From Space to Earth with John Mather

Nobel Laureate John Mather describes how technological investment in astronomy and cosmology can be used to answer questions central to all of science.

John Mather is excited about the release of the upcoming James Webb Space Telescope, sketched behind him, and how future discoveries in cosmology might benefit science as a whole. Image Credit: Chris Gunn

John Mather is excited about the release of the upcoming James Webb Space Telescope, sketched behind him, and how future discoveries in cosmology might benefit science as a whole. Image Credit: Chris Gunn

Twenty-five years after the launch of the Hubble Space Telescope, a new satellite is slowly coming together, and it’s looking like a more-than-worthy successor.

The James Webb Space Telescope (JWST), set to launch in 2018, will take images with enough resolution to make out details the size of a penny at a distance of 24 miles, and be able to detect the heat signature of a bumblebee at the distance of the moon. It’s a space telescope unlike any other, which is exactly why it’s being made.

“One of the key strategies for discovering something is to build some tool no one else has,” says John Mather, senior project scientist for JWST at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, where the telescope is being built. “If you’re the only one that has it, you’re going to see stuff nobody else can see.”

Mather knows thing or two about that. He was the principal investigator on the Far Infrared Absolute Spectrophotometer (FIRAS) aboard the Cosmic Background Explorer (COBE), which measured fluctuations in cosmic microwave background radiation (CMBR). In 2006, along with George Smoot, he received the Nobel Prize in Physics for his work with COBE which, according to the Nobel committee, “marked the inception of cosmology as a precise science.” COBE’s successor, the Wilkinson Microwave Anisotropy Probe (WMAP), continued the development of precision cosmology, and the JWST will take the science further still.  

Maps of anisotropies in the CMBR created by COBE (top) and WMAP (bottom). Image Credits: NASA, NASA

Maps of anisotropies in the CMBR created by WMAP (top) and COBE (bottom). Image Credits: NASA, NASA

Launched in 1989, COBE precisely measured anisotropies in the temperature of the CMBR and showed that the CMBR spectrum matches a blackbody spectrum at 2.725 K to within 50 parts per million, providing incredibly strong evidence for the Big Bang model of cosmology. WMAP made a CMBR anisotropy map with 33 times better resolution than COBE, and showed that the universe is composed of 4.6 percent baryonic (ordinary) matter, 24.0 percent dark matter, and 71.4 percent dark energy.

The JWST’s mission is to build on the work done by its predecessors. COBE and Hubble gave scientists an idea of what the first stars and galaxies should look like through observations of closer objects, and theoretical calculations. The JWST, says Mather, aims to see what these objects actually look like.

It’s a tall order for cosmologists to create a meaningful image of the early universe. Cosmology – the science of the form, content, organization and evolution of the universe – doesn’t readily lend itself to illustration.

“It’s months and years between new data points coming in, and of course the distant universe doesn’t change that fast, so there are not that many events for us to see,” Mather says. However, he’s simply excited with the prospect of seeing something new.

“The part (of cosmology) that’s tangible for me is measuring stuff, conceiving of new ways to build equipment that will measure something. I think that’s the heart of experimental science.”

Mather may be a cosmologist by trade, but at heart he’s an experimental scientist concerned with making better tools for better experiments.

Even from a young age, Mather was surrounded by experimentation. A year and a half after he was born in Roanoke, Virginia, in 1946, his family moved to the Rutgers Agricultural Experiment Station in Sussex County, New Jersey. There, his father researched statistics and animal husbandry for dairy cattle breeding and his mother taught elementary school.  He says his parents were instrumental in fostering his natural propensity for devouring everything scientific, from reading biographies of Darwin and Galileo aloud to taking trips to local museums and providing an allowance to eventually buy radio kits and telescopes.

Cosmology became Mather’s area of focus by chance. As a graduate student at UC the University of California, -Berkeley looking for a thesis project, Mather was intrigued by an experiment on the recently discovered CMBR being proposed by faculty members Paul Richards and Charles Townes, as well as postdoctorate Michael Werner. The experiment involved building a far-infrared spectrometer, which went well, and then an ambitious attempt at a balloon-borne far infrared interferometer, which launched but whose instrumentation did not work the first time.

Mather recalls saying after the failed balloon experiment that the concept would have worked better in space, without interference from Earth’s atmosphere. When NASA announced opportunities to submit proposals for satellite missions, Mather and some colleagues submitted a modified and extended version of Mather’s thesis project. As Mather put it in an interview for Blueshift at NASA Goddard, “The COBE satellite is basically my thesis project on steroids.”

The saga of Mather’s thesis project is a microcosm of how cosmology has been progressing. The project Mather worked on at Berkeley had four people; the COBE project had around 1,500. Mather emphasizes that it takes “thousands and thousands” of people to make the next steps in cosmology.  

Perhaps to an even greater extent, Mather cites the importance of technology development in the growth of precision cosmology.

“Precision cosmology has been based on technological advance that enabled us to put up equipment in space that was able to measure far, far, far better than we ever could have imagined doing when I started in this subject,” says Mather.

For example, several new technologies including improved wavefront optical measurement devices to measure the shapes of mirrors and advanced cryogenic integrated circuits were developed specifically for the JWST because the mission objectives required that they exist. These technologies also will go on to benefit other areas of science; the measurement devices have enabled better measurements of human eyes, and the investments in cryogenic integrated circuits led to the development of circuits that are now on the Hubble Space Telescope.

Earth science is another area that can benefit from the technological investments made by cosmology, because both sciences seek to answer similar questions, Mather says. “Precision cosmology is just the beginning of the history of how we got here. If we could understand the early universe, what we call ‘The Big Bang,’ we would understand the origin of the solar system and … whether we’re unusual in the universe.”

Where the sciences differ is in their technological focus, especially when it comes to space science.

“Earth science, at least from space, uses ancient technology compared to what we could have if we were trying to answer harder questions,” Mather says.

For a satellite orbiting and observing the Earth, for example, the object of interest is only about a light second away. On the other hand, cosmologists study objects and events billions of light years away. It stands to reason that cosmologists would have much higher demands for detector and telescope technology than Earth scientists, says Mather. The technologies produced because of those demands have the potential to help Earth science as well.

“There’s the two connections (between cosmology and Earth science),” Mather says, “the scientific path, which says basically ‘How did we get here, are we alone, and why is Earth different or similar to all the others?’ and the technology path, which says ‘Now that we’ve had impetus to develop these astonishing tools for space measurements of cosmology, can we try them out on things that are close to home?’ I certainly think so, hope so.”

Alec Drobac is a senior physics major at Middlebury College in Vermont. He hopes to pursue a career as a theoretical physicist, potentially in the field of astronomy or cosmology. Originally from California, he is particularly concerned with water usage and conservation, as well as the advancement of technology in agriculture.