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NASA Explains Why James Webb Space Telescope Uses 'Salty' Lenses – Gadgets 360

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As NASA completes all major deployments of the James Webb Space Telescope and the observatory enters a “cooling” period, the agency is sharing some interesting facts about the $10-billion (roughly Rs. 74,100 core) observatory. These include some lenses which are made out of salt. But why does this infrared telescope need a “salty” lens? In a new video, scientists working on the telescope shared why salt is vital to the deep space observatory. And the James Webb telescope uses not just one but three kinds of salt lenses.

There are various kinds of lenses. Mirrors are reflective lens, which bend the light, but there are some that allow the light to pass through them. These second types of lenses are called transmissive lenses. For James Webb, infrared light, which behaves differently than visible light, plays a vital role. The key here is: glass absorbs infrared light but salt does not.

The narrator in NASA’s video says, “Salts are more than something you sprinkle on your food.” A salt is a combination of a positively charged element and a negatively charged halide. They get their charge from either losing or gaining a negatively charged electron. The salt we usually eat is sodium chloride, but that’s not the only type of salt. Some other kinds are: lithium fluoride, Barium fluoride, and zinc selenide.

However in the long run, these lenses are threatened by space debris including micrometeoroids.

NASA Goddard Space Flight Center scientist Michelle Thaller said during a livestream that small impacts from micrometeorites are bound to happen. However, NASA scientists say they took this factor into account as the telescope is meant to last for 10 years. They said they have contingency plans in place to deal with this inevitability.

The five layers of the sunshield not only protect the telescope from the heat but also from dust and debris. But a micrometeoroid can come from any side and damage any part of the telescope. If a mirror is damaged, it can be accounted for.

NASA launched James Webb Space Telescope on December 25 and for the past two weeks, it has been working to unfold it in space. It has completed major deployments like the primary and secondary mirror.


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Anemia in astronauts could be a challenge for space missions – The Tribune

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The next “giant le” for humans may be a trip to Mars, but having enough oxygen-carrying red blood cells for the journey might present a challenge, new research suggests.

Even space tourists lining up for short trips might have to stay home if they are at risk for anemia, or red blood cell deficiency, researchers said.

Astronauts are known to experience “space anemia” but until now it was thought to be temporary. One NASA study called it “a 15-day ailment.”

Doctors attributed it to destruction of red blood cells, or hemolysis, resulting from fluid shifts as astronauts’ bodies accommodated to weightlessness and again as they re-accommodated to gravity.

In fact, anemia is “a primary effect of going to space,” said Dr. Guy Trudel of the University of Ottawa, who led a study of 14 astronauts funded by the Canadian Space Agency. “As long as you are in space, you are destroying more blood cells” than you are making.”

Normally, the body destroys and replaces nearly 2 million red blood cells per second. Trudel’s team found astronauts’ bodies destroyed 3 million red blood cells per second during their six-month missions.

“We thought we knew about space anemia, and we did not,” Trudel said.

The astronauts generated extra red cells to compensate for the destroyed ones. But, Trudel asked, how long can the body constantly produce 50% more red cells? A roundtrip mission to Mars would take about two years, NASA estimated.

“If you are on your way to Mars and … you can’t keep up” with the need to produce all those extra red blood cells, “you could be in serious trouble,” Trudel said.

Having fewer red blood cells in space is not a problem when your body is weightless, he added. But after landing on Earth, and potentially on other planets, anemia could affect astronauts’ energy, endurance and strength.

A year after returning to Earth, the astronauts’ red blood cells had not completely returned to pre-flight levels, his team reported on Friday in Nature Medicine.

Trudel also studies the effects of immobility on patients who are bedridden for weeks or months.

The new findings mimic what he sees in his patients, he said, which suggests that what happens in space may also be happening in immobile patients.

“A solution to one could also apply to the other,” he said.

Sulekha Anand, who researches human physiology at San Jose State University and was not involved in the study, agreed.

“The findings have implications for understanding the physiological consequences of space flight and anemia in patients on the ground,” she said.

Trudel’s team is studying ways to solve the problem, he said. Reuters

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How the Webb Telescope will build on Hubble's observations of the universe – USA TODAY

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After launching on Christmas, the James Webb Space Telescope is closing in on its new home 1 million miles from Earth. A gravitationally stable pocket known as the second Lagrange point, or L2, will keep the telescope in orbit for a planned five- to 10-year mission. The powerful infrared observatory is designed to study the origins of the universe, capture the formation of stars and look for chemical signatures that could signal life in other planetary systems.

