The History of Astrophysics at Goddard Space Flight Center

[This essay was written originally by Elihu Boldt. SED science writer Dan Pendick edited the original draft for concision and grammar, and added a significant amount of new content based on library research as well as interviews and email correspondence with Michael Hauser and Ted Gull.]

Science activities at Goddard began in the late 1950s, before "high energy astrophysics" existed by that name. Recollections of the early NASA days would of course vary, but any reviewer would point out that those who defined the research roles here were heroically successful. The priorities then driving space flight activities could otherwise have minimized observational science at this Center to a piggyback participation level - for example, monitoring radiation hazards to astronauts.

Research groups were initiated at Goddard in three areas: astronomy, solar physics, and a catchall category called "fields and particles." Some of the new administrators and specialists were astronomers, but most were physicists from other government labs and particularly from schools in the Midwest. In that region, building rocket and balloon-borne payloads for cosmic ray and related studies had been a way of life.

The year 1958 saw confirmation of Earth's intense "Van Allen" radiation belts and a cosmic-ray "Forbush decrease" far from the Earth's influence. Researchers with backgrounds in cosmic rays were among those who recognized the immense potential for discoveries in space. What were required for progress would be observations of energetic particles, plasmas, and the fields and radiation of various types from Earth, the sun, the Milky Way galaxy, and the universe beyond.

Frank McDonald (1925- ) [1] was a prime mover in the new arena of astrophysics at NASA. His career at NASA spanned the period from 1959 to 1989, which included stints as founding chief of the Energetic Particles Branch (1959) and serving as NASA Chief Scientist (1982-1987). McDonald presided over an extraordinary period of expansion in NASA scientific research.

While NASA Headquarters outlined the new space program, Goddard Space Flight Center developed a wide variety of small, personally designed experiments, evolving from those of the earlier balloon and rocket era. These included both the small Explorer series and, for larger satellites, the Orbiting Geophysical Observatory (OGO) series, a platform carrying dozens of experiments by university and NASA groups. Six OGOs were launched from 1963 to 1969. [2]

The Pioneers and other JPL planetary missions could make some deep-space measurements on their way to the planets, but McDonald promoted an Interplanetary Monitoring Platform (IMP) series of Earth orbiters. These were placed in highly elliptical orbits that crossed Earth's magnetopause to directly explore interplanetary space in detail. IMPs made a wide variety of discoveries regarding the properties of the near-Earth interplanetary environment and of its solar influences. Ten IMPs were launched from 1963 to 1973. [3]

McDonald's physicists placed instruments on a wide variety of spacecraft to study cosmic radiation, solar particles, trapped radiation, auroral particles and magnetic fields. At the same time, they continued to fly high-altitude balloons, and even probed the emissions from solar flares in real time with sounding rockets.

Scientists at Goddard also pursued missions to study the gamma and X-ray universe. In 1965, at the suggestion of Frank McDonald, Elihu Boldt initiated Goddard's program in X-ray astronomy with a series of balloon-borne experiments. At an early stage he was joined by Peter Serlemitsos, who had just completed his PhD space physics thesis on magnetospheric electrons, and by Guenter Riegler, a University of Maryland physics graduate student interested in doing his dissertation research in astrophysics. [4]

Astrophysicists got an early peek at the gamma-ray universe in 1961, when Explorer 11 (S-15) carried the first gamma ray detector into orbit. It could not be pointed precisely, and thus provided only a rough scan of gamma ray sources. Later, in 1972, the Small Astronomy Satellite 2 (SAS-2) carried an early gamma-ray telescope into space. In 1975, NASA launched X-ray and gamma ray experiments aboard the Orbiting Solar Observatory-8 (OSO-8).

In the late 1960s, McDonald began to plan and promote what was to become the High Energy Astronomy Observatory (HEAO) series. In 1977, the first of these missions, HEAO-1 surveyed the X-ray sky. [5] HEAO-2, renamed Einstein, followed in 1978, was the first fully imaging X-ray telescope put into space. [6] The HEAO-3 satellite (1979) was dedicated to cosmic- and gamma-ray astronomy. [7]

A rocket downsizing unfortunately had to eliminate the heaviest of the initially selected experiments. However, one of the originally proposed HEAO gamma-ray payload eventually became the Energetic Gamma Ray Experiment Telescope (EGRET) experiment on the Compton Gamma Ray Observatory (CGRO), which orbited from 1991 to 2000. These missions advanced Goddard astrophysical science in both x-ray and gamma-ray astronomy towards eventual world-class status.

