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DNA study detects mysterious human 'ghost' species – The Japan Times

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Scientists examining the genomes of West Africans have detected signs that a mysterious extinct human species interbred with our own species tens of thousands of years ago in Africa, the latest evidence of humankind’s complicated genetic ancestry.

The study indicated that present-day West Africans can trace a substantial proportion, about 2 to 19 percent, of their genetic ancestry to an extinct human species — what the researchers called a “ghost population.”

“We estimate interbreeding occurred approximately 43,000 years ago, with large intervals of uncertainty,” said University of California, Los Angeles human genetics and computer science professor Sriram Sankararaman, who led the study, published this week in the journal Science Advances.

Homo sapiens first appeared a bit more than 300,000 years ago in Africa and later spread worldwide, encountering other human species in Eurasia that have since gone extinct, including the Neanderthals and the lesser-known Denisovans.

Previous genetic research showed that our species interbred with both the Neanderthals and Denisovans, with modern human populations outside of Africa still carrying DNA from both. But while there is an ample fossil record of the Neanderthals and a few fossils of Denisovans, the newly identified “ghost population” is more enigmatic.

Asked what details are known about this population, Sankararaman said, “Not much at this stage.”

“We don’t know where this population might have lived, whether it corresponds to known fossils, and what its ultimate fate was,” Sankararaman added.

Sankararaman said this extinct species seems to have diverged roughly 650,000 years ago from the evolutionary line that led to Homo sapiens, before the evolutionary split between the lineages that led to our species and to the Neanderthals.

The researchers examined genomic data from hundreds of West Africans, including the Yoruba people of Nigeria and Benin and the Mende people of Sierra Leone, and then compared that with Neanderthal and Denisovan genomes. They found DNA segments in the West Africans that could best be explained by ancestral interbreeding with an unknown member of the human family tree that led to what is called genetic “introgression.”

It is unclear if West Africans derived any genetic benefits from this long-ago gene flow.

“We are beginning to learn more about the impact of DNA from archaic hominins on human biology,” Sankararaman said, using a term referring to extinct human species. “We now know that both Neanderthal and Denisovan DNA was deleterious in general but there were some genes where this DNA had an adaptive impact. For example, altitude adaptation in Tibetans was likely facilitated by a Denisovan introgressed gene.”

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OSIRIS-REx mission to collect asteroid sample to return to Earth thanks to Canadian technology – CBC.ca

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On Tuesday, NASA’s OSIRIS-REx mission will make history as it attempts its first collection of material from an asteroid to be returned to Earth in 2023.

The spacecraft — which arrived at the asteroid Bennu in 2018 — will conduct a touch-and-go manoeuvre, also referred to as TAG. This crucial part of the mission was made possible in part by Canadian technology, specifically the Canadian Space Agency’s OSIRIS-REx Laser Altimeter (OLA), which mapped the surface of Bennu in 3D. The asteroid lies roughly 332 million kilometres from Earth.

That mapping turned out to be extremely important. Scientists and engineers had anticipated the asteroid to be mostly smooth and dusty. But that wasn’t the case.

“When we arrived we realized very, very quickly that there wasn’t a single area on the entire asteroid that was 50 metres across that had no obstacles,” said Tim Haltigin, senior mission scientist of Planetary Exploration at the Canadian Space Agency. 

“And so we really had to rethink our planning of how we were going to select a sample site and where we could safely deliver the spacecraft. And I think that’s one of the reasons why the OLA instrument became even more crucial in terms of understanding the roughness, the topography, the slopes of the surfaces … to really be able to pick a site where we knew that we could get the spacecraft down safely to collect a sample.” 

Mike Daly, OLA’S lead instrument scientist, said that he’s very pleased with the amount of detail and precision it was able to provide. 

“When I was thinking about what this instrument had to do and what it was — how it would perform — we had a much smoother Bennu, a much more boring Bennu in mind,” said Daly, who is also a professor at York University’s Lassonde School of Engineering in Toronto. “So when you see the detail that came out of this instrument, it’s just unbelievable. It blew us all away, honestly.

