My highly referenced papers are all based on data from the Cosmic Background Explorer (COBE) satellite, which was launched in 1989. I became involved with space missions after working on both stratospheric balloon flights and airborne infrared astronomy. I was used to working in "D-mode" (discovery mode) in fields where data were practically non-existent. And having had the first three balloon flights of my thesis experiment fail completely did prepare me for the uncertainties of space flight.

My first involvement in the COBE project was with the instrument to measure the spectrum of the cosmic microwave background-radiation (CMB), the Far InfraRed Absolute Spectrophotometer (FIRAS). In 1978, Rainer Weiss asked me if I was interested in working on COBE, and when I said yes, he gave me the job of designing a brassboard version of the symmetric Martin-Puplett polarizing Michelson interferometer that John Mather had devised. This brassboard showed that the FIRAS concept would work, and it was used for many years as a laboratory submillimeter spectrometer.

The dangers of space flight came back to haunt me in January 1986. While driving from one COBE meeting to another at Goddard Space Flight Center, I heard the CBS radio news announcer talking about how something was terribly wrong with the Challenger launch. When I arrived at Building 7 there was no thought of having our meeting. Everybody stood around watching televisions replaying the horrible explosion again and again. At this time COBE was being built for a shuttle launch, and it took nearly a year to finally come up with a recovery plan. COBE would be rebuilt for an expendable Delta rocket, at one-half the mass of the shuttle design, with no loss of scientific capability. On 18 November 1989, after standing around in the cold and dark from 3:00 a.m. until the rising Sun was bisected by the horizon, COBE was finally launched from Vandenberg AFB in California.

The standard Big Bang model for cosmology predicts that the CMB should have a spectrum that is almost exactly a blackbody or Planckian spectrum. But in 1978, the best experimental data suggested that the CMB spectrum deviated from a blackbody by more than 10% of the blackbody peak. But FIRAS was specifically designed to measure deviations from a blackbody spectrum, with a specified accuracy of 0.1%. By 1989 the earlier data had been superseded twice, but the best results still showed a 5% deviation from a blackbody. But when I called the control room 12 hours after the cover was ejected, I heard that FIRAS was showing a good null with the internal calibrator at 2.76 K. This showed that all the previous measurements showing deviations from a blackbody were wrong, and the Big Bang was confirmed. FIRAS outperformed its specification, ultimately showing that the CMB spectrum deviated from a blackbody by less than 0.005%.

While FIRAS was collecting data on the CMB spectrum, it also mapped most of the sky and measured the far infrared and submillimeter spectrum of the Milky Way. This spectrum is presented in Wright et al. ("Preliminary spectral observations of the galaxy with a 7-degrees beam by the Cosmic Background Explorer [COBE]," Astrophysical Journal, 381[1]:200-9, Part 1, 1 November 1991), and it includes the first-ever detection of the 205-micron line of singly ionized nitrogen. The strongest spectral line from the Milky Way is the 158-micron line from singly ionized carbon. Two lines from neutral carbon and many lines from carbon monoxide were also seen.

The two most highly cited papers, Smoot et al. ("Structure in the COBE differential microwave radiometer 1^st-year maps," Astrophysical Journal, 396[1]:L1-5, Part 2, 1 September 1992) and Wright et al. ("Interpretation of the cosmic microwave background-radiation anisotropy detected by the COBE differential microwave radiometer," Astrophysical Journal, 396[1]:L13-8, Part 2, 1 September 1992), discuss the first detection of the intrinsic anisotropy of the CMB measured by the Differential Microwave Radiometers (DMR) on COBE and the interpretation of this anisotropy. Both of these Astrophysical Journal letters are derived from a draft paper that I presented to the COBE Science Working Group (SWG) in October 1991, following my E-mail announcement to the SWG in August 1991 of the existence of a signal. Bennett et al. ("Four-year COBE DMR cosmic microwave background observations: Maps and basic results," Astrophysical Journal, 464[1]:L1, Part 2, 10 June 1996) gives the final results from the DMR experiment based on 4 years of data.

The DMR experiment was such a success that 25 experiments have now measured the CMB anisotropy. And two future space missions, NASA's Microwave Anisotropy Probe (MAP) and ESA's PLANCK Explorer, are both seeking to repeat the DMR measurements with higher angular resolution. I am working on MAP, which will be launched in 2001.

Finally, I am also working on the Space InfraRed Telescope Facility (SIRTF) which will repeat the far-infrared measurements made by the balloon-borne telescope of my thesis research will much greater sensitivity. SIRTF is scheduled for launch in 2002.

Dr. Edward L. Wright
UCLA
Department of Physics and Astronomy
Los Angeles, CA, USA