 aerospace firms.

“We’re bringing together all the right people. These collaborators are experts in astrodynamics, space traffic management, data fusion, and cognitive engineering. It’s really an amazing team,” Holzinger said.

An additional CU Boulder partner is the university’s Center for National Security Initiatives. NSI will facilitate sponsor events and engagement, monitor cost-performance objectives, and identify adjacent defense opportunities to further advance the research and expand its national security footprint.

The project is being administered by the Universities Space Research Association and funded by the U.S. Space Force and the Air Force Research Laboratory (AFRL).

Growing People

One focus of the funding opportunity is dramatically expanding the space workforce. The funding aims to create new graduate education pathways, including summer research initiatives with minority serving institutions, student employment and mentorship opportunities, and internship programs through community colleges.

“We need more folks to go into astrodynamics. CU Boulder and other universities have increased enrollment, but there are probably two job openings for every person in these core areas,” Holzinger said. “How do we help direct students into these careers?”

Expanding Research

The grant will also boost efforts on orbital propagation and mission design for satellites and space vehicles that travel beyond low Earth orbit, including to the Moon.

Although the United States made multiple successful landings on the Moon, the drive for a space economy demands scalable toolsets and technology transfer to simplify the process and improve safety, according to Dan Scheeres, a distinguished professor of aerospace at CU Boulder and co-investigator on the grant.

“Over the last decade there have been significant advances in our understanding of the dynamics and navigation of spacecraft in cis-lunar space. However, many of these advances have not made their way into the operational tools that USSF and commercial operators use. This research is focused on transitioning these tools and concepts into some of the day-to-day operations and capabilities for cis-lunar space,” Scheeres said.

Conflict Simulations

A major reason for expanded interest in the Moon is the discovery of frozen water at the Lunar South Pole. It represents a potential game changer for space exploration, making it much easier to sustain human life on the Moon and beyond.

That creates new opportunities and challenges. With more nations and businesses targeting the Moon for economic development, the potential for conflict between them is growing. As part of the grant’s research focus, the team aims to develop new decision-making tools to avoid conflict and strategic surprise.

“This is about nation states and companies interacting and competing diplomatically and economically,” Holzinger said. “With the resources we’ve now discovered on the Moon, these are important questions that have never been explored. We’re going to learn a lot.”

As human and robotic space missions continue to expand, Holzinger is excited about the opportunities the grant presents to positively contribute to the future of science and engineering.

“This isn’t just sending people to the Moon, but engaging in economic activity there,” Holzinger said. “The first space race was about national pride and prestige. This second space race is about durable, sustainable human economic activity there long term.”

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Asteroid Landings Call For Robots With a Soft Touch

Anonymous — Fri, 08 Sep 2023 19:48:17 +0000

Asteroid Landings Call For Robots With a Soft Touch Anonymous (not verified) Fri, 09/08/2023 - 13:48

Jay McMahon's work on soft robots for space exploration and mining is being highlighted by IEEE Spectrum.

McMahon, an associate professor in the Ann and H.J. Smead Department of Aerospace Engineering Sciences, is developing Area-of-Effect Softbots (AoES) for asteroid proximity operations that can use electro-adhesion, solar radiation, or van der Waals forces to maneuver in extremely low gravity environments.

“There are electrostatic forces that will act and are not insignificant in the asteroid environment,” says McMahon. “It’s just a weird place, where gravity is so weak that those forces that exist on Earth, which we basically ignore because they’re so insignificant—you can take advantage of them in interesting ways.”

Read the full piece at IEEE Spectrum...

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McMahon interviewed for national story on DART

Anonymous — Tue, 27 Sep 2022 15:13:00 +0000

McMahon interviewed for national story on DART Anonymous (not verified) Tue, 09/27/2022 - 09:13

Associate Professor Jay McMahon was featured in an article on NASA's DART mission, which successfully crashed into the asteroid Dimorphos yesterday.

The piece, in the Christian Science Monitor, was written ahead of the collision. It outlines goals of the mission as an experiment for future planetary defense from asteroids.

McMahon, a participating scientist on the DART mission, is a faculty member in the Ann and H.J. Smead Department of Aerospace Engineering Sciences, is an expert on asteroid and comet science and autonomous guidance, navigation and control.

Read the full article...