“So, we’re pretty proud of it.”

WATCH | A rendered rotation movie of Bennu taken by the Canadian OLA instrument:

The Canadian Space Agency’s OSIRIS-REx Laser Altimeter was crucial in mapping the asteroid Bennu ahead of its “touch-and-go” mission to collect samples that will be returned to Earth in 2023. Credit: Mike Daly, et. al 0:51

Daly has been working on the instrument for 12 years, while Haltigin has been working on it for seven years. Both men said that it’s become a part of their lives.

“It’s a little bit bittersweet,” Daly said.

The great part about the sample-return mission is that, because Canada is a partner, it gets some of the material. It’s something that Haltigin is extremely excited about.

“It’s going to be owned by Canada, and so we’re going to be able to make these samples available for generations and generations of Canadian scientists,” he said. “So, we’re basically enabling the next 50 to 100 years of discoveries based on these samples.”

‘Kissing the surface’

Rather than landing on the asteroid’s surface, a set of manoeuvres will be conducted in order to collect material.

“Due to the low gravity, we can’t actually land on the surface of Bennu. So we’ll only be kissing the surface with a short touch and go, measured in just seconds,” Beth Buck, OSIRIS-REx mission operations program manager for Lockheed Martin Space, said in a teleconference on Monday.

Compressed nitrogen gas will be pumped out onto the surface, which will stir up particles that will then be collected by a sampler.

The collection will take place at 6:12 p.m. ET and will be broadcast live on NASA TV. It can also be watched on CBC.ca beginning at 5 p.m. 

A Canadian laser made a 3D map of Bennu, helping find the best sample site for NASA’s OSIRIS-REx mission. (Canadian Space Agency)

It will take roughly 18.2 minutes for a signal to be received from the spacecraft. However, while NASA expects to get confirmation that the manoeuvre took place on Tuesday, it won’t know for certain until Wednesday if material was successfully collected.

The OSIRIS-REx spacecraft has gone through a couple of rehearsals of the manoeuvre, one in April and another in August, so NASA hopes it will be successful. However, it does have two more opportunities to collect material should this be unsuccessful.

It’s not the first time material has been collected from an asteroid. The Japanese Space Agency, JAXA, is currently awaiting the return of the Hayabusa2 spacecraft with a sample from the asteroid Ryugu, scheduled to return in December. 

Think of asteroids as time capsules

OSIRIS-REx launched in 2016 and arrived at Bennu in December 2018. Since then, it has been in orbit around the asteroid.

Bennu is about 492 metres in diameter and orbits the sun once every 1.2 years. It wasn’t discovered until 1999 and wasn’t given an official name — chosen by a Grade 3 student from North Carolina — until 2012 (the name refers to an Egyptian mythological bird).

The asteroid is believed to be roughly 4.5 billion years old, as old as the solar system itself. And that’s key: astronomers hope that Bennu can shed some light on how the solar system formed and how ultimately life may have arisen on Earth.

“Collecting a sample from an asteroid is the equivalent of going back in time by over four billion years to understand what the early solar system was made of,” said Haltigin.”So, you can think of asteroids almost as time capsules that have preserved the materials from the very formation of the solar system.” 

There is also a very small chance that Bennu will collide with Earth. But there’s no need to panic: there’s only a one in 2,700 chance that will happen between the years 2175 and 2199, according to NASA.

For now, scientists and engineers will be on the edge of their seats, awaiting confirmation that the mission was successful. And the asteroid is bound to have some surprises.

“What excites me the most, I’ll be perfectly honest, is we’re going to find out something that nobody expected, and I don’t know exactly what that is,” Haltigin said. “But I do know that we are going to be shocked and surprised and amazed once we figure it out.”

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What’s Happening with Betelgeuse? Astronomers Propose a Specialized Telescope to Watch the Star Every Night – Universe Today

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Starting in late 2019, Betelgeuse began drawing a lot of attention after it mysteriously started dimming, only to brighten again a few months later. For a variable star like Betelgeuse, periodic dimming and brightening are normal, but the extent of its fluctuation led to all sorts of theories as to what might be causing it. Similar to Tabby’s Star in 2015, astronomers offered up the usual suspects (minus the alien megastructure theory!)

