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NASA's Roman mission will test competing cosmic acceleration theories

by Ashley Balzer, NASA's Goddard Space Flight Center:

NASA's Roman mission will test competing cosmic acceleration theories

These six cubes show the simulated distribution of galaxies at redshifts 9, 8, 5, 3, 2, and 1, with the corresponding cosmic ages shown. As the universe expands, the density of galaxies within each cube decreases, from more than half a million at top left to about 80 at lower right. Each cube is about 100 million light-years across. Galaxies assembled along vast strands of gas separated by large voids, a foam-like structure echoed in the present-day universe on large cosmic scales. Credit: NASA's Goddard Space Flight Center/F. Reddy and Z. Zhai, Y. Wang (IPAC) and A. Benson (Carnegie Observatories)

A team of scientists has predicted the science return from one of NASA's Nancy Grace Roman Space Telescope's groundbreaking planned surveys, which will analyze millions of galaxies strewn across space and time. The mission's enormous, deep panoramas will provide the best opportunity yet to discern between the leading theories about what's speeding up the universe's expansion.

Roman will explore this mystery using multiple methods, including spectroscopy—the study of the color information in light. This technique will allow scientists to precisely measure how fast the universe expanded in different cosmic eras and trace how the universe has evolved.

"Our study forecasts the science Roman's spectroscopy survey will enable and shows how various adjustments could optimize its design," said Yun Wang, a senior research scientist at Caltech/IPAC in Pasadena, California, and the lead author of the study. As the Roman Science Support Center, IPAC will be responsible for the mission's spectroscopic science data processing, while the Space Telescope Science Institute in Baltimore will be responsible for imaging science data processing, generating catalogs, and support for cosmology data processing pipelines. "While this survey is designed to explore cosmic acceleration, it will also offer clues about many other tantalizing mysteries. It will help us understand the first generation of galaxies, allow us to map dark matter, and even reveal information about structures that are much closer to home, right in our local group of galaxies."

The Roman Space Telescope, planned for launch by May 2027, will provide such an enormous view of the universe that it will help scientists study cosmic mysteries in an unprecedented way. Each image will contain precise measurements of so many celestial objects that it will enable statistical studies that aren't practical using telescopes with narrower views.


more at link...............................


the paper:


The High Latitude Spectroscopic Survey on the Nancy Grace Roman Space Telescope


The Nancy Grace Roman Space Telescope will conduct a High Latitude Spectroscopic Survey (HLSS) over a large volume at high redshift, using the near-IR grism (1.0–1.93 μm, R = 435–865) and the 0.28 deg2 wide-field camera. We present a reference HLSS that maps 2000 deg2 and achieves an emission-line flux limit of 10−16 erg s−1 cm−2 at 6.5σ, requiring ∼0.6 yr of observing time. We summarize the flowdown of the Roman science objectives to the science and technical requirements of the HLSS. We construct a mock redshift survey over the full HLSS volume by applying a semianalytic galaxy formation model to a cosmological N-body simulation and use this mock survey to create pixel-level simulations of 4 deg2 of HLSS grism spectroscopy. We find that the reference HLSS would measure ∼10 million Hα galaxy redshifts that densely map large-scale structure at z = 1–2 and 2 million [O iii] galaxy redshifts that sparsely map structures at z = 2–3. We forecast the performance of this survey for measurements of the cosmic expansion history with baryon acoustic oscillations and the growth of large-scale structure with redshift-space distortions. We also study possible deviations from the reference design and find that a deep HLSS at fline > 7 × 10−17 erg s−1 cm−2 over 4000 deg2 (requiring ∼1.5 yr of observing time) provides the most compelling stand-alone constraints on dark energy from Roman alone. This provides a useful reference for future optimizations. The reference survey, simulated data sets, and forecasts presented here will inform community decisions on the final scope and design of the Roman HLSS.


It will orbit at the 

Sun–Earth L2 orbit

The Nancy Grace Roman Space Telescope (shortened as NGRST, Roman or the Roman Space Telescope, and formerly the Wide-Field Infrared Survey Telescope or WFIRST) is a NASA infrared space telescope currently in development and scheduled to launch no later than May 2027. Roman was recommended in 2010 by the United States National Research Council Decadal Survey committee as the top priority for the next decade of astronomy. On 17 February 2016, WFIRST was approved for development and launch.[6]

The Roman Space Telescope is based on an existing 2.4 m (7.9 ft) wide field of view primary mirror and will carry two scientific instruments. The Wide-Field Instrument (WFI) is a 300.8-megapixel multi-band visible and near-infrared camera, providing a sharpness of images comparable to that achieved by the Hubble Space Telescope over a 0.28 square degree field of view, 100 times larger than imaging cameras on the Hubble. The Coronagraphic Instrument (CGI) is a high-contrast, small field of view camera and spectrometer covering visible and near-infrared wavelengths using novel starlight-suppression technology.


Nancy Grace Roman Space Telescope - Wikipedia


Each Roman Space Telescope image will capture a patch of the sky bigger than the apparent size of a full Moon. Hubble’s widest exposures, taken with its Advanced Camera for Surveys, are nearly 100 times smaller. Over the first five years of observations, the Roman Space Telescope will image over 50 times as much sky as Hubble has covered so far in 30 years.

The James Webb Space Telescope is an orbiting infrared observatory now being built that will also complement and extend the discoveries of the Hubble Space Telescope, with longer wavelength coverage and greatly improved sensitivity. The longer wavelengths enable Webb to look much closer to the beginning of time and to hunt for the unobserved formation of the first galaxies, as well as to look inside dust clouds where stars and planetary systems are forming today.


Both orbiting at L2. I can't find any info re how close they will be. Anyone?

Edited by beecee
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And adding a third potentially productive tool to our chest!


NASA finalizes plans for its next cosmic mapmaker

by Jet Propulsion Laboratory

NASA Finalizes Plans for Its Next Cosmic Mapmaker

NASA's upcoming SPHEREx mission will have some similarities with the James Webb Space Telescope. But the two observatories will take dramatically different approaches to studying the sky.

The SPHEREx mission will be able to scan the entire sky every six months and create a map of the cosmos unlike any before. Scheduled to launch no later than April 2025, it will probe what happened within the first second after the Big Bang, how galaxies form and evolve, and the prevalence of molecules critical to the formation of life, like water, locked away as ice in our galaxy. Achieving these goals will require cutting-edge technology, and NASA has this month approved final plans for all the observatory's components.

"We're at the transition from doing things with computer models to doing things with real hardware," said Allen Farrington, SPHEREx project manager at NASA's Jet Propulsion Laboratory in Southern California, which manages the mission. "The design for the spacecraft, as it stands, is confirmed. We have shown that it's doable down to the smallest details. So now we can really start building and putting things together."

To answer big questions about the universe, scientists need to look at the sky in different ways. Many telescopes, like NASA's Hubble Space Telescope, are built to focus on individual stars, galaxies, or other cosmic objects, and to study them in detail. But SPHEREx (which stands for Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer) belongs to another class of space telescopes that quickly observe large portions of the sky, surveying many objects in a short period of time. SPHEREx will scan over 99% of the sky every six months; by contrast, Hubble has observed about 0.1% of the sky in more than 30 years of operations. Although survey telescopes like SPHEREx can't see objects with the same level of detail as targeted observatories, they can answer questions about the typical properties of those objects throughout the universe.

more at link....................


The Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer mission will provide the first all-sky spectral survey. Over a two-year planned mission, the SPHEREx Observatory will collect data on more than 300 million galaxies along with more than 100 million stars in the Milky Way in order to explore the origins of the universe.


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