Month: May 2022

The Webb team continues to work on commissioning the science instruments, the final step before starting science operations in the summer. We recently saw the beautiful image of the black hole in the center of our Milky Way galaxy, taken by the Event Horizon Telescope. One of the puzzles of modern astronomy is how every large galaxy came to have a giant central black hole, and how some of these black holes are surprisingly large even at very early times. We asked Roberto Maiolino, a member of the Near-Infrared Spectrometer (NIRSpec) instrument science team, to tell us how Webb will help to answer some of these questions.

“One of the most exciting areas of discovery that Webb is about to open is the search for primeval black holes in the early universe. These are the seeds of the much more massive black holes that astronomers have found in galactic nuclei. Most (probably all) galaxies host black holes at their centers, with masses ranging from millions to billions of times the mass of our Sun. These supermassive black holes have grown to be so large both by gobbling matter around them and also through the merging of smaller black holes.

“An intriguing recent finding has been the discovery of hyper-massive black holes, with masses of several billion solar masses, already in place when the universe was only about 700 million years old, a small fraction of its current age of 13.8 billion years. This is a puzzling result, as at such early epochs there is not enough time to grow such hyper-massive black holes, according to standard theories. Some scenarios have been proposed to solve this conundrum. One possibility is that black holes, resulting from the death of the very first generation of stars in the early universe, have accreted material at exceptionally high rates. Another scenario is that primeval, pristine gas clouds, not yet enriched by chemical elements heavier than helium, could directly collapse to form a black hole with a mass of a few hundred thousand solar masses, and subsequently accrete matter to evolve into the hyper-massive black holes observed at later epochs. Finally, dense, nuclear star clusters at the centers of baby galaxies may have produced intermediate mass black hole seeds, via stellar collisions or merging of stellar-mass black holes, and then become much more massive via accretion.

“Webb is about to open a completely new discovery space in this area. It is possible that the first black hole seeds originally formed in the ‘baby universe,’ within just a few million years after the big bang. Webb is the perfect ‘time machine’ to learn about these primeval objects. Its exceptional sensitivity makes Webb capable of detecting extremely distant galaxies, and because of the time required for the light emitted by the galaxies to travel to us, we will see them as they were in the remote past.

“Webb’s NIRSpec instrument is particularly well suited to identify primeval black hole seeds. My colleagues in the NIRSpec Instrument Science Team and I will be searching for their signatures during ‘active’ phases, when they are voraciously gobbling matter and growing rapidly. In these phases the material surrounding them becomes extremely hot and luminous and ionizes the atoms in their surroundings and in their host galaxies. NIRSpec will disperse the light from these systems into spectra, or ‘rainbows.’ The rainbow of active black hole seeds will be characterised by specific ‘fingerprints,’ features of highly ionized atoms. NIRSpec will also measure the velocity of the gas orbiting in the vicinity of these primeval black holes. Smaller black holes will be characterized by lower orbital velocities. Black hole seeds formed in pristine clouds will be identified by the absence of features associated with any element heavier than helium.

“I look forward to using Webb’s unprecedented capabilities to search for these black hole progenitors, with the ultimate goal of understanding their nature and origin. The early universe and the realm of black holes seeds is a completely uncharted territory that my colleagues and I are very excited to explore with Webb.”

— Roberto Maiolino, professor of experimental astrophysics and director of the Kavli Institute for Cosmology, University of Cambridge

---

— Jonathan Gardner, Webb deputy senior project scientist, NASA’s Goddard Space Flight Center

— Stefanie Milam, Webb deputy project scientist for planetary science, NASA Goddard

As NASA’s James Webb Space Telescope moves through the final phases of commissioning its science instruments, we have also begun working on technical operations of the observatory.  While the telescope moves through space, it will constantly find distant stars and galaxies and point at them with extreme precision to acquire images and spectra. However, we also plan to observe planets and their satellites, asteroids, and comets in our solar system, which move across the background stars of our galaxy. Webb needs to be able to lock on to these objects and track them with sufficient precision to obtain images and spectra. The Webb team recently completed the first test to track a moving object. The test verified that Webb could conduct moving target science! As we move forward through commissioning, we will test other objects moving at various speeds to verify we can study objects with Webb that move throughout the solar system.

