After years of construction, the first of 18 primary flight mirrors has been installed onto NASA’s James Webb Space Telescope (JWST) at the agency’s Goddard Space Flight Center in Greenbelt, Maryland, signifying the start of the final assembly phase for the mammoth observatory that will eventually become the most powerful telescope ever sent to space.
The milestone first mirror installation was achieved this week just ahead of the Thanksgiving holiday as the engineering team, working inside the massive clean room at NASA Goddard, used a robotic arm to precisely lift and lower the gold coated mirror into place on the observatory’s critical mirror holding backplane assembly.
View showing actual flight structure of mirror backplane unit for NASA’s James Webb Space Telescope (JWST) that holds 18 segment primary mirror array and secondary mirror mount at front, in stowed-for-launch configuration. JWST is being assembled here by technicians inside the world’s largest cleanroom at NASA Goddard Space Flight Center, Greenbelt, Md. Credit: Ken Kremer/kenkremer.com
NASA GODDARD SPACE FLIGHT CENTER, MD – The construction pace for NASA’s James Webb Space Telescope (JWST) took a major leap forward with delivery of the actual flight structure that serves as the observatory’s critical mirror holding backbone – to NASA’s Goddard Space Flight Center in Greenbelt, Maryland and observed by Universe Today.
“We are in good shape with the James Webb Space Telescope,” said Dr. John Mather, NASA’s Nobel Prize Winning scientist, in an exclusive interview with Universe Today at NASA Goddard during a visit to the flight structure – shown in my photos herein. Note: Read an Italian language version of this story – here at Alive Universe
And the mammoth $8.6 Billion Webb telescope has mammoth scientific objectives as the scientific successor to NASA’s Hubble Space Telescope (HST) – now celebrating its 25th anniversary in Earth orbit.
“JWST has the capability to look back towards the very first objects that formed after the Big Bang,” Mather told Universe Today.
How is that possible?
“James Webb has a much bigger mirror than Hubble. So its resolution is much better,” said astronaut and NASA science chief John Grunsfeld, during an exclusive interview at NASA Goddard. Grunsfeld flew on a trio of Hubble servicing missions aboard the Space Shuttle, including the final one during STS-125 in 2009.
“JWST can look back further in time, and a greater distance than Hubble, so we can see those first stars and galaxies formed in the Universe.”
These discoveries are only possible with Webb, which will become the most powerful telescope ever sent to space when it launches in 2018.
The massive JWST flight structure unit includes the “backplane assembly” that clasps in place all of the telescopes primary and secondary mirrors, as well as its ISIM science module loaded with the observatory’s quartet of state-of-the-art research instruments.
“The backplane looks really great,” Grunsfeld told me.
Numerous NASA centers and aerospace companies are involved in building the observatory and its backplane structure holding the mirrors that will search back some 13.4 billion years.
“The backplane structure just arrived in late August from Northrop Grumman Aerospace Systems in Redondo Beach, California,” said Sandra Irish, JWST lead structural engineer during an interview with Universe Today at the NASA Goddard cleanroom facility.
“This is the actual flight hardware.”
The purpose of JWST’s backplane assembly is to hold the telescopes 18 segment, 21-foot (6.5-meter) diameter primary mirror nearly motionless while floating in the utterly frigid space environment, thereby enabling the observatory to peer out into deep space for precise science gathering measurements never before possible.
The massive telescope structure “includes the primary mirror backplane assembly; the main backplane support fixture; and the deployable tower structure that lifts the telescope off of the spacecraft. The three arms at the top come together into a ring where the secondary mirror will reside,” say officials.
The backplane traveled a long and winding road before arriving at Goddard.
“The backplane structure was designed and built at Orbital ATK with NASA oversight,” Irish explained. The assembly work was done at the firms facilities in Magna, Utah.
“Then it was sent to Northrop Grumman in Redondo Beach, California for static testing. Then it came here to Goddard. Orbital ATK also built the composite tubes for the ISIM science module structure.”
