NASA

[NASA]

10 Ways the Webb Telescope ‘Trains’ for Space

The James Webb Space Telescope will peer at the first stars and galaxies as a cosmic time machine, look beyond to distant worlds, and unlock the mysteries of the universe. But before it can do any of those things, it needs to “train” for traveling to its destination — 1 million miles away from Earth!

So how does Webb get ready for space while it’s still on the ground? Practice makes perfect. Different components of the telescope were first tested on their own, but now a fully-assembled Webb is putting all of its training together. Here are 10 types of tests that Webb went through to prepare for its epic journey:

1. Sounding Off

A rocket launch is 100 times more intense and four times louder than a rock concert! (That’s according to Paul Geithner, Webb’s deputy project manager – technical.) To simulate that level of extreme noise, Webb’s full structure was blasted with powerful sound waves during its observatory-level acoustic testing in August.

2. Shaking It Up

Webb will also have to withstand a super-bumpy ride as it launches — like a plane takeoff, but with a lot more shaking! The observatory was carefully folded into its launch position, placed onto a shaker table, and vibrated from 5 to 100 times per second to match the speeds of Webb’s launch vehicle, an Ariane 5 rocket.

3. All Systems Go

In July, Webb performed a rigorous test of its software and electrical systems as a fully connected telescope. Each line of code for Webb was tested and then retested as different lines were combined into Webb’s larger software components. To complete this test, Webb team members were staffed 24 hours a day for 15 consecutive days!

4. Hanging Out

After launch, Webb is designed to unfold (like origami in reverse) from its folded launch position into its operational form. Without recharging, the telescope’s onboard battery would only last a few hours, so it will be up to Webb’s 20-foot solar array to harness the Sun’s energy for all of the telescope’s electrical needs. To mimic the zero-gravity conditions of space, Webb technicians tested the solar array by hanging it sideways.

5. Time to Stretch

The tower connects the upper and lower halves of Webb. Once Webb is in space, the tower will extend 48 inches (1.2 meters) upward to create a gap between the two halves of the telescope. Then all five layers of Webb’s sunshield will slowly unfurl and stretch out, forming what will look like a giant kite in space. Both the tower and sunshield will help different sections of Webb maintain their ideal temperatures.

For these steps, engineers designed an ingenious system of cables, pulleys and weights to counter the effects of Earth’s gravity.

6. Dance of the Mirrors

Unfolding Webb’s mirrors will involve some dance-like choreography. First, a support structure will gracefully unfold to place the circular secondary mirror out in front of the primary mirror. Although small, the secondary mirror will play a big role: focusing light from the primary mirror to send to Webb’s scientific instruments.

Next, Webb’s iconic primary mirror will fully extend so that all 18 hexagonal segments are in view. At 6.5 meters (21 feet 4-inches) across, the mirror’s massive size is key for seeing in sharp detail. Like in tower and sunshield testing, the Webb team offloaded the weight of both mirrors with cables, pulleys and weights so that they unfolded as if weightless in space.

7. Do Not Disturb

Before a plane takeoff, it’s important for us to turn off our cell phones to make sure that their electromagnetic waves won’t interfere with navigation signals. Similarly, Webb had to test that its scientific instruments wouldn’t disrupt the electromagnetic environment of the spacecraft. This way, when we get images back from Webb, we’ll know that we’re seeing actual objects in space instead of possible blips caused by electromagnetic interference. These tests took place in the Electromagnetic Interference (EMI) Lab, which looks like a futuristic sound booth! Instead of absorbing sound, however, the walls of this chamber help keep electromagnetic waves from bouncing around.

8. Phoning Earth

How will Webb know where to go and what to look at? Thanks to Webb’s Ground Segment Tests, we know that we’ll be able to “talk” to Webb after liftoff. In the first six hours after launch, the telescope needs to seamlessly switch between different communication networks and stations located around the world. Flight controllers ran through these complex procedures in fall 2018 to help ensure that launch will be a smooth success.

