Tag: asteroids

Astronomers confirm asteroid discovered in 2020 is an Earth Trojan

9:57 am

Astronomers have now confirmed that an asteroid discovered in 2020, dubbed 2020 XL5, is an orbit that makes it the second Earth Trojan asteroid discovered, orbiting the Sun in the same orbit as the Earth but 60 degrees ahead of us.

In December 2020, 2020 XL5 was spotted by astronomers with the Pan-STARRS 1 survey telescope in Hawaii and added to the International Astronomical Union’s Minor Planet Center database. Amateur astronomer Tony Dunn went on to calculate the object’s trajectory using NASA’s publicly-available JPL-Horizon’s software and found that it orbits L4, the fourth Earth-sun Lagrange point, a gravitationally balanced region around our planet and star. 2010 TK7, the first-confirmed Earth Trojan asteroid, is also at L4.

The confirmation that it is definitely a Trojan was then made using both new observations as well as a review of archival images, allowing the astronomers to not only refine the asteroid’s orbit, but determine that it is a C-type asteroid, dark with lots of carbon. The data also suggests that in about 4,000 years, 2020 XL5 will drift from its Trojan point.

There are certainly more such asteroids, but detecting them is difficult from Earth because they can only be seen in twilight.

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Lucy update: cause of solar array issue identified

8:49 am

Lucy solar panel graphic

According to the principal scientist for the Lucy asteroid mission, engineers think they have identified what caused one of Lucy’s two fanlike solar arrays to fail to deploy completely.

The +Y array, rather than unfurling a full 360 degrees, instead went 347 degrees. In that configuration, the spacecraft is still generating more than 90% of its expected power. “Power is not an issue for the spacecraft, nor will it be through the entire mission if we have to fly it like it is.”

The arrays unfurl when a motor pulls on a lanyard, swinging one end of the array around and into place. Levison said that the most likely reason the array did not latch is that, for some reason, there was a loss of tension in the lanyard during deployment. That caused it to fall off a spool and wrap around the motor shaft. About 75 centimeters of lanyard remains to be pulled in.

It appears they in April will turn on the array’s motor to try to pull the lanyard in that last little bit. If that doesn’t work, they will then simply leave things as they are, as it appears the array is open enough to give them sufficient power for their mission.

There are risks to that course, however. Because the array is not latched open, it could begin to close, and thus result in less power to the spacecraft. Furthermore, its unlatched state appears to make some planned engine burns too risky.

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Lucy update: Engineers testing solar panel fix on ground

3:44 pm

Engineers for the asteroid probe Lucy have begun doing ground tests on a duplicate solar array motor on Earth to see if their plan will work to get the partly deployed solar panel in space opened and latched.

If all goes right, they are aiming for an April attempt at deploying the panel.

In the meantime, the spacecraft continues its coast outwards, presently being about 30 million miles from Earth. Even though one solar array is not fully open, it appears the spacecraft is getting “ample power” for its present operations. It is unclear if this power — with one solar panel not fully opened — will be sufficient once the spacecraft reaches the region of Jupiter’s Trojan asteroids, much farther from Earth.

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A tumbling 1,100-foot-wide asteroid

10:04 am

Nereus tumbling on December 10th close approach
Click for full image.

Using the Goldstone radio antenna in California, scientists have been able to take some of the highest resolution radar images of the 1,100-foot-wide asteroid Nereus during its close approach to Earth on December 10, 2021.

The montage to the right, cropped to post here, shows twelve images from the 39-image sequence, which can also be viewed as an animation here.

During the asteroid’s close approach, an image resolution of about 12.3 feet (3.75 meters) per pixel was possible, revealing surface features such as potential boulders and craters, plus ridges and other topography. Asteroid Nereus’ previous approach in 2002 was near enough to Earth to reveal the asteroid’s size and overall shape, but too distant to show surface features. The new observations will also help scientists better understand the asteroid’s shape and rotation while providing them new data to further refine its orbital path around the Sun.

The asteroid will not make a similar close-approach again until 2060.

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NASA issues vague update on Lucy’s solar panel deployment issue.

9:29 am

Lucy solar panel graphic

NASA today released a very vague update describing the work of the Lucy engineering team in trying to work out a fix to the incomplete deployment of one of Lucy’s solar panels.

A project team completed an assessment Dec. 1 of the ongoing solar array issue, which did not appear to fully deploy as planned after launch in late October. Initial ground tests determined additional motor operations are required to increase the probability of the latching Lucy’s array in place as intended, and the team has recommended additional testing.

