A New Approach to SETI: Targeting Alien Polluters

Humanity is on the threshold of being able to detect signs of alien life on other worlds. By studying exoplanet atmospheres, we can look for gases like oxygen and methane that only coexist if replenished by life. But those gases come from simple life forms like microbes. What about advanced civilizations? Would they leave any detectable signs?

They might, if they spew industrial pollution into the atmosphere. New research by theorists at the Harvard-Smithsonian Center for Astrophysics (CfA) shows that we could spot the fingerprints of certain pollutants under ideal conditions. This would offer a new approach in the search for extraterrestrial intelligence (SETI).

"We consider industrial pollution as a sign of intelligent life, but perhaps civilizations more advanced than us, with their own SETI programs, will consider pollution as a sign of unintelligent life since it's not smart to contaminate your own air," says Harvard student and lead author Henry Lin.

"People often refer to ETs as 'little green men,' but the ETs detectable by this method should not be labeled 'green' since they are environmentally unfriendly," adds Harvard co-author Avi Loeb.

The team, which also includes Smithsonian scientist Gonzalo Gonzalez Abad, finds that the upcoming James Webb Space Telescope (JWST) should be able to detect two kinds of chlorofluorocarbons (CFCs) -- ozone-destroying chemicals used in solvents and aerosols. They calculated that JWST could tease out the signal of CFCs if atmospheric levels were 10 times those on Earth. A particularly advanced civilization might intentionally pollute the atmosphere to high levels and globally warm a planet that is otherwise too cold for life.

There is one big caveat to this work. JWST can only detect pollutants on an Earth-like planet circling a white dwarf star, which is what remains when a star like our Sun dies. That scenario would maximize the atmospheric signal. Finding pollution on an Earth-like planet orbiting a Sun-like star would require an instrument beyond JWST -- a next-next-generation telescope.

The team notes that a white dwarf might be a better place to look for life than previously thought, since recent observations found planets in similar environments. Those planets could have survived the bloating of a dying star during its red giant phase, or have formed from the material shed during the star's death throes.

While searching for CFCs could ferret out an existing alien civilization, it also could detect the remnants of a civilization that annihilated itself. Some pollutants last for 50,000 years in Earth's atmosphere while others last only 10 years. Detecting molecules from the long-lived category but none in the short-lived category would show that the sources are gone.

"In that case, we could speculate that the aliens wised up and cleaned up their act. Or in a darker scenario, it would serve as a warning sign of the dangers of not being good stewards of our own planet," says Loeb.

This work has been accepted for publication in The Astrophysical Journal and is available online.

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.

For more information, contact:

David A. Aguilar
Director of Public Affairs
Harvard-Smithsonian Center for Astrophysics
617-495-7462
daguilar@cfa.harvard.edu

Christine Pulliam
Public Affairs Specialist
Harvard-Smithsonian Center for Astrophysics
617-495-7463
cpulliam@cfa.harvard.edu

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The James Webb Space Telescope: progress

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The James Webb Space Telescope (sometimes called JWST) is a large, infrared-optimized space telescope. The project is working to a 2018 launch date. Webb will find the first galaxies that formed in the early Universe, connecting the Big Bang to our own Milky Way Galaxy. Webb will peer through dusty clouds to see stars forming planetary systems, connecting the Milky Way to our own Solar System. Webb's instruments will be designed to work primarily in the infrared range of the electromagnetic spectrum, with some capability in the visible range.

Webb will have a large mirror, 6.5 meters (21.3 feet) in diameter and a sunshield the size of a tennis court. Both the mirror and sunshade won't fit onto a rocket fully open, so both will fold up and open once Webb is in outer space. Webb will reside in an orbit about 1.5 million km (1 million miles) from the Earth.

The James Webb Space Telescope was named after the NASA Administrator who crafted the Apollo program, and who was a staunch supporter of space science.

Here is a great video by TonyDarnell of space images.

The following is an up to date news report on the project from NASA.

The James Webb Space Telescope marked another year of significant progress in 2012 as flight instrumentation was completed and delivered to NASA.

The year brought forth the delivery of two types of flight mirrors, the Mid-Infrared Instrument (MIRI), the Fine Guidance Sensor and Near-Infrared Imager and Slitless Spectrograph (FGS/NIRISS), and the completion of the center section of the primary mirror backplane. The Webb project modified the historic Chamber A at NASA's Johnson Space Center, Houston, Texas, to enable the Webb telescope’s optics and instrument systems to be tested. In addition to the telescope and test chambers coming together, spinoff technology from the Webb has already been used in industries to improve people's lives.

