When will the Webb Telescope launch? James Webb Telescope's first targets announced

Illustration copyright NASA Image caption Since October last year, the telescope's scientific instruments have been tested in the Goddard Center's vacuum chamber.

Work to prepare for the launch of the successor to the Hubble orbital telescope, the James Webb Space Observatory, has entered a decisive stage.

NASA engineers are finishing assembling the main mirror of the new telescope. The launch of the new telescope is now planned for October 2018.

Cryogenic tests and calibration of the four main blocks of the telescope's scientific equipment are also being completed.

NASA's project to launch a new orbital observatory has thus entered its final stage, and the remaining pre-launch phases can be expected to be rapidly completed in the coming months.

The telescope is planned to be launched using the European Ariane 5 launch vehicle, which determined many design features of the telescope, in particular the fact that its main mirror consists of segments.

The James Webb Orbital Telescope, named after the second head of NASA, is funded by the US Aerospace Agency, the European Space Agency and the Canadian Space Agency.

Illustration copyright NASA Image caption Each beryllium mirror segment is glued into place

The primary objectives of the new telescope are to detect the light of the first stars and galaxies formed after the Big Bang, study the formation and development of galaxies, stars, planetary systems and the origin of life. Webb will also be able to talk about when and where the reionization of the Universe began and what caused it.

The telescope will make it possible to detect relatively cold exoplanets with surface temperatures of up to 300 K (which is almost equal to the surface temperature of the Earth), located further than 12 astronomical units (AU) from their stars and at a distance of up to 15 light years from Earth.

To the zone detailed observation more than two dozen stars closest to the Sun will hit. Thanks to the new telescope, a real breakthrough in exoplanetology is expected - the capabilities of the telescope will be sufficient not only to detect the exoplanets themselves, but even the satellites and spectral lines of these planets, which will be an unattainable indicator for any ground-based and orbital telescope until the early 2020s , when the European Extremely Large Telescope with a mirror diameter of 39.3 m is commissioned.

Illustration copyright NASA Image caption The last two segments of the main mirror are awaiting installation

The telescope will operate for at least five years.

In recent weeks, NASA engineers have been busy gluing beryllium primary mirror segments to the mirror's supporting structure.

Over the next few days, the last two octagonal segments will be installed in the desired position for fastening.

Meanwhile, in the adjacent room of the Goddard Center in Maryland, next to the assembly shop, cryogenic-vacuum tests of the scientific equipment of the future telescope are being completed.

James Webb will have the following scientific instruments for space exploration:

Near-Infrared Camera;
Device for working in the mid-range of infrared radiation (Mid-Infrared Instrument);
Near-Infrared Spectrograph;
Fine Guidance Sensor/Near InfraRed Imager and Slitless Spectrograph.

Since October last year, these devices have been in a vacuum chamber, the temperature in which has been reduced to minus 233 degrees Celsius.

Illustration copyright NASA Image caption Breadboard testing is already underway at the Johnson Center.

Instrument calibration data has already been obtained, which will be of great importance for controlling the telescope in deep space.

These tests helped identify a number of defects and replace unreliable equipment and parts. The telescope has 250 thousand covers and shutters, some of which have the unpleasant defect of “sticking” in a vacuum under the influence of vibrations when launched from Earth.

The vibration of the launch vehicle was simulated during the current tests, and the replaced parts proved to have increased reliability.

It remains to carry out more general optical, vibration and acoustic tests of all telescope systems.

The mirror and scientific instruments will then be transported to the Johnson Center for further cryogenic-vacuum testing in a chamber that was built in the 1960s for testing rocket technology project "Apollo". These tests will begin in about a year.

After their completion, a control systems module will be attached to the telescope, in which on-board computers and communication systems will be installed.

The last step will be to install a giant solar shield the size of a tennis court on the telescope, which will protect the optical systems from exposure to sunlight.

It's not too long to wait until October 2018.

NASA today confirmed plans for the James Webb Telescope project. Management said both the current budget and the space telescope's 2018 launch plans are current. It is worth noting that the agency itself views this telescope as the next Hubble model rather than its replacement.

