In the Neil Armstrong Operations and Checkout Building high bay at NASA's Kennedy Space Center in Florida, NASA Administrator Charlie Bolden delivers a “state of the agency” address at NASA's televised fiscal year 2016 budget rollout event with Kennedy Space Center Director Bob Cabana looking on, at right. NASA's Orion, SpaceX Dragon and Boeing CST-100 spacecraft were on display. Photo credit: NASA/Gianni Woods
The Obama Administration today (Feb. 2) proposed a NASA budget allocation of $18.5 Billion for the new Fiscal Year 2016, which amounts to a half-billion dollar increase over the enacted budget for FY 2015, and keeps the key manned capsule and heavy lift rocket programs on track to launch humans to deep space in the next decade and significantly supplements the commercial crew initiative to send our astronauts to low Earth orbit and the space station later this decade.
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.”
In the Neil Armstrong Operations and Checkout Building high bay at NASA’s Kennedy Space Center in Florida, NASA Administrator Charlie Bolden delivers a “state of the agency” address on Feb 2, 2015 at NASA’s televised fiscal year 2016 budget rollout event. Photo credit: NASA/Gianni Woods
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.
NASA Administrator Charles Bolden (left) announces the winners of NASA’s Commercial Crew Program development effort to build America’s next human spaceships launching from Florida to the International Space Station. Speaking from Kennedy’s Press Site, Bolden announced the contract award to Boeing and SpaceX to complete the design of the CST-100 and Crew Dragon spacecraft. Former astronaut Bob Cabana, center, director of NASA’s Kennedy Space Center in Florida, Kathy Lueders, manager of the agency’s Commercial Crew Program, and former International Space Station Commander Mike Fincke also took part in the announcement. Credit: Ken Kremer- kenkremer.com
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.”
Meet Dragon V2 – SpaceX CEO Elon pulls the curtain off manned Dragon V2 on May 29, 2014 for worldwide unveiling of SpaceX’s new astronaut transporter for NASA. Credit: SpaceX
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.
Boeing CST-100 capsule interior up close. Credit: Ken Kremer – kenkremer.com
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.
NASA’s first Orion spacecraft blasts off at 7:05 a.m. atop United Launch Alliance Delta 4 Heavy Booster at Space Launch Complex 37 (SLC-37) at Cape Canaveral Air Force Station in Florida on Dec. 5, 2014. Launch pad remote camera view. Credit: Ken Kremer – kenkremer.com
There are some losers in the new budget as well.
Rather incomprehensibly funding for the long lived Opportunity Mars Exploration Rover is zeroed out in 2016.
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.
NASA’s Opportunity Mars rover captures sweeping panoramic vista near the ridgeline of 22 km (14 mi) wide Endeavour Crater’s western rim. The center is southeastward and the distant rim is visible in the center. An outcrop area targeted for the rover to study is at right of ridge. This navcam panorama was stitched from images taken on May 10, 2014 (Sol 3659) and colorized. Credit: NASA/JPL/Cornell/Marco Di Lorenzo/Ken Kremer-kenkremer.com
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.
The James Webb Space Telescope, scheduled for launch in 2018 may be the first to be capable of detecting biomarker gasses in the atmospheres of extrasolar planets. When an exoplanet passes between its star and Earth, an event called a transit, light that has passed through the planet’s atmosphere can be detected from a vantage point near Earth. When light passes through the exoplanet’s atmosphere, some wavelengths are absorbed and others transmitted. By analyzing the transmitted light spectrum, astronomers can learn the composition of the planet’s atmosphere. Astrobiologists hope to find biomarker gasses indicating the metabolic waste products of life. The oxygen in Earth’s atmosphere is a waste product of photosynthesis in plants and bacteria. The Webb telescope may be capable of conducting this test for planets larger than Earth (super-earths) transiting small stars. Space telescopes capable of conducting such research on a larger scale have been delayed by budget cuts.
Credit: NASA
In the movie “Avatar”, we could tell at a glance that the alien moon Pandora was teeming with alien life. Here on Earth though, the most abundant life is not the plants and animals that we are familiar with. The most abundant life is simple and microscopic. There are 50 million bacterial organisms in a single gram of soil, and the world wide bacterial biomass exceeds that of all plants and animals. Microbes can grow in extreme environments of temperature, salinity, acidity, radiation, and pressure. The most likely form in which we will encounter life elsewhere in our solar system is microbial.
Astrobiologists need strategies for inferring the presence of alien microbial life or its fossilized remains. They need strategies for inferring the presence of alien life on the distant planets of other stars, which are too far away to explore with spacecraft in the foreseeable future. To do these things, they long for a definition of life, that would make it possible to reliably distinguish life from non-life.
Unfortunately, as we saw in the first installment of this series, despite enormous growth in our knowledge of living things, philosophers and scientists have been unable to produce such a definition. Astrobiologists get by as best they can with definitions that are partial, and that have exceptions. Their search is geared to the features of life on Earth, the only life we currently know.
In the first installment, we saw how the composition of terrestrial life influences the search for extraterrestrial life. Astrobiologists search for environments that once contained or currently contain liquid water, and that contain complex molecules based on carbon. Many scientists, however, view the essential features of life as having to do with its capacities instead of its composition.
In 1994, a NASA committee adopted a definition of life as a “self-sustaining chemical system capable of Darwinian evolution”, based on a suggestion by Carl Sagan. This definition contains two features, metabolism and evolution, that are typically mentioned in definitions of life.
Metabolism is the set of chemical processes by which living things actively use energy to maintain themselves, grow, and develop. According to the second law of thermodynamics, a system that doesn’t interact with its external environment will become more disorganized and uniform with time. Living things build and maintain their improbable, highly organized state because they harness sources of energy in their external environment to power their metabolism.
Plants and some bacteria use the energy of sunlight to manufacture larger organic molecules out of simpler subunits. These molecules store chemical energy that can later be extracted by other chemical reactions to power their metabolism. Animals and some bacteria consume plants or other animals as food. They break down complex organic molecules in their food into simpler ones, to extract their stored chemical energy. Some bacteria can use the energy contained in chemicals derived from non-living sources in the process of chemosynthesis.