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NASA is about to intentionally crash a spacecraft into an asteroid. This engineer will be watching

Anonymous — Thu, 22 Sep 2022 17:00:06 +0000

NASA is about to intentionally crash a spacecraft into an asteroid. This engineer will be watching Anonymous (not verified) Thu, 09/22/2022 - 11:00

On Monday just after 5 p.m. Mountain Time, a NASA spacecraft called the Double Asteroid Redirection Test (DART) is set to crash and burn—on purpose.

The spacecraft is aiming for a pair of asteroids orbiting around each other millions of miles from Earth: Didymos, which measures about a half-mile across, and its smaller companion Dimorphos. DART will slam into the surface of Dimorphos at more than 14,000 miles per hour, fast enough to permanently alter its orbit around Didymos. It’s all part of an attempt by NASA to determine if such impacts can shift the movement of rocky asteroids in space, potentially protecting Earth if it becomes necessary in the future.

As Jay McMahon put it: “We’re going to bump it and see how that changes things.”

McMahon is an associate professor of aerospace engineering sciences at CU Boulder and a participating scientist on the DART mission. His own research focuses on a phenomenon called the binary Yarkovsky-O’Keefe-Radzievskii-Paddock (bYORP) effect, in which sunlight gives asteroids tiny nudges to change their motion over thousands of years.

Jay McMahon

Click to enlarge
Graphic showing how DART's impact will influence the orbit of the asteroid Dimorphos around Didymos. (Credit: NASA/Johns Hopkins APL)

He sat down with CU Boulder Today to talk about this upcoming crash of epic proportions.

Disaster movies with killer asteroids are common in Hollywood—2021’s Don’t Look Up is one recent example. But how much of a threat do asteroids like the Didymos system actually pose to Earth?

We don't know of any significant danger posed by asteroids right now. But we also know for a fact that major impacts have happened in the past, the asteroid that killed the dinosaurs being the extreme case. There are also more reasonably-sized asteroids that could, and have in the past, had large effects here on Earth.

It’s really interesting to be involved in an effort to figure out how to proactively prevent those kinds of disasters, instead of just waiting until they become an imminent problem.

The collision, which is on track for Sept. 26, sounds like it will be pretty spectacular. What will we be able to see from the crash?

DART will be sending back images to Earth as it approaches the asteroid. We're coming in about six kilometers per second, or more than 14,000 miles per hour, so we’re moving really fast. Three seconds out, we’re still about 18 kilometers, or 11 miles, away. We don't know exactly how close it will be when it sends off its last image, but we should see some pretty detailed images.

Even after all that, NASA estimates that the time it takes for Dimorphos to orbit Didymos will only change by a few minutes after the impact—a relatively minor shift. Will those few minutes make a difference?

Minor in the short term. But my own research is looking further down the line, like 100,000 years. A small change in the orbit of Dimorphos might not seem like much now. But on those time scales, this test could be the difference between remaining as a stable binary system to potentially causing the two bodies to come back together or, eventually, migrate apart.

What’s going to happen in the aftermath of this crash?

The test is going to slow Dimorphos down in its orbit, so that would bring it a little closer to Didymos. But there are a lot of uncertainties. Neither of the asteroids are shaped like perfect spheres, and they’re both spinning in space as they orbit around each other. When all that stuff is thrown together, it gets really complicated to predict.

What are some of the other factors that make those calculations so complicated?

I study something called the binary YORP effect. Sunlight is hitting these asteroids all the time, and the side that's being lit up, heats up. Then as that hot side rotates away from the sun, all that heat gets reradiated into space.

It’s a very small push, but if it keeps happening in the same way over 100,000 years or more, it adds up and can change the orbit.

How will DART affect that slight nudge?

The effect is dependent on the shape of the asteroids. With DART, we’re going to make a crater on Dimorphos that's several meters across. Some people predict that it could be a lot larger. If that happens, it could dramatically change the mass distribution of the asteroid, which affects gravity and the bYORP effect.

What’s next?

The European Space Agency (ESA) is launching a follow-up mission called Hera in 2024, and that will get to Didymos in 2026. We're going to get some data from the spacecraft right when the DART experiment happens and will track and observe the asteroids with telescopes from Earth. Then a few years later, Hera will come and investigate it very closely.

It’s really cool because we’re making predictions about what will happen now. But we get to actually go test those predictions a few years later.

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McMahon part of NASA's first-ever mission to redirect the path of an asteroid

Anonymous — Mon, 29 Nov 2021 18:10:37 +0000

McMahon part of NASA's first-ever mission to redirect the path of an asteroid Anonymous (not verified) Mon, 11/29/2021 - 11:10

�ֲ��ý Boulder Associate Professor Jay McMahon is a participating scientist on NASA's DART, or Double Asteroid Redirect Test mission, which launched last week. Denver's 9News spoke with McMahon about the project, which aims to test asteroid deflection technology.