After Webb reaches its destination, operators will use the Deep Space Network, an international array of giant radio antennas, to relay commands that tell Webb where to look. To test this process when Webb isn’t in space yet, the team used special equipment to imitate the real radio link that will exist between the observatory and the network.

9. Hot and Cold

Between 2017 and 2019, Webb engineers separately tested the two halves of the telescope in different thermal vacuum chambers, which are huge, climate-controlled rooms drained of air to match the vacuum of space. In testing, the spacecraft bus and sunshield half were exposed to both boiling hot and freezing cold temperatures, like the conditions that they’ll encounter during Webb’s journey.

But Webb’s mirrors and instruments will need to be colder than cold to operate! This other half of Webb was tested in the historic Chamber A, which was used to test Apollo Moon mission hardware and specifically upgraded to fit Webb. Over about 100 days, Chamber A was gradually cooled down, held at cryogenic temperatures (about minus 387 F, or minus 232.8 C), and then warmed back up to room temperature.

10. Cosmic Vision

When the Hubble Space Telescope was first sent into space, its images were blurry due to a flaw with its mirror. This error taught us about the importance of comprehensively checking Webb’s “eyes” before the telescope gets out of reach.

Besides training for space survival, Webb also spent time in Chamber A undergoing mirror alignment and optical testing. The team used a piece of test hardware that acted as a source of artificial starlight to verify that light would travel correctly through Webb’s optical system.

Whew! That’s a lot of testing under Webb’s belt! Webb is set to launch in October 2021 from Kourou, French Guiana. But until then, it’s still got plenty of training left, including a final round of deployment tests before being shipped to its launch location.

Learn more about the James Webb Space Telescope HERE, or follow the mission on Facebook,Twitter and Instagram.

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[NASA]

8 Common Questions About Our James Webb Space Telescope

You might have heard the basics about our James Webb Space Telescope, or Webb, and still have lots more questions! Here are more advanced questions we are frequently asked. (If you want to know the basics, read this Tumblr first!)

Webb is our upcoming infrared space observatory, which will launch in 2021. It will spy the first luminous objects that formed in the universe and shed light on how galaxies evolve, how stars and planetary systems are born, and how life could form on other planets.

1. Why is the mirror segmented? 

The James Webb Space Telescope has a 6.5-meter (21.3-foot) diameter mirror, made from 18 individual segments. Webb needs to have an unfolding mirror because the mirror is so large that it otherwise cannot fit in the launch shroud of currently available rockets.

The mirror has to be large in order to see the faint light from the first star-forming regions and to see very small details at infrared wavelengths. 

Designing, building, and operating a mirror that unfolds is one of the major technological developments of Webb. Unfolding mirrors will be necessary for future missions requiring even larger mirrors, and will find application in other scientific, civil, and military space missions.

2. Why are the mirrors hexagonal?

In short, the hexagonal shape allows a segmented mirror to be constructed with very small gaps, so the segments combine to form a roughly circular shape and need only three variations in prescription. If we had circular segments, there would be gaps between them.

Finally, we want a roughly circular overall mirror shape because that focuses the light into the most symmetric and compact region on the detectors. 

An oval mirror, for example, would give images that are elongated in one direction. A square mirror would send a lot of the light out of the central region.

3. Is there a danger from micrometeoroids?

A micrometeoroid is a particle smaller than a grain of sand. Most never reach Earth’s surface because they are vaporized by the intense heat generated by the friction of passing through the atmosphere. In space, no blanket of atmosphere protects a spacecraft or a spacewalker.

Webb will be a million miles away from the Earth orbiting what we call the second Lagrange point (L2). Unlike in low Earth orbit, there is not much space debris out there that could damage the exposed mirror. 

But we do expect Webb to get impacted by these very tiny micrometeoroids for the duration of the mission, and Webb is designed to accommodate for them.