Today, we asked Heidi Hammel, Webb interdisciplinary scientist for solar system observations, to tell us about her plans for studying Earth’s nearest neighbors:

“I am really excited about Webb’s upcoming first year of science operations! I lead a team of equally excited astronomers eager to begin downloading data. Webb can detect the faint light of the earliest galaxies, but my team will be observing much closer to home. They will use Webb to unravel some of the mysteries that abound in our own solar system.

“One of the questions I get asked frequently is why we need a powerful telescope like Webb to study our nearby solar system. We planetary scientists use telescopes to complement our in situ missions (missions that we send to fly by, orbit, or land on objects). One example of this is how Hubble was used to find the post-Pluto target for the New Horizons mission, Arrokoth. We also use telescopes when we don’t have in situ missions planned – like for the distant ice giants Uranus and Neptune or to make measurements of large populations of objects, such as hundreds of asteroids or Kuiper Belt Objects (small ice worlds beyond the orbits of Neptune, including Pluto), since we can only send missions to just a few of these.

“The Webb team has already used an asteroid within our solar system to run engineering tests of the ‘moving target’ (MT) capability. The engineering team tested this capability on a small asteroid in the Main Belt: 6481 Tenzing, named after Tenzing Norgay, the famous Tibetan mountain guide who was one of the first people to reach the summit of Mount Everest. Bryan Holler, at the Space Telescope Science Institute, had a choice of about 40 possible asteroids to test the MT tracking, but, as he told our team: “Since the objects were all virtually identical otherwise, picking the one with a name linked to success seemed like a no-brainer.”  We like that sort of thing.

“My role with Webb as an ‘Interdisciplinary Scientist’ means that my program uses all of the capabilities of this forefront telescope! We need all of them to truly understand the solar system (and the universe!).

“Our solar system has far more mysteries than my team had time to solve. Our programs will observe objects across the solar system: We will image the giant planets and Saturn’s rings; explore many Kuiper Belt Objects; analyze the atmosphere of Mars; execute detailed studies of Titan; and much more! There are also other teams planning observations; in its first year, 7% of Webb’s time will be focused on objects within our solar system.

“One exciting and challenging program we plan to do is observe ocean worlds. There’s evidence from the Hubble Space Telescope that Jupiter’s moon Europa has sporadic plumes of water-rich material. We plan to take high-resolution imagery of Europa to study its surface and search for plume activity and active geologic processes. If we locate a plume, we will use Webb’s spectroscopy to analyze the plume’s composition.

“I have a soft spot in my heart for Uranus and Neptune. Indeed, it was the lack of a mission to these very distant worlds that got me involved in Webb so many decades ago. The Uranus team hopes to definitively link the chemistry and dynamics of the upper atmosphere (detectable with Webb) to the deeper atmosphere that we have been studying with other facilities over many decades. I’ve spent the past 30 years using the biggest and best telescopes humanity has ever built to study these ice giants, and we will now add Webb to that list.

“We have been planning for Webb observations for over twenty years, and that has gone into overdrive now that we are launched, deployed, and focused! I’ll note that nearly all of my team’s solar system data will be freely available to the broad planetary science community immediately. I made that choice to enable more science discoveries with Webb in future proposals.

“I am gratified to have been able to work with the team for all this time, and I especially want to give a shout out to the thousands of people who collectively have enabled this amazing facility for the astrophysics and planetary communities. Thank you! Ad astra!”