DART will travel to and then intentionally crash into the small asteroid Dimorphos, which orbits slowly around its larger companion Didymos.

Watch at 9News...

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McMahon receives Outstanding Faculty Graduate Advisor Award

Anonymous — Mon, 23 Aug 2021 17:56:03 +0000

McMahon receives Outstanding Faculty Graduate Advisor Award Anonymous (not verified) Mon, 08/23/2021 - 11:56

Associate Professor Jay McMahon has been recognized with an Outstanding Faculty Graduate Advisor Award.

The honor, bestowed by the College of Engineering and Applied Science, recognizes faculty who demonstrate exceptional advising skills and who serve as role models to other advisors. Honorees are selected based on the scores and comments from class surveys and nomination forms.

Positive submissions for McMahon included:

“As a mentor, he makes time for every one of his 20+ students in our lab and provides weekly feedback on our progress. He frequently provides us with help from general research knowledge, stress management techniques, to improving our writing skills for publications. One thing that stands out about Jay, besides being an incredibly supportive and effective advisor, is his commitment to diversity and inclusion regarding minorities in STEM. He is actively invested in providing opportunities for many students from underrepresented backgrounds and the presence of women, racial minorities, and international students in our lab shows how his recruitment practices reflect these beliefs.”

“Being an international student in the lab and staying miles apart from home during this time of the pandemic, there had been so many times that left me feeling anxious and low. But Dr. McMahon has been there to even emotionally support his students. I can be myself in front of him without having the fear of being judged. He is an amazing mentor and an amazing human being.”

“I am a first-generation college student, and I know I would not be where I am today if it were not for the support I got from Jay. He has always been there for me, looking after my interest and making sure that I have everything I need to be successful. His belief in me gives me confidence and encourages me to undertake new challenges. Since the beginning of my graduate career, I try many new things, from giving talks at conferences to have multiple internships. And this is because Jay helps nurture and elevate the scientist and researcher he saw in me the day he hired me.”

McMahon is the Associate Chair for Graduate Studies in the Ann and H.J. Smead Department of Aerospace Engineering Sciences and has been a member of the department faculty since 2013. His research focuses on astrodynamics and autonomous guidance, navigation and control. Asteroid (46829) McMahon was named in his honor in 2016.

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Building planetary defenses for killer asteroids

Anonymous — Mon, 19 Apr 2021 21:32:04 +0000

Building planetary defenses for killer asteroids Anonymous (not verified) Mon, 04/19/2021 - 15:32

Jeff Zehnder

Above: Jay McMahon.
Header image: Illustration of NASA’s DART spacecraft and the Italian Space Agency’s (ASI) LICIACube prior to impact at the Didymos binary system. Credit: NASA/Johns Hopkins APL/Steve Gribben

Jay McMahon is joining a groundbreaking NASA mission to test asteroid deflection technology.

McMahon, an assistant professor in the Ann and H.J. Smead Department of Aerospace Engineering Sciences at the �ֲ��ý Boulder, has been named a participating scientist in the Double Asteroid Redirection Test (DART).

DART is the first flight mission of NASA’s Planetary Defense Program. Scheduled for launch later this year, DART will travel to and then intentionally crash into the small asteroid Dimorphos, which orbits slowly around its larger companion Didymos.

Observations using Earth-based telescopes and planetary radar will measure the change in the orbit and determine the effectiveness of the impact in altering the motion of Dimorphos.

“We want to see how much we can deflect the asteroid. It’s definitely very exciting,” McMahon said.

DART was first announced in 2017. McMahon’s addition was announced by NASA today. His work will focus on using using the dynamical theory of interacting non-spherical bodies and radiative forces to better understand the changes in Dimorphos’s orbit caused by physical effects other than DART’s impact, in order to help interpret the post-impact Earth-based observations.

“After we impact it, the asteroid is going to move differently. If we think the change in the movement is only due to the impact, but it’s partially due to other factors, we need to know that so we can make a more accurate measurement of the effects of the impact,” McMahon said.

NASA’s goal with the mission is to demonstrate the possibilities of shifting the orbit of a small asteroid as a proof of concept in the event a large asteroid is ever discovered to be on track to hit Earth.

