Tag: asteroids

DART’s impact shortened Dimorphus’s orbit around Didymos by 32 minutes

5:51 pm

LICIACube Explorer image of DART impact
LICIACube Explorer image just after the DART
impact. Dimorphus is the blob near the top.

After two weeks of analyzing the orbit of Dimorphus around its parent asteroid Didymos, astronomers have determined that the impact of DART on Dimorphus shortened its orbit by 32 minutes.

Prior to DART’s impact, it took Dimorphos 11 hours and 55 minutes to orbit its larger parent asteroid, Didymos. Since DART’s intentional collision with Dimorphos on Sept. 26, astronomers have been using telescopes on Earth to measure how much that time has changed. Now, the investigation team has confirmed the spacecraft’s impact altered Dimorphos’ orbit around Didymos by 32 minutes, shortening the 11 hour and 55-minute orbit to 11 hours and 23 minutes. This measurement has a margin of uncertainty of approximately plus or minus 2 minutes.

Before its encounter, NASA had defined a minimum successful orbit period change of Dimorphos as change of 73 seconds or more. This early data show DART surpassed this minimum benchmark by more than 25 times.

It also appears the ejecta from the impact — much greater than expected — helped propel Dimorphus, a result that I think was also not expected.

Researchers are now shifting to studying the debris and asteroid itself, to better understand what happened as well as the nature of Dimorphus itself. This will also include a European probe dubbed Hera that will launch in 2024 an dvisit both asteroids in 2026.

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New computer simulation of theorized impact that created the Moon

8:56 am

The uncertainty of science: Before I even begin to describe this story, I must emphasize that it is pure science fiction. As much as it is founded on known data, that data is simply not sufficient to tell us exactly how the Moon was created. The data merely points to many hundreds of possibilities, of which the model below is simply one:

Computer programmers using a supercomputer at a United Kingdom university have created a new simulation of the theorized impact of a Mars-sized body to the Earth that some believe created the Moon, and determined it was possible for that impact to have created the Moon quickly, within hours.

You can read the research paper here.

The fun part of this story is to watch the video of this simulation, which I have embedded below. Whether it describes what actually happened is pure speculation, and in fact cannot be confirmed in any way at all.

It is intriguing, nonetheless.
» Read more

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Chang’e-5 samples suggest lunar meteorite impacts took place the same time as big Chicxulub impact

10:23 am

In analyzing lunar samples brought back by China’s Chang’e-5 Moon lander, Australian scientists have found evidence of lunar meteorite impacts that apparently took place the same time as big Chicxulub impact in the Yucatan 66 million years ago, thought by many scientists to have caused the extinction of the dinosaurs.

Their findings suggest that the frequency of meteorite impacts on the Moon may have been mirrored on Earth, and that major impact events on Earth were not stand-alone events and instead were accompanies by a series of smaller impacts. The study has been published in Science Advances.

“We combined a wide range of microscopic analytical techniques, numerical modelling, and geological surveys to determine how these microscopic glass beads from the Moon were formed and when,” says lead author Professor Alexander Nemchin, from the Space Science and Technology Centre (SSTC) in the School of Earth and Planetary Sciences at Curtin University in Perth.

The data suggests two possibilities, neither of which is confirmed. First, the impacts could have occurred because a cluster of large objects hit both Earth and the Moon at the same time. Second, the impacts on the Moon could have been caused by objects thrown up from the Earth when the bigger impact occurred at Chicxulub.

Either way, the data suggests a greater and more complex interaction between events on the Earth and events on the Moon.

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Hubble & Webb make first coordinated observations, tracking DART impact of Dimorphus

9:50 am

Webb and Hubble together look at DART impact of Dimorphus
Click for full image.

For the first time scientists have used both the Hubble Space Telescope and the James Webb Space Telescope to observe the same astronomical event, in this case the impact of the DART spacecraft on the asteroid Dimorphus on September 26, 2022.

The two images to the right show the asteroid several hours after impact. Both telescopes also captured images before the impact as well. From the press release:

Observations from Webb and Hubble together will allow scientists to gain knowledge about the nature of the surface of Dimorphos, how much material was ejected by the collision, and how fast it was ejected. Additionally, Webb and Hubble captured the impact in different wavelengths of light – Webb in infrared and Hubble in visible. Observing the impact across a wide array of wavelengths will reveal the distribution of particle sizes in the expanding dust cloud, helping to determine whether it threw off lots of big chunks or mostly fine dust. Combining this information, along with ground-based telescope observations, will help scientists to understand how effectively a kinetic impact can modify an asteroid’s orbit.

When Webb was first conceived in the late 1990s, it was exactly for this reason, to combine Hubble’s optical vision with Webb’s infrared view. Though more than a decade late, it has finally happened.

It will be months before scientists begin to decipher the data produced by all the telescopes and spacecraft used to observe the DART impact. What we are seeing now are merely hints at what has been learned.

