A Decade of Space Observations

A Decade of Space Observations: The Early Years of the Space Physics Laboratory

George A. Paulikas and Steven R. Strom

Little was known about the space environment when the space race kicked into high gear, but Aerospace quickly helped fill the knowledge gap.

In its initial mission statement, The Aerospace Corporation pledged "to apply the full resources of modern science and technology to achieving continuing advances in military space systems, which are basic to national security." Space systems, of course, are subject to the effects of the space environment, yet when Aerospace was established in 1960, many characteristics of that environment were completely unknown. James Van Allen had discovered the first of two major radiation belts surrounding Earth in 1958 after analyzing data from the first U.S. satellite, Explorer I. His work was widely hailed as one of the outstanding scientific achievements of the International Geophysical Year (July 1957–December 1958). And yet, despite this significant contribution to the study of space environments, many questions regarding the hazards of space radiation for spacecraft and astronauts remained unanswered. Investigating the characteristics of this radiation and applying the knowledge to the operational needs of space systems marked one of the earliest scientific and engineering challenges for the young Aerospace program.

The first president of Aerospace, Ivan Getting, and other early corporate leaders recognized that scientific research was critical for long-term success. From the start, they supported a strong technical research program. Chalmers Sherwin joined the corporation soon after it was formed as vice president and general manager of Laboratory Operations, whose goal was "to advance the state of the art in areas critical to achieving continuing scientific advances in the field of ballistic missiles and military space systems." Early space-radiation studies took place in the Space Physics Laboratory, one of five laboratories in the division. Initially directed by Robert A. Becker, the laboratory made enormous progress toward understanding the dynamics of space radiation and other aspects of the space environment.

The San Fernando Observatory was constructed in 1969 by The Aerospace Corporation at the Van Norman Reservoir near Sylmar, California. It was built for the Space Physics Laboratory with the purpose of conducting solar research.

Sherwin summarized the tasks and goals of the Space Physics Laboratory in a report for the board of trustees in August 1961. The laboratory's research responsibilities, he wrote, were to investigate "infrared sources associated with spacecraft" as well as environmental requirements for space weapons systems and military reconnaissance satellites. The laboratory would also formulate "a theoretical basis for the comprehension of the various phenomena which occur in space."

The report described the laboratory's considerable activity and notable achievements: Just one year after the founding of Aerospace, the laboratory was supporting the BAMBI Orbital Interceptor System; the VELA Hotel program (a system for detecting nuclear explosions); ADVENT, a geosynchronous communications satellite for the Army (later canceled before completion); and the MIDAS infrared satellite warning system. Laboratory scientists had also made rapid progress in understanding the space environment both inside and outside Earth's atmosphere. The group had conducted a feasibility study for analyzing the chemical composition of lunar and planetary surfaces and developed flight prototypes for a nuclear detector designed to measure particles in the Van Allen radiation belts, auroral zones, and solar flares. The laboratory had also planned and designed experiments for a vacuum-ultraviolet research program, an infrared-radiation research program, and a program to develop devices to detect nuclear explosions in space.

The rapid pace of experimentation and research during this early period created a stimulating, though challenging, work environment. Laboratory facilities were dispersed throughout the Los Angeles Air Force Base in various offices and trailers stationed in the parking lot. Despite this lack of elbow room, laboratory personnel were excited to participate in Aerospace's groundbreaking studies. By the summer of 1961, approximately 30 people had joined the lab from various organizations. Steve White and Stan Freden, early pioneers in space physics, came from Livermore National Laboratory; Forrest Mozer and David Elliott from the Lockheed Palo Alto laboratories; John Stevens from Caltech; Bernie Blake from the University of Illinois; and Al Vampola from General Dynamics. Others included Earle Mayfield, Gilbert Cook, Henry Hilton, John Mihalov, Dale Vrabec, and Sam Imamoto. Significantly, an early analysis by Freden and Mozer showed that adequate knowledge of radiation belts did not exist, and the measurement programs proposed by NASA and the Air Force would not provide it—at least not within the next few years, when the Air Force needed it most. Their analysis further spurred the laboratory's space radiation studies.

Because of its work with the Air Force, Aerospace was particularly well positioned to measure radiation in space and characteristics of the upper atmosphere. Researchers anticipated that their experiments, which required access to space, could hitch rides aboard Air Force launch vehicles. One early series of experiments, for example, flew research payloads into low polar orbit aboard the Discoverer spacecraft (now known as the declassified CORONA reconnaissance program). Plans were also made to place radiation measurement devices aboard ADVENT. In parallel, Aerospace proposed sending a self-contained, small radiation-measuring satellite on a low-cost booster, such as a Scout. Thus, by early 1962, the Space Physics Laboratory was already exploring the full range of options for studying the space environment.