Development of new technology was always encouraged in Goddard astrophysicists to exploit opportunities to advance space science. Two early and important advances were the digitized spark chamber for gamma-ray astronomy that made SAS-2 [8] (1972) and Energetic Gamma Ray Experiment Telescope (EGRET) possible, and the conical-foil mirrors of BBXRT (Broad-Band X-Ray Telescope) subsequently employed in a variety of missions, such as ASCA, a mission collaboration with the Japanese Space Agency (JAXA) launched in 1993.

McDonald's vision extended further than high-energy astrophysics. In 1974, he also created a new discipline group at Goddard in infrared astronomy. That group had important involvement in the Infrared Astronomical Satellite (IRAS), which was the first space observatory to conduct a complete survey of the sky in infrared wavelengths.

Goddard also flew the historic Cosmic Microwave Background Explorer (COBE) mission. Launched in 1989, COBE's findings have revolutionized cosmology and eventually garnered a Nobel shared by George Smoot and Goddard's John Mather. Goddard infrared astronomers teamed up with the Smithsonian Astrophysical Observatory to build the Infrared Array Camera (IRAC) for the Spitzer Space Observatory (2003). Goddard also teamed up with Princeton on the Wilkinson Microwave Anisotropy Probe (WMAP). Launched in 2001, WMAP was a follow-on to COBE. [9]

The magnetosphere and space physics group also became a separate entity from the astrophysics group after its considerable successes and growth. Cosmic ray studies here have matured with complex balloon payloads and with experiments on the International Sun-Earth Explorer (ISEE), the Global Geospace Science Program (GGS) Series, and the Advanced Composition Explorer (ACE).

Other important projects include major developments in the astronomy of transients, with efforts in the X-ray field (Rossi XTE), and gamma-ray burst work (Swift). These, and the development of the X-ray bolometer and other projects, are described in greater detail on other pages.

As the science component of Goddard expanded and matured, new organizational structures evolved. In 1970, astrophysics research activities were reorganized into Laboratories: the Laboratory for High-Energy Astrophysics (LHEA) and the Laboratory for Extraterrestrial Physics (LEP). In 1978, an additional organization came into existence: the Laboratory for Astronomy and Solar Physics (LASP). Another period of reorganization, which began in 2004, resulted in the present (2012) system of four divisions, with the Astrophysics Science Division (660) and the Heliophysics Science Division (670) containing much of the former contents of the LHEA, LEP, and LASP.

Goddard astrophysicists have made many important contributions during the era of the "Great Observatories" that started with Compton. Besides providing management and ground control for the Hubble Space Telescope, Goddard scientists and engineers helped build instruments and developed tools and techniques for the servicing missions that kept the observatory running productively for more than 20 years.

The age of the James Webb Space Telescope (JWST) is well underway, again with critical involvement by Goddard scientists, engineers, and managers.

Sources

"IMPs, EGOs, and Skyhooks", JGR, 101, 10,521-10,530, by Frank McDonald.

"Essays in Space Science", NASA Conference Publication 2464, with monographs by many of the other innovators in the field, including K. Anderson, E. Boldt, C. Fichtel, R. Giacconi, M. Hauser, S. Holt, J. Naugle, N. Ness, E. Parker, and J. Van Allen.

Footnotes

1. http://www.astronautix.com/astros/mcdonald.htm (No longer active.)
2. https://nssdc.gsfc.nasa.gov/nmc/
3. https://nssdc.gsfc.nasa.gov/nmc/
4. This entire paragraph about the early X-ray research is taken from an essay by Elihu Boldt.
5. https://heasarc.gsfc.nasa.gov/docs/heao1/heao1.html
6. https://heasarc.gsfc.nasa.gov/docs/einstein/heao2.html
7. https://heasarc.gsfc.nasa.gov/docs/heao3/heao3_about.html
8. https://nssdc.gsfc.nasa.gov/nmc/spacecraftDisplay.do?id=1972-091A
9. IR information: Michael Hauser, 11/29/2011, personal communication.