Rigorous testing is at the heart of any successful space mission. The James Webb Space Telescope (JWST) will be a million miles away when it deploys its mission-critical sun-shield, and if it doesn’t function as planned, that’s it. Game over.Continue reading “James Webb Tests its Sun-Shield. So Far, So Good.”
To assist with future efforts to locate and study exoplanets, engineers with NASA’s Jet Propulsion Laboratory – in conjunction with the Exoplanet Exploration Program (ExEP) – are working to create Starshade. Once deployed, this revolutionary spacecraft will help next-generation telescopes by blocking out the obscuring light coming from distant stars so exoplanets can be imaged directly.
While this may sound pretty straightforward, the Starshade will also need to engage in some serious formation flying in order to do its job effectively. That was the conclusion of the reached by the Starshade Technology Development team (aka. S5) Milestone 4 report – which is available through the ExEP website. As the report stated, Starshade will need to be perfectly aligned with space telescopes, even at extreme distances.Continue reading “In Order to Reveal Planets Around Another star, a Starshade Needs to Fly 40,000 km Away from a Telescope, Aligned Within Only 1 Meter”
Welcome to the 575th Carnival of Space! The Carnival is a community of space science and astronomy writers and bloggers, who submit their best work each week for your benefit. We have a fantastic roundup today including news from the IAU, so now, on to this week’s worth of stories!
Continue reading “Carnival of Space #575”
The James Webb Space Telescope is like the party of the century that keeps getting postponed. Due to its sheer complexity and some anomalous readings that were detected during vibration testing, the launch date of this telescope has been pushed back many times – it is currently expected to launch sometime in 2021. But for obvious reasons, NASA remains committed to seeing this mission through.
Once deployed, the JWST will be the most powerful space telescope in operation, and its advanced suite of instruments will reveal things about the Universe that have never before been seen. Among these are the atmospheres of extra-solar planets, which will initially consist of gas giants. In so doing, the JWST will refine the search for habitable planets, and eventually begin examining some potential candidates.
The JWST will be doing this in conjunction with the Transiting Exoplanet Survey Satellite (TESS), which deployed to space back in April of 2018. As the name suggests, TESS will be searching for planets using the Transit Method (aka. Transit Photometry), where stars are monitored for periodic dips in brightness – which are caused by a planet passing in front of them relative to the observer.
Some of Webb’s first observations will be conducted through the Director’s Discretionary Early Release Science program – a transiting exoplanet planet team at Webb’s science operation center. This team is planning on conducting three different types of observations that will provide new scientific knowledge and a better understanding of Webb’s science instruments.
As Jacob Bean of the University of Chicago, a co-principal investigator on the transiting exoplanet project, explained in a NASA press release:
“We have two main goals. The first is to get transiting exoplanet datasets from Webb to the astronomical community as soon as possible. The second is to do some great science so that astronomers and the public can see how powerful this observatory is.”
As Natalie Batalha of NASA Ames Research Center, the project’s principal investigator, added:
“Our team’s goal is to provide critical knowledge and insights to the astronomical community that will help to catalyze exoplanet research and make the best use of Webb in the limited time we have available.”
For their first observation, the JWST will be responsible for characterizing a planet’s atmosphere by examining the light that passes through it. This happens whenever a planet transits in front of a star, and the way light is absorbed at different wavelengths provides clues as to the atmosphere’s chemical composition. Unfortunately, existing space telescopes have not had the necessary resolution to scan anything smaller than a gas giant.
The JWST, with its advanced infrared instruments, will examine the light passing through exoplanet atmospheres, split it into a rainbow spectrum, and then infer the atmospheres’ composition based on which sections of light are missing. For these observations, the project team selected WASP-79b, a Jupiter-sized exoplanet that orbits a star in the Eridanus constellation, roughly 780 light-years from Earth.
