How Many Planets is TESS Going to Find?

Artist Illustration of TESS and its 4 telescopes. Credit: NASA/MIT

The Transiting Exoplanet Survey Satellite (TESS), NASA’s latest exoplanet-hunting space telescope, was launched into space on Wednesday, April 18th, 2018. As the name suggests, this telescope will use the Transit Method to detect terrestrial-mass planets (i.e. rocky) orbiting distant stars. Alongside other next-generation telescopes like the James Webb Space Telescope (JWST), TESS will effectively pick up where telescopes like Hubble and Kepler left off.

But just how many planets is TESS expected to find? That was the subject of a new study by a team researchers who attempted to estimate just how many planets TESS is likely to discover, as well as the physical properties of these planets and the stars that they orbit. Altogether, they estimate TESS will find thousands of planets orbiting a variety of stars during its two-year primary mission.

The study, titled “A Revised Exoplanet Yield from the Transiting Exoplanet Survey Satellite (TESS)“, recently appeared online. The study was led by Thomas Barclay, an associate research scientist at the NASA Goddard Space Flight Center and the University of Maryland, and included Joshua Pepper (an astrophysicist at Lehigh University) and Elisa Quintana (a research scientist with the SETI Institute and NASA Ames Research Center).

As Thomas Barclay told Universe Today via email:

“TESS builds off the legacy of Kepler. Kepler was primarily a statistical mission and taught us that planets are everywhere. However, it wasn’t optimized for finding excellent individual planets for further study. Now that we know planets are common, we can launch something like TESS to search for the planets that we will undertake intensive studies of using ground and space-based telescopes. Planets that TESS will find will on average be 10x closer and 100x brighter.”

For the sake of their study, the team created a three-step model that took into account the stars TESS will observe, the number of planets each one is likely to have, and the likelihood of TESS spotting them. These included the kinds of planets that would be orbiting around dwarf stars ranging from A-type to K-type (like our Sun), and lower-mass M-type (red dwarf) stars.

“To estimate how many planets TESS will find we took stars that will be observed by TESS and simulated a population of planets orbiting them,” said Barclay. “The exoplanet population stats all come from studies that used Kepler data. Then, using models of TESS performance, we estimated how many of those planets would be detected by TESS. This is where we get our yield numbers from.”

The first step was straightforward, thanks to the availability of the Candidate Target List (CTL) – a prioritized list of target stars that the TESS Target Selection Working Group determined were the most suitable stars for detecting small planets. They then ranked the 3.8 million stars that are included in the latest version based on their brightness and radius and determined which of these TESS is likely to observe.

Liftoff of the SpaceX Falcon 9 rocket carrying NASA’s TESS spacecraft. Image credit: NASA TV

The second step consisted of assigning planets to each star based on a Poisson distribution, a statistical technique where a given number is assigned to each star (in this case, 0 or more). Each planet was then assigned six physical properties drawn at random, including an orbital period, a radius, an eccentricity, a periastron angle, an inclination to our line of sight, and a mid-time of first transit.

Last, they attempted to estimate how many of these planets would generate a detectable transit signal. As noted, TESS will rely on the Transit Method, where periodic dips in a star’s brightness are used to determine the presence of one or more orbiting planets, as well as place constraints on their sizes and orbital periods. For this, they considered the flux contamination of nearby stars, the number of transits, and the transit duration.

Ultimately, they determined with 90% confidence that TESS is likely to detect 4430–4660 new exoplanets during its two years mission:

“The results is that we predict that TESS will find more than 4000 planets, with hundreds smaller than twice the size of Earth. The primary goal of TESS is to find planets that are bright enough for ground-based telescope to measure their mass. We estimate that TESS could lead to triple the number of planets smaller than 4 Earth-radii with mass measurements.”

As of April 1st, 2018, a total 3,758 exoplanets have been confirmed in 2,808 systems, with 627 systems having more than one planet. In other words, Barclay and his team estimate that the TESS mission will effectively double the number of confirmed exoplanets and triple the number of Earth-sized and Super-Earth’s during its primary mission.

This will begin after a series of orbital maneuvers and engineering tests, which are expected to last for about two months. With the exoplanet catalog thus expanded, we can expect that there will be many more “Earth-like” candidates available for study. And while we still will not be able to determine if any of them have life, we may perhaps find some that show signs of a viable atmosphere and water on the surfaces.

The hunt for life beyond Earth will continue for many years to come! And in the meantime, be sure to enjoy this video about the TESS mission, courtesy of NASA:

Further Reading: Astrobites, arXiv

Try to Contain Your Surprise. James Webb is Getting Delayed to 2020

Once it deploys, the James Webb Space Telescope (JWST) will be the most powerful and technically complex space telescope ever deployed. Using its powerful suite of infrared-optimized instruments, this telescope will be able to study the earliest stars and galaxies in the Universe, extra-solar planets around nearby stars, and the planets, moons and asteroids of our Solar System.