Whereas some thought that the dimming was a prelude to the star becoming a Type II supernova, others suggested that dust clouds, enormous sunspots, or ejected clouds of gas were the culprit. In any case, the “Great Dimming of Betelgeuse” has motivated an international team of astronomers to propose that a “Betelgeuse Scope” be created that cant monitor the star constantly.

The paper that outlines their proposal was recently presented at the International Society for Optics and Photonics (SPIE) Optical Engineering + Applications 2020, a virtual conference that took place from Aug. 24th to Sept. 4th. The paper, “Betelgeuse scope: single-mode-fibers-assisted optical interferometer design for dedicated stellar activity monitoring,” is also available online as part of the Proceedings of SPIE, Vol. 11490.

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To recap, Betelgeuse is a red giant star that is about 12 times as massive as our Sun and about 900 times as large. It is located about 700 light-years from Earth in the Orion constellation and is easily spotted by looking for “the Hunter’s” left shoulder. Ordinarily, Betelgeuse is the second-brightest star in Orion (after Rigel) and the tenth-brightest star in the night sky.

Starting in November of 2019, the star began to dim rather suddenly, reaching a historical minimum of just 37% of its average brightness by Feb. 10th, 2020. At this point, Betelgeuse began to brighten until the end of May, at which point the dimming started all over again. For the sake of their article, the team explored different theories as to what caused the dimming.

This included the “Dark Spots hypothesis,” which was based on submillimeter observations taken by the James Clerk Maxwell Telescope and Atacama Pathfinder Experiment. Then there’s the “Dust formation and blocking hypothesis,” which is based on observations conducted with the VLT/SPHERE and the Hubble Space Telescope that suggest that there was a mass ejection from a large convective cell in the photosphere.

According to the authors, all of these possibilities can be investigated by observing the change of Betelgeuse’s angular diameter accurately. In order to do this, telescopes that are capable of conducting high-angular resolution observations (such as optical interferometry) would be needed. In this process, visible light is gathered by two or more telescopes and then combined to obtain higher-resolution images.

Graphic showing how Betelgeuse could be dimming. Credit: NASA, ESA, and E. Wheatley (STScI)

As they state in their study, today’s optical telescope facilities are not optimized for the kind of time-evolution monitoring that would be needed. In short, conducting this type of campaign would mean committing observation time from multiple facilities, which is a very expensive prospect. For this reason, the team recommends that a telescope be commissioned for the task.

As Dr. Narsireddy Anugu, a Prize Fellow in Astronomical Instrumentation and Technology at the University of Arizona’s Steward Observatory and the lead author on the study, explained to Universe Today via email:

“High-angular observations are required to image any existing dark spots on the Betelgeuse’s surface and ‘rogue’ convection cells. Collaborators [are also needed], and we have been taken some data with the Very Large Telescope Interferometer at Paranal, Chile (led by M. Montarges) and the CHARA array at the Mount Wilson Observatory. We are currently working on image reconstruction of interferometry data to reveal any dark spots and convection cells on the Betelgeuse surface.”

As they describe it, this “Betelgeuse Scope” will leverage advancements made in the field of optical interferometry and the telecommunication industry. It will consist of an array of 12 x 4 inch Cassegrain-reflector optical telescopes, which will be mounted to the surface of a large radio dish, which will allow for snapshot imaging of convection cells and time-evolution monitoring. As Dr. Anugu described it:

“We have proposed a unique six telescope interferometer concept installing on a radio antenna. This concept aims at a low budget by cutting the costs of pointing and tracking of each individual telescope using the already existing pointing and tracking of the radio antenna. Another benefit of installing the telescope array on a common mount is that we don’t need longer delay lines as in the classical non-common mount based long-baseline interferometers. Where an active compensation of changing the geometrical delay is required between the wavefronts reaching any two telescopes.”

