Roman Space Telescope Launches to Probe Dark Matter, Dark Energy — SkimNews
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- NASA launched the Nancy Grace Roman Space Telescope on 30 August, and its 300-megapixel camera was activated two weeks later, producing unfocused test images that mission scientists called a sign the observatory is 'in really good shape.'
- Roman carries a Hubble-sized primary mirror but a field of view roughly 100 times wider and a structure less than a quarter of Hubble's weight, allowing it to map the sky about 1,000 times faster — equivalent to 1,000 years of Hubble observations every 10 months.
- Over its five-year primary mission, Roman is expected to observe about 12% of the sky in detail, compared with Hubble's 0.1% over 35 years, with the wide view designed specifically to overcome 'cosmic variance' in studies of the universe's large-scale structure.
- Roman will conduct weak gravitational lensing measurements — one of the most stringent drivers of the telescope's design — to map how foreground dark matter and dark energy warp light from background galaxies across cosmic time.
- Kristen McQuinn, who heads the Roman mission office at the Space Telescope Science Institute, will use the telescope to study small galaxies, whose shallow gravitational potential wells make them unusually sensitive to dark matter physics and the conditions of the early universe.
- Roman will also use Type Ia supernovae as 'standard candles' to measure the universe's expansion rate out to far greater distances than current instruments, testing whether the acceleration driven by dark energy has changed across different epochs.
- By measuring how galaxies cluster, Roman can help narrow down dark matter particle candidates — warmer or lighter particles would produce looser clustering, while colder or heavier ones would yield more compact clustering.
Why it matters: Dark matter and dark energy together account for about 95% of the universe, yet their nature remains unknown. Roman's combination of Hubble-class optics and a panoramic field of view gives it the statistical reach to test competing dark matter and dark energy models in a single five-year mission — potentially resolving two of the most stubborn questions in cosmology.
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