—Heidi Hammel, vice president for science, Association of Universities for Research in Astronomy (AURA)

---

–Stefanie Milam, Webb deputy project scientist for planetary science, NASA’s Goddard Space Flight Center

–Jonathan Gardner, Webb deputy senior project scientist, NASA Goddard

With the telescope optics and instruments aligned, the Webb team is now commissioning the observatory’s four powerful science instruments. There are 17 different instrument “modes” to check out on our way to getting ready for the start of science this summer. Once we have approved all 17 of these modes, NASA’s James Webb Space Telescope will be ready to begin scientific operations!

In this post we’ll describe the 17 modes, and readers are encouraged to follow along as the Webb team checks them off one by one on the Where is Webb tracker. Each mode has a set of observations and analysis that need to be verified, and it is important to note that the team does not plan to complete them in the order listed below. Some of the modes won’t be verified until the very end of commissioning.

For each mode we have also selected a representative example science target that will be observed in the first year of Webb science. These are just examples; each mode will be used for many targets, and most of Webb’s science targets will be observed with more than one instrument and/or mode. The detailed list of peer-reviewed observations planned for the first year of science with Webb ranges from our solar system to the most distant galaxies.

1.  Near-Infrared Camera (NIRCam) imaging. Near-infrared imaging will take pictures in part of the visible to near-infrared light, 0.6 to 5.0 micrometers wavelength. This mode will be used for almost all aspects of Webb science, from deep fields to galaxies, star-forming regions to planets in our own solar system. An example target in a Webb cycle 1 program using this mode: the Hubble Ultra-Deep Field.

2.  NIRCam wide field slitless spectroscopy. Spectroscopy separates the detected light into individual colors. Slitless spectroscopy spreads out the light in the whole instrument field of view so we see the colors of every object visible in the field. Slitless spectroscopy in NIRCam was originally an engineering mode for use in aligning the telescope, but scientists realized that it could be used for science as well. Example target: distant quasars.

3.  NIRCam coronagraphy. When a star has exoplanets or dust disks in orbit around it, the brightness from a star usually will outshine the light that is reflected or emitted by the much fainter objects around it. Coronagraphy uses a black disk in the instrument to block out the starlight in order to detect the light from its planets. Example target: the gas giant exoplanet HIP 65426 b.

4.  NIRCam time series observations – imaging. Most astronomical objects change on timescales that are large compared to human lifetimes, but some things change fast enough for us to see them. Time series observations read out the instruments’ detectors rapidly to watch for those changes. Example target: a pulsing neutron star called a magnetar.

5.  NIRCam time series observations – grism. When an exoplanet crosses the disk of its host star, light from the star can pass through the atmosphere of the planet, allowing scientists to determine the constituents of the atmosphere with this spectroscopic technique. Scientists can also study light that is reflected or emitted from an exoplanet, when an exoplanet passes behind its host star. Example target: lava rain on the super-Earth-size exoplanet 55 Cancri e.

6.  Near-Infrared Spectrograph (NIRSpec) multi-object spectroscopy. Although slitless spectroscopy gets spectra of all the objects in the field of view, it also allows the spectra of multiple objects to overlap each other, and the background light reduces the sensitivity. NIRSpec has a microshutter device with a quarter of a million tiny controllable shutters. Opening a shutter where there is an interesting object and closing the shutters where there is not allows scientists to get clean spectra of up to 100 sources at once. Example target: the Extended Groth Strip deep field.

7.  NIRSpec fixed slit spectroscopy. In addition to the microshutter array, NIRSpec also has a few fixed slits that provide the ultimate sensitivity for spectroscopy on individual targets. Example target: detecting light from a gravitational-wave source known as a kilonova.

8.  NIRSpec integral field unit spectroscopy. Integral field unit spectroscopy produces a spectrum over every pixel in a small area, instead of a single point, for a total of 900 spatial/spectral elements. This mode gives the most complete data on an individual target. Example target: a distant galaxy boosted by gravitational lensing.

9.  NIRSpec bright object time series. NIRSpec can obtain a time series spectroscopic observation of transiting exoplanets and other objects that change rapidly with time. Example target: following a hot super-Earth-size exoplanet for a full orbit to map the planet’s temperature.