The telescope's capabilities significantly exceed those of Hubble. The James Webb will have a composite mirror 6.5 meters in diameter (the diameter of the Hubble mirror is 2.4 meters) with a collecting surface area of 25 m² and a solar shield the size of a tennis court. The telescope will be placed at the L2 Lagrange point of the Sun-Earth system.

James Webb will be able to travel into the distant past of the Universe - for a time from 100 to 250 million years after the Big Bang. In other words, the new telescope will be able to look much further into the depths of outer space than Hubble, which can “travel” no further than 800 million to 1 billion years after the Big Bang. In addition, Webb is not “sharpened” for visible light; his specialization is the infrared spectrum. However, James Webb can also detect radiation visible to the eye person.

Simulation of what the James Webb telescope “sees” and what Hubble sees at the same point in space

Difficulties in project implementation

The main problem of such large projects as James Webb and Hubble is the budget. Both the first and second projects went beyond the budget. But, since a significant part of the budget has already been spent, there is nothing left but to continue implementing the plans.

In the case of Hubble, the situation was further complicated by the fact that the mirror was initially installed incorrectly. This affected the capabilities of the telescope, and it took a long time before the error was corrected with the help of an external expedition, during which correction lenses were installed.

As for James Webb, the mistake here is unforgivable. As mentioned above, the new telescope is planned to be installed at the L2 Lagrange point. If something goes wrong, you will have to forget about the project. However, the chances of successful implementation of the project are quite significant.

Webb will peer into the near- and mid-infrared spectrum, aided by his position at the L2 point behind the moon and solar shields that block the intrusive light of the Sun, Earth and Moon, beneficially affecting the cooling of the device. Scientists hope to see the universe's very first stars, the formation and collision of young galaxies, and the birth of stars in protoplanetary systems - which may contain the chemical components of life.

These first stars may hold the key to understanding the structure of the Universe. Theoretically, where and how they form is directly related to the first models of dark matter - an invisible, mysterious substance that is detected by its gravitational influence - and their cycles of life and death cause feedback, which influenced the formation of the first galaxies. And since supermassive stars With short period With life roughly 30 to 300 times our Sun's mass (and millions of times brighter), these first stars would have exploded as supernovae and then collapsed to form the black holes that eventually occupied the centers of most massive galaxies.

Seeing all this is certainly a feat for the tools we have made so far. Thanks to new instruments and spacecraft, we will be able to see even more.

Tour of the James Webb Space Telescope

Webb looks like a diamond-shaped raft, equipped with a thick, curved mast and sail - if it were built by giant beryllium-eating bees. Directed with its lower part towards the Sun, the “raft” from below consists of a shield - layers of Kapton, separated by slits. Each layer is separated by a vacuum gap for efficient cooling, and together they protect the main reflector and instruments.

Kapton is a very thin (think human hair) polymer film made by DuPont that is capable of maintaining stable mechanical properties under conditions of extreme heat and vibration. If you want, you can boil water on one side of the shield and keep the nitrogen in liquid form on the other. It also folds up quite well, which is important for launching.

The ship's "keel" consists of a structure that stores the solar shield during launch and solar panels to power the vehicle. In the center is a box that contains all the critical support functions that power Webb, including power, attitude control, communications, command, data processing and thermal control. Antenna decorates appearance box and helps make sure everything is oriented in the right direction. At one end of the heat shield, perpendicular to it, there is a torque trimmer, which compensates for the pressure exerted by photons on the device.

On the space side of the shield there is a “sail”, a giant Webb mirror, part of the optical equipment and a box with equipment. The 18 hexagonal beryllium sections will unfold after launch to become one large primary mirror, 6.5 meters across.

Opposite this mirror, held in place by three supports, is a secondary mirror that focuses light from the primary mirror into the aft optical subsystem, a wedge-shaped box protruding from the center of the primary mirror. This structure deflects stray light and directs light from the secondary mirror to instruments located at the rear of the "mast", which also supports the segmented structure of the primary mirror.