Spacecraft operations included discharging and charging the battery while pointed at Earth, moving the spacecraft to point to the Sun, operating the solar array motor with the launch day parameters, moving back to pointing at Earth, and then another battery discharge and recharge. The solar arrays charge the batteries, then the batteries are deliberately discharged, and the solar array circuits are used to recharge the batteries; performing these charging and discharging processes gives the team more information about the solar array circuits.

The team gathered information on two of the 10 gores – the individual solar array panel segments that make up the full array — that previously had no data. NASA now has data on all 10 gores confirming they are open, producing power as expected, and not stuck together. [emphasis mine]

Apparently they have been doing a variety of testing of the array to assess its precise condition. The highlighted words are the most important, as this data suggests that all ten fan sections, as shown in the graphic above, are partly open, and that an attempt to fully deploy the solar panel should work.

The Lucy team has apparently decided to approach this work very slowly and cautiously, that they have time to do so as Lucy continues its slow journey to Jupiter’s Trojan asteroids.

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NASA upgrades software for monitoring potentially dangerous asteroids

9:59 am

NASA has installed a major upgrade to the software it uses for monitoring, tracking, and predicting the future orbits of potentially dangerous asteroids.

Sentry [the original software used for the past 20 years] was very effective at calculating orbital paths based on how an asteroid is affected by the gravitational pull of the Sun and planets, but there were a few factors that it couldn’t account for. In the long run, these uncertainties can snowball into many possible orbits that may or may not impact Earth.

The Yarkovsky effect, for instance, is where the Sun unevenly heats the surface of an asteroid as it spins, creating thermal forces between the “day” and “night” sides of the rock that can produce thrust. Other times, asteroids that swing past Earth very closely could be nudged into different orbits by the planet’s gravity, changing the paths of their eventual return.

The first Sentry system couldn’t incorporate either of these two factors, meaning that for special case asteroids like Bennu or Apophis, astronomers would have to manually analyze their orbits, which is a complex and time-consuming process.

But Sentry-II is designed to account for things like these. This latest version uses a different algorithm that models thousands of random points within the uncertainty space of an asteroid’s orbit, then figures out which ones have a chance of striking Earth in future. This, the team says, could help find scenarios that have very low probability of impact.

What this upgrade means is that as new asteroids are discovered the software will be able to very quickly calculate with better accuracy any potential impacts in the coming centuries. The results won’t be perfect, but less manual work will be necessary, meaning fewer dangerous asteroids will fall through the cracks.

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SpaceX successfully launches NASA asteroid mission

8:58 am

Last night SpaceX’s Falcon 9 rocket successfully launched NASA’s DART asteroid mission.

The first stage landed successfully, completing its third flight. This was SpaceX’s 26th launch in 2021, setting a new record for the company and in fact for any private company ever.

DART’s mission is to test one method for changing an asteroid’s orbit.

After launch tonight, DART will take aim on an asteroid called Dimorphos. The spacecraft will strike Dimorphos at nearly 15,000 mph (about 6.6 kilometers per second).

The primary science goal of the mission is to measure how the high-speed collision next September, which will destroy the DART spacecraft, disrupts the orbit of Dimorphos around nearby Didymos. The data could help plan a future mission to deflect an asteroid on a course to hit Earth.

Dimorphos and its larger companion Didymos pose no near-term threat to Earth, but the asteroids will be close enough to our planet next year for astronomers to observe DART’s impact using ground-based telescopes. The asteroids orbit the sun in an elongated path that occasionally bring them into Earth’s neighborhood. That makes them potentially hazardous asteroids, although scientists say there is no near-term threat from the pair.

No space mission has ever explored Didymos and Dimorphos, but scientists who have observed them through telescopes say the asteroids are about a half-mile (780 meters) and 525 feet (160 meters) in diameter, respectively.

An Italian cubesat is also on board, and will separate from DART about ten days before impact so that it can observe the impact with two camera.

The leaders in 2021 launch race:

43 China
26 SpaceX
18 Russia
5 Europe (Arianespace)

China now leads the U.S. 43 to 41 in the national rankings. For the U.S. SpaceX’s launch last night topped the U.S. total from last year, which was this country’s highest launch total since the 1960s.

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Lucy update: Instruments all working, no action yet on solar array

9:22 am

According to an update from the Lucy science team today, they have completed the checkout of the asteroid probe’s instruments, and found them all operating properly. However, no action has yet been taken to try to correct the partially deployed solar panel.

The team has used an engineering model of the solar array motor and lanyard to replicate what was observed during the initial solar array deployment. The test data and findings suggest the lanyard may not have wound on the spool as intended. Testing continues to determine what caused this outcome, and a range of scenarios are possible. The team isn’t planning to attempt to move or further characterize the current state of the solar array deployment before Wednesday, Dec. 1, at the earliest.

