This summer, the OSIRIS-REx spacecraft will undertake NASA’s first-ever attempt to touch the surface of an asteroid, collect a sample of it, and safely back away. But since arriving at asteroid Bennu over a year ago, the mission team has been tackling an unexpected challenge: how to accomplish this feat at an asteroid whose surface is blanketed in building-sized boulders.
Using these hazardous boulders as signposts, the mission team developed a new precision navigation method to overcome the challenge.
The OSIRIS-REx team had originally planned to use a LIDAR system to navigate to Bennu’s surface during the Touch-And-Go (TAG) sample collection event. LIDAR is similar to radar, but it uses laser pulses rather than radio waves to measure distance. The OSIRIS-REx Guidance, Navigation, and Control (GNC) LIDAR is designed to navigate the spacecraft to a relatively hazard-free surface.
The mission had originally envisioned a touchdown site 164 ft (50 meters) in diameter, but the largest safe areas on Bennu are much smaller. The biggest site is just 52 ft (16 m) wide, or roughly 10% of the safe area envisioned. The team realized that they needed a more precise navigation technique that would allow the spacecraft to accurately target very small sites while dodging potential hazards.
In the face of this challenge, the OSIRIS-REx team switched to a new navigation method called Natural Feature Tracking (NFT). NFT provides more extensive navigation capabilities than LIDAR, and is key for executing what the team is calling “Bullseye TAG,” which delivers the spacecraft to the much smaller sampling area. As an optical navigation technique, it requires the creation of a high-resolution image catalog onboard the spacecraft.
Earlier this year, the spacecraft made reconnaissance passes over the mission’s primary and backup sample collection sites, designated Nightingale and Osprey, flying as close as 0.4 miles (625 m) over the surface. During these flyovers, the spacecraft collected images from different angles and lighting conditions to complete the NFT image catalog.
The team uses this catalog to identify boulders and craters unique to the sample site region, and will upload this information to the spacecraft before the sample collection event. NFT autonomously guides the spacecraft to Bennu’s surface by comparing the onboard image catalog with the real-time navigation images taken during descent. As the spacecraft descends to the surface, NFT updates its predicted point of contact depending on the spacecraft’s position in relation to the landmarks.
On the ground, team members created “hazard maps” for both the Nightingale and Osprey sites to document all of the surface features that could potentially harm the spacecraft, like large rocks or steep slopes. The team used the image catalog in conjunction with data from the OSIRIS-REx Laser Altimeter (OLA) to create 3D maps that closely model Bennu’s topography.
As part of NFT, these maps document boulder heights and crater depths, and guide the spacecraft away from potential hazards while targeting a very small site. During descent, if the spacecraft predicts it will touch unsafe terrain, it will autonomously wave-off and back away from the surface. However, if it sees that the area is free of hazards, it will continue to descend and attempt to collect a sample.
NFT will be used in April to navigate the spacecraft during its first sample collection rehearsal. The operations team performed preliminary testing during the Orbital B mission phase in late 2019, and the results demonstrated that NFT works in real-life conditions as designed. NFT will also be used for navigation during the second rehearsal planned for June.
OSIRIS-REx’s first sample collection attempt is scheduled for late August. The spacecraft will depart Bennu in 2021 and is scheduled to deliver the sample to Earth in September 2023.
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Asteroid Bennu’s most prominent boulder, a rock chunk jutting out 71 ft (21.7 m) from the asteroid’s southern hemisphere, finally has a name. The boulder – which is so large that it was initially detected from Earth – is officially designated Benben Saxum after the primordial hill that first arose from the dark waters in an ancient Egyptian creation myth.
Benben Saxum and 11 other features on the asteroid are the first to receive official Bennu feature names approved by the International Astronomi … read more
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.