Once the vehicle completes its six-month commissioning period, it will operate for 5-10 years, perhaps longer, depending on fuel consumption, but will be too far away to be repaired. In fact, Hubble are somewhat of an exception in this regard. But like Hubble and other shared observatories, Webb's mission will be to work with competitively selected projects from scientists around the world. The results will then find their way into the research and data available online.

Let's take a closer look at the tools that make all this research possible.

Instruments: out of sight

Although it sees something in the visual spectrum (red and gold light), Webb is a fundamentally large infrared telescope.

Its main thermal imager, near-infrared camera NIRCam, sees in the range of 0.6-5.0 microns (near infrared). It will be able to detect the infrared light from the birth of the very first stars and galaxies, conduct surveys of nearby galaxies and local objects scurrying through the Kuiper Belt - expanses of icy bodies rotating beyond the orbit of Neptune, which also house Pluto and others dwarf planets.

NIRCam is also equipped with a coronagraph, which will allow the camera to observe the thin halo surrounding bright stars, blocking their blinding light - necessary tool to identify exoplanets.

The near-infrared spectrograph operates in the same wavelength range as NIRCam. Like other spectrographs, it analyzes physical properties objects such as stars, dividing the light they emit into spectra, the structure of which varies depending on temperature, mass and chemical composition object.

NIRSpec will study thousands of ancient galaxies with emission so weak that a single spectrograph will need hundreds of hours to do the job. To simplify this daunting task, the spectrograph is equipped with a remarkable device: a grid of 62,000 individual blinds, each approximately 100 by 200 microns in size (the width of a few human hairs) and each of which can be opened and closed, blocking light more than bright stars. With this array, NIRSpec will be the first space spectrograph that can observe hundreds of different objects simultaneously.

Fine Guidance Sensor and a slitless spectrograph (FGS-NIRISS) are essentially two sensors packaged together. NIRISS includes four modes, each associated with a different wavelength. These range from slitless spectroscopy, which creates a spectrum using a prism and a grating called a grism, which together create interference patterns that can reveal exoplanetary light against the star's light.

FGS is a sensitive and unblinking camera that takes navigation pictures and transmits them to attitude control systems that keep the telescope pointing in the right direction.

Webb's latest instrument extends its range from the near-infrared to mid-infrared spectrum, which is useful for observing redshift objects as well as planets, comets, asteroids, solar-heated dust and protoplanetary disks. Being both a camera and a spectrograph, this instrument MIRI covers the widest range of wavelengths, 5-28 microns. Its wideband camera will be able to do more types pictures for which we love Hubble.

Also, infrared observations have important implications for understanding the Universe. Dust and gas can block visible light from stars in a stellar nursery, but infrared light cannot. Moreover, as the Universe expands and galaxies move apart, their light is “stretched” and becomes redshifted, moving into the long-wave spectrum of electromagnetic waves such as infrared. The further away a galaxy is, the faster it recedes and the greater its redshift becomes - that's the value of the Webb telescope.

The infrared spectrum can also provide a wealth of information about the atmospheres of exoplanets and whether they contain molecular components associated with life. On Earth, we call water vapor, methane and carbon dioxide "greenhouse gases" because they absorb heat. Because this trend holds true everywhere, scientists can use Webb to detect familiar substances in the atmospheres of distant worlds by observing the substances' absorption patterns using spectrographs.

Main contractors Northrop Grumman
Ball Aerospace Wave range 0.6-28 µm (visible and infrared parts) Location Lagrange point L 2 of the Sun - Earth system (1.5 million km from the Earth in the direction opposite to the Sun) Orbit type halo orbit Launch date March 30, 2021 Launch location Kuru Orbit launch vehicle Ariane-5 or Ariane-6 Duration 5-10 years Deorbit date around 2024 Weight 6.2 tons Telescope type reflecting telescope of the Korsch system Diameter about 6.5 m Collecting area
surfaces about 25 m² Focal length 131.4 m Scientific instruments

MIRI

mid-infrared device

NIRCam

near infrared camera

NIRSpec

near infrared spectrograph

FGS/NIRISS

precision targeting sensor with near-infrared imager and slitless spectrograph Website www.jwst.nasa.gov Media files on Wikimedia Commons

Originally called the Next Generation Space Telescope. Next-generation space telescope, NGST). In 2002, it was renamed in honor of NASA's second director, James Webb (1906-1992), who led the agency from 1961-1968 during the Apollo program.

