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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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See Astronaut's Sublime Shot of Total Lunar Eclipse Snapped From the ISS – CNET

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Earthlings on Earth weren’t the only ones who got to witness the lovely blushing of the “flower blood moon” total lunar eclipse on Sunday night and Monday morning. Residents of the International Space Station had a great view of the spectacular celestial event.

European Space Agency astronaut Samantha Cristoforetti shared a beautiful series of photos of the eclipse as seen from orbit. “A partially eclipsed moon playing hide-and-seek with our solar panel,” Cristoforetti tweeted on Monday.

The photos show the eclipse in progress, with the moon peeking under the station’s solar panels. One stunning view also shows Earth below, clouds visible against an expanse of blue. The images highlight the subtle shading of the moon as our planet threw its shadow across it.

Cristoforetti shared another look with just the eclipsed moon peeking over the curve of Earth.

Cristoforetti is an accomplished space photographer, having snapped plenty of gorgeous images during her last stay on the ISS in 2014 and 2015. Her most recent stint started in late April as part of NASA’s Crew-4 mission launched by SpaceX. 

I watched the eclipse last night from New Mexico. As the shadow moved across the moon, the ISS flew over, a bright bead of light crossing against the starry sky. So as I was seeing the ISS, Cristoforetti was likely tracking the eclipse, too. It doesn’t matter whether you’re on the ground or up in orbit, an eclipse is worth witnessing.

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NASA's InSight still hunting marsquakes as power levels diminish – Phys.org

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InSight captured this image of one of its dust-covered solar panels on April 24, 2022, the 1,211th Martian day, or sol, of the mission. Credit: NASA/JPL-Caltech

Dusty solar panels and darker skies are expected to bring the Mars lander mission to a close around the end of this year.

NASA’s InSight Mars lander is gradually losing power and is anticipated to end science operations later this summer. By December, InSight’s team expects the lander to have become inoperative, concluding a mission that has thus far detected more than 1,300 marsquakes—most recently, a magnitude 5 that occurred on May 4—and located quake-prone regions of the Red Planet.

The information gathered from those quakes has allowed scientists to measure the depth and composition of Mars’ crust, mantle, and core. Additionally, InSight (short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) has recorded invaluable weather data and studied remnants of Mars’ ancient magnetic field.

“InSight has transformed our understanding of the interiors of rocky planets and set the stage for future missions,” said Lori Glaze, director of NASA’s Planetary Science Division. “We can apply what we’ve learned about Mars’ inner structure to Earth, the Moon, Venus, and even rocky planets in other solar systems.”

InSight landed on Mars Nov. 26, 2018. Equipped with a pair of solar panels that each measures about 7 feet (2.2 meters) wide, it was designed to accomplish the mission’s primary science goals in its first Mars year (nearly two Earth years). Having achieved them, the spacecraft is now into an extended mission, and its solar panels have been producing less power as they continue to accumulate dust.

Because of the reduced power, the team will soon put the lander’s robotic arm in its resting position (called the “retirement pose”) for the last time later this month. Originally intended to deploy the seismometer and the lander’s heat probe, the arm has played an unexpected role in the mission: Along with using it to help bury the heat probe after sticky Martian soil presented the probe with challenges, the team used the arm in an innovative way to remove dust from the solar panels. As a result, the seismometer was able to operate more often than it would have otherwise, leading to new discoveries.

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NASA’s InSight Mars lander team speak about the mission’s science and the innovative ways they took on engineering challenges. During its time on Mars, InSight has achieved all its primary science goals and continues to hunt for quakes. Its mission is expected to conclude around the end of 2022. Credit: NASA/JPL-Caltech

When InSight landed, the produced around 5,000 watt-hours each Martian day, or sol—enough to power an electric oven for an hour and 40 minutes. Now, they’re producing roughly 500 watt-hours per sol—enough to power the same electric oven for just 10 minutes.

Additionally, seasonal changes are beginning in Elysium Planitia, InSight’s location on Mars. Over the next few months, there will be more dust in the air, reducing sunlight—and the lander’s energy. While past efforts removed some dust, the mission would need a more powerful dust-cleaning event, such as a “dust devil” (a passing whirlwind), to reverse the current trend.

“We’ve been hoping for a cleaning like we saw happen several times to the Spirit and Opportunity rovers,” said Bruce Banerdt, InSight’s principal investigator at NASA’s Jet Propulsion Laboratory in Southern California, which leads the mission. “That’s still possible, but energy is low enough that our focus is making the most of the science we can still collect.”

If just 25% of InSight’s panels were swept clean by the wind, the lander would gain about 1,000 watt-hours per sol—enough to continue collecting science. However, at the current rate power is declining, InSight’s non-seismic instruments will rarely be turned on after the end of May.

Energy is being prioritized for the lander’s seismometer, which will operate at select times of day, such as at night, when winds are low and marsquakes are easier for the seismometer to “hear.” The seismometer itself is expected to be off by the end of summer, concluding the science phase of the .

At that point, the lander will still have enough power to operate, taking the occasional picture and communicating with Earth. But the team expects that around December, will be low enough that one day InSight will simply stop responding.


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NASA’s InSight records monster quake on Mars


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NASA’s InSight still hunting marsquakes as power levels diminish (2022, May 17)
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Peek-a-Boo Moon: Astronaut on Space Station Captures Spectacular Photos of the Lunar Eclipse – SciTechDaily

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ESA astronaut Samantha Cristoforetti captured pictures of the May 2022 lunar eclipse from the International Space Station.

On the evening of May 15, 2022, Earth passed between the Sun and the Moon blocking sunlight and casting a shadow on the lunar surface. ESA astronaut Samantha Cristoforetti witnessed this lunar eclipse from the International Space Station and captured it in a series of photographs.

During a lunar eclipse, Earth’s atmosphere scatters sunlight. The blue light from the Sun scatters away, and longer-wavelength red, orange, and yellow light pass through, turning our Moon red.

Lunar Eclipse From International Space Station 1

An image of a lunar eclipse as seen from the International Space Station. Credit: ESA-S.Cristoforetti

In these images, the Moon appears to play hide and seek with one of the International Space Station’s solar panels:

Lunar Eclipse From International Space Station 4

A partially eclipsed Moon playing hide and seek with the solar panel of the International Space Station. Credit: ESA-S.Cristoforetti

Lunar Eclipse From International Space Station 3

A partially eclipsed Moon playing hide and seek with the solar panel of the International Space Station. Credit: ESA-S.Cristoforetti

Lunar Eclipse From International Space Station 2

A partially eclipsed Moon playing hide and seek with the solar panel of the International Space Station. Credit: ESA-S.Cristoforetti

Samantha is living and working aboard the Space Station for her second mission, ‘Minerva’. Learn more about Samantha and the Minerva mission.

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