Tag: Dimorphos

Europe’s Hera asteroid probe sends back data from Mars fly-by

1:00 pm

Deimos and Mars as seen by Hera
Click to see full movie.

The European Space Agency (ESA) Hera probe, on its way to study the Didymos/Dimorphos asteroid binary, has successfully sent back images and data obtained during its close-by of Mars yesterday.

The infrared image to the right, a screen capture from a short movie assembled from Hera’s first images, shows the Martian moon Deimos with Mars in the background. The mission scientists have compiled all of these first images taken by Hera to create a short movie, that I have embedded below. From the movie’s caption:

The car-sized Hera spacecraft was about 1000 km away from Deimos as these images were acquired. Deimos orbits approximately 23 500 km from the surface of Mars and is tidally locked, so that this side of the moon is rarely seen. Hera’s TIRI – supplied to the mission by the Japan Aerospace Exploration Agency, JAXA – sees in mid-infrared spectral bands to chart surface temperature. Because Deimos lacks an atmosphere, the side of the moon being illuminated by the Sun is considerably warmer than the planet beneath it.

Although it appears as if Deimos is passing in front of Mars from south to north, the image was actually taken as Hera passed very close to Deimos from north to south at high speed.

Deimos appears brighter than Mars. This means that the surface of airless Deimos is hotter than the surface of Mars. The material covering the surface of Deimos has low reflectivity and is pitch black. This allows it to absorb sunlight well and become hotter. In contrast, the surface of Mars is highly reflective, and its atmosphere transports heat from the warm daytime side to the cooler nighttime side. This is why there is a large temperature difference between Mars and Deimos.

These infrared images also tell us the excellent quality of the camera. Note how detailed the features are on the Martian surface. When Hera gets to Didymos/Dimorphos in December 2026 it is going to be able to document those two asteroids in remarkable detail, including the results of the Dart impact on Dimorphos in September 2022.
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Europe’s Hera probe to fly past Mars tomorrow

10:22 am

As part of its journey to the binary asteroid Didymos/Dimorphos, the European Space Agency’s (ESA) Hera probe will slingshot past Mars tomorrow, obtaining images and data of both the red planet and its moon Deimos.

Three instruments will gather data, a navigational camera, and infrared camera, and a spectral camera, with the goal mostly to calibrate the instruments and make sure they are working as designed. The data won’t be available until the next day, when the ESA will hold a webcast unveiling the images.

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First test images sent back by Hera asteroid probe

9:19 am

The Earth and Moon system as seen by Hera
Click for original image.

During its initial in-space commissioning to make sure everything is working properly after an October 7, 2024 launch, engineers have successfully taken the first test images by Hera asteroid probe, proving those instruments are operating as intended.

The picture to the right, cropped, reduced, and sharpened to post here, was taken by the spacecraft’s mid-infrared camera, and shows both the Earth (lower left) and the Moon (upper right) as seen from a little less than a million miles away. Once Hera reaches the binary asteroid system of Didymos and Dimorphos, this instrument will be used to measure the changes of temperature on the asteroids’ surface.

Images of Earth taken by two other instruments proved those instruments were functioning properly as well.

Hera is a European Space Agency (ESA) follow-up asteroid mission to see up close what changes were caused to Dimorphos by the impact of NASA’s Dart mission in 2022. It will rendezvous with the asteroid in late 2026 after flying past Mars and its moon Deimos in earlier that year. It will then spend about a half year flying in formation with the asteroids before a planned landing in late July 2027.

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SpaceX launches Europe’s Hera asteroid mission

8:41 am

SpaceX today successfully launched the European Space Agency’s (ESA) Hera asteroid mission to the binary asteroid Didymos and Dimorphos, its Falcon 9 rocket lifting off from Cape Canaveral.

The first stage completed its 23rd rocket, but was not recovered in order to maximum the fuel used to send Hera on its proper route. The fairings completed their 13th and 19th flights respectively.

Hera will do a follow-up rendezvous with the binary asteroids to get a close-up look at the consequences of the Dart impact back in 2022 of Dimorphos.

The leaders in the 2024 launch race:

96 SpaceX
44 China
11 Russia
11 Rocket Lab

American private enterprise now leads the rest of the world combined in successful launches 113 to 67, while SpaceX by itself now leads the entire world, including American companies, 96 to 84.

For SpaceX, this launch ties the record the company set last year for the number of launches of a private company in a single year, and it did so in just more than three-quarters of the year. The company’s goal of 144 launches in 2024 remains possible, assuming the federal government stopped blocking its operations. For example, the FAA granted the company permission for this one launch, but maintained its grounding of further launches because an upper stage did not land safely in the ocean in the exact right spot.