The James Webb will have a composite mirror 6.5 meters in diameter with a collecting surface area of 25 m², hidden from infrared radiation from the Sun and Earth by a heat shield. The telescope will be placed in a halo orbit at the Lagrange point L 2 of the Sun-Earth system.

The project is the result international cooperation 17 countries, led by NASA, with significant contributions from the European and Canadian Space Agencies.

Current plans call for the telescope to be launched on an Ariane 5 rocket in March 2021. In this case, the first Scientific research will begin in autumn 2021. The telescope will operate for at least five years.

Tasks

Astrophysics

The primary objectives of JWST are: detecting the light of the first stars and galaxies formed after the Big Bang, studying the formation and development of galaxies, stars, planetary systems and the origin of life. Webb will also be able to talk about when and where the reionization of the Universe began and what caused it.

Exoplanetology

The telescope will make it possible to detect relatively cold exoplanets with a surface temperature of up to 300 K (which is almost equal to the temperature of the Earth’s surface), located further than 12 AU. that is, from their stars, and distant from Earth at a distance of up to 15 light years. More than two dozen stars closest to the Sun will fall into the detailed observation zone. Thanks to JWST, a real breakthrough in exoplanetology is expected - the capabilities of the telescope will be sufficient not only to detect the exoplanets themselves, but even the satellites and spectral lines of these planets (which will be an unattainable indicator for any ground-based or space telescope until 2025, when The European Extremely Large Telescope with a mirror diameter of 39.3 m will be introduced. To search for exoplanets, data obtained by the Kepler telescope since 2009 will also be used. However, the capabilities of the telescope will not be enough to obtain images of the found exoplanets. This opportunity will not appear until the mid-2030s, when the successor telescope to the James Webb, ATLAST, is launched.

Water worlds of the solar system

The telescope's infrared instruments will be used to study water worlds solar system- Jupiter's moon Europa and Saturn's moon Enceladus. The NIRSpec instrument will be used to search for biosignatures (methane, methanol, ethane) in the geysers of both satellites.

The NIRCam instrument will be able to obtain images of Europa in high resolution, which will be used to study its surface and search for regions with geysers and high geological activity. The composition of the detected geysers will be analyzed using NIRSpec and MIRI instruments. Data obtained from these studies will also be used in the exploration of Europe by the Europa Clipper probe.

For Enceladus, due to its remoteness and small size, it will not be possible to obtain high-resolution images, but the capabilities of the telescope will allow us to analyze the molecular composition of its geysers.

Story

Changing the planned launch date and budget

Year	Planned launch date	Planned budget (billion dollars)
1997	2007	0,5
1998	2007	1
1999	2007-2008	1
2000	2009	1,8
2002	2010	2,5
2003	2011	2,5
2005	2013	3
2006	2014	4,5
2008	2014	5,1
2010	no earlier than September 2015	≥6,5
2011	2018	8,7
2013	2018	8,8
2017	spring 2019	8,8
2018	no earlier than March 2020	≥8,8
2018	March 30, 2021	9,66

Initially, the launch was scheduled for 2007, but was later postponed several times (see table). The first segment of the mirror was installed on the telescope only at the end of 2015, and the entire main composite mirror was assembled only in February 2016. As of spring 2018, the planned launch date was shifted to March 30, 2021.

Financing

The cost of the project has also increased repeatedly. In June 2011, it became known that the cost of the telescope was at least four times higher than the original estimates. NASA's budget proposed in July 2011 by Congress called for the end of funding for the telescope due to mismanagement and program overruns, but the budget was revised in September of that year and the project remained funded. The final decision to continue funding was made by the Senate on November 1, 2011.