Unfortunately, due to its complexity and the need for more testing, the launch of the JWST has been subject to multiple delays. And as of this morning, NASA announced that the launch JWST has been delayed yet again. According to a statement issued by the agency, the launch window for the JWST is now targeted for sometime around May 2020.

The decision came after an independent assessment by the project’s Standing Review Board (SRB) of the remaining tasks, all of which are part of the final stage of integration and testing before the JWST launches. These tasks consist of integrating the combined optics and science instruments onto the spacecraft element, then testing them to ensure that they will deploy properly and work once they are in space.

The Space Telescope for Air, Road, and Sea (STTARS) is a custom-designed container that holds the James Webb’s Optical Telescope and Integrated Science (OTIS) instrument module. In this image its being unloaded from a U.S. military C-5 Charlie aircraft at Los Angeles International Airport (LAX) on Feb. 2, 2018. Image: NASA/Chris Gunn

This assessment came on the heels of a report issued by the Government Accountability Office (GAO) in February that expressed concerns over further delays and cost overruns. These concerns were based on the fact that it is typically in the final phase when problems are found and schedules revised, and that only 1.5 months of schedule reserved remained (at the time) until the end of the telescope’s launch window – which was scheduled for 2019.

But as acting NASA Administrator Robert Lightfoot stressed, the JWST is still a go:

“Webb is the highest priority project for the agency’s Science Mission Directorate, and the largest international space science project in U.S. history. All the observatory’s flight hardware is now complete, however, the issues brought to light with the spacecraft element are prompting us to take the necessary steps to refocus our efforts on the completion of this ambitious and complex observatory.”

NASA also announced that it is establishing an external Independent Review Board (IRB) chaired by Thomas Young – a highly-respected NASA and industry veteran who has a long history of chairing advisory committees and analyzing organizational and technical issues. The IRB findings, along with the SRB data, will be considered by NASA to set a more specific launch date, and will be presented to Congress this summer.

In the meantime, NASA and the European Space Agency (ESA) will be setting a new launch readiness date for the Ariane 5 rocket that will bring the JWST into space. Once a launch date is set, NASA will also be providing a cost estimate that may exceed the $8 billion budget cap established by Congress in 2011. This too is in keeping with the GAO’s report, which predicted cost overruns.

The Space Telescope Transporter for Air, Road and Sea (STTARS) being opened at Northrop Grumman on March 8th, 2018, to reveal the combined optics and science instruments of NASA’s James Webb Space Telescope. Credits: NASA/Chris Gunn

For those who have been following the JWST’s development, this news should come as no surprise. Due to its complexity and the need for extensive testing, the launch of the JWST has been delayed several times in recent years. 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.

In addition, 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, deploying 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.

Not only does all of this represent a very technically-challenging feet, it is the first time that any space telescope has had to perform it. Already, the JWST has completed an extensive range of tests to ensure that it will reach its orbit roughly 1.6 million km (1 million mi) from Earth. And while delays can be discouraging, they also increase the likelihood of mission success.

As Thomas Zurbuchen, the associate administrator for NASA’s Science Mission Directorate, stated:

“Considering the investment NASA and our international partners have made, we want to proceed systematically through these last tests, with the additional time necessary, to be ready for a May 2020 launch.”

The combined optics and science instruments of NASA’s James Webb Space Telescope being removed from the Space Telescope Transporter for Air, Road and Sea (STTARS) at the Northrop Grumman company headquarters on March 8th, 2018. Credits: NASA/Chris Gunn

The next step in testing will take several months, and will consist of the spacecraft element undergoing tests to simulate the vibrational, acoustic and thermal environments it will experience during its launch and operations. Once complete, the project engineers will integrate and test the fully assembled observatory and verify that all its components work together properly.

And then (fingers crossed!) this ambitious telescope will finally be ready to take to space and start collecting light. In so doing, scientists from all around the world hope to shed new light on some of the most fundamental questions of science – namely, how did the Universe evolve, is their life in our Solar System beyond Earth, are their habitable worlds beyond our Solar System, and are there other civilizations out there?

Bottom line, NASA remains committed to deploying the James Webb Space Telescope. So even if the answers to these questions are delayed a little, they are still coming!