In a 2014 article in Astrobiology, Lucas John Mix, a Harvard evolutionary biologist, referred to the metabolic definition of life as Haldane Life after the pioneering physiologist J. B. S. Haldane. The Haldane life definition has its problems. Tornadoes and vorticies like Jupiter’s Great Red Spot use environmental energy to sustain their orderly structure, but aren’t alive. Fire uses energy from its environment to sustain itself and grow, but isn’t alive either.
Despite its shortcomings, astrobiologists have used Haldane definition to devise experiments. The Viking Mars landers made the only attempt so far to directly test for extraterrestrial life, by detecting the supposed metabolic activities of Martian microbes. They assumed that Martian metabolism is chemically similar to its terrestrial counterpart.
One experiment sought to detect the metabolic breakdown of nutrients into simpler molecules to extract their energy. A second aimed to detect oxygen as a waste product of photosynthesis. A third tried to show the manufacture of complex organic molecules out of simpler subunits, which also occurs during photosynthesis. All three experiments seemed to give positive results, but many researchers believe that the detailed findings can be explained without biology, by chemical oxidizing agents in the soil.
In 1976, two Viking spacecraft landed on Mars. The image is of a model of the Viking lander, along with astronomer and pioneering astrobiologist Carl Sagan. Each lander was equipped with life detection experiments designed to detect life based on its metabolic activities. These activities were assumed to be chemically similar to those of Earthly organisms. The three experiments included: 1) The labeled release experiment, in which radioactively labeled organic nutrients were added to Martian soil. If organisms were present, it was assumed that their metabolism would involve breaking down the nutrients for their energy content and releasing labeled carbon dioxide as a waste product. 2) The gas exchange experiment, in which Martian soil was provided with nutrients and light and monitored for the release of oxygen. On Earth, organisms that capture the energy of sunlight through the process of photosynthesis, like plants and some bacteria, release oxygen as a waste product. 3) The pyrolytic release experiment, in which Martian soil was placed in a chamber with radioactively labeled carbon dioxide. If there were organisms in the soil that photosynthesized like those on Earth, their metabolic processes would take up the gas and use the energy of sunlight to manufacture more complex organic molecules. Radioactive carbon would be given off when those more complex molecules were broken down by heating the sample. All three experiments produced what seemed like positive results. However, most scientists rejected this interpretation because the details of many of the results could be explained by supposing that there were chemical oxidizing agents in the soil instead of life, and because Viking failed to detect organic materials in Martian soil. This interpretation, especially for the labeled release experiment, remains controversial to this day and may need to be revisited based on recent findings. Credits: NASA/Jet Propulsion Laboratory, Caltech
Some of the Viking results remain controversial to this day. At the time, many researchers felt that the failure to find organic materials in Martian soil ruled out a biological interpretation of the metabolic results. The more recent finding that Martian soil actually does contain organic molecules that might have been destroyed by perchlorates during the Viking analysis, and that liquid water was once abundant on the surface of Mars lend new plausibility to the claim that Viking may have actually succeeded in detecting life. By themselves, though, the Viking results didn’t prove that life exists on Mars nor rule it out.
Most of the methane in Earth’s atmosphere is released by living organisms or their remains. Subterranean bacterial ecosystems that use chemosynthesis as a source of energy are common, and they produce methane as a metabolic waste product. Unfortunately, there are also non-biological geochemical processes that can produce methane. So, once more, Martian methane is frustratingly ambiguous as a sign of life.
Extrasolar planets orbiting other stars are far too distant to visit with spacecraft in the foreseeable future. Astrobiologists still hope to use the Haldane definition to search for life on them. With near future space telescopes, astronomers hope to learn the composition of the atmospheres of these planets by analyzing the spectrum of light wavelengths reflected or transmitted by their atmospheres. The James Webb Space Telescope scheduled for launch in 2018, will be the first to be useful in this project. Astrobiologists want to search for atmospheric biomarkers; gases that are metabolic waste products of living organisms.
Once more, this quest is guided by the only example of a life-bearing planet we currently have; Earth. About 21% of our home planet’s atmosphere is oxygen. This is surprising because oxygen is a highly reactive gas that tends to enter into chemical combinations with other substances. Free oxygen should quickly vanish from our air. It remains present because the loss is constantly being replaced by plants and bacteria that release it as a metabolic waste product of photosynthesis.
Traces of methane are present in Earth’s atmosphere because of chemosynthetic bacteria. Since methane and oxygen react with one another, neither would stay around for long unless living organisms were constantly replenishing the supply. Earth’s atmosphere also contains traces of other gases that are metabolic byproducts.
In general, living things use energy to maintain Earth’s atmosphere in a state far from the thermodynamic equilibrium it would reach without life. Astrobiologists would suspect any planet with an atmosphere in a similar state of harboring life. But, as for the other cases, it would be hard to completely rule out non-biological possibilities.
Besides metabolism, the NASA committee identified evolution as a fundamental ability of living things. For an evolutionary process to occur there must be a group of systems, where each one is capable of reliably reproducing itself. Despite the general reliability of reproduction, there must also be occasional random copying errors in the reproductive process so that the systems come to have differing traits. Finally, the systems must differ in their ability to survive and reproduce based on the benefits or liabilities of their distinctive traits in their environment. When this process is repeated over and over again down the generations, the traits of the systems will become better adapted to their environment. Very complex traits can sometimes evolve in a step-by-step fashion.
Mix named this the Darwin life definition, after the nineteenth century naturalist Charles Darwin, who formulated the theory of evolution. Like the Haldane definition, the Darwin life definition has important shortcomings. It has trouble including everything that we might think of as alive. Mules, for example, can’t reproduce, and so, by this definition, don’t count as being alive.
