After NASA’s DART mission slammed into asteroid Dimorphous in September 2022, scientists determined the impact caused tons of rock to be ejected from the small asteroid’s surface. But more importantly, DART’s impact altered Dimorphos’ orbital period, decreasing it by about 33 minutes.
However, a group of researchers measured the orbital period about a month later and discovered that it had increased to 34 minutes — 1 minute longer than the first measurements. Even though it was a single impact from DART, some force continued to slow the asteroid’s orbit, and astronomers don’t yet know what that mechanism might be.
“We find that no mechanism previously presented for this system can account for this large of a period change, and drag from impact ejecta is an unlikely explanation,” the researchers wrote in their paper, published as a preprint on arXiv. “Further observations of the (65803) Didymos system are needed to both confirm our result and to further understand this system post impact.”
DART’s purpose was a test of how asteroids respond to impacts. When the first data following the impact was released, the change in orbital period was great news, since this type of kinetic impact is a planetary defense technique, where a spacecraft intentionally collides with a Potentially Hazardous Asteroid to alter its course. The data from DART is helping both NASA and ESA prepare for the possibility of having to redirect an asteroid away from an eventual impact with Earth.
“We know the initial experiment worked. Now we can start to apply this knowledge,” said Andy Rivkin, DART investigation team co-lead at the Johns Hopkins Applied Physics Lab (APL), back in December 2022 when the first DART data was released.
Image captured by the Italian Space Agency’s LICIACube a few minutes after the intentional collision of NASA’s Double Asteroid Redirection Test (DART) mission with its target asteroid, Dimorphos, captured on Sept. 26, 2022. Credits: ASI/NASA
DART weighed 610 kg (1,340 lb) and it crashed into Dimorphos at approximately 22,530 km/h (14,000 mph. DART excavated a crater on the Dimorphos’ surface that ejected more than 900,000 kg (990 US tons) of debris into space. Data also indicated DART’s impact into Dimorphos also changed the trajectory of the moonlet’s parent asteroid, Didymos.
Scientists estimated DART’s impact displaced over one million kilograms (two million pounds) of the dusty rock into space – or enough to fill six or seven railroad cars. The DART science team is continuing to analyze their data, as well as new information on the composition of the asteroid moonlet and the characteristics of the ejecta to learn just how much DART’s initial hit moved the asteroid, and how much came from the recoil.
But now another group of researchers, led by Taylor Gudebski and Elisabeth Heldridge, used the 0.7m telescope at the Thacher Observatory located on the campus of The Thacher School in Ventura County, California to make their observations.
They measured the post-collision period change in observations taken about 20-30 days after the initial data, and their results indicate that the system period may have shortened during this brief time.
One thought was that since the debris cloud was so large and changed over time, it could influence Dimorphos’ orbit. In a study released in March 2023, astronomers tracked the evolution of the debris cloud from the collision for a month and found that as the debris expanded outward, structures started forming, such as clumps, spirals and a long tail pushed away by the Sun’s radiation. But Gudebski and Heldridge’s team doesn’t think the debris would account for the change they observed.
The James Webb Space Telescopecaptured this sequence of the DART collision on Dimorphos. Credit: NASA, ESA, CSA, and STScI.
Interestingly, the researchers said, even before the DART collision, the period of Dimorphos was observed to be slowly changing. But, the researchers wrote, even that amount of change can’t account for the difference, “as it was 4 orders of magnitude too small to account for the difference we see.”
“Therefore, whatever effect was causing the orbital decay before the collision cannot account for the discrepancy we observe; this includes the binary YORP effect, mutual tides, differential Yarkovsky force, nodal precession, and mass loss,” they said.
This group of researchers and the DART team will continue to observe and study DART’s impact. It will be interesting to find out if the orbital period continues to decline or not, and how that might affect the use of kinetic impactors.
Additionally, another spacecraft will launch in 2024 to study Dimorphos even closer. ESA’s Hera mission should arrive at Didymos and Dimorphos in December 2026. Hera will undertake a detailed study of Dimorphos to understand more deeply how the impact affected it.
NAIROBI, Kenya (AP) — The body of Ugandan Olympic athlete Rebecca Cheptegei — who died after being set on fire by her partner in Kenya — was received Friday by family and anti-femicide crusaders, ahead of her burial a day later.
Cheptegei’s family met with dozens of activists Friday who had marched to the Moi Teaching and Referral Hospital’s morgue in the western city of Eldoret while chanting anti-femicide slogans.
She is the fourth female athlete to have been killed by her partner in Kenya in yet another case of gender-based violence in recent years.
Viola Cheptoo, the founder of Tirop Angels – an organization that was formed in honor of athlete Agnes Tirop, who was stabbed to death in 2021, said stakeholders need to ensure this is the last death of an athlete due to gender-based violence.