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Research from DART impact mission determines approximate ages of the asteroid Didymos and its moon Dimorphos

12:54 pm

Computer simulation of formation of Dimorphos
Click for full animation

A release this week of new research papers based on data obtained during the impact mission of DART on the asteroid Dimorphos in 2022 has determined the approximate ages of both Dimorphos and the larger asteroid Didumos that it orbits.

Analysis suggested that both Didymos and Dimorphos have weak surface characteristics, which led the team to posit that Didymos has a surface age 40–130 times older than Dimorphos, with the former estimated to be 12.5 million years and the latter less than 300,000 years old.

This research also did a computer simulation that suggests Dimorphos was formed because of Didymos’ fast rotation rate, the fastest asteroid rotation rate so far measured. The spin caused first the development of a ridge on the equator of Didymos, which later literally threw material into space which later coalesced to form the satellite Dimorphus. The graphic to the right is from that simulation.

Other research studied the boulder distribution of Dimorphos, and structural nature of both asteroids.

A European mission, Hera, is scheduled to launch in October 2024 and rendezvous with Didymos and Dimorphos in 2026, obtaining close-up data following the DART 2022 impact.

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Scientists: DART impact of Dimorphos changed its orbit and reshaped the asteroid

9:18 am

Dimorphos shape change
Click for original graphic.

According to a new study, the DART impact of Dimorphos in September 2022 not only shortened its orbit around the larger asteroid Didymos, it reshaped the asteroid itself, warping its widest point sideways from its equator.

You can read the paper here.

More important, the scientists found that the changes evolved over time.

Over the following weeks, the asteroid’s orbital period continued to shorten as Dimorphos lost more rocky material to space, finally settling at 11 hours, 22 minutes, and 3 seconds per orbit – 33 minutes and 15 seconds less time than before impact. This calculation is accurate to within 1 ½ seconds, Naidu said. Dimorphos now has a mean orbital distance from Didymos of about 3,780 feet (1,152 meters) – about 120 feet (37 meters) closer than before impact.

Similarly, the reshaping of the asteroid into its present shape took time. As the scientists noted in their conclusion, “it takes time for a binary system to settle after a kinetic impact event.”

Because of Dimorphus’s rubble pile nature, its shape and orbit should continue to evolve over the coming decades, as more of the ejecta from the impact slowly falls back onto its surface and the asteroid surface adjusts over time. This in turn should also effect the orbit, though by only very tiny amounts.

I continue to wonder if the entire solar orbit of this asteroid binary system was impacted at all by these changes. Any changes would likely be tiny, but it is important to know to see if such an impact can actually do such a thing. To find out will take several more years, as ground telescopes continue to track the asteroid.

In October 2024 the European probe Hera will launch on a mission to this asteroid binary, with its arrival expected in December 2026. At that time we will get a much better look at both asteroids and how the impact affected them.

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High School students discover new orbital changes from asteroid impacted by DART

10:26 am

In observing Dimorphos, the small asteroid that the probe DART impacted in September 2022, researchers as well as students at a California high school have discovered unexpected orbital changes.

Recent observations have indicated the asteroid is tumbling since the impact. However:

Dimorphos also appeared to be continuously slowing down in its orbit for at least a month after the rocket impact, contrary to NASA’s predictions. California high school teacher Jonathan Swift and his students first detected these unexpected changes while observing Dimorphos with their school’s 2.3-foot (0.7 meter) telescope last fall. Several weeks after the DART impact, NASA announced that Dimorphos had slowed in its orbit around Didymos by about 33 minutes. However, when Swift and his students studied Dimorphos one month after the impact, the asteroid seemed to have slowed by an additional minute — suggesting it had been slowing continuously since the collision. “The number we got was slightly larger, a change of 34 minutes,” Swift told New Scientist. “That was inconsistent at an uncomfortable level.”

Swift presented his class’s findings at the American Astronomical Society conference in June. The DART team has since confirmed that Dimorphos did indeed continue slowing in its orbit up to a month after the impact — however, their calculations show an additional slowdown of 15 seconds, rather than a full minute. A month after the DART collision, the slowdown plateaued.

One explanation proposed for this slowdown points at the spray of rocks and boulders that surrounded Dimorphos after DART’s impact. When some of those boulders fell back onto the asteroid, they might have caused the orbital slowdown, and as the number of new impacts dropped, the slowdown stabilized.

Now that a full year has passed since the impact, it is possible to assess the full orbital changes to the asteroid. Thus, a new report is expected shortly.

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Dimorphus is dry, based on data obtained before and after DART hit it

10:52 am

Data collected by the ground-based Very Large Telescope (VLT) in Chile before and after the impact by the DART probe in September 2022 has revealed that the rubble-pile asteroid Dimorphos is very dry, with little or no water.