Despite such shortcomings, the Darwin life definition is critically important, both for scientists studying the origin of life and astrobiologists. The modern version of Darwin’s theory can explain how diverse and complex forms of life can evolve from some initial simple form. A theory of the origin of life is needed to explain how the initial simple form acquired the capacity to evolve in the first place.
The chemical systems or life forms found on other planets or moons in our solar system might be so simple that they are close to the boundary between life and non-life that the Darwin definition establishes. The definition might turn out to be vital to astrobiologists trying to decide whether a chemical system they have found really qualifies as a life form. Biologists still don’t know how life originated. If astrobiologists can find systems near the Darwin boundary, their findings may be pivotally important to understanding the origin of life.
Can astrobiologists use the Darwin definition to find and study extraterrestrial life? It’s unlikely that a visiting spacecraft could detect to process of evolution itself. But, it might be capable of detecting the molecular structures that living organisms need in order to take part in an evolutionary process. Philosopher Mark Bedau has proposed that a minimal system capable of undergoing evolution would need to have three things: 1) a chemical metabolic process, 2) a container, like a cell membrane, to establish the boundaries of the system, and 3) a chemical “program” capable of directing the metabolic activities.
Here on Earth, the chemical program is based on the genetic molecule DNA. Many origin-of-life theorists think that the genetic molecule of the earliest terrestrial life forms may have been the simpler molecule ribonucleic acid (RNA). The genetic program is important to an evolutionary process because it makes the reproductive copying process stable, with only occasional errors.
Both DNA and RNA are biopolymers; long chainlike molecules with many repeating subunits. The specific sequence of nucleotide base subunits in these molecules encodes the genetic information they carry. So that the molecule can encode all possible sequences of genetic information it must be possible for the subunits to occur in any order.
Steven Benner, a computational genomics researcher, believes that we may be able to develop spacecraft experiments to detect alien genetic biopolymers. He notes that DNA and RNA are very unusual biopolymers because changing the sequence in which their subunits occur doesn’t change their chemical properties. It is this unusual property that allows these molecules to be stable carriers of any possible genetic code sequence.
DNA and RNA are both polyelectrolytes; molecules with regularly repeating areas of negative electrical charge. Benner believes that this is what accounts for their remarkable stability. He thinks that any alien genetic biopolymer would also need to be a polyelectrolyte, and that chemical tests could be devised by which a spacecraft might detect such polyelectrolyte molecules. Finding the alien counterpart of DNA is a very exciting prospect, and another piece to the puzzle of identifying alien life.
Deoxyribonucleic acid (DNA) is the genetic material for all known life on Earth. DNA is a biopolymer consisting of a string of subunits. The subunits consist of nucleotide base pairs containing a purine (adenine A, or guanine G) and a pyrimidine (thymine T, or cytosine C). DNA can contain nucleotide base pairs in any order without its chemical properties changing. This property is rare in biopolymers, and makes it possible for DNA to encode genetic information in the sequence of its base pairs. This stability is due to the fact that each base pair contains phosphate groups (consisting of phosphorus and oxygen atoms) on the outside with a net negative charge. These repeated negative charges make DNA a polyelectrolyte. Computational genomics researcher Steven Benner has hypothesized that alien genetic material will also be a polyelectrolyte biopolymer, and that chemical tests could therefore be devised to detect alien genetic molecules. Credit: Zephyris
In 1996 President Clinton, made a dramatic announcement of the possible discovery of life on Mars. Clinton’s speech was motivated by the findings of David McKay’s team with the Alan Hills meteorite. In fact, the McKay findings turned out to be just one piece to the larger puzzle of possible Martian life. Unless an alien someday ambles past our waiting cameras, the question of whether or not extraterrestrial life exists is unlikely to be settled by a single experiment or a sudden dramatic breakthrough. Philosophers and scientists don’t have a single, sure-fire definition of life. Astrobiologists consequently don’t have a single sure-fire test that will settle the issue. If simple forms of life do exist on Mars, or elsewhere in the solar system, it now seems likely that that fact will emerge gradually, based on many converging lines of evidence. We won’t really know what we’re looking for until we find it.
S. Tirard, M. Morange, and A. Lazcano, (2010), The definition of life: A brief history of an elusive scientific endeavor, Astrobiology, 10(10):1003-1009.
Center section of the "pathfinder" (test) backplane of NASA's James Webb Space Telescope is hoisted into place in the assembly stand in NASA Goddard's giant cleanroom. Engineers will practice mirror installations over the next several months. Credit: NASA/Chris Gunn
The central piece of the “pathfinder” backplane that will hold all the mirrors for NASA’s James Webb Space Telescope (JWST) has arrived at the agency’s Goddard Space Flight Center in Maryland for critical assembly testing on vital parts of the mammoth telescope.
The pathfinder backplane arrived at Goddard in July and has now been hoisted in place onto a huge assembly stand inside Goddard’s giant cleanroom where many key elements of JWST are being assembled and tested ahead of the launch scheduled for October 2018.
The absolutely essential task of JWST’s backplane is to hold the telescopes 18 segment, 21-foot-diameter primary mirror nearly motionless while floating in the utterly frigid space environment, thereby enabling the telescope to peer out into deep space for precise science gathering measurements never before possible.
Over the next several months, engineers will practice installing two spare primary mirror segments and one spare secondary mirror onto the center part of the backplane.
JWST pathfinder backplane has arrived here at NASA Goddard clean room.
JWST is being assembled here inside the world’s largest clean room at NASA Goddard Space Flight Center, Greenbelt, Md. Primary mirror segments stored in silver colored containers at top left. Technicians practice mirror installation on test piece of backplane (known as the BSTA or Backplane Stability Test Article) at center, 3 hexagonals. Pathfinder backplane has been hoisted into telescope assembly bays at right. Credit: Ken Kremer- kenkremer.com
The purpose is to gain invaluable experience practicing the delicate procedures required to precisely install the hexagonal shaped mirrors onto the actual flight backplane unit after it arrives.
The telescopes primary and secondary flight mirrors have already arrived at Goddard.
