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Starts With A Bang

How Much Better Than Hubble Would A Roman Deep Field Image Be?

The scale of the Hubble Ultra Deep Field (blue box) versus the field of view of the Nancy Roman Telescope (orange boxes). Each of Roman’s 18 independent viewing instruments is more than 10 times the field of view of the most famous deep Hubble image. (NASA, ESA, AND A. KOEKEMOER (STSCI); ACKNOWLEDGEMENT: DIGITIZED SKY SURVEY)

One image can give over 100 times the data we now get from Hubble.


NASA’s Hubble Space Telescope, launched in 1990, revealed the previously unseen Universe.

The most distant galaxy ever found: GN-z11, in the GOODS-N field as imaged deeply by Hubble. The same observations that Hubble made to obtain this image will give WFIRST/Nancy Roman more than 100 times the number of ultra-distant galaxies with the same exposure time. (NASA, ESA, AND P. OESCH (YALE UNIVERSITY))

Its large aperture, excellent instrumentation, and location in space enabled ultra-distant views.

The original Hubble Deep Field, which discovered thousands of new galaxies in the abyss of deep space. This region was previously thought to be entirely devoid of galaxies with only a few faint Milky Way stars present. The original Deep Field found thousands of galaxies lurking in this region of sky. (R. WILLIAMS (STSCI), THE HUBBLE DEEP FIELD TEAM AND NASA)

Iconically, Hubble’s deep field images best showcase its capabilities.

The full UV-visible-IR composite of the Hubble eXtreme Deep Field; the greatest image ever released of the distant Universe. There are 5,500 galaxies identified in this tiny region of sky; it would take 32 million of them to cover the ~40,000 square degrees of what’s present in the entire sky. (NASA, ESA, H. TEPLITZ AND M. RAFELSKI (IPAC/CALTECH), A. KOEKEMOER (STSCI), R. WINDHORST (ARIZONA STATE UNIVERSITY), AND Z. LEVAY (STSCI))

By repeatedly pointing its “eye” on a single region, it compiles photons one-at-a-time from the distant Universe.

The Hubble eXtreme Deep Field (XDF) may have observed a region of sky just 1/32,000,000th of the total, but was able to uncover a whopping 5,500 galaxies within it: an estimated 10% of the total number of galaxies actually contained in this pencil-beam-style slice. The remaining 90% of galaxies are either too faint or too red or too obscured for Hubble to reveal. (HUDF09 AND HXDF12 TEAMS / E. SIEGEL (PROCESSING))

Through multi-wavelength observations, Hubble uncovered thousands of the Universe’s most distant objects.

Galaxies identified in the eXtreme Deep Field image can be broken up into nearby, distant, and ultra-distant components, with Hubble only revealing the galaxies it’s capable of seeing in its wavelength ranges and at its optical limits. The dropoff in the number of galaxies seen at very great distances may indicate the limitations of our observatories, rather than the non-existence of faint, small, low-brightness galaxies at great distances. (NASA, ESA, AND Z. LEVAY, F. SUMMERS (STSCI))

Viewing larger regions, Hubble’s Frontier Fields campaign was also revolutionary.

The streaks and arcs present in Abell 370, a distant galaxy cluster some 5–6 billion light-years away, are some of the strongest evidence for gravitational lensing and dark matter that we have. The lensed galaxies are even more distant, with some of them making up the most distant galaxies ever seen. This imagery was part of the Hubble Frontier Fields program. (NASA, ESA/HUBBLE, HST FRONTIER FIELDS)

Gravitation from distant, massive galaxy clusters magnifies and distorts light from background galaxies.

The galaxy cluster MACS 0416 from the Hubble Frontier Fields, with the mass shown in cyan and the magnification from lensing shown in magenta. That magenta-colored area is where the lensing magnification will be maximized. Mapping out the cluster mass allows us to identify which locations should be probed for the greatest magnifications and ultra-distant candidates of all. (STSCI/NASA/CATS TEAM/R. LIVERMORE (UT AUSTIN))

Even today, Hubble remains astronomy’s best space-based optical observatory.