Artist’s impression of a red supergiant star, of which interferometry has allowed detailed observations to be made. Credit: ESO/M. Kornmesser

Polarization-maintaining single-mode optical fibers will then carry the coherent beams from the individual optical telescopes to a central beam-combining facility. To compensate for atmospheric turbulence, vibrations, and pointing errors caused by windy conditions, the team recommends a fast steering mirror, a standard tip-tilt correction system, a fast frame rate detector, and a metrology laser system to measure vibrations.

In addition to being able to monitor Betelgeuse and resolve the mystery of its dimming, the Betelgeuse Scope will also allow for significant advancements in the field of astronomy. Said Dr. Anugu:

“Our proposed telescope monitors the Betelgeuse every-night with high-angular resolutions, makes a movie of motion of dynamic convection activity on the surface. This way, we will probe future mysterious dimming events such as 2019-2020 and origins of the dust formation around the Betelgeuse.”

At present, Anugu and his team are building a prototype of their proposed telescope, which will be mounted on the University of Arizona’s 6-meter (~20 foot) radio dish. So far, they have procured one set of light-collecting and fiber injection optics (12 are needed overall) and are integrating them into their lab at the Steward Observatory. They anticipate that the prototype will be finished and ready to be installed by the end of the year.

“Our proposed concept is straight forward, but we are building a pathfinder to test them,” said Dr. Anugu. “Once successful, we reuse the same optics and actuators for the actual 12-m radio antenna, and 12 telescope interferometer array as this concept is scalable and modular.”

Further Reading: arXiv

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Elon Musk's SpaceX gets CRTC application approval for Starlink satellite internet – CTV News

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TORONTO —
Space Exploration Technologies Corp, better known as SpaceX, moved closer to launching its high-speed satellite internet service in Canada after the Canadian Radio-television and Telecommunications Commission approved the company’s application for a licence.

SpaceX, founded by Elon Musk, applied for a Basic International Telecommunications Services (BITS) licence in May. The approval for the application was granted last week, according to a letter to the company posted on the CRTC website.

A BITS licence authorizes telecommunications providers or carriers to carry international telecommunications traffic between Canada and any other country.

The CRTC said it received 2,585 interventions regarding the application and approved the application after considering all the comments received. Interventions are submissions by the public on whether they support or oppose the issue in question and why, or if they would simply like to make a comment. The application garnered significant support from rural Canadians who lack reliable, fast, and affordable internet service in remote parts of the country.

Musk tweeted earlier this month that Starlink would be “revolutionary” for remote regions and in emergency services situations where landlines are damaged.

The Commission noted in its approval letter to SpaceX that the “BITS licence does not by itself authorize an entity to operate as a facilities-based carrier or non-facilities based service provider,” adding that a carrier or service provider must comply with regulatory requirements, including those around ownership and control.

Starlink, the internet service SpaceX is launching, is made up of a constellation of low-Earth orbit satellites. The company already has U.S. FCC approval to launch thousands of satellites and has a goal to launch tens of thousands more. There are more than 800 Starlink satellites in orbit now.

According to the Starlink website, it was targeting service in the northern part of the United States and Canada this year, and aiming for a rapid expansion “to near global coverage of the populated world by 2021.”

There has been some criticism about SpaceX and other similar types of initiatives, however, due to concerns including space debris and light pollution.

Several astronomical organizations had previously issued public statements of concern on the light pollution caused by these satellite constellations, which they say impacts scientific observations. Earlier this year the company said it was introducing sunshades that would help reduce the brightness and solar reflection from its satellites. Musk said in a tweet that it will become “increasingly difficult to see Starlink satellites, as we are actively working with the astronomer community to ensure that even the most sensitive telescopes are fine & scientific progress is not impeded.”

To address space debris concerns, Starlink said on its website that its satellites have an on-board propulsion system that would allow it to eventually deorbit at the end of life and should that method not work, the satellites would burn within one to five years in the Earth’s atmosphere. 

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