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In August 2026 NASA launched a space telescope with a 2.4-metre mirror, the same size as Hubble's. It carries the name of the woman NASA calls the "mother" of Hubble. Nancy Grace Roman did not build telescopes with her hands. She built the programme that made them possible. This post covers what she did, why telescopes go to space at all, and a short calculation on mirror size and sharpness.
Who was Nancy Grace Roman?
NASA's 2020 naming announcement records that she was born on 16 May 1925 in Nashville, Tennessee, and knew by seventh grade that she wanted to be an astronomer. The head of physics at Swarthmore College told her he usually discouraged girls from majoring in physics, but that she "might make it". She earned a bachelor's degree in astronomy from Swarthmore in 1946 and a doctorate from the University of Chicago in 1949.
Her obituary in the Bulletin of the American Astronomical Society, by the historian David DeVorkin, adds that her research at Yerkes Observatory found a link between how stars move through the galaxy and their abundance of heavy elements. It was not highly valued at the time, but she felt most proud of it late in life. She left academic research partly because she judged that, as a woman, she would not advance beyond junior posts at places like Yerkes.
What did she do at NASA?
Roman joined NASA in 1959, six months after it was founded, as chief of astronomy and relativity in the Office of Space Science. NASA's release says she managed astronomy programmes and grants. She also said in one interview that she had to use the title "Dr." because "otherwise, I could not get past the secretaries."
Under her leadership NASA launched four Orbiting Astronomical Observatories between 1966 and 1972. Only two worked, but they showed what space astronomy could do. She also championed the International Ultraviolet Explorer and the Cosmic Background Explorer. DeVorkin counts some 20 satellite missions in her two decades. She retired in 1979 and died on 25 December 2018.
Why put a telescope in space?
NASA's release gives the reasons in plain terms. Earth's atmosphere blocks much of the radiation from the distant universe, so some wavelengths can only be measured from above it. And only a telescope in space has "perpetual nighttime" and never has to stop for daylight.
How did the Hubble mirror end up 2.4 metres?
In the mid-1960s, NASA's release says, Roman set up a committee of astronomers and engineers to define a large space telescope. DeVorkin writes that the hardest question was size. Working with project scientist C. R. O'Dell and the science working group, she balanced scientific goals against engineering, cost, what Congress might accept and what the Space Shuttle could launch. The 120-inch goal for the mirror was reduced to 94 inches, about 2.4 metres.
What did that cost in sharpness? The smallest angle a telescope can resolve, set by diffraction, is about θ = 1.22λ/D.
Worked example, for visible light with λ = 500 nm:
94-inch mirror. D = 94 × 0.0254 = 2.39 m. θ = 1.22 × 5.0 × 10⁻⁷ / 2.39 ≈ 2.55 × 10⁻⁷ rad.
Convert to arcseconds. Multiply by 206,265: about 0.053 arcseconds.
120-inch mirror. D = 3.05 m gives θ ≈ 2.00 × 10⁻⁷ rad, about 0.041 arcseconds.
Compare. The ratio is 3.05/2.39 ≈ 1.28. The bigger mirror would have been about 28% sharper and, with area going as D², would have collected about 63% more light.
Common mistakes: forgetting the factor 1.22 for a circular mirror, mixing nanometres with metres, and leaving the answer in radians when the question asks for arcseconds. Our post on optical instruments covers resolving power for school exams.
What is the Roman Space Telescope doing now?
In May 2020 NASA renamed its Wide Field Infrared Survey Telescope after her. The release says the telescope's primary mirror is 2.4 metres across, the same as Hubble's, and its Wide Field Instrument has a field of view 100 times larger than Hubble's infrared instrument. Its goals include dark energy and the search for exoplanets.
NASA's Roman mission page gives the launch date as 30 August 2026. On 22 October 2026 the Roman blog reported that the observatory had entered its science commissioning phase after checkout of the observatory and its main instrument. Check NASA's pages for the latest status.
What can a student take from how Roman worked?
Learn to speak to two groups. She translated between scientists and engineers.
Accept the workable version. A 94-inch telescope that flew beat a 120-inch one on paper.
Do not let doubt set your limits. Her physics head said she "might make it". She went on to shape space astronomy.
If θ = 1.22λ/D still feels like a formula without a picture, the Fermi Simulation Lab has interactive simulations for ideas that are easier to see than read.
Next step: work out the diffraction limit of a 2.4-metre mirror at an infrared wavelength of 1.5 micrometres, and compare it with the visible result above.