In 2013, $626.7 million was allocated for the construction of the telescope.

By the spring of 2018, the cost of the project had increased to $9.66 billion.

Manufacturing of the optical system

Problems

The sensitivity of a telescope and its resolving power are directly related to the size of the mirror area that collects light from objects. Scientists and engineers have determined that the minimum diameter of the primary mirror must be 6.5 meters to measure light from the most distant galaxies. Simple manufacturing of a mirror similar to the Hubble telescope mirror, but bigger size, was unacceptable because its mass would be too large to launch a telescope into space. The team of scientists and engineers needed to find a solution so that the new mirror would have 1/10 the mass of the Hubble telescope mirror per unit area.

Development and testing

Production

A special type of beryllium is used for the Webb mirror. It is a fine powder. The powder is placed in a stainless steel container and pressed into a flat shape. Once the steel container is removed, the beryllium piece is cut in half to make two mirror blanks about 1.3 meters across. Each mirror blank is used to create one segment.

The process of forming the mirror begins by cutting away excess material from the back of the beryllium blank so that a fine ridge structure remains. The front side of each workpiece is smoothed taking into account the position of the segment in a large mirror.

Then the surface of each mirror is ground down to give it a shape close to the calculated one. After this, the mirror is carefully smoothed and polished. This process is repeated until the shape of the mirror segment is close to ideal. Next, the segment is cooled to a temperature of −240 °C, and the dimensions of the segment are measured using a laser interferometer. Then the mirror, taking into account the information received, undergoes final polishing.

Once the segment is processed, the front of the mirror is coated with a thin layer of gold to better reflect infrared radiation in the range of 0.6-29 microns, and the finished segment is re-tested at cryogenic temperatures.

Testing

July 10, 2017 - The final cryogenic test of the telescope begins at a temperature of 37 at the Johnson Space Center in Houston, which lasted 100 days.

In addition to testing in Houston, the vehicle underwent a series of mechanical checks at the Goddard Space Flight Center that showed it could withstand launch from a heavy launch vehicle.

In early February 2018, the giant mirrors and various instruments arrived at Northrop Grumman's Redondo Beach facility for the final stage of telescope assembly. The construction of the telescope's propulsion module and its sun shield is already underway there. When the entire structure is assembled, it will be sent on a sea vessel from California to French Guiana.

Equipment

JWST will have the following scientific instruments to conduct space exploration:

Near-Infrared Camera;
Device for working in the mid-range of infrared radiation (English: Mid-Infrared Instrument, MIRI);
Near-infrared spectrograph Near-Infrared Spectrograph, NIRSpec);
Fine Guidance Sensor (FGS) and near-infrared imager and slitless spectrograph. Near InfraRed Imager and Slitless Spectrograph, NIRISS).

Near-infrared camera

The near-infrared camera is the main imaging unit of the Webb and will consist of an array mercury-cadmium-tellurium detectors The operating range of the device is from 0.6 to 5 µm. Its development is entrusted to the University of Arizona and the Lockheed Martin Advanced Technology Center.

The tasks of the device include:

detection of light from the earliest stars and galaxies at the stage of their formation;
study of stellar populations in nearby galaxies;
study of young stars of the Milky Way and Kuiper Belt objects;
determination of the morphology and color of galaxies at high redshift;
determination of light curves of distant supernovae;
creating a map of dark matter using gravitational lensing.

Many of the objects Webb will study emit so little light that the telescope must collect light from them for hundreds of hours to analyze the spectrum. To study thousands of galaxies over the telescope's 5 years of operation, the spectrograph was designed to observe 100 objects over a 3×3 arcminute area of the sky simultaneously. To achieve this, Goddard scientists and engineers have developed new technology microshutters to control the light entering the spectrograph.