The team expects to detect and measure the abundances of water, carbon monoxide, and carbon dioxide in WASP-79b, but is also hoping to find molecules that have not yet been detected in exoplanet atmospheres. For their second observation, the team will be monitoring a “hot Jupiter” known as WASP-43b, a planet which orbits its star with a period of less than 20 hours.
Like all exoplanets that orbit closely to their stars, this gas giant is tidally-locked – where one side is always facing the star. When the planet is in front of the star, astronomers are only able to see its cooler backside; but as it orbits, the hot day-side slowly comes into view. By observing this planet for the entirety of its orbit, astronomers will be able to observe those variations (known as a phase curve) and use the data to map the planet’s temperature, clouds, and atmospheric chemistry.
This data will allow them to sample the atmosphere to different depths and obtain a more complete picture of the planet’s internal structure. As Bean indicated:
“We have already seen dramatic and unexpected variations for this planet with Hubble and Spitzer. With Webb we will reveal these variations in significantly greater detail to understand the physical processes that are responsible.”
For their third observation, the team will be attempting to observe a transiting planet directly. This is very challenging, seeing as how the star’s light is much brighter and therefore obscures the faint light being reflected off the planet’s atmosphere. One method for addressing this is to measure the light coming from a star when the planet is visible, and again when it disappears behind the star.
By comparing the two measurements, astronomers can calculate how much light is coming from the planet alone. This technique works best for very hot planets that glow brightly in infrared light, which is why they selected WASP-18b for this observation – a hot Jupiter that reaches temperatures of around 2,900 K (2627 °C; 4,800 °F). In the process, they hope to determine the composition of the planet’s smothering stratosphere.
In the end, these observations will help test the abilities of the JWST and calibrate its instruments. The ultimate goal will be to examine the atmospheres of potentially-habitable exoplanets, which in this case will include rocky (aka. “Earth-like”) planets that orbit low mass, dimmer red dwarf stars. In addition to being the most common star in our galaxy, red dwarfs are also believed to be the most likely place to find Earth-like planets.
“TESS should locate more than a dozen planets orbiting in the habitable zones of red dwarfs, a few of which might actually be habitable. We want to learn whether those planets have atmospheres and Webb will be the one to tell us. The results will go a long way towards answering the question of whether conditions favorable to life are common in our galaxy.”
The James Webb Space Telescope will be the world’s premier space science observatory once deployed, and will help astronomers to solve mysteries in our Solar System, study exoplanets, and observe the very earliest periods of the Universe to determine how its large-scale structure evolved over time. For this reason, its understandable why NASA is asking that the astronomical community be patient until they are sure it will deploy successfully.
When the payoff is nothing short of ground-breaking discoveries, it’s only fair that we be willing to wait. In the meantime, be sure to check out this video about how scientists study exoplanet atmospheres, courtesy of the Space Telescope Science Institute:
Further Reading: NASA
The Kepler space telescope has had a relatively brief but distinguished career of service with NASA. Having launched in 2009, the space telescope has spent the past nine years observing distant stars for signs of planetary transits (i.e. the Transit Method). In that time, it has been responsible for the detection of 2,650 confirmed exoplanets, which constitutes the majority of the more than 38oo planets discovered so far.
Earlier this week, the Kepler team was notified that the space telescope’s fuel tank is running very low. NASA responded by placing the spacecraft in hibernation in preparation for a download of its scientific data, which it collected during its latest observation campaign. Once the data is downloaded, the team expects to start its last observation campaign using whatever fuel it has left.
Since 2013, Kepler has been conducting its “Second Light” (aka. K2) campaign, where the telescope has continued conducting observations despite the loss of two of its reaction wheels. Since May 12th, 2018, Kepler has been on its 18th observation campaign, which has consisted of it studying a patch of sky in the vicinity of the Cancer constellation – which it previously studied in 2015.
In order to send the data back home, the spacecraft will point is large antenna back towards Earth and transmit it via the Deep Space Network. However, the DSN is responsible for transmitting data from multiple missions and time needs to be allotted in advance. Kepler is scheduled to send data from its 18th campaign back in August, and will remain in a stable orbit and safe mode in order to conserve fuel until then.