As with many other programs in the early years of the corporation, space radiation studies received a boost by a startling development in the arms race between the United States and the Soviet Union. Beginning in 1958, the United States had exploded a series of low-yield nuclear devices at high altitudes, but the scale and scope of nuclear testing in space escalated dramatically in the summer of 1962, leading to unforeseen consequences. The United States detonated a high-yield (1.4 megaton) nuclear device, code-named "Starfish," on July 9 above Johnston Island west of Hawaii at an altitude of 400 kilometers. The enormous explosion created a new radiation belt and produced an aurora that lasted about seven minutes. In the aftermath, the intensity of radiation in space increased a thousandfold. Several spacecraft were damaged or destroyed. The need to understand the characteristics of space radiation now acquired greater urgency, as it was clear that a nuclear detonation in space could conceivably disable military satellites. The sense of urgency was heightened when the Soviets began their own series of high-altitude nuclear detonations later that year.

Research at the laboratory accelerated to a pace that is hardly imaginable today. For example, three radiation-measuring devices flew as secondary payloads on the Agena spacecraft that carried the CORONA payloads into orbit in the fall of 1962. The radiation measurement program evolved and expanded to include plans for not only additional piggyback payloads, but also several types of free-flying satellites flown aboard Scout, Atlas, and Titan boosters as well as additional payloads flown aboard several NASA spacecraft. The measurements obtained through these devices established in greater detail the characteristics of the near-Earth radiation belts—the fluxes, spectra, and spatial distribution of electrons, protons, and alpha particles trapped in Earth's magnetic field.

Members of space physics lab, circa 1970

Planning the development of a solar pointer are C. K. Howey, W. T. Chater, and A. B. C. Walker Jr., of the Space Physics Laboratory, circa 1970.

Aerospace scientists were able to determine the decay time of the energetic electrons injected into Earth's magnetic field by the American and Soviet nuclear detonations. The data on space radiation were communicated in real time to Aerospace program satellite offices and, as appropriate, more broadly to the nation's technical community. With NASA support, Aerospace initiated a program under the leadership of Jim Vette to construct models of the space environment, resulting in the NASA series of AE (Aerospace electron) and AP (Aerospace proton) models of the space radiation environment. These early models and their successors have been instrumental in establishing standards for space-system design and space radiation protection.

Data obtained from these efforts put Aerospace at the forefront of space radiation studies. By 1962, new findings led to new initiatives, including a program to study the phenomenon of spacecraft charging and its effects on electronic systems. New insights were gained into how Earth's magnetic field shields the local region of space from solar cosmic rays and how the flow of solar wind modulates radiation trapped in Earth's magnetic field.

The United States was committed to sending an astronaut to the moon by the end of the decade, but had little experience with human spaceflight. Aerospace measurements of space radiation revealed potential hazards for astronauts traveling through certain regions of space, but also indicated that if these regions were avoided, the hazards were manageable. Aerospace studies also determined that a properly hardened spacecraft could operate for many years in the space environment. For the most part, the early Aerospace research provided information that was entirely new in the field of space physics, although some of it served to confirm or extend earlier findings.

Bruce H. Billings took over as head of Laboratory Operations following Sherwin's departure in April 1963. Meanwhile, Becker continued to direct the Space Physics Laboratory, guiding its course through the mid-to-late 1960s. By the end of 1963, the lab was assisting the Air Force with the Manned Orbiting Laboratory (MOL), a program that would increase in importance at Aerospace throughout the decade. Even though the MOL program was not formally approved by President Lyndon Johnson until 1965, Billings noted in his first Quarterly Technical Report in February 1964 that all of the laboratories were involved in preliminary studies of "the various types of experiments that can be done in the Manned Orbiting Laboratory." The MOL program was of particular interest to the Space Physics Laboratory, because, as Billings noted, "knowledge of the space environment is certainly a requirement for any military space operation." Laboratory personnel were involved with the series of experiments scheduled for the Air Force astronauts onboard MOL, as it was believed that there were "many areas where the presence of a man can vastly facilitate the collection of space environmental data." Programs to support MOL included ground-based and space-based observations of the sun, studies of solar activity, and studies of x-ray emissions from the sun. Participating in this work were Mayfield, Vrabec, Hugh Rugge, Arthur Walker, and Ernest Rogers.

Also in 1964, two previously planned projects came to successful conclusions. A series of experiments dealing with space radiation were flown on a Discoverer satellite, which also carried several experiments designed to characterize the infrared and ultraviolet backgrounds of Earth. These backgrounds needed to be understood so they could be filtered out by any proposed missile-launch detection systems. In addition to these discoveries, Mayfield, Vrabec, and Richard Hall designed an advanced interferometer, which helped usher in the new field of far-infrared spectroscopy.

Scientists developing research instruments

A model of an inner radiation belt Cerenkov counter is tested by Samuel Solow, Norman Katz, and W. A. Kolasinski (seated).