HE0435–1223, located in the centre of this wide-field image, is among the five best lensed quasars discovered to date. The foreground galaxy creates four almost evenly distributed images of the distant quasar around it. Quasars are the most distant objects found in the observable Universe. (ESA/HUBBLE, NASA, SUYU ET AL.)

Many often ask, “why don’t we just build another Hubble?”

The Hubble Space Telescope, as imaged during its last and final servicing mission. Although it hasn’t been serviced in over a decade, Hubble continues to be humanity’s flagship ultraviolet, optical, and near-infrared telescope in space, and has taken us beyond the limits of any other space-based or ground-based observatory. (NASA)

For the same price, current technology enables superior options.

This is an illustration of the different elements in NASA’s exoplanet program, including ground-based observatories, like the W. M. Keck Observatory, and space-based observatories, like Hubble, Spitzer, Kepler, Transiting Exoplanet Survey Satellite, James Webb Space Telescope, Wide Field Infrared Survey Telescope (now the Nancy Roman telescope) and future missions. The power of TESS and James Webb combined will reveal the most Moon-like exomoons to date, possibly even in their star’s habitable zone, while ground-based 30 meter telescopes, the Nancy Roman telescope (formerly WFIRST), and possibly a next-generation space-based observatory like LUVOIR or HabEx is required to truly find what humanity has been dreaming of for so long: an inhabited world outside of our Solar System. (NASA)

NASA’s post-James Webb flagship will be the Nancy Grace Roman Telescope.

American astronomer Dr. Nancy Grace Roman, who was one of the first female executives at NASA, attends the Earth Day March for Science Rally on April 22, 2017. Nancy Grace Roman was NASA’s first chief astronomer, who paved the way for space telescopes focused on the broader universe. (Paul Morigi/Getty Images)

Formerly known as WFIRST, it’s similarly Hubble-sized, but with much wider fields-of-view.

NASA’s Wide Field Infrared Survey Telescope (WFIRST) is now named the Nancy Grace Roman Space Telescope, after NASA’s first Chief of Astronomy. It is designed to perform wide-field imaging and spectroscopy of the infrared sky. One of the Roman Space Telescope’s objectives will be looking for clues about dark energy — the mysterious force that is accelerating the expansion of the universe. Another objective of the mission will be finding and studying exoplanets. (NASA)

Roman could create images with Hubble-like depth, but spanning over 100 times Hubble’s viewing area.

The Hubble Ultra-Deep Field, shown in blue, is currently the largest, deepest long-exposure campaign undertaken by humanity. For the same amount of observing time, the Nancy Grace Roman Telescope will be able to image the orange area to the exact same depth, revealing over 100 times as many objects as are present in the comparable Hubble image. (NASA, ESA, AND A. KOEKEMOER (STSCI); ACKNOWLEDGEMENT: DIGITIZED SKY SURVEY)

Instead of thousands of ultra-distant galaxies, a single deep-field campaign will uncover millions.

A small section of the original Hubble Deep Field, featuring hundreds of easily distinguishable galaxies. The original Hubble Deep Field may have only covered a tiny region of the sky, but taught us that there were at least hundreds of billions of galaxies contained within the observable Universe. Today, superior data and analysis has placed that figure closer to ~2 trillion. The Nancy Roman telescope’s field of view will be approximately ~1000 times the area of this portion of a deep Hubble image. (R. WILLIAMS (STSCI), THE HUBBLE DEEP FIELD TEAM AND NASA)

They will include the faintest, most distant, most active galaxies ever discovered.

Its Wide-Field Instrument might, upon launch, become astronomy’s greatest imager in history.

The main imaging camera for the Nancy Roman Telescope, the Wide Field Instrument (WFI), may immediately become the most advanced imaging instrument in history when Roman launches and deploys. Its 300-megapixel infrared camera will image, during its primary 5 year mission, 50 times the amount of sky that Hubble imaged during its entire 31 year lifetime. (NASA’S GODDARD SPACE FLIGHT CENTER)

Mostly Mute Monday tells an astronomical story in images, visuals, and no more than 200 words. Talk less; smile more.

Starts With A Bang is written by Ethan Siegel, Ph.D., author of Beyond The Galaxy, and Treknology: The Science of Star Trek from Tricorders to Warp Drive.


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