On August 2nd, the Kepler team will command the spacecraft to awaken and will maneuver the craft to the correct orientation to transmit the data. If all goes well, they will begin Kepler’s 19th observation campaign on August 6th with what fuel the spacecraft still has. At present, NASA expects that the spacecraft will run out of fuel in the next few months.
However, even after the Kepler mission ends, scientists and engineers will continue to mine the data that has already been sent back for discoveries. According to a recent study by an international team of scientists, 24 new exoplanets were discovered using data from the 10th observation campaign, which has brought the total number of Kepler discoveries to 2,650 confirmed exoplanets.
In the coming years, many more exoplanet discoveries are anticipated as the next-generation of space telescopes begin collecting their first light or are deployed to space. These include the Transiting Exoplanet Survey Satellite (TESS), which launched this past April, and the James Webb Space Telescope (JWST) – which is currently scheduled to launch sometime in 2021.
However, it will be many years before any mission can rival the accomplishments and contributions made by Kepler! Long after she is retired, her legacy will live on in the form of her discoveries.
Further Reading: NASA
In the coming decade, a number of next-generation instruments will take to space and begin observing the Universe. These will include the James Webb Space Telescope (JWST), which is likely to be followed by concepts like the Large Ultraviolet/Optical/Infrared Surveyor (LUVOIR), the Origins Space Telescope (OST), the Habitable Exoplanet Imager (HabEx) and the Lynx X-ray Surveyor.
These missions will look farther into the cosmos than ever before and help astronomers address questions like how the Universe evolved and if there is life in other star systems. Unfortunately, all these missions have two things in common: in addition to being very large and complex, they are also very expensive. Hence why some scientists are proposing that we rely on more cost-effective ideas like swarm telescopes.
Two such scientists are Jayce Dowell and Gregory B. Taylor, a research assistant professor and professor (respectively) with the Department of Physics and Astronomy at the University of New Mexico. Together, the pair outlined their idea in a study titled “The Swarm Telescope Concept“, which recently appeared online and was accepted for publication by the Journal of Astronomical Instrumentation.
As they state in their study, traditional astronomy has focused on the construction, maintenance and operation of single telescopes. The one exception to this is radio astronomy, where facilities have been spread over an extensive geographic area in order to obtain high angular resolution. Examples of this include the Very Long Baseline Array (VLBA), and the proposed Square Kilometer Array (SKA).
In addition, there’s also the problem of how telescopes are becoming increasingly reliant on computing and digital signal processing. As they explain in their study, telescopes commonly carry out multiple simultaneous observation campaigns, which increases the operational complexity of the facility due to conflicting configuration requirements and scheduling considerations.
A possible solution, according to Dowell and Taylor, is to rethink telescopes. Instead of a single instrument, the telescope would consist of a distributed array where many autonomous elements come together through a data transport system to function as a single facility. This approach, they claim, would be especially useful when it comes to the Next Generation Very Large Array (NGVLA) – a future interferometer that will build on the legacy of the Karl G. ansky Very Large Array and Atacama Large Millimeter/submillimeter Array (ALMA). As they state in their study:
“At the core of the swarm telescope is a shift away from thinking about an observatory as a monolithic entity. Rather, an observatory is viewed as many independent parts that work together to accomplish scientific observations. This shift requires moving part of the decision making about the facility away from the human schedulers and operators and transitioning it to “software defined operators” that run on each part of the facility. These software agents then communicate with each other and build dynamic arrays to accomplish the goals of multiple observers, while also adjusting for varying observing conditions and array element states across the facility.”
This idea for a distributed telescope is inspired by the concept of swarm intelligence, where large swarms of robots are programmed to interact with each other and their environment to perform complex tasks. As they explain, the facility comes down to three major components: autonomous element control, a method of inter-element communication, and data transport management.
