A MEETING WITH THE UNIVERSE

Chapter 7-4



The Violence Around Us

The universe beyond the solar system has become almost unrecognizable since the Space Age began. It is no longer viewed as the peaceful stellar background that earlier astronomers envisioned; instead, it is a region filled with strange forces, turbulent clouds of dispersed matter, and unexplained floods of energy. How can we begin to comprehend it all?

First, we need to observe the universe from space over longer periods of time. Much of our knowledge comes from instruments lifted above our atmosphere, on rockets or satellites, for short periods of time, a few minutes, a few months and, in a few cases, a year or two. Each instrument has seen only a limited spectral range - ultraviolet or X-rays, for example - so that it has been difficult to observe different radiations from a single object at the same time. We have many fragmentary and exciting observations, but still no systematic view of the puzzling and awesome phenomena that have been discovered.

concept drawing of an orbital space telescope
Looking toward the dawn of time.
The Space Telescope, with a planned launch into Earth orbit in the mid-1980s, will give astronomers the most powerful view yet of the universe around us. Provided with a complement of advanced cameras, spectrographs, and other devices, it will see much further than ground based telescopes and with far greater clarity, obtaining pictures of unprecedented sharpness and astrophysical measurements of unique sensitivity. Researchers can then observe distant galaxies as they appeared when light rays left them billions of years ago.
 

This knowledge gap will be partly filled in the mid-1980s, when we finally realize the age-old dream of astronomers to place a long-lived observatory outside the Earth's atmosphere, where it would command an unobstructed view of space. This project, the Space Telescope, is now under way and scheduled for launch in the mid-1980s aboard the Space Shuttle. The spacecraft will carry a mighty telescope 2.4 meters (94 inches) in diameter, highly automated, and capable of seeing, not only in visible light, but in ultraviolet and eventually in infrared as well.

The launch of Space Telescope will be a major event in astronomical history, like the construction of the great Mount Wilson and Mount Palomar reflectors several decades ago. It will truly be a major observatory in space.

Although the Space Telescope is only about half the size of the 200-inch (5-meter) Hale Telescope on Mount Palomar, it has no cloudy, wavering air to look through, and it will see five times as far into the universe as well as obtain images of unprecedented sharpness. With the Space Telescope, we can study many other galaxies almost as easily as we now study the stars of our own Milky Way. We will see more clearly the distant, energetic objects that puzzle us: quasars, active galaxies, and neutron star binary systems. Because we will see galaxies so much further away, we will view the universe as it was long ago, and we can begin to better comprehend how it has evolved. We will doubtless see many strange new things that we can not now imagine because we have never been able to see so far or so well before.

Space Telescope cannot do every thing, however. It cannot detect all the radiations and energies that astronomers need to examine. Although it will be the heart of astronomical research during the 1980 sand 1990s, other specialized space instruments are required to complement its work.

Among these is IRAS (Infrared Astronomy Satellite), which is under development as a collaborative project by the United States, the Netherlands, and the United Kingdom. This is a smaller telescope that can detect infrared radiation of types that the Space Telescope cannot observe. IRAS will give us a view of the cooler regions of the universe, the dust clouds that are the birthplaces of the stars, and the core of our galaxy, where intense and unseen energies apparently are hidden behind a screen of dust.

The Space Age has shown us not only a universe of light and heat, but a universe of high-energy radiations X-rays, gamma rays, and cosmic-ray particles-which come from violent and mysterious sources. To study this aspect of the universe, we need more sensitive and capable instruments in space. No single instrument or spacecraft can record all of these radiations at once, so a series of projects is under consideration. Each would observe a part of the complex array of radiation; together they would give us a better view of the energetic side of the universe.

One project would focus entirely on the highest-energy radiations of all - gamma rays. An Earth-orbiting spacecraft (the Gamma Ray Observatory) will carry several detectors to look at gamma rays of all kinds and energies. It will detect and observe new gamma ray sources in the sky, investigate the gamma ray background radiation that comes toward Earth from all directions in space, and analyze the "bursters", those mysterious powerfully erupting sources of intense gamma rays. During the few seconds of a typical gamma ray burst, its unknown source briefly outshines the whole universe in gamma rays.

Different instruments, carried by other spacecraft, could make detailed observations of the other powerful radiations from space. A wide variety of possible programs could be pursued. For example, an advanced system for detecting X-rays would make a systematic study of the X-ray sky and its puzzling sources and explosions. Another spacecraft, carrying instruments to detect weak microwave and infrared radiation, would look even further out and much further back in time. It would look for radiation from the early expanding universe and would scan the sky for slight differences in the background that should give us clues to the details of exactly what happened shortly after the universe was born.

When such advanced instruments are finally placed in space, above the blanketing atmosphere in which we live, we will have made a major step forward in seeing the universe as it really is. We can then sense all of its energies, from the weakest microwave (radio) radiations to the strongest bursts of gamma rays. We will see faint and mysterious objects clearly, and we will be able to look steadily at objects that have only been seen in quick, snatched glances. We will then begin to accumulate the facts we need to answer the many questions about the universe, to plan future experiments and new missions, and to discover new mysteries and questions whose existence we do not now even suspect.



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