After a 30-year effort involving 20,000 people around the world at a cost of $10 billion, the James Webb Space Telescope is now hard at work imaging the cosmos. The reward of understanding our universe will outweigh the costs. The reward of scientific literacy – public understanding of science – will perhaps be its greatest benefit. Democracy can only thrive when its citizens have scientific knowledge.
Webb has five times the light-gathering power of its predecessor, the Hubble Space Telescope. The light collected by Webb will be more scientifically significant because it will be mostly longer wavelength infrared radiation. Webb will collect light from great distances, from events that occurred billions of years ago. Because the expansion of the universe has stretched this radiation, a telescope that detects infrared is more useful.
Webb’s location is mind blowing. It executes a small orbit around a point of balance resulting from the gravity of the sun and the Earth, a point 1 million kilometers beyond the orbit of the moon. This balance point is called “L2”. Here, the combined effects of gravity and “centrifugal forces” (like the effects one feels when driving in a car executing a sharp turn) will maintain a relatively stable orbit.
Webb is so far away that NASA cannot repair or refuel it. The plan was that Webb would have 10 active years before running out of rocket fuel needed for periodic course corrections. But the launch and positioning over the past six months has been so successful that far less rocket fuel has been consumed than expected, extending Webb’s useful life to perhaps 20 years.
During these years Webb collected volumes on the birth and development of the first galaxies (these are large clusters of stars, similar to our own Milky Way galaxy), the births and deaths of stars and how this relates to the formation of galaxies, how stars form planetary systems, and the nature of the many planets we know of that orbit other stars.
Teams of scientists, 286 different groups, have been allocated telescope time for just the first year of operation. Some of these projects are already underway. One, led by Misty Bentz of Georgia State University, uses a unique type of detection: the telescope stares at an object for several hours and records a “spectrum” (a record of the wavelengths precise) of the light coming from each location. on the object. She uses this detector to study a single distant galaxy, dubbed the “Eye of Sauron”. As in almost all galaxies, a giant black hole sits at the center of the galaxy. This particular giant black hole emits an eerie glow that occasionally lights up when gas is sucked into its maw, hence the galaxy’s title. The special detector allows Bentz to study the changes in the swirling gas and dust as they are sucked into the black hole’s maw in order to uncover, perhaps, the secret of the Eye.
Another project involves the possibility of extraterrestrial life. A certain “exoplanet” (a planet orbiting another star beyond our sun) called WASP-96b orbits near a star in the Milky Way that is 1,150 “light years” from the Earth. A light year is the distance traveled by light in one year. Since light travels a distance equal to seven times around the Earth in one second, a light year is huge by human standards. Nevertheless, 1,150 light-years is relatively close to our sun in galactic terms.
WASP-96b happens to make regular orbital passes directly in front of its star (as seen from Earth). This means that a small fraction of its star’s light passes through WASP-96b’s atmosphere. After passing through this atmosphere, this starlight carries the “signature” of the chemicals in the planet’s atmosphere. This is because these chemicals absorb particular wavelengths of light from the star, so these wavelengths “miss” from the light that arrives at the telescope. Theoretical predictions, before Webb, were that the atmosphere of this planet should contain carbon monoxide, carbon dioxide and methane, but the Hubble telescope had been unable to detect them. Webb’s first look at this light has already detected water vapor that indicates the presence of clouds and haze, but scientists expect Webb to provide much more data in the future.
Using such detection methods, we will learn about the possibility of life on other planets. In my opinion, many of these planets will support life, but few, if any, will have the advanced plants and animals found on Earth. We will see.
Stay tuned. Webb will amaze us all for years to come.