Of these components, the most critical is the autonomous element control which governs the actions of each element of the facility. While similar to traditional monitoring and control systems used to control individual robotic telescopes, this system would be different in that it would be responsible for far more. Overall, the element control would be responsible for ensuring the safety of the telescope and maximizing the utilization of the element.
“The first, safety of the element, requires multiple monitoring points and preventative actions in order to identify and prevent problems,” they explain. “The second direction requires methods of relating the goals of an observation to the performance of an element in order to maximize the quantity and quality of the observations, and automated methods of recovering from problems when they occur.”
The second component, inter-element communication, is what allows the individual elements to come together to form the interferometer. This can take the form of a leaderless system (where there is no single point of control), or an organizer system, where all of the communication between the elements and with the observation queue is done through a single point of control (i.e. the organizer).
Lastly, their is the issue of data transport management, which can take one of two forms based on existing telescopes. These include fully 0ff-line systems, where correlation is done post-observation – used by the Very Long Baseline Array (VLBA) – to fully-connected systems, where correlation is done in real-time (as with the VLA). For the sake of their array, the team emphasized how connectivity and correlation are a must.
After considering all these components and how they are used by existing arrays, Dowell and Taylor conclude that the swarm concept is a natural extension of the advances being made in robotic and thinking telescopes, as well as interferometry. The advantages of this are spelled out in their conclusions:
“It allows for more efficient operations of facilities by moving much of the daily operational work done by humans to autonomous control systems. This, in turn, frees up personnel to focus on the scientific output of the telescope. The swarm concept can also combine the unused resources of the different elements together to form an ad hoc array.”
In addition, swarm telescopes will offer new opportunities and funding since they will consist of small elements that can be owned and operated by different entities. In this way, different organizations would be able to conduct science with their own elements while also being able to benefit from large-scale interferometric observations.
This concept is similar to the Modular Active Self-Assembling Space Telescope Swarms, which calls for a swarm of robots that would assemble in space to form a 30 meter (~100 ft) telescope. The concept was proposed by a team of American astronomers led by Dmitri Savransky, an assistant professor of mechanical and aerospace engineering at Cornell University.
This proposals was part of the 2020 Decadal Survey for Astrophysics and was recently selected for Phase I development as part of the 2018 NASA Innovative Advanced Concepts (NIAC) program. So while many large-scale telescopes will be entering service in the near future, the next-next-generation of telescopes could include a few arrays made up of swarms of robots directed by artificial intelligence.
Such arrays would be capable of achieving high-resolution astronomy and interferometry at lower costs, and could free up large, complex arrays for other observations.
Further Reading: arXiv
When it is deployed to space, the James Webb Space Telescope (JWST) will be the most powerful and advanced telescope ever deployed. As the spiritual and scientific successor to the Hubble, Spitzer, and Kepler Space Telescopes, this space observatory will use its advanced suite of infrared instruments to look back at the early Universe, study the Solar System, and help characterize extra-solar planets.
Unfortunately, after many delays, there’s some good news and bad news about this mission. The good news is that recently, the Independent Review Board (IRB) established by NASA to assess the progress on the JWST unanimously decided that work on the space telescope should continue. The bad news is that NASA has decided to push the launch date back again – this time to March 30th, 2021.
As part of their assessment, the IRB was established in April of 2018 to address a range of factors influencing Webb’s schedule and performance. These included the technical challenges and tasks that need to be tackled by its primary contractor (Northrop Grumman) before the mission can launch. A summary of the report’s recommendations, and NASA’s response, can be read here.
In the report, the IRB identified technical issues, which including human errors, that they claim have greatly impacted the development schedule. As they stated in their Overview:
“The observation that there are no small JWST integration and test problems was not initially recognized by the Webb IRB, and this also may be true of others involved with JWST. It is a most important observation that will be apparent in subsequent Findings and Recommendations. It is caused by the complexity and highly integrated nature of the observatory. Specifically, it implies, as an example, that a very small human error or test anomaly can impact the schedule by months and the cost by tens of millions of dollars.”