The mirrors must remained precisely aligned in space 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.
The backplane and every other component must function and unfold perfectly and to precise tolerances in space because JWST has not been designed for servicing or repairs by astronaut crews voyaging beyond low-Earth orbit into deep space, William Ochs, Associate Director for JWST at NASA Goddard told me in an interview during a visit to JWST at Goddard.
Watch this video showing movement of the pathfinder backplane into the Goddard cleanroom.
Video Caption: This is a time-lapse video of the center section of the ‘pathfinder’ backplane for NASA’s James Webb Space Telescope being moved into the clean room at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. Credit: NASA/Chris Gunn
The actual flight backplane is comprised of three segments – the main central segment and a pair of outer wing-like parts which will be folded over into launch configuration 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.
Both the backplane flight unit and the pathfinder unit, which consists only of the center part, are being assembled and tested by prime contractor Northrop Grumman in Redondo Beach, California.
Gold coated flight spare of a JWST primary mirror segment made of beryllium and used for test operations inside the NASA Goddard clean room. Credit: Ken Kremer- kenkremer.com
The test unit was then loaded into a C-5, flown to the U.S. Air Force’s Joint Base Andrews in Maryland and unloaded for transport by trailer truck to NASA Goddard in Greenbelt, Maryland.
JWST is the successor to the 24 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.
A comparison of the primary mirror used by Hubble and the primary mirror array used by the James Webb Space Telescope. Photo Credit: NASA
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.
Read my story about the recent unfurling test of JWST’s sunshade – here.
Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.
The Webb telescope backplane “pathfinder” or practice-model was unloaded from a C-5 aircraft at the U.S. Air Force’s Joint Base Andrews in Maryland. Image Credit: NASA/Desiree Stover Artist’s concept of the James Webb Space Telescope (JWST) with Sunshield at bottom. Credit: NASA/ESA
The sunshield test unit on NASA's James Webb Space Telescope is unfurled for the first time. Credit: NASA
GODDARD SPACE FLIGHT CENTER, MD – The huge Sunshield test unit for NASA’s James Webb Space Telescope (JWST) has been successfully unfurled for the first time in a key milestone ahead of the launch scheduled for October 2018.
Engineers stacked and expanded the tennis-court sized Sunshield test unit last week inside the cleanroom at a Northrop Grumman facility in Redondo Beach, California.
NASA reports that the operation proceeded perfectly the first time during the test of the full-sized unit.
The Sunshield and every other JWST component must unfold perfectly and to precise tolerances in space because it has not been designed for servicing or repairs by astronaut crews voyaging beyond low-Earth orbit into deep space, William Ochs, Associate Director for JWST at NASA Goddard told me in an exclusive interview.
Artist’s concept of the James Webb Space Telescope (JWST) with Sunshield at bottom. Credit: NASA/ESA
The five layered Sunshield is the largest component of the observatory and acts like a parasol.
Its purpose is to protect Webb from the suns heat and passively cool the telescope and its quartet of sensitive science instruments via permanent shade to approximately 45 kelvins, -380 degrees F, -233 C.
The kite-shaped Sunshield provides an effective sun protection factor or SPF of 1,000,000. By comparison suntan lotion for humans has an SPF of 8 to 40.
Two sides of the James Webb Space Telescope (JWST). Credit: NASA
The extreme cold is required for the telescope to function in the infrared (IR) wavelengths and enable it to look back in time further than ever before to detect distant objects.
The shield separates the observatory into a warm sun-facing side and a cold anti-sun side.
Its five thin membrane layers also provides a stable thermal environment to keep the telescopes 18 primary mirror segments properly aligned for Webb’s science investigations.
JWST is the successor to the 24 year old Hubble Space Telescope and will become the most powerful telescope ever sent to space.
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.
Webb will launch folded up inside the payload fairing of an ESA Ariane V ECA rocket from the Guiana Space Center in Kourou, French Guiana.
In launch configuration, the Sunshield will surround the main mirrors and instruments like an umbrella.
During the post launch journey to the L2 observing orbit at the second Sun-Earth Lagrange point nearly a million miles (1.5 million Km) from Earth, the telescopes mirrors and sunshield will begin a rather complex six month long unfolding and calibration process.
The science instruments have been mounted inside the ISIM science module and are currently undergoing critical vacuum chamber testing at NASA Goddard Space Flight Center which provides overall management and systems engineering.
Gold coated flight spare of a JWST primary mirror segment made of beryllium and used for test operations inside the NASA Goddard clean room. Credit: Ken Kremer- kenkremer.com
The mirror segments have arrived at NASA Goddard where I’ve had the opportunity to observe and report on work in progress.
Stay tuned here for Ken’s continuing JWST, MMS, ISS, Curiosity, Opportunity, SpaceX, Orbital Sciences, Boeing, Orion, MAVEN, MOM, Mars and more Earth and Planetary science and human spaceflight news.
Artist's conception of NASA's Space Launch System with Orion crewed deep space capsule. Credit: NASA
In three years, NASA is planning to light the fuse on a huge rocket designed to bring humans further out into the solar system.
We usually talk about SLS here in the context of the astronauts it will carry inside the Orion spacecraft, which will have its own test flight later in 2014. But today, NASA advertised a possible other use for the rocket: trying to find life beyond Earth.
At a symposium in Washington on the search for life, NASA associate administrator John Grunsfeld said SLS could serve two major functions: launching bigger telescopes, and sending a mission on an express route to Jupiter’s moon Europa.
The James Webb Space Telescope, with a mirror of 6.5 meters (21 feet), will in part search for exoplanets after its launch in 2018. Next-generation telescopes of 10 to 20 meters (33 to 66 feet) could pick out more, if SLS could bring them up into space.
“This will be a multi-generational search,” said Sara Seager, a planetary scientist and physicist at the Massachusetts Institute of Technology. She added that the big challenge is trying to distinguish a planet like Earth from the light of its parent star; the difference between the two is a magnitude of 10 billion. “Our Earth is actually extremely hard to find,” she said.