Further Reading: NASA

Kepler’s Almost Out of Fuel. It’ll Make its Last Observation in a Few Months

Artist's concept of the Kepler mission with Earth in the background. Credit: NASA/JPL-Caltech

Since its deployment in March of 2009, the Kepler space telescope has been a boon for exoplanet-hunters. As of March 8th, 2018, a total of 3,743 exoplanets have been confirmed, 2,649 of which were discovered by Kepler alone. At the same time, the telescope has suffered its share of technical challenges. These include the failure of two reaction wheels, which severely hampered the telescope’s ability to conduct its original mission.

Nevertheless, the Kepler team was able to return the telescope to a stable configuration by using small amounts of thruster fuel to compensate for the failed reaction wheels. Unfortunately, after almost four years conducting its K2 observation campaign, the Kepler telescope is now running out fuel. Based on its remaining fuel and rate of consumption, NASA estimates that the telescope’s mission will end in a few months.

For years, the Kepler space telescope has been locating planets around distant stars using the Transit Method (aka. Transit Photometry). This consists of monitors stars for periodic dips in brightness, which are caused by a planet passing in front of the star (i.e. transiting). Of all the methods used to hunt for exoplanets, the Transit Method is considered the most reliable, accounting for a total of 2900 discoveries.

Naturally, this news comes as a disappointment to astronomers and exoplanet enthusiasts. But before anyone starts lamenting the situation, they should keep some things in mind. For one, the Kepler mission has managed to last longer than anyone expected. Ever since the K2 campaign began, the telescope has been required to shift its field of view about every three months to conduct a new observation campaign.

Based on their original estimates, the Kepler team believed they had enough fuel to conduct 10 more campaigns. However, the mission has already completed 16 campaigns and the team just began their 17th. As Charlie Sobeck, a system engineer for the Kepler space telescope mission, explained in a recent NASA press statement:

“Our current estimates are that Kepler’s tank will run dry within several months – but we’ve been surprised by its performance before! So, while we anticipate flight operations ending soon, we are prepared to continue as long as the fuel allows. The Kepler team is planning to collect as much science data as possible in its remaining time and beam it back to Earth before the loss of the fuel-powered thrusters means that we can’t aim the spacecraft for data transfer. We even have plans to take some final calibration data with the last bit of fuel, if the opportunity presents itself.”

So while the mission is due to end soon, the science team hopes to gather as much scientific data as possible and beam it back to Earth before then. They also hope to gather some final calibration data using the telescope’s last bit of fuel, should the opportunity present itself. And since they cannot refuel the spacecraft, they hope to stop collecting data so they can use their last bit of fuel to point the spacecraft back towards Earth and bring it home.

NASA’s Kepler spacecraft has been on an extended mission called K2 after two of its four reaction wheels failed in 2013. Credit: NASA

“Without a gas gauge, we have been monitoring the spacecraft for warning signs of low fuel— such as a drop in the fuel tank’s pressure and changes in the performance of the thrusters,” said Sobeck. “But in the end, we only have an estimate – not precise knowledge. Taking these measurements helps us decide how long we can comfortably keep collecting scientific data.”

This has been standard practice for many NASA missions, where enough fuel has been reserved to conduct one last maneuver. For example, the Cassini mission had to reserve fuel in order to descend into Saturn’s atmosphere so it would avoid colliding with one of its moons and contaminating a potentially life-bearing environment. Satellites also regularly conduct final maneuvers to ensure they don’t crash into other satellites or fall to Earth.

While deep-space missions like Kepler are in no danger of crashing to Earth or contaminating a sensitive environment, this final maneuver is designed to ensure that the science team can squeeze every last drop of data from the spacecraft. So before the mission wraps up, we can expect that this venerated planet-hunter will have some final surprises for us!

Artist’s rendition of TESS in space. (Credit: MIT Kavli Institute for Astrophysics Research).

In the coming years, next-generation telescopes will be taking to space to pick up where Kepler and other space telescopes left off. These include the Transiting Exoplanet Survey Satellite (TESS), which will be conducting Transit surveys shortly after it launches in April of 2018. By 2019, the James Webb Space Telescope (JWST) will also take to space and use its powerful infrared instruments to aid in the hunt for exoplanets.

So while we will soon be saying goodbye to the Kepler mission, its legacy will live on. In truth, the days of exoplanet discovery are just getting started!

Stay tuned for updates from the Kepler and K2 Science Center.

Further Reading: NASA

James Webb is Enduring its Final Stage of Testing Before it Ships off for Kourou, French Guiana

Once deployed, the James Webb Space Telescope (JWST) will be the most powerful telescope ever built. 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 the look back at the earliest stars and galaxies, study the Solar System in depth, and help characterize extra-solar planets (among other things).

