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James Webb Space Telescope preparing to keep an eye on space – Skywatching – Castanet.net

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The James Webb Space Telescope is now at its parking place about 1.5 million kilometres from Earth, located so that the Earth is between it and the Sun.

Now it is being set up to start observing. This will take a while since it is a very complex task and if a mistake is made, and it isn’t fixable by remote control, the repairs would require a longer servicing trip than any manned mission so far, and a far bigger launch vehicle than we have.

When we look at something through binoculars or a telescope, whether it something wild in the woods or something far off in space, the same process happens. A light collector, usually a convex lens, called the objective, captures light and brings it together to form an image, which we then observe through another lens, called the eyepiece. We can use a concave mirror to catch the light and form the image.

In this case the light is reflected back in the direction it came, forming the image in front of the mirror. Big, concave mirrors are usually chosen for large telescopes because large, convex lenses are very heavy and can only be supported around the edges, because the light has to go through them. Mirrors can be fully supported from behind. Moreover large mirrors or lenses are generally very heavy.

Since the mirror goes at the bottom of the telescope, the heavy weight is low down. It does not have to be supported high in the air.

Whether we are using lenses or mirrors, they have to be shaped with great precision. Errors in the shape of that lens or mirror must be far smaller than the wavelength of light, which is less than a millionth of a metre. This is precision engineering and it is amazing we can do it at all. It is even more amazing that amateur telescope makers have been achieving this for centuries.

The main way to ensure the lens or mirror maintains its accuracy is to make it all from one piece of material. Then we just need to ensure that it is stiff enough to stay in shape and is not exposed to temperature variations large enough to make it change shape. This is an area where mirrors come into their own; we can make the support structure as strong as we like and even add computer controlled actuators to keep the mirror in shape.

The single-piece mirror design was used in the Hubble Space Telescope (HST), which is equipped with a 2.4 metre diameter mirror. This easily fitted into the cargo bay on the Space Shuttle so this telescope was intended to be launched in a “ready to go” condition.

The 6.5 metre mirror on the James Webb Space Telescope (JWST) was another issue entirely. The mirror had to be this large (larger would have been even better) in order to meet its intended project requirements. However no available launch vehicles can handle objects with such diameters. There was no alternative to folding the instrument up and the unfolding it when on station in space.

The concave mirror was made in 18 hexagonal segments. Each segment was precisely manufactured. However, all those segments had to be attached to a folding structure that would withstand the noise and vibration of launch and then unfold so that all those segments would act together as a single, big mirror. This meant unfolding into a surface accurate to better than a millionth of a metre. The process has begun.

Since each hexagon is part of the same concave mirror, each one can make an image on its own. The roughly set up telescope was pointed at a bright star, and each hexagon projected a star image into the camera, so the image shows eighteen star images – just bright dots. The procedure now is to adjust each panel until all those dots combine to become one much sharper and brighter dot. This will be done slowly and very carefully.

There are a few months of work to go yet. We just have to be patient for a bit longer.

•••

• Venus is conspicuous in the southeast before dawn, with Mars and Mercury low in the glow.

• The Moon will reach its last quarter on Feb. 23.

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The body of a Ugandan Olympic athlete who was set on fire by her partner is received by family

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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.

Kenya’s high rates of violence against women have prompted marches by ordinary citizens in towns and cities this year.

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.

The Canadian Press. All rights reserved.

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The ancient jar smashed by a 4-year-old is back on display at an Israeli museum after repair

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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.”

The Canadian Press. All rights reserved.

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B.C. sets up a panel on bear deaths, will review conservation officer training

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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.

The Canadian Press. All rights reserved.

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