Much like our solar system, Kepler-62 is home to two habitable zone worlds. The small shining object seen to the right of Kepler-62f is Kepler-62e. Orbiting on the inner edge of the habitable zone, Kepler-62e is roughly 60 percent larger than Earth. Image credit: NASA Ames/JPL-Caltech.
While the symposium was not talking much about life in the solar system, Europa is considered one of the top candidates due to the presence of a possible subsurface ocean beneath its ice. NASA is now seeking ideas for a mission to this moon, following news that water plumes were spotted spewing from the moon’s icy south pole. A mission to Europa would take seven years with the technology currently in NASA’s hands, but the SLS would be powerful enough to speed up the trip to only three years, Grunsfeld said.
And that’s not all that SLS could do. If it does bring astronauts deeper in space as NASA hopes it will, this opens up a range of destinations for them to go to. Usually NASA talks about this in terms of its human asteroid mission, an idea it has been working on and pitching for the past year to a skeptical, budget-conscious Congress.
But in passing, John Mather (NASA’s senior project scientist for Webb) said it’s possible astronauts could be sent to maintain the telescope. Webb is supposed to be parked in a Lagrange point (gravitationally stable location) in the exact opposite direction of the sun, almost a million miles away. It’s a big contrast to the Hubble Space Telescope, which was conveniently parked in low Earth orbit for astronauts to fix every so often with the space shuttle.
An Artist’s Conception of the James Webb Space Telescope. Credit: ESA.
While NASA works on the funding and design for larger telescope mirrors, Webb is one of the two new space telescopes it is focusing on in the search for life. Webb’s infrared eyes will be able to peer at solar systems being born, once it is launched in 2018. Complementary to that will be the Transiting Exoplanet Survey Satellite, which will fly in 2017 and examine planets that pass in front of their parent stars to find elements in their atmospheres.
The usual cautions apply when talking about this article: NASA is talking about several missions under development, and it is unclear yet what the success of SLS or any of these will be until they are battle-tested in space.
But what this discussion does show is the agency is trying to find many purposes for its next-generation rocket, and working to align it to astrophysics goals as well as its desire to send humans further out in the solar system.
A screen grab of the new zoomable Milky Way mosaic that uses Microsoft's WorldWide Telescope viewer. Click to use. Credit: NASA
Touring the Milky Way’s a blast with this brand new 360-degree interactive panorama. More than 2 million infrared photos taken by NASA’s Spitzer Space Telescope were jigsawed into a 20-gigapixel click-and-zoom mosaic that takes the viewer from tangled nebulae to stellar jets to blast bubbles around supergiant stars.
Magnetic loops carry gas and dust above disks of planet-forming material circling stars, as shown in this artist’s conception. These loops give off extra heat, which NASA’s Spitzer Space Telescope detects as infrared light. The colors in this illustration show what an alien observer with eyes sensitive to both visible light and infrared wavelengths might see. Credit: NASA/JPL-Caltech/R. Hurt (IPAC)
The new composite, using infrared images taken over the past decade, was compiled by a team led by UW-Madison astronomer Barbara Whitney and unveiled at a TEDactive conference in Vancouver, Canada Thursday. Unlike visual light, infrared penetrates the ubiquitous dust concentrated in the galactic plane to reveal structures otherwise obscured.
Catching a GLIMPSE of the Milky Way in this short video presentation
“For the first time, we can actually measure the large-scale structure of the galaxy using stars rather than gas,” explained Edward Churchwell, UW-Madison professor of astronomy and team co-leader. “We’ve established beyond the shadow of a doubt that our galaxy has a large bar structure that extends halfway out to the sun’s orbit. We know more about where the Milky Way’s spiral arms are.”
Named GLIMPSE360 (Galactic Legacy Mid-Plane Survey Extraordinaire project), the deep infrared survey captures only about 3% of the sky, but because it focuses on the plane of the Milky Way, where stars are most highly concentrated, it shows more than half of all the galaxy’s 300 billion suns.
The Milky Way is a spiral galaxy with several prominent arms containing stellar nurseries swathed in pink clouds of hydrogen gas. The sun is shown near the bottom in the Orion Spur. Credit: NASA
Using your imagination to hover high above the galactic plane, you’d see the Milky Way is a flat spiral galaxy sporting a stubby bar of stars crossing its central bulge. The solar system occupies a tiny niche in a minor spiral arm called the Orion Spur two-thirds of the way from the center to the edge. At 100,000 light years across, the Milky Way is vast beyond comprehension and yet it’s only one of an estimated 100 billion galaxies in the observable universe.
Bubbles of gas and sites of star formation are seen in this close up in a region in the constellation Sagittarius. Credit:
While you and I sit back and marvel at all the stellar and nebular eye candy, the Spitzer images are helping astronomers determine where the edge of the galaxy lies and location of the spiral arms. GLIMPSE images have already revealed the Milky Way to be larger than previously thought and shot through with bubbles of expanding gas and dust blown by giant stars.
Spitzer can see faint stars in the “backcountry” of our galaxy — the outer, darker regions that went largely unexplored before.
Barbara Whitney, co-leader of the GLIMPSE360 team
“There are a whole lot more lower-mass stars seen now with Spitzer on a large scale, allowing for a grand study,” said Whitney. “Spitzer is sensitive enough to pick these up and light up the entire ‘countryside’ with star formation.”
The new 360-degree view will also help NASA’s upcoming James Webb Space Telescope target the most interesting sites of star-formation, where it will make even more detailed infrared observations.
When you play around with the interactive mosaic, you’ll notice a few artifacts here and there among the images. Minor stuff. What took some getting used to was how strikingly different familiar nebulae appeared when viewed in infrared instead of visual light. The panorama is also available on the Aladin viewing platform which offers shortcuts to regions of interest.
Neil deGrasse Tyson, astrophysicist and host of the new Cosmos TV series, gave the third line of our “cosmic address” as the Milky Way after ‘Earth’ and ‘Solar System’. After a few minutes with GLIMPSE360 you’ll better appreciate the depth and breadth of our galactic home.