Unfortunately, the launch of the JWST has been subject to multiple delays, with the launch date now set for some time in 2019. Luckily, on Thursday, March 8th, engineers at the Northrop Grumman company headquarters began the final step in the observatory’s integration and testing. Once complete, the JWST will be ready to ship to French Guiana, where it will be launched into space.

This final phase consisted of removing the combined optics and science instruments from their shipping containers – known as the Space Telescope Transporter for Air, Road and Sea (STTARS) – which recently arrived after being testing at NASA’s Johnson Space Center in Houston. This constitutes half the observatory, and includes the telescope’s 6.5 meter (21.3 foot) golden primary mirror.

The Space Telescope Transporter for Air, Road and Sea (STTARS) being opened at Northrop Grumman on March 8th, 2018, to reveal the combined optics and science instruments of NASA’s James Webb Space Telescope. Credits: NASA/Chris Gunn

The science payload was also tested at NASA’s Goddard Space Flight Center last year to ensure it could handle the vibrations associated with space launches and the temperatures and vacuum conditions of space. The other half of the observatory consists of the integrated spacecraft and sunshield, which is in the final phase of assembly at the Northrop Grumman company headquarters.

These will soon undergo a launch environment test to prove that they are ready to be combined with the science payload. Once both halves are finished being integrated, addition testing will be performed to guarantee the  fully assembled observatory can operate at the L2 Earth-Sun Lagrange Point. As Eric Smith, the program director for the JWST at NASA Headquarters, said in a recent NASA press statement:

“Extensive and rigorous testing prior to launch has proven effective in ensuring that NASA’s missions achieve their goals in space. Webb is far along into its testing phase and has seen great success with the telescope and science instruments, which will deliver the spectacular results we anticipate.”

These final tests are crucial to ensuring that that the observatory deploys properly and can operate once it is in space. This is largely because of the telescope’s complicated design, which needs to be folded in order to fit inside the Ariane 5 rocket that it will carry it into space. Once it reaches its destination, the telescope will have to unfold again, deploying its sunshield, mirrors and primary mirror.

The James Webb Space Telescope’s sunshield being deployed inside a cleanroom at Northrop Grumman’s company headquarter’s, in October 2017. Credits: Northrop Grumman

Not only does all of this represented a very technically-challenging feet, it is the first time that any space telescope has had to perform it. Beyond that, there are also the technical challenges of building a complex observatory that is designed to operate in space. While the JWST’s optics and science instruments were all built at room temperature here on Earth, they had to be designed to operate at cryogenic temperatures.

As such, its mirrors had to be precisely polished and formed that they would achieve the correct shape once they cool in space. Similarly, its sunshield will be operating in a zero gravity environment, but was built and tested here on Earth where the gravity is a hefty 9.8 m/s² (1 g). In short, the James Webb Space Telescope is the largest and most complex space telescope ever built, and is one of NASA’s highest priority science projects.

It is little wonder then why NASA has had to put the JWST through such a highly-rigorous testing process. As Smith put it:

“At NASA, we do the seemingly impossible every day, and it’s our job to do the hardest things humankind can think of for space exploration. The way we achieve success is to test, test and retest, so we understand the complex systems and verify they will work.”

The James Webb Space Telescope (which is scheduled to launch in 2019) will be the most powerful telescope ever deployed. Credit: NASA/JPL

Knowing that the JWST is now embarking on the final phase of its development – and that its engineers are confident it will perform up to task – is certainly good news. Especially in light of a recent report from the US Government Accountability Office (GAO), which stated that more delays were likely and that the project would probably exceed its original budget cap of $8 billion.

As the report indicated, it is the final phase of integration and testing where problems are most likely to be found and schedules revised. However, the report also stated that “Considering the investment NASA has made, and the good performance to date, we want to proceed very systematically through these tests to be ready for a Spring 2019 launch.”

In other words, there is no indication whatsoever that Congress is considering cancelling the project, regardless of further delays or cost overruns. And when the JWST is deployed, it will use its 6.5 meter (21-foot) infrared-optimized telescopes will search to a distance of over 13 billion light years, allow astronomers to study the atmospheres of Solar Planets, exoplanets, and other objects within our Solar System.

So while the JWST may not make its launch window in 2019, we can still expect that it will be taking to space in the near future. And when it does, we can also expect that what it reveals about our Universe will be mind-blowing!

Further Reading: NASA

James Webb Telescope is Probably Going to be Delayed Again, and Could Exceed a Congress Spending Cap

The James Webb Space Telescope will be the first of the Super Telescopes to see first light. It is scheduled to be launched in October, 2018. Image credit: NASA/Desiree Stover

When the James Webb Space Telescope takes to space, some tremendous scientific discoveries are expected to result. 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 the look back at the early Universe, study the Solar System, and help characterize extra-solar planets.