The observatory’s complete flight structure measures about 26 feet (nearly 8 meters) from its base to the tip of the tripod arms and mirror mount holding the round secondary mirror.
The flight structure and backplane assembly arrived at Goddard in its stowed-for-launch configuration after being flown cross country from California.
“It is here for the installation of all the mirrors to build up the entire telescope assembly here at Goddard. It will be fully tested here before it is delivered to the Johnson Space Center in Houston and then back to California,” Irish elaborated.
The overall assembly is currently attached to a pair of large yellow and white fixtures that firmly secure the flight unit, to stand it upright and rotate as needed, as it undergoes acceptance testing by engineers and technicians before commencement of the next big step – the crucial mirror installation that starts soon inside the world’s largest cleanroom at NASA Goddard.
Overhead cranes are also used to maneuver the observatory structure as engineers inspect and test the unit.
But several weeks of preparatory work are in progress before the painstakingly precise mirror installation can begin under the most pristine cleanroom operating conditions.
“Right now the technicians are installing harnesses that we need to mount all over the structure,” Irish told me.
“These harnesses will go to our electronic systems and the mirrors in order to monitor their actuation on orbit. So that’s done first.”
What is the construction sequence at Goddard for the installation of the mirrors and science instruments and what comes next?
“This fall we will be installing every mirror, starting around late October/early November. Then next April 2016 we will install the ISIM science module inside the backplane structure.”
“The ISIM mounts all four of the telescope science instrument. So the mirrors go on first, then the ISIM gets installed and then it will really be the telescope structure.” ISIM carries some 7,500 pounds (2400 kg) of telescope optics and instruments.
“Then starting about next July/August 2016 we start the environmental testing.”
The actual flight mirror backplane is comprised of three segments – the main central segment and a pair of outer wing-like parts holding three mirrors each. They will be unfolded from the stowed-for-launch configuration to the “deployed” configuration to carry out the mirror installation. Then be folded back over into launch configuration for eventual placement inside the payload fairing of the Ariane V ECA booster rocket.
The telescope will launch from the Guiana Space Center in Kourou, French Guiana in 2018.
The telescopes primary and secondary flight mirrors have already arrived at Goddard.
The mirrors must remained precisely aligned and nearly motionless in order for JWST to successfully carry out science investigations. While operating at extraordinarily cold temperatures between -406 and -343 degrees Fahrenheit the backplane must not move more than 38 nanometers, approximately 1/1,000 the diameter of a human hair.
To account for the tiniest of errors and enhance science, each of the primary mirrors is equipped with actuators for minute adjustments.
“A beautiful advantage of Webb that’s different from Hubble is the fact that we do have actuation [capability] of every single one of our mirrors. So if we are off by just a little bit on either our calculations or from misalignment from launch or the zero gravity release, we can do some fine adjustments on orbit.”
“We can adjust every mirror within 50 nanometers.”
“That’s important because we can’t send astronauts to fix our telescope. We just can’t.”
“The telescope is a million miles away.”
NASA’s team at Goddard has already practiced mirror installation because there are no second chances.
“We only have one shot to get this right!” Irish emphasized.
Watch for more on the mirror installation in my upcoming story.
JWST is the successor to the 25 year old Hubble Space Telescope and will become the most powerful telescope ever sent to space.
Webb is designed to look at the first light of the Universe and will be able to peer back in time to when the first stars and first galaxies were forming.
The Webb Telescope is a joint international collaborative project between NASA, the European Space Agency (ESA) and the Canadian Space Agency (CSA).
NASA has overall responsibility and Northrop Grumman is the prime contractor for JWST.
“The telescope is on schedule for its launch in 2018 in October,” Mather told me.
And the payoff from JWST will be monumental!
“On everything from nearby planets to the most distant universe, James Webb will transform our view of the Universe,” Grunsfeld beams.
Watch for more on JWST construction and mirror installation in part 2 soon.
Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.
The atmosphere keeps us alive and breathing, but it really sucks for astronomy. Fortunately, humanity has built and launched space telescopes that get above the pesky atmosphere, where the skies are really clear. Let’s take a look at the past, current and future of orbital observation.
For countless generations, human beings have looked out at the night sky and wondered if they were alone in the universe. With the discovery of other planets in our Solar System, the true extent of the Milky Way galaxy, and other galaxies beyond our own, this question has only deepened and become more profound.
And whereas astronomers and scientists have long suspected that other star systems in our galaxy and the universe had orbiting planets of their own, it has only been within the last few decades that any have been observed. Over time, the methods for detecting these “extrasolar planets” have improved, and the list of those whose existence has been confirmed has grown accordingly (to over 3000!)
An extrasolar planet, also called an exoplanet, is a planet that orbits a star (i.e. is part of a solar system) other than our own. Our Solar System is only one among billions and many of them most likely have their own system of planets. As early as the sixteenth century, there have been astronomers who hypothesized of the existence of extrasolar planets.
The first recorded mention was made by Italian philosopher Giordano Bruno, an early supporter of the Copernican theory. In addition to supporting the idea that the Earth and other planets orbit the Sun (heliocentrism), he put forward the view that the fixed stars are similar to the Sun and are likewise accompanied by planets.
In the eighteenth century, Isaac Newton made a similar suggestion in the “General Scholium” section which concludes his Principia. Making a comparison to the Sun’s planets, he wrote “And if the fixed stars are the centers of similar systems, they will all be constructed according to a similar design and subject to the dominion of One.”
Since Newton’s time, various claims have been made, but which were rejected by the scientific community as false positives. In the 1980’s, some astronomers claimed that they had identified a some extrasolar planets in nearby star systems, but were unable to confirm their existence until years later.
One of the reasons why extrasolar planets are so difficult to detect is because they are even fainter than the stars they orbit. Additionally, these stars give off light that “washes” the planets out – i.e. obscures them from direct observation. As a result, the first discovery was not made until 1992 when astronomers Aleksander Wolszczan and Dale Frail – using the Arecibo Observatory in Puerto Rico – observed several terrestrial-mass planets orbiting the pulsar PSR B1257+12.
It was not until 1995 that the first confirmation of an exoplanet orbiting a main-sequence star was made. In this case, the planet observed was 51 Pegasi b, a giant planet found in a four-day orbit around the Sun-like star 51 Pegasi (approx 51 light years from our Sun).
Initially, most of the planets detected were gas giants similar to, or larger than, Jupiter – which led to the term “Super-Jupiter” being coined. Far from suggesting that gas giants were more common than rocky (i.e. “Earth-like“) planets, these findings were simply due to the fact that Jupiter-sized planets are simply easier to detect because of their size.
The Kepler Mission:
Named after the Renaissance astronomer Johannes Kepler, the Kepler space observatory was launched by NASA on March 7th, 2009 for the purpose of discovering Earth-like planets orbiting other stars. As part of NASA’s Discovery Program, a series of relatively low-cost project focused on scientific research, Kepler’s mission is to survey a portion of our region of the Milky Way to find evidence of extrasolar planets and estimate how many stars in our galaxy have planetary systems.
Relying on the Transit Method of detection (see below), Kepler’s sole instrument is a photometer that continually monitors the brightness of over 145,000 main sequence stars in a fixed field of view. This data is transmitted back to Earth where it is analyzed by scientists to look for any signs of periodic dimming caused by extrasolar planets transiting (passing) in front of their host star.
The initial planned lifetime of the Kepler mission was 3.5 years, but greater-than-expected results led to the mission being extended. In 2012, the mission was expected to last until 2016, but this changed due to the failure of one the spacecraft’s reaction wheels – which are used for pointing the spacecraft. On May 11, 2013, a second of four reaction wheels failed, disabling the collection of science data and threatening the continuation of the mission.