Much of what astronomers have learned in the past three decades has come from the Hubble Space Telescope, the space-based observatory that has made more than 1.4 million observations since its deployment in 1990. 

The Webb Telescope is designed to build on these observations.

Here’s an overview of the $10 billion Webb Telescope, what to expect as it prepares for its mission and some of the ways it compares with the Hubble.

The telescope’s namesake, James E. Webb, was NASA’s second administrator. The telescope was built by NASA with support from the European Space Agency and the Canadian Space Agency. The observatory’s Mission Operations Center is at the Space Telescope Science Institute (STScI) in Baltimore.

How Webb compares with Hubble

Though NASA prefers to call Webb the successor to Hubble – not a replacement – it’s difficult to not draw comparisons. Hubble data has been used in thousands of papers published in academic journals. 

Roughly the size of a tennis court and three stories high, the Webb Telescope is the largest telescope ever sent into space.

Hubble is capable of reaching into a small piece of the infrared range of the electromagnetic spectrum – light from which is invisible to optical telescopes. The Webb Telescope is designed to perceive light from a large swath of the infrared. The Webb’s infrared capabilities will help astronomers peer into star-forming dust clouds and collect ancient, faint heat from galaxies that formed 100 million years after the Big Bang.

Because the Webb is designed for infrared research to detect the faintest of heat signatures emanating from distant galaxies, it needs to be kept cool. The mirrors and instruments are protected by a solar shield that blocks harmful light from the sun, Earth and the moon.

The temperature difference between the two sides is significant – the solar shield absorbs heat from the sun that warms the surface to about 230 degrees Fahrenheit, while the side with the instruments drops to around -390 degrees.

Webb’s mirror – made of 18 gold-coated hexagonal mirrors that fit together to form a single large mirror more than 21 feet high – is much larger than Hubble’s primary mirror and can collect more light.

The Webb’s vantage point

Unlike Hubble, which orbits 340 miles above the Earth, the Webb Space Telescope will orbit the sun, settling into a pocket a million miles from Earth called the second Lagrange point, or L2. This point balances the gravitational pull of the sun and Earth and will keep the Webb directly in line with the Earth as both orbit the sun. 

To put itself into proper orbit, the last milestone for Webb’s journey is a mid-course insertion burn maneuver that will employ small on-board thrusters and propellant to overcome the initial thrust from the Ariane 5 rocket used in the launch and put the observatory into position in L2.

Though the remote positioning and its sunshield free the telescope from light and heat interference from the sun, Webb is too far away to manually service and upgrade. Hubble, by comparison, has been repaired and updated by astronauts on five separate servicing missions while in orbit. 

What’s next?

After arriving in L2, Webb will turn on instruments and cool down to its cryogenic operating temperature in a roughly five-month process called commissioning. During this time, the Webb team will align the telescope’s optics and calibrate instruments. 

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Published
2:11 pm UTC Jan. 16, 2022

Updated
2:11 pm UTC Jan. 16, 2022

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Being in space destroys astronauts red blood cells, new study shows – TweakTown

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A world-first study on the problem has been published in Nature Medicine.

Fourteen astronauts were studied over their six-month space missions, having direct measurements of their red blood cells taken. The study found that the astronauts lost 54% more red blood cells in space than they would otherwise on Earth, about 3 million per second being created and destroyed compared to only 2 million on Earth. The same result was observed for both female and male astronauts.

“Space anemia has consistently been reported when astronauts returned to Earth since the first space missions, but we didn’t know why. Our study shows that upon arriving in space, more red blood cells are destroyed, and this continues for the entire duration of the astronaut’s mission,” said lead author Dr. Guy Trudel, a rehabilitation physician and researcher at The Ottawa Hospital and professor at the University of Ottawa.

Of the fourteen returning astronauts, thirteen had their blood drawn and tested, and five of those thirteen were considered clinically anemic. Within three to four months, space-related anemia was reversed as red blood cells returned to normal levels.

“Thankfully, having fewer red blood cells in space isn’t a problem when your body is weightless. But when landing on Earth and potentially on other planets or moons, anemia affecting your energy, endurance, and strength can threaten mission objectives. The effects of anemia are only felt once you land, and must deal with gravity again,” Dr. Trudel continued.

You can read more from the study here.

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