10.  Near-Infrared Imager and Slitless Spectrograph (NIRISS) single object slitless spectroscopy. To observe planets around some of the brightest nearby stars, NIRISS takes the star out of focus and spreads the light over lots of pixels to avoid saturating the detectors. Example target: small, potentially rocky exoplanets TRAPPIST-1b and 1c.

11.  NIRISS wide field slitless spectroscopy. NIRISS includes a slitless spectroscopy mode optimized for finding and studying distant galaxies. This mode will be especially valuable for discovery, finding things that we didn’t already know were there. Example target: pure parallel search for active star-forming galaxies.

12.  NIRISS aperture masking interferometry. NIRISS has a mask to block out the light from 11 of the 18 primary mirror segments in a process called aperture masking interferometry. This provides high-contrast imaging, where faint sources next to bright sources can be seen and resolved for images. Example target: a binary star with colliding stellar winds.

13.  NIRISS imaging. Because of the importance of near-infrared imaging, NIRISS has an imaging capability that functions as a backup to NIRCam imaging. Scientifically, this is used mainly while other instruments are simultaneously conducting another investigation, so that the observations image a larger total area. Example target: a Hubble Frontier Field gravitational lensing galaxy cluster.

14.  Mid-Infrared Instrument (MIRI) imaging. Just as near-infrared imaging with NIRCam will be used on almost all types of Webb targets, MIRI imaging will extend Webb’s pictures from 5 to 27 microns, the mid-infrared wavelengths. Mid-infrared imaging will show us, for example, the distributions of dust and cold gas in star-forming regions in our own Milky Way galaxy and in other galaxies. Example target: the nearby galaxy Messier 33.

15.  MIRI low-resolution spectroscopy. At wavelengths between 5 and 12 microns, MIRI’s low-resolution spectroscopy can study fainter sources than its medium-resolution spectroscopy. Low resolution is often used for studying the surface of objects, for example, to determine the composition. Example target: Pluto’s moon Charon.

16.  MIRI medium-resolution spectroscopy. MIRI can do integral field spectroscopy over its full mid-infrared wavelength range, 5 to 28.5 microns. This is where emission from molecules and dust display very strong spectral signatures. Example targets: molecules in planet-forming disks.

17.  MIRI coronagraphic imaging. MIRI has two types of coronagraphy: a spot that blocks light and three four-quadrant phase mask coronagraphs. These will be used to directly detect exoplanets and study dust disks around their host stars. Example target: searching for planets around our nearest neighbor star Alpha Centauri A.

— Jonathan Gardner, Webb deputy senior project scientist, NASA’s Goddard Space Flight Center

NASA’s James Webb Space Telescope is aligned across all four of its science instruments, as seen in a previous engineering image showing the observatory’s full field of view. Now, we take a closer look at that same image, focusing on Webb’s coldest instrument: the Mid-Infrared Instrument, or MIRI.

The MIRI test image (at 7.7 microns) shows part of the Large Magellanic Cloud. This small satellite galaxy of the Milky Way provided a dense star field to test Webb’s performance.

Here, a close-up of the MIRI image is compared to a past image of the same target taken with NASA’s Spitzer Space Telescope’s Infrared Array Camera (at 8.0 microns). The retired Spitzer telescope was one of NASA’s Great Observatories and the first to provide high-resolution images of the near- and mid-infrared universe. Webb, with its significantly larger primary mirror and improved detectors, will allow us to see the infrared sky with improved clarity, enabling even more discoveries.

For example, Webb’s MIRI image shows the interstellar gas in unprecedented detail. Here, you can see the emission from “polycyclic aromatic hydrocarbons,” or molecules of carbon and hydrogen that play an important role in the thermal balance and chemistry of interstellar gas. When Webb is ready to begin science observations, studies such as these with MIRI will help give astronomers new insights into the birth of stars and protoplanetary systems.