Unfortunately, the launch of this mission has been delayed several times now, with the launch date now set for some time in 2019. And based on the amount of work NASA needs to do complete the JWST before launch, the Government Accountability Office (GAO) believes that more delays are coming and believes that the project is likely to exceed the cost cap set by Congress in 2011 at $8 billion. 

Part of the problem is that all the remaining schedule reserve – the extra time set aside in the event of delays or unforeseen risks – was recently used to address technical issues. These include the “anomalous readings” 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.

The JWST sunshield being unfolded in the clean room at Northrop Grumman Aerospace Systems in Redondo Beach, California. Credits: Northrop Grumman Corp.

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 sunshield. As Eric Smith, the program director for the James Webb Space Telescope at NASA Headquarters, explained to Congress at the time:

“Webb’s spacecraft and sunshield are larger and more complex than most spacecraft. The combination of some integration activities taking longer than initially planned, such as the installation of more than 100 sunshield membrane release devices, factoring in lessons learned from earlier testing, like longer time spans for vibration testing, has meant the integration and testing process is just taking longer. Considering the investment NASA has made, and the good performance to date, we want to proceed very systemmatically through these tests to be ready for a Spring 2019 launch.”

Given the remaining integration and test work that lies ahead, more delays are expected. According to the GAO, it is this phase where problems are most likely to be found and schedules revised. Coupled with the fact that only 1.5 months of schedule reserves remain until the end of the launch window, they anticipate that additional launch delays are likely, which will also require budget increases.

Initially, the budget estimates that were set by Congress indicated that the observatory would cost $1.6 billion and would launch by 2011, with an overall cost cap set at $8 billion. However, NASA has revised the budget multiple times since then (in conjunction with the multiple delays) and estimates that the budget for a 2019 launch window would now be $8.8 billion.

The James Webb Space Telescope being placed in the Johnson Space Center’s historic Chamber A on June 20th, 2017. Credit: NASA/JSC

Once deployed, the JWST will be the most powerful space telescope ever built and will serve thousands of astronomers worldwide. As a collaborative project between NASA, the European Space Agency (ESA), and the Canadian Space Agency (CSA), it also representative of the new era of international cooperation. But by far, the most impressive thing about this mission is the scientific discoveries it is expected to make.

It’s 6.5 meter (21-foot) infrared-optimized telescopes will search to a distance of over 13 billion light years, allowing it to study the first stars and galaxies that formed. It will also allow astronomers to study the atmospheres of Solar Planets and exoplanets and other objects within our Solar System. As such, and delays and cost overruns in the project are cause for concern.

In the meantime, the project’s Standing Review Board will conduct an independent review in early 2018 to determine if the June 2019 launch window can still be met. With so many experiments and surveys planned for the telescope, it would be no exaggeration to say that a lot is riding on its successful completion and deployment. Best of luck passing review James Webb Space Telescope!

Further Reading: Government Accountability Office

James Webb Makes The Journey From Houston To Los Angeles; Last Stop Before It Heads To The Launch Facility In 2019

The two halves of the James Webb Space Telescope are now in the same location and ready to take the next step on JWST’s journey. On February 2nd, Webb’s Optical Telescope and Integrated Science instrument module (OTIS) arrived at Northrop Grumman Aerospace Systems in Redondo Beach, California. The integrated spacecraft, consisting of the spacecraft bus and sunshield, were already there, waiting for OTIS so they could join together and become a complete spacecraft.

“The team will begin the final stages of integration of the world’s largest space telescope.” – Scott Willoughby, Northrop Grumman’s Program Manage for the JWST.

“It’s exciting to have both halves of the Webb observatory – OTIS and the integrated spacecraft element – here at our campus,” said Scott Willoughby, vice president and program manager for Webb at Northrop Grumman. “The team will begin the final stages of integration of the world’s largest space telescope.”

The Space Telescope for Air, Road, and Sea (STTARS) is a custom-designed container that holds the James Webb’s Optical Telescope and Integrated Science (OTIS) instrument module. In this image its being unloaded from a U.S. military C-5 Charlie aircraft at Los Angeles International Airport (LAX) on Feb. 2, 2018. Image: NASA/Chris Gunn

OTIS arrived from the Johnson Space Center in Houston, where it had successfully completed its cryogenic testing. To prepare for that journey, OTIS was placed inside a custom shipping container designed to protect the delicate and expensive Webb Telescope from any damage. That specially designed container is called the Space Telescope Transporter for Air, Road and Sea (STTARS).

