After Solar Orbiter, ESA’s next mission observing the Sun will not be one spacecraft but two: the double satellites making up Proba-3 will fly in formation to cast an artificial solar eclipse, opening up the clearest view yet of the Sun’s faint atmosphere – probing the mysteries of its million degree heat and magnetic eruptions.
Aiming for launch in mid-2022, Proba-3 comprises two small metre-scale satellites to be placed together in Earth orbit. They will line up to cast a precise shadow across space to block out the solar disc for six hours at a time during each 20 hour orbit, giving researchers a sustained view of the Sun’s immediate vicinity.
Precision formation flying
“To achieve this the satellite pair must achieve an unprecedented precision of flight control,” explains Proba-3 system manager Damien Galano. “They must align along an average distance of 144 m apart, maintained to an accuracy of a few millimetres. By achieving such precision formation flying techniques, in future multiple small satellites could perform equivalent tasks to individual giant spacecraft.”
Proba-3’s focus will be the Sun’s faint atmosphere, or corona, which extends millions of kilometres from the solar surface and is the source of the solar wind and coronal mass ejections – huge magnetic eruptions that can affect space weather all the way to Earth itself.
The corona is also the basis of a long-standing scientific mystery: while the Sun’s surface is a comparatively cool 6000 C, the corona rises to a sizzling million degrees or more – in apparent defiance to the laws of thermodynamics.
But the dazzling face of the Sun usually masks the faint, wispy corona, like a blazing bonfire next to a firefly.
Revealing the solar corona
“Up until now, the best way to see the corona is briefly during a solar eclipse on Earth, or else using a ‘coronagraph’ instrument incorporating one or more blocking – or ‘occulting’ – discs to blot out the Sun’s disc,” says solar scientist Andrei Zhukov of the Royal Observatory of Belgium (ROB).
He is the principal investigator of Proba-3’s main ASPIICS (Association of Spacecraft for Polarimetric and Imaging Investigation of the Corona of the Sun) telescope, while also serving as ROB’s project scientist of Solar Orbiter’s Extreme Ultraviolet Imager (EUI).
“But sunlight still bends around such blocking discs- known as ‘diffraction’ – which can leads to a high level of straylight within an instrument, degrading the resulting image,” adds Andrei.
“The idea behind Proba-3 is to cut that straylight fivefold and in the same time observe very close to the edge of the Sun, by flying the external blocking disc far away from the rest of the telescope, aboard a separate satellite.
“I’m looking forward to the time when Proba-3 is operating along with other Sun-watching missions. While Solar Orbiter’s EUI observes changes on the solar surface in extreme ultraviolet, Proba-3 will clearly show associated features within the inner corona in visible light, revealing interactions between the Sun and its surroundings.”
Mission taking shape
The mission has passed its ‘critical design review’, leading to the manufacturing and testing of satellite hardware.
“The prototype of the 1.4-m diameter external occulting disc has undergone testing,” explains Delphine Jollet, platform system engineer.
“Its rim, made of temperature-resistant carbon fibre reinforced polymer (CFRP), has to meet very stringent requirements to precisely hold its torus shape, designed to minimise the straylight spilling over its edges into ASPIICS. Skilled workmanship is essential to prepare the CFRP layout for moulding.”
“A secondary internal occulting disc is mounted within the instrument, this one just 3.5 mm in diameter, but having similarly stringent dimensional standards,” notes Proba-3 payload engineer Jorg Versluys.
“This internal occulter is part of the qualification model of the ASPIICS instrument that is being tested in simulated space conditions.”
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When Solar Orbiter launches on its journey to the Sun, there’s one key piece of engineering making this ESA-NASA mission possible: the heat shield.
Seeking a view of the Sun’s north and south poles, Solar Orbiter will journey out of the ecliptic plane – the belt of space, roughly in line with the Sun’s equator, through which the planets orbit. Slinging repeatedly past Venus in order to draw near the Sun and climb higher above the ecliptic, the spacecraft bounds from the Sun and back toward the orb … 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.