 

In the meantime, the Webb team has begun the process of setting up and testing Webb’s instruments to begin science observations this summer. Today at 11 a.m., Webb experts will preview these next two months of instrument preparations in a teleconference for media. Listen to the audio stream live at nasa.gov/live.

NASA’s James Webb Space Telescope is now experiencing all seasons – from hot to cold – as it undergoes the thermal stability test. Meanwhile, activities are underway for the final phase of commissioning: digging into the details of the science instruments, the heart of Webb. To complete commissioning, we will measure the detailed performance of the science instruments before we start routine science operations in the summer.

Today, the lead commissioning scientist for Webb, Scott Friedman of the Space Telescope Science Institute (STScI), gives us all the details on this final phase of commissioning.

“With the telescope beautifully aligned and the observatory near its final cryogenic temperature, we are ready to begin the last group of activities before the science observations start: science instrument commissioning. Here I describe just a few of those activities.

“The instruments, the Near-Infrared Camera (NIRCam), Near-Infrared Spectrometer (NIRSpec), Near-Infrared Imager and Slitless Spectrometer (NIRISS), Mid-Infrared Instrument (MIRI), and the Fine Guidance Sensor (FGS) have been powered up and safely cooled. We have operated their mechanisms and detectors, including filter wheels, grating wheels, and the NIRSpec microshutter assembly. The Webb optics team used images of isolated stars taken with each of the instruments to align the primary and secondary mirrors of the observatory. But we have more work to do before Webb is fully ready to embark on the ambitious science observations that will reveal the secrets of the universe.

“We will now begin an extensive suite of calibrations and characterizations of the instruments using a rich variety of astronomical sources. We will measure the instruments’ throughput – how much of the light that enters the telescope reaches the detectors and is recorded. There is always some loss with each reflection by the mirrors of the telescope and within each instrument, and no detector records every photon that arrives. We will measure this throughput at multiple wavelengths of light by observing standard stars whose light emission is known from data obtained with other observatories combined with theoretical calculations.

“The astrometric calibration of each instrument maps the pixels on the detectors to the precise locations on the sky, to correct the small but unavoidable optical distortions that are present in every optical system. We do this by observing the Webb astrometric field, a small patch of sky in a nearby galaxy, the Large Magellanic Cloud. This field was observed by the Hubble Space Telescope to establish the coordinates of about 200,000 stars to an accuracy of 1 milli-arcsec (less than 0.3 millionths of a degree). Calibrating this distortion is required to precisely place the science targets on the instruments’ field of view. For example, to get the spectra of a hundred galaxies simultaneously using the NIRSpec microshutter assembly, the telescope must be pointed so that each galaxy is in the proper shutter, and there are a quarter of a million shutters!

“We will also measure the sharpness of the stellar images, what astronomers call the ‘point spread function.’ We already know the telescope is delivering to the instruments image quality that exceeds our prelaunch expectations, but each instrument has additional optics. These optics perform a function, such as passing the light through filters to get color information about the astronomical target or using a diffraction grating to spread the incoming light into its constituent colors. Measuring the point spread function within each instrument at different wavelengths provides an important calibration for interpreting the data.

“We will test target acquisition for each instrument. For some observations, it is sufficient to point the telescope using the position of a guide star in the Fine Guidance Sensor and know the location of the science target relative to that guide star. This places the science target to an accuracy of a few tenths of an arcsecond. However, in some cases more precision is necessary, approximately a hundredth of an arcsecond. For example, for coronagraphy, the star has to be placed behind a mask so its light is blocked, allowing the nearby exoplanet to shine through. In time series observations, we measure how an exoplanet’s atmosphere absorbs the stellar light during the hours it takes to pass in front of its star, allowing us to measure the properties and constituents of the planet’s atmosphere. Both of these applications require that the instrument send corrections to the telescope pointing control system to put the science target precisely in the correct location within the instrument’s field of view.

“A final example of our instrument commissioning activities is observations of moving targets. Most astronomical objects are so far away that they appear to be stationary on the sky. However, this is not true of the planets, satellites and rings, asteroids, and comets within our own solar system. Observing these requires that the observatory change its pointing direction relative to the background guide stars during the observation. We will test this capability by observing asteroids of different apparent speeds using each instrument.