NASA's Stratospheric Observatory for Infrared Astronomy 747SP aircraft flies over Southern California's high desert during a test flight in 2010. Credit: NASA/Jim Ross
NASA is prepared to axe an airborne telescope to keep “higher-priority” programs such as the Saturn Cassini mission going, according to budget documents the agency released today (March 4). We have more information about the budget below the jump, including the rationale for why NASA is looking to shelve its Stratospheric Observatory for Infrared Astronomy (SOFIA).
NASA’s has been flying the telescope for just over three years and recently took some nice snapsnots of the M82 supernova that astronomers have been eager to image. The agency’s administrator, however, said SOFIA has had its shot and it’s time to reallocate the money for other programs.
“SOFIA has earned its way, and it has done very well, but we had to make a choice,” said NASA administrator Charlie Bolden in a conference call with reporters regarding the fiscal 2015 $17.46 billion budget request. He added that NASA is in discussions with partner DLR (the German space agency) to look at alternatives, but pending an agreement, the agency will shelve the telescope in 2015.
In a short news conference focusing on the telescope only, NASA said the observatory had been slated to run for another 20 years, at a cost of about $85 million on NASA’s end per year. (That adds up to $1.7 billion in that timeframe by straight math, but bear in mind the detailed budget estimates are not up yet, making that figure a guess on Universe Today’s part.) DLR funds about 25% of the telescope’s operating budget, and NASA the rest.
NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA) during a flight in 2010. Credit: NASA
“SOFIA does have a rather large operating cost compared to other missions, second only to Hubble [Space Telescope],” said NASA chief financial officer Beth Robinson in the second conference call. “There is a distinct trade in the operating mission universe about how many keep going and how much you free up (for new missions).”
The telescope isn’t the only such “trade” NASA made, Robinson added. Although not an exhaustive list, she said funding for the Orbiting Carbon Observatory 3 (OCO-3) is not in the base budget request, nor funding to accelerate development of the Pre-Aerosol, Clouds and ocean Ecosystem (PACE) mission.
SOFIA examines a “unique” part of the infrared spectrum, added NASA’s Paul Hertz, who heads the astrophysics division, but he noted infrared science is also performed by the Spitzer Space Telescope and the European Southern Observatory’s Atacama Large Millimeter Array. Coming up soon is the James Webb Space Telescope. Also, the budget allocates development money for a new infrared observatory called Wide-Field Infrared Survey Telescope (WFIRST).
Below are other notable parts of the 2015 budget. These are high-level statements missing some detail, as the rest of NASA’s documentation won’t be released publicly until late this week or early next.
The full mosaic from the Cassini imaging team of Saturn on July 19, 2013… the “Day the Earth Smiled”
– NASA’s budget falls overall to $17.46 billion, down one percent from $17.64 billion. Planetary science and human exploration each had nearly equal reductions of around three percent, with education taking the deepest cut (24%) in high-level categories as NASA moves to consolidate that directorate with other agencies.
– Funding continues for 14 operating planetary missions, which are presumably the same 14 missions that are contained here. (That list includes Cassini, Dawn, Epoxi, GRAIL, Juno, Lunar Reconnaissance Orbiter, Mars Exploration Rover/Opportunity, Mars Express, Mars Odyssey, Mars Reconnaissance Orbiter, Mars Science Laboratory/Curiosity, MESSENGER, New Horizons and Rosetta.) Separately, James Webb Space Telescope funding stays about the same as fiscal 2014, keeping it on track for a 2018 launch.
– NASA plans a mission to Europa. This was identified as the “second highest priority Flagship mission for the decade” in the National Research Council planetary science decadal survey, which called for a mission for “characterization of Europa’s ocean and interior, ice shell, chemistry and composition, and the geology of prospective landing sites.” NASA has allocated $15 million in fiscal 2015 for this mission, but it’s unclear if it’s going to be a big mission or a small one as the agency is still talking with the science community (and presumably checking its budget, although officials didn’t say that). If this goes through, it would fly in the 2020s.
Reprocessed Galileo image of Europa’s frozen surface by Ted Stryk (NASA/JPL/Ted Stryk)
– NASA’s humans-to-asteroid mission gets some more money. The agency requests $133 million for goals including “advancing solar electric propulsion and capture systems, and conduct of the Mission Concept Review in which the mission architecture will be established.” During the conference call with reporters, Bolden said the asteroid capture mission is a key step for NASA’s aim to have a manned Mars mission in the 2030s.
– Funding continues for NASA’s commercial crew program and Orion/Space Launch System program. It remains to be seen if the amounts allocated will be enough for what industry insiders hope for, but on a numbers basis, the Orion/SLS infrastructure funding falls to $2.78 billion (down 12% from $3.115 billion in FY 2014) and commercial crew funding increases to $848.3 million (up 20% from $696 million in FY 2014). Note the 2014 numbers are not finalized yet. NASA says the commercial funding will allow the program to maintain “competition”, although details are under wraps as the agency is evaluating proposals.
– The International Space Station is extended to 2024. That news was made public in early January, but technically speaking that is a part of the fiscal 2015 budget.
There’s far more to the budget that could be covered in a single news article, and it should be noted there was an entire aviation component as well. We encourage you to check out the budget documents below for the full story so far.
An artist's conception of how common exoplanets are throughout the Milky Way Galaxy. Image Credit: Wikipedia
A new study suggests that the number of habitable exoplanets within the Milky Way alone may reach 60 billion.
Previous research performed by a team at Harvard University suggested that there is one Earth-sized planet in the habitable zone of each red dwarf star. But researchers at the University of Chicago and Northwestern University have now extended the habitable zone and doubled this estimate.
The research team, lead by Dr. Jun Yang considered one more variable in their calculations: cloud cover. Most exoplanets are tidally locked to their host stars – one hemisphere continually faces the star, while one continuously faces away. These tidally locked planets have a permanent dayside and a permanent nightside.