STTARS is a massive container, measuring 4.6 meters (15 feet) wide, 5.2 meters (17 feet) tall, and 33.5 meters feet (110) long, and weighing approximately 75,000 kilograms (almost 165,000 pounds). It’s much larger than the James Webb itself, but even then, the primary mirror wings and the secondary mirror tripod must be folded into flight configuration in order to fit.

The Space Telescope Transporter for Air, Road and Sea (STTARS) NASA’s at Johnson Space Center in Houston. Image: NASA/Chris Gunn

The next step for the JWST is to join the spacecraft itself with OTIS. Once that happens, JWST will be complete and fully integrated. Then there’ll be more tests called observatory-level testing. After that, another journey inside STTARS to Kouru, French Guiana, where the JWST will be launched in 2019.

“This is a major milestone.” – Eric Smith, director of the James Webb Space Telescope Program at NASA.

“This is a major milestone,” said Eric Smith, director of the James Webb Space Telescope Program at NASA. “The Webb observatory, which is the work of thousands of scientists and engineers across the globe, will be carefully tested to ensure it is ready to launch and enable scientists to seek the first luminous objects in the universe and search for signs of habitable planets.”

You can’t fault people, either NASA personnel or the rest of us, for getting excited about each development in the James Webb Space Telescope story. Every time the thing twitches or moves, our excitement re-spawns. It seems like everything that happens with the JWST is now a milestone in its long, uncertain journey. It’s easy to see why.

The Space Telescope That Almost Wasn’t

The James Webb ran into a lot of problems during its development. As can be expected for a ground-breaking, technology-pushing project like the Webb, it’s expensive. In 2011, when the project was well underway, it was revealed that the Webb would cost $8.8 billion, much more than the initial budget of $1.6 billion. The House of Representatives cancelled the project, then restored it, though funding was capped at $8 billion.

That was the main hurdle facing the development of the JWST, but there were others, including timeline delays. The most recent timeline change moved the launch date from 2017 to Spring 2019. As of now, the James Webb is on schedule, and on target to meet its revised budget.

The First “Super Telescope”

The JWST is the first of the “Super Telescopes” to be in operation. Once it’s in place at LaGrange Point 2 (L2), about 1.5 million km (930,000 miles) from Earth, it will begin observing, primarily in infrared. It will surpass both the Hubble Telescope and the Spitzer Telescope, and will “look back in time” to some of oldest stars and galaxies in the universe. It will also examine exoplanets and contribute to the search for life.

Icy Worlds Like Europa and Enceladus Might Actually be too Soft to Land On

Some truly interesting and ambitious missions have been proposed by NASA and other space agencies for the coming decades. Of these, perhaps the most ambitious include missions to explore the “Ocean Worlds” of the Solar System. Within these bodies, which include Jupiter’s moon Europa and Saturn’s moon Enceladus, scientists have theorized that life could exist in warm-water interior oceans.

By the 2020s and 2030s, robotic missions are expected to reach these worlds and set down on them, sampling ice and exploring their plumes for signs of biomarkers. But according to a new study by an international team of scientists, the surfaces of these moons may have extremely low-density surfaces. In other words, the surface ice of Europa and Enceladus could be too soft to land on.

The study, titled “Laboratory simulations of planetary surfaces: Understanding regolith physical properties from remote photopolarimetric observations“, was recently published in the scientific journal Icarus. The study was led by Robert M.Nelson, the Senior Scientist at the Planetary Science Institute (PSI) and included members from NASA’s Jet Propulsion Laboratory, the California Polytechnic State University at Pomona, and multiple universities.

Artist’s rendering of a possible Europa Lander mission, which would explore the surface of the icy moon in the coming decades. Credit: NASA/JPL-Caltech

For the sake of their study, the team sought to explain the unusual negative polarization behavior at low phase angles that has been observed for decades when studying atmosphereless bodies. This  polarization behavior is thought to be the result of extremely fine-grained bright particles. To simulate these surfaces, the team used thirteen samples of aluminum oxide powder (Al²O³).

Aluminum oxide is considered to be an excellent analog for regolith found on high aldebo Airless Solar System Bodies (ASSB), which include Europa and Encedalus as well as eucritic asteroids like 44 Nysa and 64 Angelina.  The team then subjected these samples to photopolarimetric examinations using the goniometric photopolarimeter at Mt. San Antonio College.

What they found was that the bright grains that make up the surfaces of Europa and Enceladus would measure about a fraction of a micron and have a void space of about 95%. This corresponds to material that is less dense than freshly-fallen snow, which would seem to indicate that these moon’s have very soft surfaces.  Naturally, this does not bode well for any missions that would attempt to set down on Europa or Enceladus’ surface.