The essence of the technology that makes it possible to obtain 100 simultaneous spectra, consists of a microelectromechanical system called a “microshutter array”. The NIRSpec spectrograph's microshutter cells have covers that open and close when exposed to magnetic field. Each 100 by 200 µm cell is individually controlled and can be open or closed, exposing or blocking part of the sky to the spectrograph, respectively.

It is this adjustability that allows the device to perform spectroscopy on so many objects simultaneously. Because the objects that NIRSpec will study are far away and dim, the instrument needs to suppress radiation from closer bright sources. Micro shutters work in a similar way to how people squint to focus on an object by blocking out an unwanted light source.

The device has already been developed and this moment is being tested in Europe.

Device for working in the mid-infrared range

Device for working in the mid-range of infrared radiation (5 - 28 µm) consists of a camera with a sensor having a resolution of 1024x1024 pixels and a spectrograph.

MIRI consists of three arsenic-silicon detector arrays. The instrument's sensitive detectors will allow us to see the redshift of distant galaxies, the formation of new stars and faintly visible comets, as well as objects in the Kuiper belt. The camera module provides the ability to image objects in a wide range of frequencies with a large field of view, and the spectrograph module provides medium-resolution spectroscopy with a smaller field of view, which will allow obtaining detailed physical data about distant objects.

Rated operating temperature for MIRI-7. This temperature cannot be achieved using only a passive cooling system. Instead, cooling is carried out in two stages: a pulse tube pre-cooler cools the device to 18 K, then an adiabatic throttling heat exchanger (Joule-Thomson effect) lowers the temperature to 7 K.

MIRI is being developed by a group called the MIRI Consortium, consisting of scientists and engineers from Europe, a team from the Jet Propulsion Laboratory in California, and scientists from a number of US institutions.

FGS/NIRISS

The Fine Guidance Sensor (FGS) and the Near-Infrared Imaging and Slitless Spectrograph (NIRISS) will be packaged together in Webb, but they are essentially two different devices. Both devices are being developed by the Canadian Space Agency, and they have already been nicknamed "Canadian eyes" by analogy with the "Canadian hand". This tool has already been integrated with the structure ISIM in February 2013.

Precise guidance sensor

Precision guidance sensor ( FGS) will allow Webb to perform precise targeting so that it can obtain high-quality images.

Camera FGS can form an image from two adjacent areas of the sky measuring 2.4 × 2.4 arcminutes each, and also read information 16 times per second from small groups of 8 × 8 pixels, which is enough to find the corresponding reference star with 95% probability anywhere in the sky, including high latitudes.

Main functions FGS include:

obtaining an image to determine the position of the telescope in space;
obtaining pre-selected guide stars;
provision of position control system eng. Attitude Control System measures the centroid of guide stars at a rate of 16 times per second.

During the launch of the telescope into orbit FGS will also report deviations when deploying the main mirror.

Near-infrared imager and slitless spectrograph

The Near Infrared Imaging and Slitless Spectrograph (NIRISS) operates in the range 0.8 - 5.0 µm and is a specialized tool with three main modes, each of which works with a separate range.

NIRISS will be used to perform the following scientific tasks:

receiving “first light”;
exoplanet detection;
obtaining their characteristics;
transit spectroscopy.