On August 15, 2013, NASA announced that they had given up trying to fix the two failed reaction wheels and modified the mission accordingly. Rather than scrap Kepler, NASA proposed changing the mission to utilizing Kepler to detect habitable planets around smaller, dimmer red dwarf stars. This proposal, which became known as K2 “Second Light”, was approved on May 16th, 2014.
Since that time, the K2 mission has focused more on brighter stars (such as G- and K-class stars). As of October 13th, 2016, astronomers have confirmed the presence of 3,397 exoplanets and 573 multi-planet systems, the vast majority of which were found using data from Kepler. All told, the space probe has observed over 150,000 stars in the course of its primary and K2 missions.
In November 2013, astronomers reported, based on Kepler space mission data, that there could be as many as 40 billion Earth-sized planets orbiting in the habitable zones of Sun-like and red dwarf stars within the Milky Way. It is estimated that 11 billion of these planets may be orbiting Sun-like stars.
The discovery of exoplanets has also intensified interest in the search for extraterrestrial life, particularly for those that orbit in the host star’s habitable zone. Also known as the “goldilocks zone“, this is the region of the solar system where conditions are warm enough (but not too warm) so that it is possible for liquid water (and therefore life) to exist on the planet’s surface.
The first planet confirmed by Kepler to have an average orbital distance that placed it within its star’s habitable zone was Kepler-22b. This planet is located about 600 light years from Earth in the constellation of Cygnus, and was first observed on May 12th, 2009, and then confirmed on Dec 5th, 2011. Based on all the data obtained, scientists believe that this world is roughly 2.4 times the radius of Earth, and is likely covered in oceans or has a liquid or gaseous outer shell.
Prior to the deployment of Kepler, the vast majority of confirmed exoplanets fell into the category of Jupiter-sized or larger. However, as of Sept. 18th, 2015, Kepler has identified 4,696 potential candidates, many of them falling into the categories of Earth-size or “Super-Earth” size. Many of these are located in the habitable zone of their parent stars, and some even around Sun-like stars.
And according to a recent study from NASA Ames Research Center, analysis of the Kepler mission data indicated that about 24% of M-class stars may harbor potentially habitable, Earth-size planets (i.e. those that are smaller than 1.6 times the radius of Earth’s). Based upon the number of M-class stars in the galaxy, that alone represents about 10 billion potentially habitable, Earth-like worlds.
Meanwhile, analyses of the K2 phase suggests that about one-quarter of the larger stars surveyed may also have Earth-size planet orbiting within their habitable zones. Taken together, the stars observed by Kepler make up about 70% of those found within the Milky Way. So one can estimate that there are literally tens of billions of potentially habitable planets in our galaxy alone.
While some exoplanets have been observed directly with telescopes (a process known as “Direct Imaging”), the vast majority have been detected through indirect methods such as the transit method and the radial-velocity method. In the case of the Transit Method, a planet is observed when crossing the path (i.e. transiting) in front of its parent star’s disk.
When this occurs, the observed brightness of the star drops by a small amount, which can be measured and used to determine the size of the planet. The transit method reveals the radius of a planet, and it has the benefit that it sometimes allows a planet’s atmosphere to be investigated through spectroscopy.
However, it also suffers from a substantial rate of false positives, and generally requires that part of the planet’s orbit intersect a line-of-sight between the host star and Earth. As a result, confirmation from another method is usually considered necessary. Nevertheless, it remains the most widely-used means of detection and is responsible for more exoplanet discoveries than all other methods combined. The Kepler telescope uses this method (see above).
The Radial Velocity (or Doppler Method) involves measuring the star’s radial velocity – i.e. the speed with which it moves towards or away from Earth. The is one means of detecting planets because, as planet’s orbit a star, they exert a gravitational influence that causes the star itself to move in its own small orbit around the system’s center of mass.
This method has the advantage of being applicable to stars with a wide range of characteristics. However, one of its disadvantages is that it cannot determine a planet’s true mass, but can only set a lower limit on that mass. It remains the second-most effective technique employed by exoplanet hunters.