But as Nelson explained in PSI press release, this is not necessarily bad news, and such fears have been raised before:

“Of course, before the landing of the Luna 2 robotic spacecraft in 1959, there was concern that the Moon might be covered in low density dust into which any future astronauts might sink. However, we must keep in mind that remote visible-wavelength observations of objects like Europa are only probing the outermost microns of the surface.”

Enceladus in all its glory. NASA has announced that Enceladus, Saturn’s icy moon, has hydrogen in its oceans. Image: NASA/JPL/Space Science Institute

So while Europa and Enceladus may have surfaces with a layer of low-density ice particles, it does not rule out that their outer shells are solid. In the end, landers may be forced to contend with nothing more than a thin sheet of snow when setting down on these worlds. What’s more, if these particles are the result of plume activity or action between the interior and the surface, they could hold the very biomarkers the probes are looking for.

Of course, further studies are needed before any robotic landers are sent to bodies like Europa and Enceladus. In the coming years, the James Webb Space Telescope will be conducting studies of these and other moons during its first five months in service. This will include producing maps of the Galilean Moons, revealing things about their thermal and atmospheric structure, and searching their surfaces for signs of plumes.

The data the JWST obtains with its advanced suite of spectroscopic and near-infrared instruments will also provide additional constraints on their surface conditions. And with other missions like the ESA’s proposed Europa Clipper conducting flybys of these moons, there’s no shortage to what we can learn from them.

Beyond being significant to any future missions to ASSBs, the results of this study are also likely to be of value when it comes to the field of terrestrial geo-engineering. Essentially, scientists have suggested that anthropogenic climate change could be mitigated by introducing aluminum oxide into the atmosphere, thus offsetting the radiation absorbed by greenhouse gas emissions in the upper atmosphere. By examining the properties of these grains, this study could help inform future attempts to mitigate climate change.

This study was made possible thanks in part to a contract provided by NASA’s Jet Propulsion Laboratory to the PSI. This contract was issued in support of the NASA Cassini Saturn Orbiter Visual and Infrared Mapping Spectrometer instrument team.

Further Reading: Planetary Science Institute, Icarus

Upcoming Telescopes Should be Able to Detect Mountains and Other Landscapes on Extrasolar Planets

The study of exoplanets has advanced by leaps and bounds in the past few decades. Between ground-based observatories and spacecraft like the Kepler mission, a total of 3,726 exoplanets have been confirmed in 2,792 systems, with 622 systems having more than one planet (as of Jan. 1st, 2018). And in the coming years, scientists expect that many more discoveries will be possible thanks to the deployment of next-generation missions.

These include NASA’s James Webb Space Telescope (JWST) and several next-generation ground based observatories. With their advanced instruments, these and other observatories are not only expected to find many more exoplanets, but to reveal new and fascinating things about them. For instance, a recent study from Columbia University indicated that it will be possible, using the Transit Method, to study surface elevations on exoplanets.

The study, which recently appeared online under the title “Finding Mountains with Molehills: The Detectability of Exotopography“, was conducted by Moiya McTier and David Kipping – and graduate student and an Assistant Professor of Astronomy at Columbia University, respectively. Based on models they created using bodies in our Solar System, the team considered whether transit surveys might be able to reveal topographical data on exoplanets.

Artist’s impression of an extra-solar planet transiting its star. Credit: QUB Astrophysics Research Center

To recap, the Transit Method (aka. Transit Photometry) is currently the most popular and reliable means for detecting exoplanets. It consists of astronomers measuring the light curve of distant stars over time and looking for periodic dips in brightness. These dips are the result of exoplanets passing in front of the star (i.e. transiting) relative to the observer.

By measuring the rate at which the star’s light dips, and the period with which the dimming occurs, astronomer are not only able to determine the presence of exoplanets, but also place accurate constraints on their size and orbital periods. According to McTier and Kipping, this same method could also reveal the presence of geographical features – for instance, mountain ranges, volcanoes, trenches, and craters.

As they indicate in their study, in lieu of direct imaging, indirect methods are the only means astronomers have for revealing data on an exoplanet’s surface. Unfortunately, there is no conceivable way that the radial velocity, microlensing, astrometry, and timing methods could reveal exotopography. This leaves the transit method, which has some potential in this respect. As they state:

“The transit method directly measures the sky-projected area of a planet’s silhouette relative to that of a star, under the assumption that the planet is not luminous itself… This fact implies that there is indeed some potential for transits to reveal surface features, since the planet’s silhouette is certainly distorted from a circular profile due to the presence of topography.”