One would expect the temperature gradient between the two to be very high, as the dayside is continuously receiving stellar flux, while the nightside is always in darkness. Computer simulations that take into account cloud cover show that this is not the case.
The dayside is covered by clouds, which lead to a “stabilizing cloud feedback” on climate. It has a higher cloud albedo (more light is reflected off the clouds) and a lower greenhouse effect. The presence of clouds actually causes the dayside to be much cooler than expected.
“Tidally locked planets have low enough surface temperatures to be habitable,” explains Jang in his recently published paper. Cloud cover is so effective it even extends the habitable zone to twice the stellar flux. Planets twice as close to their host star are still cool enough to be habitable.
But these new statistics do not apply to just a few stars. Red dwarfs “represent about ¾ of the stars in the galaxy, so it applies to a huge number of planets,” Dr. Abbot, co-author on the paper, told Universe Today. It doubles the number of planets previously thought habitable throughout the entire galaxy.
Not only is the habitable zone around red dwarfs much larger, red dwarfs also live for much longer periods of time. In fact, the Universe is not old enough for any of these long-living stars to have died yet. This gives life the amount of time necessary to form. After all, it took human beings 4.5 billions years to appear on Earth.
Another study we reported on earlier also revised and extrapolated the habitable zone around red dwarf stars.
Future observations will verify this model by measuring the cloud temperatures. On the dayside, we will only be able to see the high cool clouds. A planet resembling this model will therefore look very cold on the dayside. In fact, “a planet that does show the cloud feedback will look hotter on the nightside than the dayside,” explains Abbot.
This effect will be testable with the James Webb Space Telescope. All in all, the Milky Way is likely to be teeming with life.
WISE J104915.57-531906 from NASA's WISE survey (centered) and resolved to should its binary nature by the Gemini Observatory (inset). (Credit: NASA/JPL/Gemini Observatory/AURA/NSF).
We now know our stellar neighbors just a little better, and a new discovery may help tell us how common brown dwarfs are in our region of the galaxy. Early this week, researchers at Pennsylvania State University announced the discovery of a binary brown dwarf system. With a parallax measurement of just under 0.5”, this pair is only 6.5 light years distant making it the third closest system to our own and the closest example of the sub-stellar class of objects known as brown dwarfs yet discovered.
Named WISE J104915.57-531906, the system was identified by analysis of multi-epoch astrometry carried out by NASA’s Wide-field Infrared Survey Explorer (WISE). The discovery was made by associate professor of astronomy and astrophysics at Penn State’s Center for Exoplanets and Habitable Worlds Kevin Luhman. The system’s binary nature and follow up observations were confirmed by spectroscopic analysis carried out by the Gemini Observatory’s Multi-Object Spectrographs (GMOS).
Animation showing the motion of WISE 1049-5319 across the All-WISE, 2MASS & Sloan Digital Sky Surveys from 1978 to 2010. (Credit: NASA/STScI/JPL/IPAC/University of Massachusetts.)
This find is also the closest stellar system discovered to our own solar system since the discovery of Barnard’s star by astronomer E.E. Barnard in 1916. Incidentally, Barnard’s star was the center of many spurious and controversial claims of extrasolar planet discoveries in the mid-20th century. Barnard’s star is 6 light years distant, and the closest star system to our own is Alpha Centauri measured to be 4.4 light years distant in 1839. In 1915, the Alpha Centauri system was determined to have a faint companion now known as Proxima Centauri at 4.2 light years distant. The Alpha Centauri system also made headlines last year with the discovery of the closest known exoplanet to Earth. WISE 1506+7027 is the closest brown dwarf to our solar system yet discovered. This also breaks the extended the All-WISE survey’s own previous record of the closest brown dwarf released in 2011, WISE 1506+7027 at 11.1 light years distant.
When looking for nearby stellar suspects, astronomers search for stars displaying a high proper motion across the sky. The very first parallax measurement of 11 light years distant was obtained by Friedrich Bessel for the star 61 Cygni in 1838. 61 Cygni was known as “Piazzi’s Flying Star” for its high 4.2” proper motion across the sky. To giving you an idea of just how tiny an arc second is, a Full Moon is about 1800” in diameter. With a proper motion of just under 3” per year, it would take WISE 1049-5319 over 600 years to cross the same apparent distance in the sky as viewed from the Earth!
An artist’s conception of looking back at Sol from the binary brown dwarf system WISE 1049-5319, 6.5 light years distant. (Credit: Janella Williams, Penn State University).
“Based on how this star system was moving in images from the WISE survey, I was able to extrapolate back in time to predict where it should have been located in older surveys,” stated Luhman. And sure enough, the brown dwarf was there in the Deep Near-Infrared Survey of the Southern Sky (DENIS), the Two Micron All-Sky Survey (2MASS) and the Sloan Digitized Sky Survey (SDSS) spanning a period from 1978 to 1999. Interestingly, Luhman also points out in the original paper that the pair’s close proximity to the star rich region of galactic plane in the constellation Vela deep in the southern hemisphere sky is most likely the reason why they were missed in previous surveys.
The discovery of the binary nature of the pair was also “an unexpected bonus,” Luhman said. “The sharp images from Gemini also revealed that the object actually was not just one, but a pair of brown dwarfs orbiting each other.” This find of a second brown dwarf companion will go a long way towards pinning down the mass of the objects. With an apparent separation of 1.5”, the physical separation of the pair is 3 astronomical units (1 AU= the Earth-Sun distance) in a 25 year orbit.
Size comparison of stellar vs substellar objects. (Credit: NASA/JPL-Caltech/UCB).
Brown dwarfs are sub-stellar objects with masses too low (below ~75 Jupiter masses) to sustain the traditional fusion of hydrogen into helium via the full proton-proton chain process. Instead, objects over 13 Jupiter masses begin the first portion of the process by generating heat via deuterium fusion. Brown dwarfs are thus only visible in the infrared, and run a spectral class of M (hottest), L, T, and Y (coolest). Interestingly, WISE 1049-5319 is suspected to be on the transition line between an L and T-class brown dwarf. To date, over 600 L-type brown dwarfs have been identified, primarily by the aforementioned SDSS, 2MASS & DENIS infrared surveys.
