Webb shows what humans can do
Astronomers like myself around the world greeted the spectacular sharp images released by NASA from the James Webb Space Telescope on Tuesday with a combination of delight, anticipation and a great deal of relief.
It has been a long and risky road. Conceived over 25 years ago and subject to numerous delays, cost overruns and even near-cancellation, the Webb telescope is often portrayed as a successor to the Hubble Space Telescope, though there is essentially no overlap in their respective capabilities. The Hubble telescope observes visible and ultraviolet light, while the Webb operates almost exclusively in the infrared, and this difference creates several new avenues of research into some of the most pressing questions in astronomy. It has been the promise of such great discoveries that has retained support for the mission despite its enormous technical challenges.
And those challenges were indeed formidable. An infrared telescope like the Webb must be larger than the Hubble to produce images of comparable quality. Engineers had to figure out how to fold such a large telescope to fit into an available rocket, and then unfold it later on its way to its final destination while preserving perfect mirror alignments. Such a scheme was new and could have failed easily.
A second major challenge was to keep the telescope extremely cold, less than 50 degrees above absolute zero. If this was not done, the telescope itself would have glowed in the infrared, interfering with what it is trying to measure. But maintaining a low temperature requires an ultra-lightweight shield to block radiation from the sun, Earth and moon at all times. For the shield to block all three objects at once, the telescope must be located at a position in space where the three bodies always lie in the same direction.
To accomplish this alignment, the Webb hovers just outside the Earth’s orbit near a special location known as the second Lagrange point, at a distance about four times farther away from us than the moon. Hence, unlike the Hubble which was launched into reasonably reachable low-Earth orbit, astronauts couldn’t travel to service the Webb telescope if something needed to be fixed. The technology had to work perfectly the first time and be engineered to adapt to anomalies.
Only the thickness of a human hair and the size of a tennis court, the shield alone is a technological marvel. The years of engineering design and testing paid off: The shield did not tear as it unfolded and deployed in space.
On Tuesday, with entire careers of mission developers and over 25 years of collective astronomical community support on the line, the Webb did not disappoint, and delivered crystal clear images of nebulae and galaxies and a tantalizing spectrum of the atmosphere of an exoplanet. At least as exciting for astronomers like me is the report that all 17 instrumental configurations of the telescope are working and open for business. The image releases were the final part of a checkout phase, and now the real science projects can begin. Astronomers have already gone through two rounds of a highly competitive process of proposal review to acquire Webb telescope time, and we are eager to see what we can learn. Star formation is my own area of research, and I am a part of two approved projects that will make use of the groundbreaking information offered by Webb’s infrared capabilities.
Three words encapsulate what the infrared offers scientifically over the optical — dust, molecules and time. Stars form out of clouds of gas and dust. Dust absorbs optical light but is largely transparent in the infrared, so the Webb telescope allows us to peer into the densest regions where stars and planets form.
Such observations will greatly enhance our understanding of how the sun and Earth came to be, and we can also study large-scale star formation that results from colliding galaxies. Greenhouse gas molecules such as carbon dioxide, water vapor and methane all absorb infrared light, so to detect these on planets around other stars we must get above the Earth’s atmosphere and use a large infrared telescope like Webb.
The universe is basically a time machine. The speed of light is finite, so the farther away you look, the farther back in time you can see. But because the universe is expanding, the optical light waves from the first galaxies get stretched out, or “redshifted,” into infrared wavelengths. The Webb telescope is specifically designed to discover these first galaxies.
Though the $10 billion price tag of the Webb only represents about 1/9000 of the federal budget between 1995 and today, one can ask whether it was worth the expense. Surely one can go through life not learning anything about astronomy, or any other science for that matter. But even ignoring the technology spin-offs of this and all spacerelated activities, societies that are at the forefront of scientific research are the ones best poised to nurture the creative talents of their populations.
The Webb is an example of what our talented young people might become a part of as we move through this next century and try to answer the biggest questions in science and technology that lie before us. Barring misfortune, the Webb telescope should have a lifetime of over two decades. Today’s middle school student may someday instruct this great telescope as to where to point, and observe things that no one else in the history of mankind has ever seen.
The results that follow from the Webb telescope in the next decades will remind us of what scientists and engineers can accomplish with the support of the public when we combine well-reasoned long-term goals with talented and extremely dedicated people. The Webb project has spanned three Democratic and two Republican administrations and involved international collaboration. There were many ways this decades-long project could have failed. Yet it prevailed.
All cutting-edge endeavors entail risk. But if we are willing to embrace the risks, have the courage to think big, and have the patience and political will to tackle projects that take decades to complete, together as a society we can accomplish great things.