All of Webb’s systems are designed to survive micrometeoroid impacts.

4. Why does the sunshield have five layers?

Webb has a giant, tennis-court sized sunshield, made of five, very thin layers of an insulating film called Kapton.  

Why five? One big, thick sunshield would conduct the heat from the bottom to the top more than would a shield with five layers separated by vacuum. With five layers to the sunshield, each successive one is cooler than the one below. 

The heat radiates out from between the layers, and the vacuum between the layers is a very good insulator. From studies done early in the mission development five layers were found to provide sufficient cooling. More layers would provide additional cooling, but would also mean more mass and complexity. We settled on five because it gives us enough cooling with some “margin” or a safety factor, and six or more wouldn’t return any additional benefits.

Fun fact: You could nearly boil water on the hot side of the sunshield, and it is frigid enough on the cold side to freeze nitrogen!

5. What kind of telescope is Webb?

Webb is a reflecting telescope that uses three curved mirrors. Technically, it’s called a three-mirror anastigmat.

6. What happens after launch? How long until there will be data?

We’ll give a short overview here, but check out our full FAQ for a more in-depth look.

In the first hour: About 30 minutes after liftoff, Webb will separate from the Ariane 5 launch vehicle. Shortly after this, we will talk with Webb from the ground to make sure everything is okay after its trip to space.

In the first day: After 24 hours, Webb will be nearly halfway to the Moon! About 2.5 days after launch, it will pass the Moon’s orbit, nearly a quarter of the way to Lagrange Point 1 (L2).

In the first week: We begin the major deployment of Webb. This includes unfolding the sunshield and tensioning the individual membranes, deploying the secondary mirror, and deploying the primary mirror.

In the first month: Deployment of the secondary mirror and the primary mirror occur. As the telescope cools in the shade of the sunshield, we turn on the warm electronics and initialize the flight software. As the telescope cools to near its operating temperature, parts of it are warmed with electronic heaters. This prevents condensation as residual water trapped within some of the materials making up the observatory escapes into space.

In the second month: We will turn on and operate Webb’s Fine Guidance Sensor, NIRCam, and NIRSpec instruments. 

The first NIRCam image, which will be an out-of-focus image of a single bright star, will be used to identify each mirror segment with its image of a star in the camera. We will also focus the secondary mirror.

In the third month: We will align the primary mirror segments so that they can work together as a single optical surface. We will also turn on and operate Webb’s mid-infrared instrument (MIRI), a camera and spectrograph that views a wide spectrum of infrared light. By this time, Webb will complete its journey to its L2 orbit position.

In the fourth through the sixth month: We will complete the optimization of the telescope. We will test and calibrate all of the science instruments.

After six months: The first scientific images will be released, and Webb will begin its science mission and start to conduct routine science operations.

7. Why not assemble it in orbit?

Various scenarios were studied, and assembling in orbit was determined to be unfeasible.

We examined the possibility of in-orbit assembly for Webb. The International Space Station does not have the capability to assemble precision optical structures. Additionally, space debris that resides around the space station could have damaged or contaminated Webb’s optics. Webb’s deployment happens far above low Earth orbit and the debris that is found there.

Finally, if the space station were used as a stopping point for the observatory, we would have needed a second rocket to launch it to its final destination at L2. The observatory would have to be designed with much more mass to withstand this “second launch,” leaving less mass for the mirrors and science instruments.

8. Who is James Webb?

This telescope is named after James E. Webb (1906–1992), our second administrator. Webb is best known for leading Apollo, a series of lunar exploration programs that landed the first humans on the Moon. 

However, he also initiated a vigorous space science program that was responsible for more than 75 launches during his tenure, including America’s first interplanetary explorers.

Looking for some more in-depth FAQs? You can find them HERE.

Learn more about the James Webb Space Telescope HERE, or follow the mission on Facebook, Twitter and Instagram.