General location of WISE 1049-5319 in the constellation Vela. Note its proximity to the galactic plane. (Created by the author using Starry Night).
This discovery and others like it may go a long ways towards telling us how common brown dwarfs are in our region of the galaxy. Faint and hard to detect, we’re just now getting a sampling thanks to surveys such as WISE and 2MASS. The James Webb Space Telescope will do work in the infrared as well, possibly extending these results. Interestingly, Luhman notes in an interview with Universe Today that the potential still exists for the discovery of a brown dwarf closer to our solar system than Alpha Centauri. “No published study of the data from WISE or any other survey has ruled out this possibility… WISE is much more capable of doing this than any previous survey, but the necessary analysis would be fairly complex and time consuming. It’s easier to find something than to rule out its existence.” Said Luhman. Note that we’re talking a nearby brown dwarf that isn’t gravitationally bound to the Sun… this discussion is separate from such hypothetical solar companions as Nemesis and Tyche…and Nibiru conspiracy theorists need not apply!
The WISE 1049-5319 system is also a prime target in the search for nearby extra-solar planets. “Because brown dwarfs have very low masses, they exhibit larger reflex motions due to orbiting planets than more massive stars, and those larger reflex motions will be easier to detect.” Luhman told Universe Today. Said radial surveys for exoplanets would also be carried out in the IR band, and brown dwarfs also have the added bonus of not swamping out unseen planetary companions in the visible spectrum.
Congrats to Mr. Luhman and the Center for Exoplanets and Habitable Worlds on the discovery. You just never know what’s lying around in your own stellar backyard!
A ghostly blue ring is a planetary nebula - hydrogen gas the star ejected as it evolved from a red giant to a white dwarf.
Credit: David A. Aguilar (CfA)
We’ve currently found 867 different exoplanets, but have yet to definitely determine if one of those harbors life. How will astronomers make that determination? They’ll look at things such as its composition, orbital properties, atmosphere, and potential chemical interactions. While oxygen is relatively abundant in the Universe, finding it in the atmosphere of a distant planet could point to its habitability because its presence – in large quantities — would signal the likely presence of life.
But where to look first? A new study finds that we could detect oxygen in the atmosphere of a habitable planet orbiting a white dwarf – a star that is in the process of dying — much more easily than for an Earth-like planet orbiting a Sun-like star.
“In the quest for extraterrestrial biological signatures, the first stars we study should be white dwarfs,” said Avi Loeb, theorist at the Harvard-Smithsonian Center for Astrophysics (CfA) and director of the Institute for Theory and Computation.
Loeb and his colleague Dan Maoz from Tel Aviv University estimate that a survey of the 500 closest white dwarfs could spot one or more habitable Earths.
Potential habitable exoplanets, as of Feb. 18, 2013. Credit: The Planetary Habitability Labratory at UPR/Arecibo.
A white dwarf is what stars like the Sun become after they have exhausted their nuclear fuel. It puffs off its outer layers, leaving behind a hot core which can be about the size of Earth. It slowly cools and fades over time, but it can retain heat long enough to warm a nearby world for billions of years.
Currently, most planets that we’ve found orbit close to their parent star, since astronomers find planets using astrometry by the gravitational influence the planet has on the star, causing it to wobble ever so slightly. Massive planets close to the star have the biggest effect and so are the easiest to detect.
Using the photometry, astronomers see a dip in the amount of light a star gives off when a planet passes in front of the star. Since a white dwarf is about the same size as Earth, an Earth-sized planet would block a large fraction of its light and create an obvious signal. Photometry, or the transit method, has proven the best way to find exoplanets.
A white dwarf is much smaller and fainter than the Sun, and a planet would have to be much closer in to be habitable with liquid water on its surface, so that should make planets around a white dwarf star easier to detect. A habitable planet would circle the white dwarf once every 10 hours at a distance of about a million miles.
More importantly, we can only study the atmospheres of transiting planets. When the white dwarf’s light shines through the ring of air that surrounds the planet’s silhouetted disk, the atmosphere absorbs some starlight. This leaves chemical fingerprints showing whether that air contains water vapor, or even signatures of life, such as oxygen.
But there’s a caveat: Before a star becomes a white dwarf it swells into a red giant, engulfing and destroying any nearby planets. Therefore, a planet would have to arrive in the habitable zone after the star evolved into a white dwarf. Either it would migrate towards the star from a more distant orbit or be a new planet formed from leftover dust and gas.
However, we have yet to find a exoplanet around a white dwarf, even though Loeb and Moaz say the abundance of heavy elements on the surface of white dwarfs suggests that a significant fraction of them have rocky planets.
We need a better eye in the sky to find planets around white dwarfs, say Loeb and Maoz, and the James Webb Space Telescope (JWST), scheduled for launch by the end of this decade, promises to sniff out the gases of these alien worlds.
Loeb and Maoz created a synthetic spectrum, replicating what JWST would see if it examined a habitable planet orbiting a white dwarf. They found that both oxygen and water vapor would be detectable with only a few hours of total observation time.
“JWST offers the best hope of finding an inhabited planet in the near future,” said Maoz.
The James Webb Space Telescope. Credit: NASA
Recent research by CfA astronomers Courtney Dressing and David Charbonneau showed that the closest habitable planet is likely to orbit a red dwarf star (a cool, low-mass star undergoing nuclear fusion). Since a red dwarf, although smaller and fainter than the Sun, is much larger and brighter than a white dwarf, its glare would overwhelm the faint signal from an orbiting planet’s atmosphere. JWST would have to observe hundreds of hours of transits to have any hope of analyzing the atmosphere’s composition.
“Although the closest habitable planet might orbit a red dwarf star, the closest one we can easily prove to be life-bearing might orbit a white dwarf,” said Loeb.