Other methods include Transit Timing Variation (TTV) and Gravitational Microlensing. The former relies on measuring the variations in the times of transit for one planet to determine the existence of others. This method is effective in determining the existence of multiple transiting planets in one system, but requires that the existence of at least one already be confirmed.
In another form of the method, timing the eclipses in an eclipsing binary star can reveal an outer planet that orbits both stars. As of August 2013, a few planets have been found with this method while numerous more were confirmed.
In the case of Gravitational Microlensing, this refers to the effect a star’s gravitational field can have, acting like a lens to magnify the light of a distance background star. Planets orbiting this star can cause detectable anomalies in the magnification over time, thus indicating their presence. This technique is effective in detecting stars that have wider orbits (1-10 AUs) from Sun-like stars.
Other methods exist, and – alone or in combination – have allowed for the detection and confirmation of thousands of planets. As of May 2015, a total of 1921 planets in 1214 planetary systems have been confirmed, as well as 482 multiple planetary systems.
With the winding down of Kepler’s mission, and so many discoveries made within a short period of time, NASA and other federal space agencies plan to continue in the hunt for extrasolar planets. Proposed NASA missions that will pick up where Kepler has left off include the Transiting Exoplanet Survey Satellite (TESS) – which is scheduled for launch sometime in 2017 – and the James Webb Space Telescope, which is to be deployed in October of 2018.
In addition, the European Space Agency (ESA) hopes to continue to map out a significant portion of the Milky Way Galaxy (including exoplanets) using its Gaia spacecraft – which commenced operations in 2013. The Herschel Space Observatory, and ESA mission with participation from NASA, has been in operation since 2009 and is also expected to make many interesting discoveries in the coming years.
There’s a an entire Universe of worlds out there to discover, and we’ve barely scratched the surface!
NASA Administrator Charles Bolden formally announced the rollout of NASA’s FY 2016 budget request today during a “state of the agency” address at the Kennedy Space Center (KSC), back dropped by the three vehicles at the core of the agency’s human spaceflight exploration strategy; Orion, the Boeing CST-100 and the SpaceX Dragon.
“To further advance these plans and keep on moving forward on our journey to Mars, President Obama today is proposing an FY 2016 budget of $18.5 billion for NASA, building on the significant investments the administration has made in America’s space program over the past six years,” Administrator Bolden said to NASA workers and the media gathered at the KSC facility where Orion is being manufactured.
“These vehicles are not things just on paper anymore! This is tangible evidence of what you [NASA] have been doing these past few years.”
Bolden said the $18.5 Billion budget request will enable the continuation of core elements of NASA’s main programs including first launch of the new commercial crew vehicles to orbit in 2017, maintaining the Orion capsule and the Space Launch System (SLS) rocket to further NASA’s initiative to send ‘Humans to Mars’ in the 2030s, extending the International Space Station (ISS) into the next decade, and launching the James Webb Space Telescope in 2018. JWST is the long awaited successor to NASA’s Hubble Space Telescope.
“NASA is firmly on a journey to Mars. Make no mistake, this journey will help guide and define our generation.”
Funding is also provided to enable the manned Asteroid Redirect Mission (ARM) by around 2025, to continue development of the next Mars rover, and to continue formulation studies of a robotic mission to Jupiter’s icy moon Europa.
“That’s a half billion-dollar increase over last year’s enacted budget, and it is a clear vote of confidence in you – the employees of NASA – and the ambitious exploration program you are executing,” said Bolden.
Overall the additional $500 million for FY 2016 translates to a 2.7% increase over FY 2015. That compares to about a 6.4% proposed boost for the overall US Federal Budget amounting to $4 Trillion.
The Boeing CST-100 and the SpaceX Dragon V2 will restore the US capability to ferry astronauts to and from the International Space Station (ISS).
