Asteroids, Comets, and Meteors

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NASA's Lucy spacecraft discovers 2nd asteroid during Dinkinesh flyby

https://phys.org/news/2023-11-nasa-lucy ... eroid.html

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Near Earth Asteroid May Be a Chunk of the Moon
by Niranjana Rajalakshmi
October 24, 2023

Introduction:

(Futurity) In 2021, a team of astronomers suggested that a recently discovered near-Earth asteroid, Kamo`oalewa, could be a chunk of the moon. Two years later, another research group finds that a rare pathway could have enabled this to happen.

So far, only distant asteroids from beyond the orbit of Mars have been considered a source of near-Earth asteroids, says Renu Malhotra, professor of planetary sciences at the University of Arizona and a senior author of the paper in the journal Communications Earth & Environment.
“We are now establishing that the moon is a more likely source of Kamo`oalewa,” Malhotra says.

The implication is that many more lunar fragments remain to be discovered among the near-Earth asteroid population.

Read more here: https://www.futurity.org/near-earth-as ... 90712-2/

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NASA's Lucy spacecraft discovers 2nd asteroid during Dinkinesh flyby

https://phys.org/news/2023-11-nasa-lucy ... eroid.html

Hidden Moon Discovered During Asteroid Flyby Isn't What We Thought
by Michele Starr
November 8, 2023

Introduction:

(Science Alert) It seems like yesterday we were marveling over Dinkinesh (because it practically was) and its secret little moon, and the main belt asteroid has already given us another huge surprise.

The small moonlet orbiting the larger rock, NASA scientists have discovered, is not one moon at all. It's two moons that are glued together like a little snowman, in a type of object called a contact binary.

You may have seen this before, in outer Solar System object Arrokoth – but Dinkinesh's little double moon is the first time we've seen one orbiting an asteroid.

"Contact binaries seem to be fairly common in the Solar System," says astronomer John Spencer of the Southwest Research Institute (SwRI).
"We haven't seen many up-close, and we've never seen one orbiting another asteroid. We'd been puzzling over odd variations in Dinkinesh's brightness that we saw on approach, which gave us a hint that Dinkinesh might have a moon of some sort, but we never suspected anything so bizarre!"

Read more here: https://www.sciencealert.com/hold-up-h ... -thought



Two moonlets for the price of one, like two gummi bears stuck together.
NASA/Goddard/SwRI/Johns Hopkins APL

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Halley’s Comet Has Begun Its 38-Year Journey Back Toward Earth
by Regina Seinra
December 12, 2023

Introduction:

(My Modern Met) Halley's Comet is one of the most fascinating astronomic events ever, with records dating back to a thousand years ago. It was last visible from Earth in 1986, and since it comes around every 75 to 79 years, its next sighting will take place in July 2061. And while that seems a while away, we can now start looking forward to its return. As of December 8, 2023, Halley's Comet is on its way back through the solar system towards Earth.

The comet travels around the Sun in a flattened elliptical orbit that takes it beyond the outer limits of the solar system, before bringing it back right around the Sun. And after decades of traveling away from our star, it has reached the farthest point of its orbit, also known as aphelion. Located 3.27 billion miles away from the Sun, it's roughly 472.2 million miles beyond the orbit of Neptune. The last time Halley's Comet was at this point in its orbit was in April 1948.

Now that Halley's comet is on its way back, it means that for the first time in nearly 38 years it will be getting closer to the Sun. It currently holds a speed of 0.565 miles per second, or about 2,034 miles per hour, which is expected to increase as it gets closer to the inner solar system. “In concert with Kepler's second law of motion, a celestial body moves fastest when it is at perihelion and slowest at aphelion,” writes Joe Rao from Space. So, once Halley passes through aphelion, its orbital velocity will begin to—very slowly at first—increase, on its way inbound toward the Sun.”

Halley's Comet last reached perihelion—its closest point to the Sun—on February 9, 1986, and it will be at that point again on July 28, 2061. Since the comet will be on the same side of the Sun as the Earth during the summer, it will appear at least 10 times brighter than it did 38 years ago—light pollution permitting.

Read more here: https://mymodernmet.com/halleys-comet- ... -earth/

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Miniaturized Jumping Robots Could Study an Asteroid’s Gravity
by Andy Tomaswick
December 23, 2023

Introduction:

(Universe Today) Missions focusing on small bodies in the solar system have been coming thick and fast lately. OSIRIS-Rex, Psyche, and Rosetta are all examples of projects that planned or did rendezvous with a small body in the solar system. But one of their biggest challenges is understanding the gravity of these bodies – which was especially evident when Philae, Rosetta’s lander, had a hard time staying on the surface of its intended comet. A new idea from researchers at the University of Colorado Boulder and NASA’s Jet Propulsion Laboratory could help solve that problem – by bouncing small probes around.

