By Emily Levesque, University of Washington
In 1946, astrophysicist Lyman Spitzer published a research paper titled, ‘Astronomical Advantages of an Extraterrestrial Observatory’. In it, he meticulously laid out the scientific arguments and engineering challenges of launching and operating a space telescope. Half a century later, NASA would achieve the successful operation of a telescope similar to the one that Spitzer had conceived: the Hubble Space Telescope.
Ideas that Changed the World’s Vision about Space
The initial ideas of placing telescopes in space can be traced back to the early 20th century. In the 1920s, as rocketry was taking off, German engineer and physicist Hermann Oberth published work from his doctoral thesis mentioning that telescopes could be propelled into the Earth’s orbit by the rockets he was working on.
In the 1930s and 1940s, astronomers such as Henry Norris Russell fantasized about the epic possibilities that would be opened up to them by observatories built on the Moon. The appeal of telescopes in Earth’s orbit or on the Moon was clear and simple: it put our most valuable tools for astronomical research beyond the boundaries of the Earth’s atmosphere. When using a telescope here on the Earth, the atmosphere basically causes nothing but problems.
Turbulence in the atmosphere causes ‘seeing’—that same phenomenon that modern deformable mirrors and adaptive optics systems work so hard to counter—which inevitably blurs the images captured by telescopes. Wouldn’t it be better, and make for easier and clearer astronomical observations, to simply put the atmosphere behind us entirely and take observations from space?
The Challenges of Launching a Space Telescope
A telescope in space would unarguably be better for the practice of astronomy, but the engineering challenges were immense. When Lyman Spitzer wrote his paper, no object had ever been launched into Earth’s orbit. During the following decade, a few astronomers took observations from space using detectors onboard sub-orbital rockets, but the detectors were tiny and the rockets only spent a few minutes at the altitudes required to carry out their observations.
Even as the space program was beginning, everyone understood that weight would be a major concern, since heavier objects required larger and more powerful rockets to carry them into orbit. Sputnik weighed less than 200 pounds when it was launched into orbit in 1957; the Hubble Space Telescope ultimately weighed just over 12 tons when it launched in 1990.
(And remember that the mirror for the 200-inch telescope at Palomar weighed 14.5 tons by itself!)
Even beyond weight, telescopes here on the ground were delicate and complex systems, requiring support infrastructure, regular repair and maintenance, and, most important of all, perfectly shaped mirrors.
Astronomers also worried about pouring years of time and effort into a telescope that could simply explode on a launchpad, destroying an immense investment by the field. Still, telescopes were a part of early space program efforts.
This article comes directly from content in the video series Great Heroes and Discoveries of Astronomy. Watch it now, on Wondrium.
Lyman Spitzer’s Plan
These facts made Spitzer’s publication audacious, but not impossible. He was the first scientist to propose a concrete and carefully reasoned plan for putting telescopes in space. Combining the latest research on rocket technology and telescope building, he had grand plans for the potential of space-based astronomy, imagining the possibilities of everything from a petite 10-inch telescope to an enormous 50-foot observatory.
His proposals were largely met with mild skepticism within the astronomy community until Sputnik was launched into space, bringing Earth-orbit satellites and all of their accompanying possibilities to the world stage. Even then, astronomers were still nervous about throwing support behind a space-based telescope.
At the time, the 200-inch telescope was working wonderfully, and it had been built for a tenth of the estimated 100 million dollar cost to launch a single, simple, space satellite.
The OAO and the LST
By 1968, NASA had launched several small space telescopes, including the Orbiting Astronomical Observatory, or OAO, a collection of small telescopes that observed ultraviolet light—a wavelength impossible to capture from beneath the Earth’s atmosphere because most of it is absorbed by the ozone layer.
The OAO relayed data for four years, quadrupling its expected lifetime and conclusively demonstrating that space-based astronomy was a successful and worthwhile endeavor. Fresh off of these early successes, in 1968, NASA began planning for a space-based telescope with a 10-foot mirror—creatively nicknamed the Large Space Telescope, or LST—with a planned launch date of 1979. However, the LST quickly ran into setbacks. Public interest in space exploration waned following the 1969 Moon landing and the conclusion of the Apollo program in 1975.
Moreover, building a telescope to operate in space was far more costly than building one here on the Earth, and with the public questioning more spending on space programs the United States Congress grew critical of the project. Spending cuts in 1974 eventually led to Congress removing all funding for the telescope project. This definitely put a damper on Spitzer’s plan.
Common Questions about the Challenges of Building, Launching, and Operating a Space Telescope
Lyman Spitzer was an astrophysicist who published a research paper in which he carefully elaborated on the scientific arguments and engineering challenges of launching and operating a space telescope. Spitzer was the first scientist to propose a precise plan for placing a telescope in space.
The OAO, short for the Orbiting Astronomical Observatory, was a collection of small space telescopes that were launched by NASA in 1968. The OAO was successful to observe the ultraviolet light from space, a light that is impossible to be observed from the Earth.
The LST, or Large Space Telescope, was planned to be launched by NASA in 1979. But public interest in space exploration declined after the end of the Apollo program in 1975. In addition, the US Congress criticized the high cost of building a space telescope and then cut off all funding needed to build it. Obviously, things didn’t go as was planned for, and the project quickly ran into setbacks.