“On its face it still sounds kind of crazy. Can we run a probe into an asteroid and make it miss the Earth? But actually I don’t think we’re very far off in terms of technology or that there’s a huge amount of show stopping uncertainty,” McMahon said.

DART is slated for a November launch aboard a SpaceX Falcon 9 rocket from Vandenberg Air Force Base in California. It will intercept the asteroids in late September 2022.

Jay McMahon is joining a groundbreaking NASA mission to test asteroid deflection technology. McMahon, an assistant professor in the Ann and H.J. Smead Department of Aerospace Engineering Sciences at the �ֲ��ý Boulder has been named a participating scientist in the Double Asteroid Redirection Test (DART). DART is the first...

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Scientists peer inside an asteroid

Anonymous — Fri, 09 Oct 2020 15:38:46 +0000

Scientists peer inside an asteroid Anonymous (not verified) Fri, 10/09/2020 - 09:38

New findings from NASA’s OSIRIS-REx mission suggest that the interior of the asteroid Bennu could be weaker and less dense than its outer layers—like a crème-filled chocolate egg flying though space.

The results appear in a study published today in the journal Science Advances and led by the �ֲ��ý Boulder’s OSIRIS-REx team, including professors Daniel Scheeres and Jay McMahon. The findings could give scientists new insights into the evolution of the solar system’s asteroids—how bodies like Bennu transform over millions of years or more.

OSIRIS-REx rendezvoused with Bennu, an asteroid orbiting the sun more than 200 million miles from Earth, in late 2018. Since then, the spacecraft, built by Colorado-based Lockheed Martin, has studied the object in more detail than any other asteroid in the history of space exploration.

So far, however, one question has remained elusive: What’s Bennu like on the inside?

Scheeres, McMahon and their colleagues on the mission’s radio science team now think that they have an answer—or at least part of one. Using OSIRIS-REx’s own navigational instruments and other tools, the group spent nearly two years mapping out the ebbs and flows of Bennu’s gravity field. Think of it like taking an X-ray of a chunk of space debris with an average width about the height of the Empire State Building.

Top: Diagram of the orbit of Bennu in relation to Earth and other planets; bottom: Particles ejected from the surface of Bennu. (Credits: NASA/Goddard/University of Arizona/Lockheed Martin)

“If you can measure the gravity field with enough precision, that places hard constraints on where the mass is located, even if you can’t see it directly,” said Andrew French, a coauthor of the new study and a former graduate student at CU Boulder, now at NASA’s Jet Propulsion Laboratory (JPL).

What the team has found may also spell trouble for Bennu. The asteroid’s core appears to be weaker than its exterior, a fact that could put its survival at risk in the not-too-distant future.

“You could imagine maybe in a million years or less the whole thing flying apart,” said Scheeres, a distinguished professor in the Ann and H.J. Smead Department of Aerospace Engineering Sciences.

Evolution of asteroids

Of course, that’s part of the fun of studying asteroids. Scheeres explained that Bennu belongs to a class of smaller bodies that scientists call “rubble pile” asteroids—which, as their name suggests, resemble loosely held-together mounds of debris.

Asteroids also change over time more than people think.

“None of them have sat out there unchanging since the dawn of the solar system,” Scheeres said. “They’re being changed by things like sunlight affecting how they spin and collisions with other asteroids.”

To study how Bennu and other similar asteroids may change, however, he and his colleagues needed to take a peek inside.

This is where the team got lucky. When OSIRIS-REx first arrived at Bennu, the spacecraft spotted something unusual: Over and over again, tiny bits of material, some just the size of marbles, seemed to pop off the asteroid and into space. In many cases, those particles circled Bennu before falling back down to the surface. Members of the mission’s radio science team at JPL were able to witness how the body’s gravity worked first-hand—a bit like the apocryphal story of Isaac Newton inferring the existence of gravity after observing an apple falling on his head.

“It was a little like someone was on the surface of the asteroid and throwing these marbles up so they could be tracked,” Scheeres said. “Our colleagues could infer the gravity field in the trajectories those particles took.”

Squishy center

In the new study, Scheeres and his colleagues combined those records of Bennu’s gravity at work with data from OSIRIS-REx itself—precise measurements of how the asteroid tugged on the spacecraft over a period of months. They discovered something surprising: Before the mission began, many scientists had assumed that Bennu would have a homogenous interior. As Scheeres put it, “a pile of rocks is a pile of rocks.”