“We are here to say that enough is enough, we are tired of burying our sisters due to GBV,” she said.
It was a somber mood at the morgue as athletes and family members viewed Cheptegei’s body which sustained 80% of burns after she was doused with gasoline by her partner Dickson Ndiema. Ndiema sustained 30% burns on his body and later succumbed.
Ndiema and Cheptegei were said to have quarreled over a piece of land that the athlete bought in Kenya, according to a report filed by the local chief.
Cheptegei competed in the women’s marathon at the Paris Olympics less than a month before the attack. She finished in 44th place.
Cheptegei’s father, Joseph, said that the body will make a brief stop at their home in the Endebess area before proceeding to Bukwo in eastern Uganda for a night vigil and burial on Saturday.
“We are in the final part of giving my daughter the last respect,” a visibly distraught Joseph said.
He told reporters last week that Ndiema was stalking and threatening Cheptegei and the family had informed police.
Four in 10 women or an estimated 41% of dating or married Kenyan women have experienced physical or sexual violence perpetrated by their current or most recent partner, according to the Kenya Demographic and Health Survey 2022.
TEL AVIV, Israel (AP) — A rare Bronze-Era jar accidentally smashed by a 4-year-old visiting a museum was back on display Wednesday after restoration experts were able to carefully piece the artifact back together.
Last month, a family from northern Israel was visiting the museum when their youngest son tipped over the jar, which smashed into pieces.
Alex Geller, the boy’s father, said his son — the youngest of three — is exceptionally curious, and that the moment he heard the crash, “please let that not be my child” was the first thought that raced through his head.
The jar has been on display at the Hecht Museum in Haifa for 35 years. It was one of the only containers of its size and from that period still complete when it was discovered.
The Bronze Age jar is one of many artifacts exhibited out in the open, part of the Hecht Museum’s vision of letting visitors explore history without glass barriers, said Inbal Rivlin, the director of the museum, which is associated with Haifa University in northern Israel.
It was likely used to hold wine or oil, and dates back to between 2200 and 1500 B.C.
Rivlin and the museum decided to turn the moment, which captured international attention, into a teaching moment, inviting the Geller family back for a special visit and hands-on activity to illustrate the restoration process.
Rivlin added that the incident provided a welcome distraction from the ongoing war in Gaza. “Well, he’s just a kid. So I think that somehow it touches the heart of the people in Israel and around the world,“ said Rivlin.
Roee Shafir, a restoration expert at the museum, said the repairs would be fairly simple, as the pieces were from a single, complete jar. Archaeologists often face the more daunting task of sifting through piles of shards from multiple objects and trying to piece them together.
Experts used 3D technology, hi-resolution videos, and special glue to painstakingly reconstruct the large jar.
Less than two weeks after it broke, the jar went back on display at the museum. The gluing process left small hairline cracks, and a few pieces are missing, but the jar’s impressive size remains.
The only noticeable difference in the exhibit was a new sign reading “please don’t touch.”
VICTORIA – The British Columbia government is partnering with a bear welfare group to reduce the number of bears being euthanized in the province.
Nicholas Scapillati, executive director of Grizzly Bear Foundation, said Monday that it comes after months-long discussions with the province on how to protect bears, with the goal to give the animals a “better and second chance at life in the wild.”
Scapillati said what’s exciting about the project is that the government is open to working with outside experts and the public.
“So, they’ll be working through Indigenous knowledge and scientific understanding, bringing in the latest techniques and training expertise from leading experts,” he said in an interview.
B.C. government data show conservation officers destroyed 603 black bears and 23 grizzly bears in 2023, while 154 black bears were killed by officers in the first six months of this year.
Scapillati said the group will publish a report with recommendations by next spring, while an independent oversight committee will be set up to review all bear encounters with conservation officers to provide advice to the government.
Environment Minister George Heyman said in a statement that they are looking for new ways to ensure conservation officers “have the trust of the communities they serve,” and the panel will make recommendations to enhance officer training and improve policies.
Lesley Fox, with the wildlife protection group The Fur-Bearers, said they’ve been calling for such a committee for decades.
“This move demonstrates the government is listening,” said Fox. “I suspect, because of the impending election, their listening skills are potentially a little sharper than they normally are.”
Fox said the partnership came from “a place of long frustration” as provincial conservation officers kill more than 500 black bears every year on average, and the public is “no longer tolerating this kind of approach.”
“I think that the conservation officer service and the B.C. government are aware they need to change, and certainly the public has been asking for it,” said Fox.
Fox said there’s a lot of optimism about the new partnership, but, as with any government, there will likely be a lot of red tape to get through.
“I think speed is going to be important, whether or not the committee has the ability to make change and make change relatively quickly without having to study an issue to death, ” said Fox.
This report by The Canadian Press was first published Sept. 9, 2024.