Make sure to follow us on Tumblr for your regular dose of space!

[NASA]

10 Frequently Asked Questions About the James Webb Space Telescope

Got basic questions about the James Webb Space Telescope and what amazing things we’ll learn from it? We’ve got your answers right here! 

The James Webb Space Telescope, or Webb, is our upcoming infrared space observatory, which will launch in 2021. It will spy the first luminous objects that formed in the universe and shed light on how galaxies evolve, how stars and planetary systems are born, and how life could form on other planets.

1. What is the James Webb Space Telescope?

Our James Webb Space Telescope is a giant space telescope that observes infrared light. Rather than a replacement for the Hubble Space Telescope, it’s a scientific successor that will complement and extend its discoveries.

Being able to see longer wavelengths of light than Hubble and having greatly improved sensitivity will let Webb look further back in time to see the first galaxies that formed in the early universe, and to peer inside dust clouds where stars and planetary systems are forming today.

2. What are the most exciting things we will learn?

We have yet to observe the era of our universe’s history when galaxies began to form. 

We have a lot to learn about how galaxies got supermassive black holes in their centers, and we don’t really know whether the black holes caused the galaxies to form or vice versa.

We can’t see inside dust clouds with high resolution, where stars and planets are being born nearby, but Webb will be able to do just that. 

We don’t know how many planetary systems might be hospitable to life, but Webb could tell whether some Earth-like planets have enough water to have oceans.

We don’t know much about dark matter or dark energy, but we expect to learn more about where the dark matter is now, and we hope to learn the history of the acceleration of the universe that we attribute to dark energy. 

And then, there are the surprises we can’t imagine!

3. Why is Webb an infrared telescope?

By viewing the universe at infrared wavelengths with such sensitivity, Webb will show us things never before seen by any other telescope. For example, it is only at infrared wavelengths that we can see the first stars and galaxies forming after the Big Bang. 

And it is with infrared light that we can see stars and planetary systems forming inside clouds of dust that are opaque to visible light, such as in the above visible and infrared light comparison image of the Carina Nebula.

4. Will Webb take amazing pictures like Hubble? Can Webb see visible light?

YES, Webb will take amazing pictures! We are going to be looking at things we’ve never seen before and looking at things we have seen before in completely new ways.

The beauty and quality of an astronomical image depends on two things: the sharpness and the number of pixels in the camera. On both of these counts, Webb is very similar to, and in many ways better than, Hubble. 

Additionally Webb can see orange and red visible light. Webb images will be different, but just as beautiful as Hubble’s. Above, there is another comparison of infrared and visible light Hubble images, this time of the Monkey Head Nebula.

5. What will Webb’s first targets be?

The first targets for Webb will be determined through a process similar to that used for the Hubble Space Telescope and will involve our experts, the European Space Agency (ESA), the Canadian Space Agency (CSA), and scientific community participants.

The first engineering target will come before the first science target and will be used to align the mirror segments and focus the telescope. That will probably be a relatively bright star or possibly a star field.

6. How does Webb compare with Hubble?

Webb is designed to look deeper into space to see the earliest stars and galaxies that formed in the universe and to look deep into nearby dust clouds to study the formation of stars and planets.

In order to do this, Webb has a much larger primary mirror than Hubble (2.5 times larger in diameter, or about 6 times larger in area), giving it more light-gathering power. It also will have infrared instruments with longer wavelength coverage and greatly improved sensitivity than Hubble. 

Finally, Webb will operate much farther from Earth, maintaining its extremely cold operating temperature, stable pointing and higher observing efficiency than with the Earth-orbiting Hubble.

7. What will Webb tell us about planets outside our solar system? Will it take photos of these planets?

Webb will be able to tell us the composition of the atmospheres of planets outside our solar system, aka exoplanets. It will observe planetary atmospheres through the transit technique. A transit is when a planet moves across the disc of its parent star. 