[The astronomers] observed the Didymos–Dimorphos system on 11 occasions, from just before the impact to about a month afterwards. MUSE [one of VLT’s instruments] is able to split the light from the double-asteroid into a spectrum, or rainbow, of colors, to look for emission at specific wavelengths that corresponds to specific molecules. In particular, Opitom’s team searched the ejecta for water molecules and for oxygen that could have come from the break-up of water molecules by the impact. However, no evidence of water was detected. Dimorphos, at least, seems to be a dry asteroid.

You can read the paper here.

Some theories prior to DART’s impact suggested that there could be ice within some inner solar system asteroids. Finding none instead suggests that inner solar system asteroids are very distinct and different from the icy comets and asteroids either coming from or orbiting in the outer solar system.

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Scientists publish their results from the impact of Dimorphos by DART

10:53 am

Seconds after impact
Seconds after impact. Click for movie, taken by amateur
astronomer Bruno Payet from the Réunion Island.

Scientists today published five papers outlining their results from the impact of Dimorphos by DART, summed up as follows:

  • Dimorphos’s density is about half that of Earth’s, illustrating its rubble pile nature.
  • The orbital period around the larger asteroid Didymos was changed by 33 minutes.
  • The ejection of material from Dimorphos during the impact had a greater effect on the asteroid’s momentum than the impact itself
  • The mass ejected was only 0.3 to 0.5% of Dimorphos’s mass, showing that the asteroid was not destroyed by the impact.
  • The impact turned Dimorphos into an active asteroid, with a tail like a comet.

The data not only tells us a great deal about this asteroid binary itself, it suggests that this impact method might be of use in defending the Earth from an asteroid impact. There are caveats however. First, the orbital change was not to the system’s solar orbit, the path that would matter should an asteroid threaten the Earth, but to Dimorphos’s orbit around its companion asteroid. We don’t yet know the effect on the solar orbit. Second, the impact did not destroy this small rubble pile asteroid, which means such an asteroid might still be a threat to the Earth even after impact. Third, in order for an impact to be the right choice for planetary defense, detailed information about the target asteroid has to be obtained. Without it such an impact mission might be a complete waste of time.

The irony to all this is that we knew all this before the mission. DART in the context of planetary defense taught us nothing, so NASA’s claim that this mission was to learn more about planetary defense was always utter bunkum. The mission’s real purpose was the study of asteroids, but selling it that way was hard. The sizzle of planetary defense however was a better lobbying technique, and it worked, even if it was dishonest.

That the press was also fooled by it, and continues to be fooled by it, is a subject for a different essay.

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More results from DART impact of Dimorphos

9:44 am

Didymos and Dimorphos as seen from Earth
Click for movie.

At a science conference this week scientists provided an update on the changes that occurred to the asteroid Dimorphos after it was impacted by the DART spacecraft in September, shortening its orbit around the larger asteroid Didymos by 33 minutes.

The image to the right is a screen capture from a short movie made from 30 images taken by the Magdalena Ridge Observatory in New Mexico, and part of a new image release of the asteroid pair.

It shows the motion of the Didymos system across the sky over the course of roughly 80 minutes, and features a long, linear tail stretching to the right from the asteroid system to the edge of the frame. The animation is roughly 32,000 kilometers across the field of view at the distance of Didymos.

According to the scientists, the impact displaced more than two million pounds of material from Dimorphos.

Observations before and after impact, reveal that Dimorphos and its larger parent asteroid, Didymos, have similar makeup and are composed of the same material – material that has been linked to ordinary chondrites, similar to the most common type of meteorite to impact the Earth. These measurements also took advantage of the ejecta from Dimorphos, which dominated the reflected light from the system in the days after impact. Even now, telescope images of the Didymos system show how solar radiation pressure has stretched the ejecta stream into a comet-like tail tens of thousands of miles in length.

Putting those pieces together, and assuming that Didymos and Dimorphos have the same densities, the team calculates that the momentum transferred when DART hit Dimorphos was roughly 3.6 times greater than if the asteroid had simply absorbed the spacecraft and produced no ejecta at all – indicating the ejecta contributed to moving the asteroid more than the spacecraft did.

This information is teaching us a great deal about these two particular asteroids, which could be used if for some reason their totally safe orbit got changed and they were going to impact Earth. However, NASA’s repeated effort to make believe this info would be useful for deflecting other asteroids is somewhat absurd. It is helpful, but each asteroid is unique. The data from DART is mostly helping astronomers get a better understanding of the geology of these specific asteroids, which will widen their understanding of asteroids in general. Planetary defense is really a very minor aspect of this work.

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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:
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