The history of science is filled with great debates over fundamental questions concerning the universe in which we live. Is the Earth flat or round? Does the Earth orbit the Sun, or is the Earth the center of the known universe? Are the "spiral nebulae" clusters of stars within our own Galaxy, or are they entire galaxies unto themselves located at great distances? These are but three of many challenges that astronomers have had to face as they ask questions to learn about the nature of the universe. Today, we find that another great debate confronts us, provided by data from NASA's Burst and Transient Source Experiment (BATSE) aboard the Compton Gamma Ray Observatory. The late great debate concerns the nature of puzzling astrophysical events known as gamma-ray bursts.
Although
gamma-ray bursts are a phenomenon that have been studied for over 25 years,
the debate regarding their nature is far from being solved. Gamma-ray burst
data from the BATSE experiment are obtained daily, continually adding new
observations to the controversy that has enveloped the scientific community.
The seeming difficulties scientists are facing in unlocking the secrets
of gamma-ray bursts are not from a lack of effort or poor-quality data.
Some of the world's best and brightest scientists are engaged in efforts
to learn about these enigmatic events. The BATSE experiment and the Compton
Gamma Ray Observatory are unparalleled in terms of the quality, quantity,
and impact of the scientific data they have produced since their launch
in April 1991. In fact, the high-quality data is partially the reason for
the dilemma we find ourselves in. The quality of data is such a vast improvement
over previous instrumentation, the new and more detailed look at gamma-ray
bursts has led to the rejection of almost everything that scientists had
theorized about these explosive events prior to the observations of BATSE
and the Compton Observatory.
The gamma-ray burst debate is a fundamentally
interesting phenomenon to both scientists and non-scientists alike. How
many other events can you think of which occur on a daily basis, yet defy
scientists to answer even simple questions such as "How far away are
the bursts?" This is a controversy that can be well-understood at some
level by almost anyone, regardless of their scientific background. The fact
that we can have such a vibrant, interesting, and controversial debate such
as this is a testament to the quality engineering of the spacecraft and
instrument development teams, to the skill and capability of the scientists
involved, and to the general public, without whom the financial resources
would not exist to pursue such an exciting endeavor.
We begin in Chapter 1 with a review of some fundamental astronomy concepts. It is essential to have a minimal familiarity with some terminology and basics of astronomy in order to fully appreciate the puzzle that scientists face in learning about gamma-ray bursts. Chapter 2 is a summary of some of the basic gamma-ray burst properties. This will familiarize the reader with what a gamma-ray burst looks like and what its general characteristics are. The subsequent chapter discusses how gamma-rays are detected. When fishing, the proper lure can make a large difference in the type of fish one catches. Likewise in astronomy, the detection of different kinds of radiation requires different types of detectors. After these three chapters, the reader is prepared to play the part of the astronomer and to detect some bursts. The fourth chapter discusses the fundamentals of early burst observations, theories, and speculations. Based on these, we make predictions for the outcome of the observations of BATSE, a new and more sensitive detector. The revolutionary results of BATSE are presented in Chapter 5, and Chapter 6 discusses the implications of these observations. Chapter 7 presents some additional observations as well as a brief summary. The text has been presented so that it may be read at many different levels. In the chapters, a general account of the exciting and bewildering observations of the gamma-ray bursts is provided. The reader who is interested in more technical and scientific detail underlying the concepts of the chapter is offered a supplement section at the end of the chapter.
The mysteries surrounding the gamma-ray bursts are far from being resolved. Scientists find themselves at a critical period in the discovery of the nature of these events. This text is motivated partly out of a desire to impart the excitement and wonder of working on the mystery, not necessarily to present the problem in its solved and completed form. The rewards of science are as much intertwined with the pursuit of an answer as they are with the final solution to a given problem. Regardless of the reader's scientific literacy level, in these following pages one will discover some of the prominent features of the current great debate, learn some of the primary questions that scientists are struggling to understand, and explore the role of NASA's Compton Gamma Ray Observatory and BATSE experiment in the study of gamma-ray bursts.
 Chapter 1: The Playing Field |
Chapter 2: The Gamma-Ray Burst Baseball Card |
Chapter 3: Watching The Game |
| Chapter 4: Pre-Game Analysis |
Chapter 5: The First Pitch |
Chapter 6: What Game Are We Playing? |
| Chapter 7: Extra Innings |
Glossary | |
This educational resource was developed at the NASA/Marshall Space Flight Center with the assistance of Ms. Sherene Rizvi and Ms. Labraunna Friend as part of the 1995 Summer High School Apprenticeship Research Program (SHARP).
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Author: Dr. John M. Horack
Curator: Linda Porter
Responsible Official: Gregory
S. Wilson