John Mather (2012) - Seeing Farther with New Telescopes

John Mather (2012)

Seeing Farther with New Telescopes

John Mather (2012)

Seeing Farther with New Telescopes

Abstract

John Mather
Senior Project Scientist, James Webb Space Telescope

Title: Seeing farther with new telescopes

Abstract:
Since Galileo’s telescope in 1609, new technologies in space and on the ground have been extending astronomers’ reach every year, and this is truly the Golden Age of Astronomy. Already three satellites (COBE, WMAP, and Planck) have clearly observed the tiny fluctuations of the cosmic microwave background radiation from the Big Bang, and we now have a standard model for cosmology that includes dark matter, dark energy, neutrinos, heat radiation, and ordinary matter, all set going by processes in the first few minutes of the Universe. For further cosmic microwave background radiation studies, arrays of thousands of pixels operating below 1 Kelvin are producing astonishing sensitivity in the search for the nano-kelvin polarizations in the CMB that would be produced by gravitational waves in the Big Bang. At far infrared wavelengths, single photon counting is becoming feasible, and coupled with microstrip spectrometers printed on substrates, will enable enormous breakthroughs in studying the cold universe of dust and molecules. At mid-infrared wavelengths the 3.5 m Herschel observatory, launched in 2009, carries instruments to observe the physical and molecular composition of gas clouds, the formation of stars and galaxies, and the atmospheres of the planets in the Solar System. At near- and mid-infrared wavelengths, the James Webb Space Telescope will be launched in 2018 to carry many megapixels of nearly-ideal detectors into space, connected to a 6.5 m deployable cold telescope, to advance our knowledge of the first stars and black holes, the growth of galaxies, the formation of stars and planetary systems near by, and the evolution of planetary systems and the search for life outside the solar system. The 2.4 m Hubble Space Telescope, now 22 years old but upgraded in 2009 with new instruments, continues to amaze with scientific discoveries ranging from distant supernovae and measures of the cosmic acceleration, to the measurement of atmospheric properties of planets around other stars. The Kepler mission, launched in 2009, has revealed over 2000 planet candidates, many in multi-planet systems, and some resemble the Earth in having the right size and temperature to support life. The Chandra X-ray observatory, launched in 1999, takes pictures of material falling into black holes, or being expelled at extreme speeds, and looks at the debris of supernova explosions, the hot gas clouds where galaxies collide, and tells us of the existence of dark matter. The Fermi mission, launched in 2008, observes gamma rays from extremely hot places, has seen the remains of Tycho Brahe’s supernova of 1572 and discovered the youngest millisecond pulsar in its catalog of over 100 gamma-ray pulsars, and has given hints that dark matter may be annihilating to produce part of the gamma ray glow of our Galaxy. And although no detections have yet been made, the LIGO (Laser Interferometer Gravitational Wave Observatory) has pushed the technology so far that motions far smaller than the size of an atomic nucleus can be measured. When the sensitivity improves enough, possibly with new space observatories now under study, a new domain of astronomy will be opened up, inspecting the collapse and collision of neutron stars and black holes to the farthest reaches of the universe.

On the ground, telescope technology continues to advance as well. Both Europe and the US are working on gigantic observatories with 30-m diameter mirrors, all made of segments. They work with advanced laser guide stars and adaptive optics to compensate for the shimmering of the Earth’s atmosphere, giving the chance for incredibly sharp new images of extremely faint objects. Advanced photonic technologies using fiber optics are leading to ways to block molecular emission lines of the Earth’s upper atmosphere, improving telescope sensitivity in the near IR. And the ALMA (Atacama Large Millimeter/submillimeter Array) in the very high (5000 m) desert in Chile is now coming online with a set of dishes up to 16 km apart. It is a joint project of the US, Europe, and Japan, with the sensitivity and angular resolution to see galaxies forming in the early universe and stars forming nearby.

Some of the new technologies behind these great successes are wavefront sensing and control (to achieve sharp focus despite telescope errors or atmospheric turbulence), deployable optics, ultralight mirrors with a variety of fabrication methods and materials, extraordinary semiconductor designs and purity to enable high sensitivity detectors, cryogenic coolers, superconducting detectors and readout circuits, and fantastically complex electronic circuits and correlators to enable the ALMA to combine the signals from all its dish antennas. In addition, atom interferometry is being mastered for practical purposes and may enable extreme sensitivity for gravitational wave detection. So far, Moore’s law for telescopes has not reached its natural limits, although progress is a little slower than for transistors.

And for exploring the Solar System, technological advances continue as well. NASA’s Mars Science Lander, christened “Curiosity”, is scheduled to land on August 6 (UT), 2012. As large as a Volkswagen, it carries instruments for chemical and geological analysis, with a strong interest in whether Mars is or was alive. ESA has just selected the Jupiter Icy moons Explorer (JUICE) mission, scheduled to arrive at Jupiter in 2030 with the goal of studying its Galilean moons as potential habitats for life. ESA has already announced Solar Orbiter and Euclid as the first two missions selected for its Cosmic Vision 2015-2025 plan in October last year. The EUCLID will measure the history of the Dark Energy and as a side benefit can find exoplanets through the microlensing effect.

Suggested reading:
1. The Very First Light, paperback, by John Mather and John Boslough
2. ESA’s Cosmic Vision, http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=46510
3. Astro 2010 Decadal Survey, (US), http://sites.nationalacademies.org/bpa/BPA_049810
4. ALMA, http://www.almascience.org/

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