Webb will also carry coronographs to enable photography of exoplanets (planets outside our solar system) near bright stars (if they are big and bright and far from the star), but they will be only “dots,” not grand panoramas. Coronographs block the bright light of stars, which could hide nearby objects like exoplanets.

Consider how far away exoplanets are from us, and how small they are by comparison to this distance! We didn’t even know what Pluto really looked like until we were able to send an observatory to fly right near it in 2015, and Pluto is in our own solar system!

8. Will we image objects in our own solar system?

Yes! Webb will be able to observe the planets at or beyond the orbit of Mars, satellites, comets, asteroids and objects in the distant, icy Kuiper Belt.

Many important molecules, ices and minerals have strong characteristic signatures at the wavelengths Webb can observe. 

Webb will also monitor the weather of planets and their moons. 

Because the telescope and instruments have to be kept cold, Webb’s protective sunshield will block the inner solar system from view. This means that the Sun, Earth, Moon, Mercury, and Venus, and of course Sun-grazing comets and many known near-Earth objects cannot be observed.

9. How far back will Webb see? 

Webb will be able to see what the universe looked like around a quarter of a billion years (possibly back to 100 million years) after the Big Bang, when the first stars and galaxies started to form.

10. When will Webb launch and how long is the mission?

Webb will launch in 2021 from French Guiana on a European Space Agency Ariane 5 rocket. 

Webb’s mission lifetime after launch is designed to be at least 5-½ years, and could last longer than 10 years. The lifetime is limited by the amount of fuel used for maintaining the orbit, and by the possibility that Webb’s components will degrade over time in the harsh environment of space.

Looking for some more in-depth FAQs? You can find them HERE.

Learn more about the James Webb Space Telescope HERE, or follow the mission on Facebook, Twitter and Instagram.

IMAGE CREDITS
Carina Nebula: ESO/T. Preibisch
Monkey Head Nebula: NASA, ESA, the Hubble Heritage Team (STScI/AURA), and J. Hester

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[NASA]

Infrared is Beautiful

Why was James Webb Space Telescope designed to observe infrared light? How can its images hope to compare to those taken by the (primarily) visible-light Hubble Space Telescope? The short answer is that Webb will absolutely capture beautiful images of the universe, even if it won’t see exactly what Hubble sees. (Spoiler: It will see a lot of things even better.)

The James Webb Space Telescope, or Webb, is our upcoming infrared space observatory, which will launch in 2019. It will spy the first luminous objects that formed in the universe and shed light on how galaxies evolve, how stars and planetary systems are born, and how life could form on other planets.

What is infrared light? 

This may surprise you, but your remote control uses light waves just beyond the visible spectrum of light—infrared light waves—to change channels on your TV.

Infrared light shows us how hot things are. It can also show us how cold things are. But it all has to do with heat. Since the primary source of infrared radiation is heat or thermal radiation, any object that has a temperature radiates in the infrared. Even objects that we think of as being very cold, such as an ice cube, emit infrared.

There are legitimate scientific reasons for Webb to be an infrared telescope. There are things we want to know more about, and we need an infrared telescope to learn about them. Things like: stars and planets being born inside clouds of dust and gas; the very first stars and galaxies, which are so far away the light they emit has been stretched into the infrared; and the chemical fingerprints of elements and molecules in the atmospheres of exoplanets, some of which are only seen in the infrared.

In a star-forming region of space called the ‘Pillars of Creation,’ this is what we see with visible light:

And this is what we see with infrared light:

Infrared light can pierce through obscuring dust and gas and unveil a more unfamiliar view.

Webb will see some visible light: red and orange. But the truth is that even though Webb sees mostly infrared light, it will still take beautiful images. The beauty and quality of an astronomical image depends on two things: the sharpness of the image and the number of pixels in the camera. On both of these counts, Webb is very similar to, and in many ways better than, Hubble. Webb will take much sharper images than Hubble at infrared wavelengths, and Hubble has comparable resolution at the visible wavelengths that Webb can see.