Notes

Footnotes

Jim Bridenstine on Twitter: "The James Webb Space Telescope will produce the first of its kind, world-class science. Based on recommendations by an Independent Review Board, the n...
With further delays, Webb telescope at risk of seeing its rocket retired | Ars Technica
https://www.ama-science.org/proceedings/details/368
NASA Completes Webb Telescope Review, Commits to Launch in Early 2021(English) . NASA (27 June 2018). Retrieved June 28, 2018.
Icy Moons, Galaxy Clusters, and Distant Worlds Among Selected Targets for James Webb Space Telescope (undefined) (June 15, 2017).
https://nplus1.ru/news/2017/06/16/webb-telescope (undefined) (June 16, 2017).
Webb Science: The End of the Dark Ages: First Light and Reionization (undefined) . NASA. Retrieved March 18, 2013. Archived March 21, 2013.
A pinch of infinity (undefined) (March 25, 2013). Archived from the original on April 4, 2013.
Kepler finds ten new possible Earth twins (undefined) (June 19, 2017).
NASA's Webb Telescope Will Study Our Solar System's “Ocean Worlds” (undefined) (August 24, 2017).
Berardelli, Phil. Next Generation Space Telescope will peer back to the beginning of time and space, CBS (October 27, 1997).
The Next Generation Space Telescope (NGST) (undefined) . University of Toronto (November 27, 1998).
Reichhardt, Tony. US astronomy: Is the next big thing too big? (English) // Nature. - 2006. - March (vol. 440, no. 7081). - P. 140-143. - DOI:10.1038/440140a. - Bibcode: 2006Natur.440..140R.
Cosmic Ray Rejection with NGST (undefined) .
MIRI spectrometer for NGST (undefined) (unavailable link). Archived from the original on September 27, 2011.
NGST Weekly Missive (undefined) (April 25, 2002).
NASA Modifies James Webb Space Telescope Contract (undefined) (November 12, 2003).

Cosmonautics,

Astronomy

Almost immediately after the launch of the Hubble telescope into orbit, scientists began to prepare a more advanced device, which was planned to be equipped with more functions and capabilities. Now, almost twenty years later, this project has already been implemented, and the system has been tested and is ready for use. We are talking about the James Webb orbital telescope, which is equipped with a 6.5-meter mirror. This is twice as much as Hubble.

At the end of last year, the project's scientific director, John Mather, announced that the telescope was ready and quite capable of starting work in orbit. According to experts involved in the project, the new telescope will help begin the study of galaxies that are billions of light years away from Earth. We are talking about the opportunity to use a kind of time machine, observing galaxies that appeared almost immediately after the Big Bang. This will help scientists clarify the origin of the Universe.

Recent problems and their solutions

The assembly of the telescope's main mirrors was completed in February last year. Then NASA announced the successful installation of the last fragment. Each of the hexagonal fragments with a mass of 40 kg has a diameter of about 1.3 m. The main mirror with a diameter of 6.5 meters is made from the fragments. It is created from beryllium, which is covered with a gold film.

The installation of the mirrors was carried out not by people, but by a robot - a specialized manipulator was developed for this purpose. On the mirror, in addition to the mirrors themselves, scientists installed servos and spacers that correct the curvature of the surface. According to experts, in order for focusing to be accurate, the fastener cannot move more than 38 nanometers.

In November last year, scientists began testing the mirrors - this is an extremely important stage that made it possible to judge the performance of the device. When conducting tests, experts simulated external factors that could damage the structure. First of all, we are talking about the sound and vibration generated when the ship is launched - these factors, without proper attention to them, may well damage the telescope. Generally speaking, sending the James Webb into orbit is a difficult stage, during which a lot of trouble can happen if all components of the sending process are not carefully controlled.

“The test will show whether there is any damage to the optical system after the test,” said Ritva Keski-Kuha, head of telescope testing at NASA's Goddard Space Flight Center (GSFC). .

For testing, an interferometer was used, a device that allows one to determine the characteristics of a telescope mirror with extremely high accuracy. The problem is that to check you cannot directly contact the mirror; all tests must be performed remotely. Otherwise, micro-scratches may appear on the mirror, which will lead to a decrease in the efficiency of the entire system.

"That's why we do the review - to know how things actually are, instead of guessing," said deputy project manager Paul Geithner.

An interferometer solves this problem. It allows you to record the smallest changes in the arrangement of elements of a complex telescope mirror and the surface characteristics of individual fragments. The interferometer generates light waves of different lengths, the characteristics of which, after reflection by the mirror, are studied by experts.

“The previous four years could be considered preparation for the current test,” David Cheney, chief mirror metrologist at Goddard Space Flight Center, said last November. “We measure the size of the main mirror, its radius of curvature, background noise. Our test is so sensitive that we detect changes in the mirror's characteristics even when people are talking in the room."