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Watch DART smash into asteroid today

9:27 am

At 7:14 pm (Eastern) the NASA’s Double Asteroid Redirection Test (DART) spacecraft will crash into the small and harmless asteroid Dimorphus to see if such an impact could be used in the future to change the path of another asteroid aimed at Earth.

Dimorphus is 525 feet in diameter, and is a small moon of the larger half-mile-wide asteroid Didymos. Both are presently about 7 million miles away from Earth.

I have embedded the live streams below, one from a DART camera, dubbed DRACO, that will view the asteroid as the spacecraft approaches, and the other from NASA’s official live stream. From the DRACO live stream webpage:
» Read more

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Watching DART impact asteroid on September 26, 2022

9:35 am

A NASA planetary probe, dubbed DART, is on course for a planned impact of the asteroid Dimorphos this coming Monday, September 26, 2022, at 4:14 PM (Pacific).

DART was launched from Vandenberg Space Force Base, CA on November 23, 2021 PST (November 24 EST) headed to the asteroid Didymos and its tiny moon Dimorphos 7 million miles away. The plan is for DART to ram itself into Dimorphos while scientists on Earth measure whether its orbit around Didymos changes.

Dimorphos is about 525 feet in diameter, while Didymos is much larger, about a half mile in width. The goal is to see if this method can be used in the future to adjust an asteroid’s orbit enough to shift it away from hitting the Earth.

The impact will be observed by a camera on DART, as well as an Italian cubesat dubbed LICIACube.

NASA TV will be live streaming the event, and I will embed that live stream here when it goes live. Once DART gets close, its camera will record the asteroid’s approach through impact.

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Samples from Ryugu prove the truly delicate and long-lived nature of the rubble-pile asteroid

9:27 am

Two new studies of samples brought back from the rubble-pile asteroid Ryugu by the Japanese probe Hayabusa-2 have found that the asteroid not only was never heated above 86 degrees Fahrenheit, it also contained dust grains older than the solar system itself.

The evidence from the first study, completed by Japanese scientists, suggested that:

  • 1.Asteroid Ryugu accreted some components that originated in the outer Solar System and contained abundant water and organics. The asteroid then traveled to the inner Solar System.
  • 2.Organics associated with coarse-grained phyllosilicates may serve as one of the potential sources of water and organics to the Earth.

The second study, using samples provided to American scientists, found two tiny dust grains that must have come from the material that existed before the formation of our solar system.

The team detected all the previously known types of presolar grains—including one surprise, a silicate that is easily destroyed by chemical processing that is expected to have occurred on the asteroid’s parent body. It was found in a less-chemically-altered fragment that likely shielded it from such activity.

This is not the first discovery of presolar grains, but their delicate existence in Ryugu confirms the conclusions of the first study, that Ryugu had to have formed in the outer solar system and then migrated inward over eons.

The second study also reviewed the make-up of the sample and concluded that Ryugu appears to most closely match the family of carbonaceous Ivuna-type (CI) chondrites, thought to be among the most primitive asteroids known, of which very few have been studied because of they rarely survive the journey through the Earth’s atmosphere.

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Mapping the break-up and impact of one of the first asteroid’s tracked from space to the ground

11:33 am

Computer simulation of asteroid break-up
Click for full figure.

By analyzing 600 scattered pieces recovered from a 20-foot wide asteroid that broke-up and landed in the Sudan in 2008, scientists have discovered that some surface pieces were able to reach the ground unscathed because they were on the asteroid’s protected aft as it plowed through the atmosphere.

This asteroid was one of the first ever discovered shortly before impact and then tracked as it hit the atmosphere and broke up, the pieces falling as meteorites. The image to the right, figure 4 of the paper, shows the computer simulation of the asteroid’s break-up, based on the data obtained by mapping the location of its pieces on the ground. From the press release:

“Because of the high speed coming in, we found that the asteroid punched a near vacuum wake in the atmosphere,” says Robertson. “The first fragments came from the sides of the asteroid and tended to move into that wake, where they mixed and fell to the ground with low relative speeds.”

While falling to the ground, the smallest meteorites were soon stopped by friction with the atmosphere, falling close to the breakup point, while larger meteorites were harder to stop and fell further downrange. As a result, most recovered meteorites were found along a narrow 1-km wide strip in the asteroid’s path. “The asteroid melted more and more at the front until the surviving part at the back and bottom-back of the asteroid reached a point where it suddenly collapsed and broke into many pieces,” said Robertson. “The bottom-back surviving as long as it did was because of the shape of the asteroid.”

No longer trapped by the shock from the asteroid itself, the shocks from the individual pieces now repulsed them, sending these final fragments flying outwards with much higher relative speed. “The largest meteorites from 2008 TC3 were spread wider than the small ones, which means that they originated from this final collapse,” said Jenniskens. “Based on where they were found, we concluded that these pieces stayed relatively large all the way to the ground.”

The location of the large meteorites on the ground still reflects their location in the back and bottom-back part of the original asteroid.