It appears the spacecraft is still on its planned course.

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Scientists: Asteroid in an orbit entwined with the Earth might be Moon rock

11:45 am

Data obtained by scientists using ground-based telescopes now suggests that the small asteroid Kamo`oalewa, which has an orbit that makes it a quasi-Moon of the Earth, might have originally come from the Moon.

From their paper’s abstract:

We find that (469219) Kamoʻoalewa rotates with a period of 28.3 (+1.8/−1.3) minutes and displays a reddened reflectance spectrum from 0.4–2.2 microns. This spectrum is indicative of a silicate-based composition, but with reddening beyond what is typically seen amongst asteroids in the inner solar system. We compare the spectrum to those of several material analogs and conclude that the best match is with lunar-like silicates. This interpretation implies extensive space weathering and raises the prospect that Kamo’oalewa could comprise lunar material.

Kam’oalewa — which is only about 150 feet across — is one of five such quasi-Earth-moons. All orbit the Sun in orbits that are similar to the Earth’s and are such that the asteroids periodically loop around our planet each year.

This data will be useful to the Chinese, who are planning a mission to Kamo-oalewa in ’24 to grab samples.

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Lucy’s solar panel problem could be due to strap

9:20 am

According to the engineering team for the Lucy asteroid mission, they now think the incomplete deployment of one of the probe’s solar panels was caused by a strap.

The joint Anomaly Response Team has been studying the array using an engineering model. Initial tests indicate that the lanyard that pulls out the solar array may not have completed the process successfully; however, it is still uncertain what caused this condition. The team is conducting more tests to determine if this is indeed the case, and what the root cause might be.

An attempt to characterize the array deployment by attempting to move it would occur no earlier than Nov. 16.

Meanwhile, they have been turning on Lucy’s instruments one by one, with everything functioning as planned, except for that one solar panel. The panel however is a serious concern, as the spacecraft is heading out to the orbit of Jupiter, where it will need every inch of solar panel surface area to get enough power to operate. At the moment it appears the panel is deployed somewhere between 75% to 95%.

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Update on Lucy: panels generating more than 90% of expected power

9:38 pm

According the Lucy science team, the spacecraft’s solar panels are generating more than 90% of the expected power at this stage of the mission, despite the fact that one panel did not deploy completely and has not latched in final position.

“We’re very happy to report that we are getting most of the power we expected at this point in the mission,” said Joan Salute, associate director for flight programs at NASA’s planetary science division. “It’s not 100%, but it is fairly close. So that is great news.’

In an interview with Spaceflight Now, Salute said the power output from the solar arrays appears to be “most likely above 90%” of the expected level of 18,000 watts. “We don’t know if it’s a latch problem, or that it is only partially deployed,” Salute said.

If correct, there is an excellent chance the mission will not be seriously hindered, even if they cannot get the panel fully deployed or latched. At the same time, there are worries about firing Lucy’s main engine for major course corrections with the panel unlatched. The first major course correction is scheduled for mid-November.

The engineers are presently reviewing their data. One option might be to order the spacecraft to re-attempt a full deployment, in the hope that the process will complete during that second attempt.

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Early solar system had gap separating its inner and outer regions

9:29 am

New research looking at the make-up of asteroids now suggests that the early solar system had a gap that separated the formation of planets between its inner and outer regions.

Earlier data had suggested that asteroids come in two fundamentally different groups. This new research, looking the magnetic field strength of these two groups, has confirmed this distinction, and provided additional information about the formation process of each.

Surprisingly, they found that their field strength was stronger than that of the closer-in noncarbonaceous meteorites they previously measured. As young planetary systems are taking shape, scientists expect that the strength of the magnetic field should decay with distance from the sun.

In contrast, Borlina and his colleagues found the far-out chondrules had a stronger magnetic field, of about 100 microteslas, compared to a field of 50 microteslas in the closer chondrules. For reference, the Earth’s magnetic field today is around 50 microteslas.

A planetary system’s magnetic field is a measure of its accretion rate, or the amount of gas and dust it can draw into its center over time. Based on the carbonaceous chondrules’ magnetic field, the solar system’s outer region must have been accreting much more mass than the inner region.

In other words, the accretion of planets in the outer region was faster and producing larger objects, while the inner region was slower and producing smaller objects. The data also suggests that gap existed about 4.5 billion years ago, at about the location of the asteroid belt. All in all, this scenario matches the solar system we see today.

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