In September 2014, Bolden announced the selections of Boeing and SpaceX to continue development and certification of their proposed spaceships under NASA’s Commercial Crew Program (CCP) and Launch America initiative started back in 2010.
Since the retirement of the Space Shuttle program in 2011, all NASA astronauts have been totally dependent on Russia and their Soyuz capsule as the sole source provider for seats to the ISS.
“The commercial crew vehicles are absolutely critical to our journey to Mars, absolutely critical. SpaceX and Boeing have set up operations here on the Space Coast, bringing jobs, energy and excitement about the future with them. They will increase crew safety and drive down costs.”
CCP gets a hefty and needed increase from $805 Million in FY 2015 to $1.244 Billion in FY 2016.
To date the Congress has not fully funded the Administration’s CCP funding requests, since its inception in 2010.
The significant budget slashes amounting to 50% or more by Congress, have forced NASA to delay the first commercial crew flights of the private ‘space taxis’ from 2015 to 2017.
As a result, NASA has also been forced to continue paying the Russians for crew flights aboard the Soyuz that now cost over $70 million each under the latest contract signed with Roscosmos, the Russian Federal Space Agency.
Bolden has repeatedly stated that NASA’s overriding goal is to send astronauts to Mars in the 2030s.
To accomplish the ‘Journey to Mars’ NASA is developing the Orion deep space crew capsule and mammoth SLS rocket.
However, both programs had their budgets cut in the FY 2016 proposal compared to FY 2015. The 2015 combined total of $3.245 Billion is reduced in 2016 to $2.863 Billion, or over 10%.
The first test flight of an unmanned Orion atop the SLS is now slated for liftoff on Nov. 2018, following NASA’s announcement of a launch delay from the prior target of December 2017.
Since the Journey to Mars goal is already underfunded, significant cuts will hinder progress.
This comes despite the fact that the renowned robot just reached the summit of a Martian mountain at Cape Tribulation and is now less than 200 meters from a science goldmine of water altered minerals.
Funding for the Lunar Reconnaissance Orbiter (LRO) is also zeroed out in FY 2016.
Both missions continue to function quite well with very valuable science returns. They were also zeroed out in FY 2015 but received continued funding after a senior level science review.
So their ultimate fate is unknown at this time.
Overall, Bolden was very upbeat about NASA’s future.
“I can unequivocally say that the state of NASA is strong,” Bolden said.
He concluded his remarks saying:
“Because of the dedication and determination of each and every one of you in our NASA Family, America’s space program is not just alive, it is thriving! Together with our commercial and international partners, academia and entrepreneurs, we’re launching the future. With the continued support of the Administration, the Congress and the American people, we’ll all get there together.”
Stay tuned here for Ken’s continuing Earth and planetary science and human spaceflight news.
Host: Fraser Cain (@fcain) Special Guest:Andy Weir , author of “The Martian”
Andy was first hired as a programmer for a national laboratory at age fifteen and has been working as a software engineer ever since. He is also a lifelong space nerd and a devoted hobbyist of subjects like relativistic physics, orbital mechanics, and the history of manned spaceflight. “The Martian” is his first novel.
With a big universe around us, where the heck do you point your telescope when looking for planets? Bigger observatories are set to head to orbit in the next decade, including NASA’s James Webb Space Telescope and the European Space Agency’s PLATO (PLAnetary Transits and Oscillations of stars). Telling them where to look will be a challenge.
But it’s less of an issue thanks to the dedicated efforts of amateurs. Volunteers sifting through data from a NASA mission called WISE (Wide-field Infrared Survey Explorer) have now classified an astounding one million potential debris disks and disks surrounding young stars.
“Combing through objects identified by WISE during its infrared survey of the entire sky, Disk Detective aims to find two types of developing planetary environments,” NASA stated in a press release touting the achievement.
“The first, known as a YSO disk, typically is less than 5 million years old, contains large quantities of gas, and often is found in or near young star clusters. The second planetary habitat, known as a debris disk, tends to be older than 5 million years, holds little or no gas, and possesses belts of rocky or icy debris that resemble the asteroid and Kuiper belts found in our own solar system.”