Webb’s infrared data can be translated by computer into something our eyes can appreciate – in fact, this is what we do with Hubble data. The gorgeous images we see from Hubble don’t pop out of the telescope looking fully formed. To maximize the resolution of the images, Hubble takes multiple exposures through different color filters on its cameras.

The separate exposures, which look black and white, are assembled into a true color picture via image processing. Full color is important to image analysis of celestial objects. It can be used to highlight the glow of various elements in a nebula, or different stellar populations in a galaxy. It can also highlight interesting features of the object that might be overlooked in a black and white exposure, and so the images not only look beautiful but also contain a lot of useful scientific information about the structure, temperatures, and chemical makeup of a celestial object.

This image shows the sequences in the production of a Hubble image of nebula Messier 17:

Here’s another compelling argument for having telescopes that view the universe outside the spectrum of visible light – not everything in the universe emits visible light. There are many phenomena which can only be seen at certain wavelengths of light, for example, in the X-ray part of the spectrum, or in the ultraviolet. When we combine images taken at different wavelengths of light, we can get a better understanding of an object, because each wavelength can show us a different feature or facet of it. 

Just like infrared data can be made into something meaningful to human eyes, so can each of the other wavelengths of light, even X-rays and gamma-rays.

Below is an image of the M82 galaxy created using X-ray data from the Chandra X-ray Observatory, infrared data from the Spitzer Space Telescope, and visible light data from Hubble. Also note how aesthetically pleasing the image is despite it not being just optical light:

Though Hubble sees primarily visible light, it can see some infrared. And despite not being optimized for it, and being much less powerful than Webb, it still produced this stunning image of the Horsehead Nebula.

It’s a big universe out there – more than our eyes can see. But with all the telescopes now at our disposal (as well as the new ones that will be coming online in the future), we are slowly building a more accurate picture. And it’s definitely a beautiful one. Just take a look…

…At this Spitzer infrared image of a shock wave in dust around the star Zeta Ophiuchi.

…this Spitzer image of the Helix Nebula, created using infrared data from the telescope and ultraviolet data from the Galaxy Evolution Explorer.

…this image of the “wing” of the Small Magellanic Cloud, created with infrared data from Spitzer and X-ray data from Chandra.

…the below image of the Milky Way’s galactic center, taken with our flying SOFIA telescope. It flies at more than 40,000 feet, putting it above 99% of the  water vapor in Earth’s atmosphere– critical for observing infrared because water vapor blocks infrared light from reaching the ground. This infrared view reveals the ring of gas and dust around a supermassive black hole that can’t be seen with visible light. 

…and this Hubble image of the Mystic Mountains in the Carina Nebula.

Learn more about the James Webb Space Telescope HERE, or follow the mission on Facebook, Twitter and Instagram.

Image Credits
Eagle Nebula: NASA, ESA/Hubble and the Hubble Heritage Team
Hubble Image Processing - Messier 17: NASA/STScI
Galaxy M82 Composite Image: NASA, CXC, JHU, D.Strickland, JPL-Caltech, C. Engelbracht (University of Arizona), ESA, and The Hubble Heritage Team (STScI/AURA)
Horsehead Nebula: NASA, ESA, and The Hubble Heritage Team (STScI/AURA)
Zeta Ophiuchi: NASA/JPL-Caltech
Helix Nebula: NASA/JPL-Caltech
Wing of the Small Magellanic Cloud
X-ray: NASA/CXC/Univ.Potsdam/L.Oskinova et al; Optical: NASA/STScI; Infrared: NASA/JPL-Caltech
Milky Way Circumnuclear Ring: NASA/DLR/USRA/DSI/FORCAST Team/ Lau et al. 2013
Mystic Mountains in the Carina Nebula: NASA/ESA/M. Livio & Hubble 20th Anniversary Team (STScI)

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