The anomaly mentioned in the report refers to the “anomalous readings” that were detected from the telescope during vibration testing back in December 2016. NASA responded to this by giving the project up to 4 months of schedule reserve by extending the launch window. However, in 2017, NASA delayed the launch window again by 5 months, from October 2018 to a between March and June 2019.
This delay was requested by the project team, who indicated that they needed to address lessons learned from the initial folding and deployment of the observatory’s sun shield. In February of 2018, the Government Accountability Office (GAO) issued a report that expressed concerns over further delays and cost overruns. Shortly thereafter, the JWST’s Standing Review Board (SRB) made an independent assessment of the remaining tasks.
In May of 2018, NASA issued a statement indicating that they now estimated that the launch window would be some time in May 2020. However, they chose to await the findings of the IRB and consider the data from the JWST’s Standing Review Board before making the final determination. The new launch date was set to accommodate environmental testing and work performances challenges on the sunshield and propulsion system.
According to the IRB report, this latest delay will also result in a budget overrun. “As a result of the delay, Webb’s total lifecycle cost to support the March 2021 launch date is estimated at $9.66 billion,” they concluded. “The development cost estimate to support the new launch date is $8.8B (up from the $8B development cost estimate established in 2011).”
As Jim Bridenstine, the NASA Administrator, indicated in a message to the NASA workforce on Wednesday about the report:
“Webb is vital to the next generation of research beyond NASA’s Hubble Space Telescope. It’s going to do amazing things – things we’ve never been able to do before – as we peer into other galaxies and see light from the very dawn of time. Despite major challenges, the board and NASA unanimously agree that Webb will achieve mission success with the implementation of the board’s recommendations, many of which already are underway.”
In the end, the IRB, SRB and NASA are all in total agreement that the James Webb Space Telescope is a crucial mission that must be seen through. In addition to shedding light on a number of mysteries of the Universe – ranging from the earliest stars and galaxies in the Universe to exoplanet habitability – the JWST will also complement and enhance the discoveries made by other missions.
These include not only Hubble and Spitzer, but also missions like the Transiting Exoplanet Survey Satellite (TESS), which launched this past April. Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate, also issued a statement on the recent report:
“The more we learn more about our universe, the more we realize that Webb is critical to answering questions we didn’t even know how to ask when the spacecraft was first designed. Webb is poised to answer those questions, and is worth the wait. The valuable recommendations of the IRB support our efforts towards mission success; we expect spectacular scientific advances from NASA’s highest science priority.”
The JWST will also be the first telescope of its kind, being larger and more complex than any previous space telescope – so challenges were anticipated from its very inception. In addition, the final phase consists of some of the most challenging work, where the 6.5-meter telescope and science payload element are being joined with the spacecraft element to complete the observatory.
The science team also needs to ensure that the observatory can be folded up to fit inside the Ariane 5 rocket that will launch it into space. They also need to ensure that it will unfold again once it reaches space, deploy its sunshield, mirrors and primary mirror. Beyond that, there are also the technical challenges of building a complex observatory that was created here on Earth, but designed to operate in space.
As a collaborative project between NASA, the European Space Agency (ESA), and the Canadian Space Agency (CSA), the JWST is also representative of the new era of international cooperation. As such, no one wishes to see the mission abandoned so close to completion. In the meantime, any delays that allow for extra testing will only ensure success in the long run.
Good luck JWST, we look forward to hearing about your first discoveries!
Further Reading: NASA
Welcome to the 558th Carnival of Space! The Carnival is a community of space science and astronomy writers and bloggers, who submit their best work each week for your benefit. We have a fantastic roundup today, so now, on to this week’s stories!
Continue reading “Carnival of Space #558”
When the James Webb Space Telescope finally takes to space, it will study some of the most distant objects in the Universe, effectively looking back in time to see the earliest light of the cosmos. It will also study extra-solar planets around nearby stars and even bodies within the Solar System. In this respect, the JWST is the natural successor to Hubble and other pioneering space telescopes.