What’s more astounding is how little time it took — the program Disk Detective was only launched in January 2014. These are ripe environments in which young planets can form, providing plenty of spots for telescopes to turn their eyes. The search is expected to go on through 2018.
The search for exoplanets is heating up, thanks to the deployment of space telescopes like Kepler and the development of new observation methods. In fact, over 1800 exoplanets have been discovered since the 1980s, with 850 discovered just last year. That’s quite the rate of progress, and Earth’s scientists have no intention of slowing down!
Hot on the heels of the Kepler mission and the ESA’s deployment of the Gaia space observatory last year, NASA is getting ready to launch TESS (the Transiting Exoplanet Survey Satellite). And to provide the launch services, NASA has turned to one of its favorite commercial space service providers – SpaceX.
The launch will take place in August 2017 from the Cape Canaveral Air Force Station in Florida, where it will be placed aboard a Falcon 9 v1.1 – a heavier version of the v 1.0 developed in 2013. Although NASA has contracted SpaceX to perform multiple cargo deliveries to the International Space Station, this will be only the second time that SpaceX has assisted the agency with the launch of a science satellite.
This past September, NASA also signed a lucrative contract with SpaceX worth $2.6 billion to fly astronauts and cargo to the International Space Station. As part of the Commercial Crew Program, SpaceX’s Falcon 9 and Dragon spacecraft were selected by NASA to help restore indigenous launch capability to the US.
The total cost for TESS is estimated at approximately $87 million, which will include launch services, payload integration, and tracking and maintenance of the spacecraft throughout the course of its three year mission.
As for the mission itself, that has been the focus of attention for many years. Since it was deployed in 2009, the Kepler spacecraft has yielded more and more data on distant planets, many of which are Earth-like and potentially habitable. But in 2013, two of four reaction wheels on Kepler failed and the telescope has lost its ability to precisely point toward stars. Even though it is now doing a modified mission to hunt for exoplanets, NASA and exoplanet enthusiasts have been excited by the prospect of sending up another exoplanet hunter, one which is even more ideally suited to the task.
Once deployed, TESS will spend the next three years scanning the nearest and brightest stars in our galaxy, looking for possible signs of transiting exoplanets. This will involve scanning nearby stars for what is known as a “light curve”, a phenomenon where the visual brightness of a star drops slightly due to the passage of a planet between the star and its observer.
By measuring the rate at which the star dims, scientists are able to estimate the size of the planet passing in front of it. Combined with measurements the star’s radial velocity, they are also able to determine the density and physical structure of the planet. Though it has some drawbacks, such as the fact that stars rarely pass directly in front of their host stars, it remains the most effective means of observing exoplanets to date.
In fact, as of 2014, this method became the most widely used for determining the presence of exoplanets beyond our Solar System. Compared to other methods – such as measuring a star’s radial velocity, direct imaging, the timing method, and microlensing – more planets have been detected using the transit method than all the other methods combined.
In addition to being able to spot planets by the comparatively simple method of measuring their light curve, the transit method also makes it possible to study the atmosphere of a transiting planet. Combined with the technique of measuring the parent star’s radial velocity, scientists are also able to measure a planet’s mass, density, and physical characteristics.
With TESS, it will be possible to study the mass, size, density and orbit of exoplanets. In the course of its three-year mission, TESS will be looking specifically for Earth-like and super-Earth candidates that exist within their parent star’s habitable zone.
This information will then be passed on to Earth-based telescopes and the James Webb Space Telescope – which will be launched in 2018 by NASA with assistance from the European and Canadian Space Agencies – for detailed characterization.