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Contamination control engineers conducted a "receiving inspection" of the Webb telescope's Mid-Infrared Instrument (or MIRI) in the giant clean room at NASA's Goddard Space Flight Center in Greenbelt, Md. Credit: NASA/Chris Gunn
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This image shows the four different types of mirrors on the Webb telescope. From left to right are: a primary mirror segment, the secondary mirror, tertiary mirror and the fine steering mirror. The bottom right shows an artist's conception of the Webb telescope optics with its 18 primary mirror segments. Credit: NASA/Ball Aerospace/Tinsley
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Engineers at ATK work on the center section of the "backplane" support structure that will hold Webb's mirror segments. Credit: ATKMirrors

On Sept. 17, 2012, two primary mirror segments that will fly aboard NASA's James Webb Space Telescope arrived at NASA's Goddard Space Flight Center in Greenbelt, Md. The flight secondary mirror and a third primary mirror segment arrived at NASA Goddard on Nov. 5, 2012, and are currently being stored in the giant clean room. All of the mirrors are made of beryllium, which was selected for its stiffness, light weight and stability at extremely cold cryogenic temperatures. Bare beryllium is not very reflective at Webb’s shortest wavelengths, so each mirror is coated with gold. The microscopic gold coating enables the mirrors to efficiently reflect infrared light (which is what the Webb telescope's cameras see).

MIRI

The Mid-infrared Instrument (MIRI) flight hardware was delivered to NASA’s Goddard Space Flight Center on May 28 2012, for integration into the ISIM. The MIRI will allow scientists to study cold and distant objects in greater detail than ever before and with unprecedented sensitivity. MIRI will observe light with wavelengths in the mid-infrared range of 5 microns to 28.5 microns, which is longer wavelength than human eyes can detect. Of Webb’s four instruments, MIRI is the only one that works at the longest wavelengths. MIRI will be integrated into Webb’s science instrument payload known as the Integrated Science Instrument Module (ISIM). An international team of European scientists and engineers collaborated with JPL to produce this instrument.

FGS/NIRISS 

The second of four instruments to fly aboard NASA's James Webb Space Telescope was delivered to NASA Goddard on July 30. The Fine Guidance Sensor (FGS) will enable the telescope to accurately and precisely point at the correct targets. The FGS is packaged together as a single unit with the Near-Infrared Imager and Slitless Spectrograph (NIRISS) science instrument. The FGS/NIRISS will also be integrated into Webb's ISIM.

The FGS consists of two identical cameras that will allow the telescope to determine its position, locate its celestial targets, and remain pointed to collect high-quality data. The FGS will guide the telescope with incredible precision, with an accuracy of one millionth of a degree of angle. Although the NIRISS is packaged with the FGS, it is functionally independent. NIRISS provides unique capabilities that will aid in finding the earliest and most distant objects in the Universe’s history. It will also peer through the glare of nearby stars to detect and study planets in other Solar Systems. The FGS/NIRISS was developed by the Canadian Space Agency.

Backplane

The center section of the Webb telescope's flight backplane structure that will fly on the Webb telescope was completed in April, 2012. The structure will support twelve of the eighteen beryllium mirrors, thermal control systems and other elements during ground tests, launch and during science operations. Measuring approximately 24 by 12 feet yet weighing only 500 pounds, the center section of the backplane meets unprecedented thermal stability requirements. The center section is the first of the three sections of the backplane to be completed.

Chamber A Completed

For three years, engineers at NASA's Johnson Space Center in Houston, Texas have been building and remodeling the interior of Chamber A, the largest thermal vacuum chamber in the world, so it will meet the temperature requirements to test the Webb. They installed a gaseous helium cooling system that brought the interior of the chamber down to 11 degrees kelvin above absolute zero (-439.9 F/-262.1C). Chamber A testing will confirm that the telescope and science instrument systems will perform properly together in the cold temperatures of space. Additional test support equipment includes mass spectrometers, infrared cameras and television cameras so that engineers can keep an eye on the Webb while it's being tested.

Spinoff Technologies

New technologies developed for NASA's James Webb Space Telescope have already been adapted and applied to commercial applications in various industries including optics, aerospace, astronomy, medical and materials. Some of these technologies can be explored for use and licensed through NASA's Office of the Chief Technologist at NASA's Goddard Space Flight Center, Greenbelt, Md.

For example, the optical measuring technology developed for the Webb, called "wavefront sensing" has been applied to eye health and has allowed improvements in measurement of human eyes, diagnosis of ocular diseases and potentially improved surgery.

About Webb

The powerful primary mirrors of the James Webb Space Telescope will be able to detect the light from the first luminous objects that formed when the universe was young, as well as distant galaxies and nearby stars and their planets. Altogether, 21 mirrors comprise the Webb's telescope optics -- 18 primary mirror segments working together as one large 21.3-foot (6.5-meter) primary mirror, the secondary mirror mounted on a tripod above the primary mirror, and the tertiary mirror and the fine steering mirror that are both located inside an assembly near the center of the primary mirror.

The most powerful space telescope ever built, the Webb telescope will provide images of the first galaxies ever formed, and explore planets around distant stars. It is a joint project of NASA, the European Space Agency and the Canadian Space Agency.

NASA

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