In November, the tests went smoothly and no problems were identified. But in early December, the accelerometers that were connected to the telescope detected some anomalies while the device was undergoing vibration tests. Scientists conducted low-level vibration tests, comparing the data obtained with those transmitted by sensors before the anomaly appeared. Once the problem was identified, the test automatically stopped to protect the device hardware. Scientists once again examined the telescope, but did not find any abnormalities.

At the end of December, NASA representatives announced that no problems were found in the instruments and other components of the system. Both a visual inspection and analysis of images of the device in ultraviolet radiation were performed. In addition, two additional low-level vibration tests were conducted, which also did not reveal any problems with the James Webb Telescope. More information about testing can be found in the document prepared by NASA specialists.

In December, John Mather announced that project participants expected the telescope to successfully pass all the necessary tests. At the same time, the agency plans to use any available precautionary methods to ensure the successful launch of the telescope into orbit. So far, unfortunately, it is not entirely clear what these anomalies were and how they could affect the system when it is sent into space. The agency will formulate final conclusions later this month.

The James Webb will be shipped to a Northrop-Grumman facility mid-year for final assembly and connection to the solar shield and in-orbit maneuvering system. Before that, the telescope's optical system and scientific instruments will be tested in the Johnson Space Center's thermal vacuum chamber.

So far, program participants are showing optimism. "We don't think we'll run into anything that's difficult to fix," says Paul Hertz.

Astronomers can prepare their proposals for working with the telescope

At the 229th meeting of the American Astronomical Society, project representatives announced that scientists could begin submitting proposals for proposed methods for operating the telescope. Direct operation of the telescope will begin in April 2019, six months after the planned launch of this system. Various test procedures and checks will be carried out over the course of six months; if everything goes as planned, the scientists will be able to implement their ideas.

"I'm impressed by this," says Eric Smith, the program's director. The fact is that over the past years the team has been exclusively engaged in technical side business, not science. Now you can move on to the final stage and practice scientific work. “This year provides an opportunity for the scientific community to get back to work on the program.”

At the meeting discussed above, program management stated that the scientists who participated in the development of the instruments software or various functions of the James Webb Telescope, will be able to obtain guaranteed operating time with the telescope. In addition, early access to the system's capabilities will be provided to those scientists who submit compelling applications that enable the telescope's full functionality to be demonstrated to the scientific community. As a result, other scientists will be able to understand how best to use James Webb's functionality to observe the Universe and submit their own suggestions. At least that's the idea. Scientists will be able to submit “regular” proposals at the end of 2017.

Now the specialists who are taking part in the development of the system continue to test the telescope, including the optical part and scientific instruments. Checks are performed at the Goddard Space Flight Center.

Telescope components and its capabilities

James Webb is a very complex system that consists of thousands of individual elements. They form the telescope's mirror and its scientific instruments. As for the latter, these are the following devices:

Near-Infrared Camera;
Device for working in the mid-range of infrared radiation (Mid-Infrared Instrument);
Near-Infrared Spectrograph;
Fine Guidance Sensor/Near InfraRed Imager and Slitless Spectrograph.

These instruments will perform scientific tasks such as:

detection of light from the earliest stars and galaxies at the stage of their formation;
study of stellar populations in nearby galaxies;
study of young stars of the Milky Way and Kuiper belt objects;
determination of the morphology and color of galaxies at high redshift;
determination of light curves of distant supernovae;
creating a map dark matter using gravitational lensing;
detection of "first light";
exoplanet detection;
obtaining their characteristics;
transit spectroscopy.

What's next?

The project remains on budget, Eric Smith said. So far, everything is going according to plan and there are no obstacles that could prevent the telescope from launching in October 2018. The only detected problem - vibration anomalies - is already close to resolution, specialists are actively working to finalize the problem and get rid of it. But, of course, difficulties may still arise. “We're now at a point in the program where we're facing new challenges that are different from the challenges we've faced to date,” says Smith. But at the same time, he is confident in the team’s strengths: “When problems arise, I am confident that the team can solve them.”

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