The TESS Mission is led by the Massachusetts Institute of Technology – who developed it with seed funding from Google – and is overseen by the Explorers Program at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
NASA’s ongoing hunt for exoplanets has entered a new phase as NASA officially confirmed that the Transiting Exoplanet Survey Satellite (TESS) is moving into the development phase. This marks a significant step for the TESS mission, which will search the entire sky for planets outside our solar system (a.k.a. exoplanets). Designed as the first all-sky survey, TESS will spend two years of an overall three-year mission searching both hemispheres of the sky for nearby exoplanets.
Previous sky surveys with ground-based telescopes have mainly picked out giant exoplanets. In contrast, TESS will examine a large number of small planets around the very brightest stars in the sky. TESS will then record the nearest and brightest main sequence stars hosting transiting exoplanets, which will forever be the most favorable targets for detailed investigations. During the third year of the TESS mission, ground-based astronomical observatories will continue monitoring exoplanets identified by the TESS spacecraft.
“This is an incredibly exciting time for the search of planets outside our solar system,” said Mark Sistilli, the TESS program executive from NASA Headquarters, Washington. “We got the green light to start building what is going to be a spacecraft that could change what we think we know about exoplanets.”
“During its first two years in orbit, the TESS spacecraft will concentrate its gaze on several hundred thousand specially chosen stars, looking for small dips in their light caused by orbiting planets passing between their host star and us,” said TESS Principal Investigator George Ricker of the Massachusetts Institute of Technology..
All in all, TESS is expected to find more than 5,000 exoplanet candidates, including 50 Earth-sized planets. It will also find a wide array of exoplanet types, ranging from small, rocky planets to gas giants. Some of these planets could be the right sizes, and orbit at the correct distances from their stars, to potentially support life.
“The most exciting part of the search for planets outside our solar system is the identification of ‘earthlike’ planets with rocky surfaces and liquid water as well as temperatures and atmospheric constituents that appear hospitable to life,” said TESS Project Manager Jeff Volosin at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Although these planets are small and harder to detect from so far away, this is exactly the type of world that the TESS mission will focus on identifying.”
Now that NASA has confirmed the development of TESS, the next step is the Critical Design Review, which is scheduled to take place in 2015. This would clear the mission to build the necessary flight hardware for its proposed launch in 2017.
“After spending the past year building the team and honing the design, it is incredibly exciting to be approved to move forward toward implementing NASA’s newest exoplanet hunting mission,” Volosin said.
TESS is designed to complement several other critical missions in the search for life on other planets. Once TESS finds nearby exoplanets to study and determines their sizes, ground-based observatories and other NASA missions, like the James Webb Space Telescope, would make follow-up observations on the most promising candidates to determine their density and other key properties.
By figuring out a planet’s characteristics, like its atmospheric conditions, scientists could determine whether the targeted planet has a habitable environment.
“TESS should discover thousands of new exoplanets within two hundred light years of Earth,” Ricker said. “Most of these will be orbiting bright stars, making them ideal targets for characterization observations with NASA’s James Webb Space Telescope.”
“The Webb telescope and other teams will focus on understanding the atmospheres and surfaces of these distant worlds, and someday, hopefully identify the first signs of life outside of our solar system,” Volosin said.
TESS will use four cameras to study sections of the sky’s north and south hemispheres, looking for exoplanets. The cameras would cover about 90 percent of the sky by the end of the mission.
This makes TESS an ideal follow-up to the Kepler mission, which searches for exoplanets in a fixed area of the sky. Because the TESS mission surveys the entire sky, TESS is expected to find exoplanets much closer to Earth, making them easier for further study.
In addition, Ricker said TESS would provide precision, full-frame images for more than 20 million bright stars and galaxies.
“This unique new data will comprise a treasure trove for astronomers throughout the world for many decades to come,” Ricker said.
Now that TESS is cleared to move into the next development stage, it can continue towards its goal of being a key part of NASA’s search for life beyond Earth.
“I’m still hopeful that in my lifetime, we will discover the existence of life outside of our solar system and I’m excited to be part of a NASA mission that serves as a key stepping stone in that search,” Volosin said.