The concept, called Gravity Poppers, resulted from a NIAC grant back in 2020. The idea is simple enough – release a bunch of probes onto the surface of a small body and have them periodically jump off it. When they do so, keep track of them. If you know the force they jumped off with and can track them as they return to the surface, you can estimate the gravity of the area they’re floating over more accurately than alternative techniques.
Scientists use three main alternative techniques to calculate the gravity of small bodies – radar tomography, seismic imaging, and gravimetry. Each has disadvantages that the Gravity Poppers can overcome.

Radar tomography uses reflections of radio signals to estimate what the gravity is like in a particular area. However, it’s difficult to penetrate the deeper sections of a small body. Some materials don’t reflect electromagnetic waves at all, making it impossible to characterize areas with these materials.

Seismic imaging is commonly used on Earth. By tracking the movement of seismic waves across the surface of a body, scientists can estimate the gravity of regions surrounding them. However, some small bodies, especially asteroids, are just piles of rubble with no internal coherent structure. Seismic waves don’t do very well in such environments. Ryugu, the asteroid Hayabusa-2 visited, absorbed the seismic energy of an impact event such that the spacecraft couldn’t even discern any changes in its surface features.

Read more here: https://www.universetoday.com/164977/m ... e-164977

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NASA's Asteroid Sampler Begins its New Mission with a New Name
OSIRIS-REx is now OSIRIS-APEX, and it's on the way to an asteroid encounter in 2029.
By Ryan Whitwam December 27, 2023

https://www.extremetech.com/science/nas ... a-new-name
NASA's OSIRIS-REx mission was a smashing success—probably. Technicians are still struggling to open the sample canister that was delivered to Earth in October, but the spacecraft has a whole new mission to complete while NASA puzzles over those stuck screws. NASA flipped the switch from OSIRIS-REx to OSIRIS-APEX. This endeavor will end with a visit to another

asteroid, this one fresh off a close encounter with Earth.

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NASA Reveals Massive OSIRIS-REx Asteroid Sample
The mission is likely a success several times over.
By Ryan Whitwam January 24, 2024
https://www.extremetech.com/science/nas ... oid-sample

NASA's OSIRIS-REx mission collected a sample from the asteroid Bennu in 2020, returning its precious cargo to Earth in late 2023. However, technicians at Johnson Space Center had more trouble than expected getting a look at the payload. NASA reports that the canister has finally been opened and photographed. You're looking at a big, heaping mound of material from the dawn of the solar system.

OSIRIS-REx was designed to scoop up at least 60 grams of material from the asteroid, which is one of a class of objects that have remained unaltered since the formation of the solar system. Even before opening the container, NASA collected 70 grams of asteroidal dust from the exterior of the Touch-and-Go Sample Acquisition Mechanism (TAGSAM). So, the mission was already a success, but now it's a success several times over.

While the spacecraft dropped off the sample container last year, we're only getting a look inside now because NASA had trouble opening it. The TAGSAM is sealed with 35 fasteners, and two of them refused to budge with the approved tools. NASA ended up designing custom tools that could be used safely inside the sealed glovebox to loosen the bolts. It reported success earlier this month, but it delayed opening the container until late last week.

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Asteroid that Impacted Near Berlin Identified as a Rare Aubrite
February 5, 2024

Introduction:

(Eurekalert) February 5, 2024, Mountain View, CA – The official classification now aligns with what many suspected from merely looking at the images of the strange meteorites that fell near Berlin on January 21, 2024. They belong to a rare group called “aubrites”.

“They were devilishly difficult to find because, from a distance, they look like other rocks on Earth,” said SETI Institute meteor astronomer Dr. Peter Jenniskens. “Close up, not so much.”

Jenniskens traveled from San Francisco to Berlin to search the fields just south of the village of Ribbeck with Museum für Naturkunde (MfN) researcher Dr. Lutz Hecht, guiding a team of students and staff from the MfN, the Freie Universität Berlin, the Deutches zentrum für Luft und Raumfahrt, and the Technische Universität Berlin in the days following the fall.

“Even with superb directions by meteor astronomers Drs. Pavel Spurný, Jiří Borovička and Lukáš Shrbený of the Astronomical Institute of the Czech Academy of Sciences, who calculated how the strong winds blew the meteorites, and predicted that these could be rare enstatite-rich meteorites based on the light emitted by the fireball, our search team initially could not easily spot them on the ground,” said Jenniskens.

Unlike other meteorites which have a thin crust of black glass from atmospheric heat, these meteorites have a mostly translucent glass crust.

Read more here: https://www.eurekalert.org/news-releases/1033487