Satellite image of the Himalayan mountain chain, as imaged by NASA’sLandsat-7 imagery of Himalayas. Credit: NASA

In other words, as a planet transits in front of its host star, the light passing around the planet itself could be measured for small variations. These could indicate the presence of mountain ranges and other large-scale features like massive chasms. To test this theory, they considered planets in the Solar System as templates for how the scattering of light during a transit could reveal large-scale features.

As an example, they consider what an Earth analog planet would reveal if the Himalayan mountain range ran from north to south and was wide enough to span 1° in longitude:

“Now assume that the planet completes half of one rotation as it transits its parent star from our point of view, which is all that is necessary to see all of the planet’s features appear on its silhouette without repeating. As our hypothetical planet rotates and the Himalayan block moves into and out of view, the change in silhouette will result in different transit depths…”

Ultimately, they consider that Mars would be the ideal test case due to its combination of small size, low surface gravity, and active internal volcanism, which has caused it become what they describe as the “bumpiest body in the Solar System”. When paired with a white dwarf star, this presents the optimal case for using light curves to determine exotopography.

Color Mosaic of Olympus Mons on Mars
Color mosaic of Mars’ greatest mountain, Olympus Mons, viewed from orbit. Credit NASA/JPL

At a distance of about 0.01 AU (which would be within a white dwarf’s habitable zone), they calculate that a Mars-sized planet would have an orbital period of 11.3 hours. This would allow for many transits to be observed in a relatively short viewing period, thus ensuring a greater degree of accuracy. At the same time, the team admits that their proposed methods suffers from drawbacks.

For instance, due to the presence of astrophysical and instrumental noise, they determined that their method would be unproductive when it comes to studying exoplanets around Sun-like stars and M-type (red dwarf) stars. But for Mars-like planets orbiting low mass, white dwarf stars, the method could produce some highly valuable scientific returns.

While this might sound rather limited, it would present some rather fascinating opportunities to learn more about planets beyond our Solar System. As they explain:

“Finding the first evidence of mountains on planets outside our solar system would be exciting in its own right, but we can also infer planet characteristics from the presence and distribution of surface features. For example, a detection of bumpiness could lead to constraints on a planet’s internal processes.”

In short, planets with a high degree of bumpiness would indicate tectonic activity or the buildup of lava caused by internal heating sources. Those with the highest bumpiness (i.e. like Mars) would indicate that they too experience a combination internal processes, low surface gravity, volcanism, and a lack of tectonic plate movement. Meanwhile, low-bumpiness planets are less likely to have any of these internal processes and their surfaces are more likely to be shaped by external factors – like asteroid bombardment.

Artist’s impression of the OWL Telescope being deployed at night from its enclosure, where it will operated during the daytime. Credit: ESO

Based on their estimates, they conclude that the various super telescopes that are scheduled to be commissioned in the coming years would be up to task. These include the ESO’s OverWhelmingly Large (OWL) Telescope, a 100-meter proposed optical and near-infrared telescope that would build on the success of the Very Large Telescope (VLT) and the upcoming Extremely Large Telescope (ELT).

Another example is the Colossus Telescope, a 74-meter optical and infrared telescope that is currently being commissioned by an international consortium. Once operational, it will be the largest telescope optimized for detecting extrasolar life and extraterrestrial civilizations.

In the past, the success of exoplanet hunters has come down to a combination of factors. In addition to greater levels of cooperation between institutions, amateur astronomers and citizen scientists, there has also been the way in which improved technology has coincided with new theoretical models. As more data become available, scientists are able to produce more educated estimates on what we might be able to learn once new instruments come online.

When the next-generation telescopes take to space or are finished construction here on Earth, we can anticipate that thousands more exoplanets will be found. At the same time, we can anticipate that important details will be also discovered about these planets that were not possible before. Do they have atmospheres? Do they have oceans? Do they have mountain ranges and chasms? We hope to find out!

Further Reading: arXiv

James Webb Wraps up 3 Months in the Freezer. It’s Ready for Space

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).

NASA’s James Webb Space Telescope sits in Chamber A at NASA’s Johnson Space Center in Houston awaiting the colossal door to close in July 2017 for cryogenic testing. Credits: NASA/Chris Gunn

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.

The sunshield test unit on NASA’s James Webb Space Telescope is unfurled for the first time. Credit: NASA

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:

Further Reading: ArsTechnica, NASA

Weekly Space Hangout – Jan 3, 2018: Dr. Jeyhan Kartaltepe of the Cosmic Evolution Early Release Science (CEERS) Survey

Fraser Cain ( / @fcain)
Dr. Paul M. Sutter ( / @PaulMattSutter)
Dr. Kimberly Cartier ( / @AstroKimCartier )
Dr. Morgan Rehnberg ( / @MorganRehnberg &

Special Guest:
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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