“We are now in the last two months of Webb’s commissioning before it is fully ready for its scientific mission. We still have important properties and capabilities of the instruments to test, measure, and demonstrate. When these are complete, we will be ready to begin the great science programs that astronomers and the public alike have been eagerly awaiting. We are almost there.”

– Scott Friedman, lead commissioning scientist for Webb, STScI

---

-Jonathan Gardner, Webb deputy senior project scientist, NASA Goddard

-Stefanie Milam, Webb deputy project scientist for planetary science, NASA Goddard

 

On May 1, the nonprofit, nonpartisan Partnership for Public Service announced the 2022 finalists for the Samuel J. Heyman Service to America Medal (Sammies) – an  awards program honoring excellence and innovation in federal service. Among the finalists is Gregory L. Robinson, program director for the James Webb Space Telescope at NASA Headquarters.

Selected from more than 400 nominations, Robinson has been named a Management Excellence finalist for his achievements in overseeing NASA’s largest and most complex international space science program, which will enable scientific breakthroughs in nearly every branch of astronomy.

“Greg Robinson is a leader who epitomizes excellence,” said Thomas Zurbuchen, NASA’s associate administrator for the Science Mission Directorate. “Across a massive international program of diverse teams and perspectives, he built the trust, consensus, and motivation to see this revolutionary mission to launch.”

Webb launched on Dec. 25, 2021, and endured a harrowing multi-week spacecraft commissioning period where hundreds of intricate parts synchronized to work successfully in the harsh environment of space while on its journey to its final orbit one million miles from Earth.

“I am very honored to be considered for a Service to America Medal,” Robinson said. “Working with an incredible, resilient team and partners across the globe to overcome many challenges has been a great privilege. I have enjoyed a great career at NASA for over 30 years, and to be a part of the mission’s historic moment when Webb launched flawlessly on Christmas Day was an awe-inspiring gift.”

Since its inception in 2002, the Sammies have honored more than 650 outstanding federal employees. Robinson is among 30 federal employees across 22 federal agencies honored as 2022 Sammies finalists for their outstanding contributions to safety, public health, and sustainability across our nation and the world.

Prior to leading Webb, Robinson served as the deputy associate administrator for programs in NASA’s Science Mission Directorate. He is a veteran executive, who previously served as deputy center director at NASA’s Glenn Research Center in Cleveland, NASA deputy chief engineer, and as the acting National Environmental Satellite, Data, and Information Service deputy assistant administrator at the National Oceanic and Atmospheric Administration.

Webb is the first space science telescope to use a large primary mirror that consists of 18 segments and an unparalleled optical system that recently showed the world its first focused image of a single star. Recently, the Webb team successfully aligned the telescope, confirming it can capture focused images with its four onboard science instruments. Now, it is undergoing the process of commissioning the instruments so it can deliver spectacular images and spectra this summer.

The observatory will enable the study of every phase of 13.5 billion years of cosmic history – from within our solar system to the most distant observable galaxies in the early universe – to everything in between.

More About the Sammies

More information about the program and the 2022 finalists is available online. All finalists are eligible for the Service to America Medals People’s Choice Award. Beginning Monday, May 2, members of the public may vote online for the federal employee they believe has made the most significant contribution to the American people. The People’s Choice winner will be announced in the summer.

More About the Webb Mission

The James Webb Space Telescope, the largest and most complex science observatory ever built, is an international program led by NASA with its partners, the European Space Agency and the Canadian Space Agency. As the scientific successor to the Hubble Space Telescope, Webb will explore the secrets of the universe and reveal new discoveries to help us understand our  place in the cosmos.

For more information about NASA’s Webb mission, visit https://www.nasa.gov/webb.

By Natasha R. Pinol, James Webb Space Telescope program communications lead at NASA Headquarters, Washington