It is therefore understandable why the world is so eager for the JWST to be launched into space (which is now scheduled to take place in 2019). And recently, the telescope passed another major milestone along the road towards deployment. After spending three months in a chamber designed to simulate the temperatures and vacuum conditions of space, the JWST emerged and was given a clean bill of health.
The tests took place inside Chamber A, a thermal vacuum testing facility located at the Johnson Space Center in Houston, Texas. This chamber was built back in 1965 as part of NASA’s race to the Moon, where it conducted tests to ensure that the Apollo command and service modules were space-worthy. Beginning in mid-July, the telescope was put into the chamber and subjected to temperatures ranging from 20 to 40 K (-253 to -233 °C; 423 to 387 °F).
Once the temperature and vacuum conditions were just right, a team of NASA engineers began testing the alignment of the JWST’s 18 primary mirror segments to make sure they would act as a single, 6.5-meter telescope. As Bill Ochs – the James Webb telescope project manager at NASA’s Goddard Space Flight Center – indicated to ArsTechnica, this latest test has shown that the telescope is indeed space-worthy.
“We now have verified that NASA and its partners have an outstanding telescope and set of science instruments,” he said. “We are marching toward launch.”
The team of engineers also tested the JWST’s guidance and optical systems by simulating the light of a distant star. Not only was the telescope able to detect the light, its optical systems were able to process it. The telescope was also able to track the simulated star’s movement, which demonstrated that the JWST will be able to acquire and hold research targets once it is in space.
Many tests are still needed before the JWST can take to space next year. These will be conducted at Northrop Grumman’s company headquarters in Los Angeles, where the telescope will be transported after leaving the Johnson Space Center in late January or early February. Once there, the optical instrument will mated to the spacecraft and sunshield to complete the construction of the telescope.
These tests are necessary since NASA will be hard-pressed to service the telescope once it is in space. This is due to the fact that it will be operating at the Earth-Sun L2 Lagrange Point (which will place farther away from Earth than the Moon) for a minimum of five years. At this distance, any servicing missions will be incredibly difficult, time-consuming and expensive to mount.
However, once the JWST has passed its entire battery of tests and NASA is satisfied it is ready to take to space, it will be shipped off to the Guiana Space Center in Kourou, French Guiana. Once there, it will launch aboard a European Space Agency (ESA) Ariane V booster. Originally, this was scheduled to take place in October of 2017, but is now expected to take place no earlier than Spring of 2018.
When the James Webb Space Telescope is operational, it is expected to reveal some truly amazing things about our Universe. In addition to looking farther into space than any previous telescope (and further back in time), its other research goals include studying nearby exoplanets in unprecedented detail, circumstellar debris disks, supermassive black holes at the centers of galaxies, and even searching for life in the Solar System by examining Jupiter’s moons.
For this reason, NASA can be forgiven for pushing the launch back to make sure everything is in working order. But of course, we can be forgiven for wanting to see it launched as soon as possible! There are mysteries out there that are just waiting to be revealed, and some amazing scientific finds that need to be followed up on.
In the meantime, be sure to check out this video about the JWST, courtesy of NASA:
Fraser Cain (universetoday.com / @fcain)
Dr. Paul M. Sutter (pmsutter.com / @PaulMattSutter)
Dr. Kimberly Cartier (KimberlyCartier.org / @AstroKimCartier )
Dr. Morgan Rehnberg (MorganRehnberg.com / @MorganRehnberg & ChartYourWorld.org)
Dr. Jeyhan Kartaltepe is an Assistant Professor of Physics at Rochester Institute of Technology, and is the Deputy Director of the Laboratory for Multiwavelength Astrophysics. She is also a leading member of the Cosmic Evolution Early Release Science (CEERS) Survey team that has been selected as part of the James Webb Space Telescope Director’s Discretionary Early Release Science Program. It is one of 13 science teams that will use the $8 billion telescope first, conducting experiments during its initial cycle and testing the instruments’ capabilities.
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