But the gravity field measurements suggested something different. To explain those patterns, certain chunks of Bennu’s interior would likely need to be more tightly packed together than others. And some of the least dense spots in the asteroid seemed to lie around the distinct bulge at its equator and at its very core.

“It’s as if there is a void at its center, within which you could fit a couple of football fields,” Scheeres said.

The asteroid’s spin may be responsible for that void. Scientists know that the asteroid is spinning faster and faster over time. That building momentum could, Scheeres said, be slowly pushing material away from the asteroid’s center and toward its surface. Bennu, in other words, may be in the process of spinning itself into pieces.

“If its core has a low density, it’s going to be easier to pull the entire asteroid apart,” Scheeres said.

For the scientist, the new findings are bittersweet: After measuring Bennu’s gravity field, Scheeres and his team have mostly wrapped up their work on the OSIRIS-REx mission.

Their results have contributed to the mission’s sample analysis plan—currently in development. The returned sample will be analyzed to determine the cohesion between grains—a key physical property that affects the mass distribution observed in their study.

“We were hoping to find out what happened to this asteroid over time, which can give us better insight into how all of these small asteroids are changing over millions, hundreds of millions or even billions of years,” Scheeres said. “Our findings exceeded our expectations.”

The University of Arizona leads science operations for OSIRIS-REx. NASA’s Goddard Space Flight Center in Maryland manages the overall mission.

Other coauthors on the new study include researchers at the Jet Propulsion Laboratory, Smithsonian Institution, The Open University, Northern Arizona University, KinetX Aerospace, Inc., NASA Goddard Space Flight Center, University of Maryland, Johns Hopkins University, York University, University of British Columbia, Southwest Research Institute, Université Côte d’Azur and University of Arizona.

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Seminar: Autonomous Guidance, Navigation and Control for Small Body Exploration (and beyond!) - Sept. 25

Anonymous — Sat, 19 Sep 2020 06:00:00 +0000

Seminar: Autonomous Guidance, Navigation and Control for Small Body Exploration (and beyond!) - Sept. 25 Anonymous (not verified) Sat, 09/19/2020 - 00:00

Jay McMahon
Assistant Professor, Smead Aerospace
Friday, Sep. 25 | 12:30 P.M. | Zoom Webinar - Registration Required

Abstract: Small bodies in the solar system - both asteroids and comets - have complex dynamical environments that create unique challenges to operating spacecraft in close proximity. Future missions will desire to more efficiently explore these bodies, as well as wanting to spend more time closer to or on their surfaces, which will necessitate having more capable autonomous spacecraft.

This talk will lay out some of the challenges that face such missions, provide an overview of the state-of-the-art for current small body exploration missions such as OSIRIS-REx and Hayabusa2, and will then discuss recent research in small body autonomy at the �ֲ��ý.

In particular, my lab focuses on developing autonomous algorithms for guidance, navigation, and control for small body missions that will advance our exploration capabilities for future government and/or commercial missions to these bodies and beyond.

Bio: Jay McMahon is currently an Assistant Professor in the Smead Aerospace Engineering Sciences department and CCAR at the �ֲ��ý in Boulder where he heads the Orbital Research Cluster for Celestial Applications (ORCCA) lab. ORCCA's research focuses on: autonomous space vehicle guidance, navigation, and control; asteroid science and missions; resource utilization; and space situational awareness. He has been in Boulder for a while - he received his PhD in Aerospace Engineering Sciences in 2011, was a Research Associate following that until early 2013 when he became an Assistant Research Professor until Fall 2016.

Prior to Boulder he lived in Los Angeles where he worked in the Guidance Analysis department at The Aerospace Corporation from 2004-2008. His previous degrees include a MS in Astronautical Engineering from the University of Southern California in 2006 and a BS in Aerospace Engineering from the University of Michigan in 2004.

He is currently an Associate Editor for the AIAA Journal of Spacecraft and Rockets and the AIAA Journal of Guidance Control and Dynamics, as well as being an Associate Fellow in AIAA. He was named a NASA Institute for Advanced concepts (NIAC) fellow in 2017, and a NASA Early Career Faculty fellow in 2018, and a DARPA Young Faculty Award winner in 2020. Asteroid (46829) McMahon (a main-belt binary asteroid) was named in his honor.