Payload capacity gradually increased in the mid-1960s, and researchers enjoyed a shorter waiting period to get their experiments into orbit. The increase in payload size, together with the Air Force's acceptance that some payloads could be used for pure research, enabled the laboratory to expand the number of its onboard experiments. Beginning in 1965, Aerospace was also assisted by the Air Force Space Systems Division's Space Experiments Support Program, which was created, in part, to match experiments with available satellite payload space. The program clearly demonstrated the Air Force's recognition of the practical benefits of Aerospace research. Billings remarked that the growing awareness of the need for these experiments was "increasing the stature of our Space Physics Laboratory and increasing their usefulness to Aerospace and [the Space Systems Division]."

Additional research between 1964 and 1966 helped expand the space radiation knowledge base. Experiments mounted on P-11, a small radiation-measuring satellite instrumented by the laboratory, returned a steady stream of data that enabled Aerospace scientists to measure high-energy proton spectra over a wide portion of the outer radiation belt. The laboratory also participated in the Space Systems Division Satellite Survivability Program, which was initiated to determine the survival chances of a satellite that had been exposed to radiation from a nuclear device. In 1966, as part of its ongoing support for MOL, the lab was assigned to study the hazards that solar flare particles might cause for astronauts.

The years 1967–1968 witnessed the continuation of what Billings called the "frantic pace" of work in the Space Physics Laboratory. The first NASA Advanced Technology Satellite, launched in December 1966, carried an Aerospace experiment, and it continued to return data for several years. This satellite provided the first opportunity to study a radiation belt in a synchronous orbit and helped Aerospace scientists ascertain the hazards posed by radiation to various detector systems.

The Solar Perturbation and Atmospheric Density Experiments Satellite (SPADES) with nine experiments onboard was successfully launched into a polar orbit on July 11, 1968. According to Gilbert King, vice president of the laboratories at the time, SPADES was "the most elaborate satellite ever orbited by the [Air Force] Office of Aerospace Research." It was conceived to help the Air Force Space and Missile Systems Center better predict the ephemerides of satellites at low altitudes. The laboratory in 1968 also participated in projects to develop sensors for Project 949, a satellite to detect nuclear explosions and missile launches. Aerospace was assigned the task of completely redesigning the nuclear-burst detection package for the program's second block of satellites. The research for this work was completed that year, and the results filled a four-volume study.

Scientists from Space Physics Lab, circa 1970

D. D. Elliott, S. R. LaValle, and R. L. Williams examine photometers to measure altitude and latitude distribution of atmospheric airglow layers, circa 1970.

Administrative changes affected the laboratory in 1968. In August, Becker was promoted to associate general manager of laboratories, and George Paulikas, who had served as head of the laboratory's particles and fields department, became the laboratory's new director. Department heads were Blake, particles and fields; Mayfield, solar physics; Rugge, laboratory aeronomy; and Elliott, space radiation and atmospherics.

The laboratory continued its involvement in a variety of pathbreaking projects as the end of the 1960s approached. Because 1969–1970 was a period of maximum solar activity, members of the laboratory spent a good deal of time at Aerospace's San Fernando Observatory, which was dedicated on February 19, 1969. The observatory, built at the Van Norman Reservoir near Sylmar, California, was part of the Space Physics Laboratory. One of the observatory's missions was to support the MOL program with investigations of the active regions of the sun that contribute to changes in the space environment. Although MOL was canceled in the summer of 1969, important data on the evolution of active solar regions were gathered at the observatory, which continued as an important source of solar observations until 1976. In the related area of "space weather," T. Y. Chiu made an important contribution through his studies of gravity waves. Chiu solved the differential equation for wave propagation in the upper atmosphere, thereby contributing to the operational procedures of controlling satellites.

By 1970, the reputation of the Space Physics Laboratory was solidly established after only 10 years of operations. In April, laboratory personnel were called upon to assist NASA with the return of the crippled Apollo 13 spacecraft because of their "extensive knowledge of the inner radiation belts." Aerospace data confirmed that the thin-skinned Lunar Module could safely travel through the radiation belts, thereby relieving "considerable apprehension" at NASA about earlier, short-term readings from instruments flown aboard Apollo 12. In a very different project, the laboratory conducted a study for the U.S. Department of Transportation in 1970 to determine whether the planned supersonic transport would change the ozone concentration in the stratosphere and lead to enhanced ultraviolet radiation at Earth's surface.

Robert Becker wrote in a 1970 report that the great respect that the laboratory had so quickly gained in scientific circles resulted from its "decade of observations from space." By that time, the laboratory had conducted experiments on 30 NASA and Air Force satellites and listed among its many achievements the first identification of solar electrons over the polar regions, the collection of detailed data of the radiation environment in the range of synchronous orbit, the formulation of dynamic and predictive models of the upper atmosphere, and the first satellite measurements of atmospheric density at altitudes below 275 kilometers. Getting noted in his memoirs that "much of the work done at Aerospace was at the frontiers of science"; clearly, that describes the early research work of the Space Physics Laboratory.