While there is a certain randomness in how any asteroid breaks up, this data will help scientists better understand the make-up of future meteorites they find. The bigger more widely scattered pieces likely came from the asteroid’s rear surface.

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Lucy science team ends attempt to deploy solar array

9:12 am

Lucy's planned journey
Lucy’s planned mission, the yellow dot indicating approximately
its present position. Click for full image.

The Lucy science team has decided to end further attempts to fully deploy one of the spacecraft’s two solar arrays, leaving it just short of fully deployed.

On seven occasions in May and June, the team commanded the spacecraft to simultaneously run the primary and backup solar array deployment motors. The effort succeeded, pulling in the lanyard, and further opening and tensioning the array.

The mission now estimates that Lucy’s solar array is between 353 degrees and 357 degrees open (out of 360 total degrees for a fully deployed array). While the array is not fully latched, it is under substantially more tension, making it stable enough for the spacecraft to operate as needed for mission operations.

The press release announcing this decision is horribly written. First, it buries this decision to the release’s last three paragraphs so that it can rave about the brilliance of Lucy’s engineers and scientists in solving the overall problem. Second, it never actually states that this is the decision that has been made. It implies it.

Regardless, it appears the engineers are satisfied that the almost fully deployed array will hold its position for the rest of the mission. They have decided that the risk of trying to fully deploy it is greater than the risk of having it slightly open.

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OSIRIS-REx’s sample grab at Bennu in 2020 proved the rubble-pile asteroid has far less cohesion than predicted

10:10 am

The post touchdown crater on Bennu

The OSIRIS-REx science team, using data gathered during the spacecraft’s sample grab at Bennu in 2020, has determined that the rubble-pile asteroid has far less cohesion than predicted, with its rubble behaving less like a solid object and more like the playground ball-pits found in amusement parks.

After analyzing data gathered when NASA’s OSIRIS-REx spacecraft collected a sample from asteroid Bennu in October 2020, scientists have learned something astonishing: The spacecraft would have sunk into Bennu had it not fired its thrusters to back away immediately after it grabbed dust and rock from the asteroid’s surface.

It turns out that the particles making up Bennu’s exterior are so loosely packed and lightly bound to each other that if a person were to step onto Bennu they would feel very little resistance, as if stepping into a pit of plastic balls that are popular play areas for kids.

The image above shows what the touch down crater looked like after the sample grab, taken from the video that was part of the press release. The false colors indicate the depth changes produced by the touch down. The final crater was 26 feet across and more than two feet in depth, far larger than expected. Moreover, the energy from the spacecraft’s thrusters as it lifted off had increased the size of that crater further, by about 40%.

These results about the asteroid’s lack of cohesion match the earlier results studying a different impact crater on Bennu.

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Scientists: Comet 67P/C-G’s make-up matches the rest of the solar system

9:33 am

A detailed review of the archived data from the Rosetta mission that studied Comet 67P/Churyumov-Gerasimenko closely in 2014-2016 now strongly suggests that the comet’s overall make-up closely matches the rest of the solar system.

“It turned out that, on average, [the comet’s] complex organics budget is identical to the soluble part of meteoritic organic matter”, explains [Nora Hänni of the University of Bern] and adds: “Moreover, apart from the relative amount of hydrogen atoms, the molecular budget of [comet 67P/C-G] also strongly resembles the organic material raining down on Saturn from its innermost ring, as detected by the INMS mass spectrometer onboard NASA’s Cassini spacecraft”.

“We do not only find similarities of the organic reservoirs in the Solar System, but many of [comet 67P/C-G]’s organic molecules are also present in molecular clouds, the birthplaces of new stars”, complements Prof. Dr. Susanne Wampfler, astrophysicist at the Center for Space and Habitability (CSH) at the University of Bern and co-author of the publication. “Our findings are consistent with and support the scenario of a shared presolar origin of the different reservoirs of Solar System organics, confirming that comets indeed carry material from the times long before our Solar System emerged.”

These results are not unexpected, but having those expectations confirmed was one of the main scientific goals of the Rosetta mission. Now, almost a decade later, the results are in.

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Lucy solar panel almost completely open

11:19 am

Engineers have now been able to get the one solar panel that did not deploy completely after launch on the Lucy asteroid probe almost completely open.

From May 6 to June 16, NASA’s Lucy mission team carried out a multi-stage effort intended to further deploy the spacecraft’s unlatched solar array. The team commanded the spacecraft to operate the array’s deployment motor for limited periods of time, allowing them to closely monitor the response of the spacecraft. As a result of this effort, the mission succeeded in further deploying the array and now estimates that the solar array is between 353 degrees and 357 degrees open (out of 360 total degrees for a fully deployed array). Additionally, the array is under substantially more tension, giving it significantly more stabilization. The mission team is increasingly confident the solar array will successfully meet the mission’s needs in its current tensioned and stabilized state.

The spacecraft’s orbit is now moving into a position where communications will be limited until October, so further attempts to completely open the array will have to wait until then.

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