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How small particles could reshape Bennu and other asteroids

Anonymous — Wed, 09 Sep 2020 16:48:59 +0000

How small particles could reshape Bennu and other asteroids Anonymous (not verified) Wed, 09/09/2020 - 10:48

In January 2019, NASA’s OSIRIS-REx spacecraft was orbiting the asteroid Bennu when the spacecraft’s cameras caught something unexpected: Thousands of tiny bits of material, some just the size of marbles, began to bounce off the surface of the asteroid—like a game of ping-pong in space. Since then, many more such particle ejection events have been observed at Bennu’s surface.

OSIRIS-REx is an unprecedented effort to investigate what makes up asteroids like Bennu and how they move through space. But, as those leaping particles show, the mission has already delivered a few surprises.

“We’ve been studying asteroids for a long time and no one had ever seen this phenomenon before—these little particles getting shot off of the surface,” said Daniel Scheeres, distinguished professor in the Ann and H.J. Smead Department of Aerospace Engineering Sciences. He leads the radio science team for OSIRIS-REx along with CU Boulder’s Jay McMahon.

Now, a series of new studies seeks to recreate and understand the observed particle ejection events, piecing together what happened and why. Scheeres and McMahon are focusing on one question in particular: How might the leaping particles change the long-term fate of Bennu and other asteroids like it?

In research published in the Journal of Geophysical Research: Planets, the duo and their colleagues report that such seemingly small occurrences may add up over time—perhaps even helping to give the asteroid its telltale shape, which is often compared to a spinning top.

“We want to know what that means for the bigger picture of how asteroids live their lives,” said McMahon, an assistant professor of aerospace engineering.

The University of Arizona leads science operations for OSIRIS-REx, which was built by the Colorado-based Lockheed Martin. NASA’s Goddard Space Flight Center in Maryland manages the overall mission.

Mass loss

McMahon added that the life of some asteroids can be pretty chaotic. One class of these bodies, which scientists call “active” asteroids, loses a significant amount of material on an ongoing basis.

“They’re almost a cross between a comet and an asteroid,” McMahon said. “They’re losing mass, and it’s substantial enough that we can see it from Earth.”

Top: A view of the Asteroid Bennu showing the bulge at its equator; bottom: An artist's depiction of OSIRIS-REx using its extendable arm to collect a sample of material from the surface of Bennu. (Credits: NASA/Goddard/University of Arizona)

Until recently, no one knew that the same thing could happen on a much smaller scale. But that’s precisely the case on Bennu. One hypothesis suggests that rapid shifts in temperature could be causing the surface of the asteroid to warp and crack, popping off small bits of material. Another study has contended that the ejections could be the result of small meteoroids smacking into Bennu.

Based on OSIRIS-REx’s observations, the particles ejected from Bennu can be as big as softballs and hit speeds of about 7 miles an hour. Even more surprising, McMahon said, a small number of these bits of debris seemed to do the impossible: They flew off the surface of Bennu, then orbited the asteroid for several days or longer.

“That shouldn’t happen in typical orbital mechanics,” McMahon said.

Put differently, basic orbital calculations suggest that all of these particles should do one of two things: Jump off the surface and fall right back down or escape from Bennu’s gravity and never come back.

Close misses

To find out why some aren’t playing by the rules, McMahon and his colleagues used detailed computer models to track the trajectories of more than 17,000 test particles ejected from Bennu. They discovered a small subset of those seem to get an assist from an unlikely source: the sun.

McMahon explained that as these objects leap off the asteroid, they are exposed to heat and radiation coming from the sun and from Bennu itself—just a little bit, but enough to occasionally give them a slight boost in speed. With the right push, those particles can, essentially, fail at falling.

“The particle gets really close to the surface and just misses,” McMahon said. “If it can do that a few times then it can get into a situation where it can live in orbit for quite a while.”

In another study published in the same series, a team led by Scheeres and McMahon tried to figure out if ejection events might even influence Bennu’s own orbit around the sun—the answer is probably not.

The group did discover something else unusual: When particles eventually land on Bennu’s surface, many appear to disproportionately fall near its equator where the asteroid has a distinct bulge. As a result, these events could be reshaping the asteroid over thousands or millions of years by moving mass from its north and south to its middle.

The findings are a prelude to another major event in the life of Bennu. Next month, OSIRIS-REx will get closer to the asteroid than ever before. Once there, the spacecraft will use a retractable arm to grab a sample from the surface and bring it back home.

Scheeres and colleagues expect even more unexpected findings from an already surprising asteroid.

Coauthors on the new study include researchers from the Jet Propulsion Laboratory, Planetary Science Institute, NASA Goddard Space Flight Center, Lockheed Martin, University of Arizona, The Open University and University of Tennessee.

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