SPHEREx (Spectro-Photometer for the History of the Universe, Epoch of Reionization, and Ices Explorer) is a future
near-infrared
Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of Light, visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from ...
space observatory
A space telescope or space observatory is a telescope in outer space used to observe astronomical objects. Suggested by Lyman Spitzer in 1946, the first operational telescopes were the American Orbiting Astronomical Observatory, OAO-2 launche ...
that will perform an all-sky survey to measure the
near-infrared
Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of Light, visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from ...
spectra of approximately 450 million
galaxies. In February 2019, SPHEREx was selected by
NASA
The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the US federal government responsible for the civil List of government space agencies, space program ...
for its next
Medium-Class Explorers mission, beating out two competing mission concepts: ''
Arcus'' and
FINESSE
In contract bridge and similar games, a finesse is a type of card play technique which will enable a player to win an additional trick or tricks should there be a favorable position of one or more cards in the hands of the opponents.
The player a ...
.
[ ][ ] , SPHEREx is targeted to launch no earlier than April 2025 on a
Falcon 9
Falcon 9 is a partially reusable medium lift launch vehicle that can carry cargo and crew into Earth orbit, produced by American aerospace company SpaceX.
The rocket has two stages. The first (booster) stage carries the second stage and pay ...
launch vehicle from
Vandenberg Space Force Base
Vandenberg Space Force Base , previously Vandenberg Air Force Base, is a United States Space Force Base in Santa Barbara County, California. Established in 1941, Vandenberg Space Force Base is a space launch base, launching spacecraft from ...
.
The principal investigator is James Bock at
California Institute of Technology
The California Institute of Technology (branded as Caltech or CIT)The university itself only spells its short form as "Caltech"; the institution considers other spellings such a"Cal Tech" and "CalTech" incorrect. The institute is also occasional ...
(Caltech) in
Pasadena, California.
Overview
Mission
SPHEREx will use a
spectrophotometer to perform an all-sky survey that will measure
near-infrared
Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of Light, visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from ...
spectra from 0.75 to 5.0 micrometers. It will employ a single instrument with a single observing mode and no moving parts to map the entire sky (in 96
different color bands, far exceeding the color resolution of previous all-sky maps
) four times during its nominal 25-month mission; the crucial technology is a
linear variable filter,
[ ] as demonstrated by LEISA on
New Horizons.
[
It will classify galaxies according to redshift accuracy, categorizing approximately 450 million galaxies and fitting measured spectra to a library of galaxy templates. Specifically, SPHEREx will probe signals from the intra-halo light and from the ]epoch of reionization
In the fields of Big Bang theory and cosmology, reionization is the process that caused matter in the universe to reionize after the lapse of the " dark ages".
Reionization is the second of two major phase transitions of gas in the universe (t ...
.inflation
In economics, inflation is an increase in the general price level of goods and services in an economy. When the general price level rises, each unit of currency buys fewer goods and services; consequently, inflation corresponds to a reduct ...
, explore the origin and history of galaxies, and explore the origin of water
Water (chemical formula ) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living ...
in planetary systems. spectroscopic surveys. High precision redshift information of foreground galaxies provided by SPHEREx in correspondence with weak gravitational lensing measurements of background galaxies from Euclid and Nancy Grace Roman Space Telescope will allow a for a direct measurement of the dark matter distribution surrounding the foreground galaxies.
to be mostly independent to provide a new line of evidence.
The triple mirror telescope will have an aperture diameter of 20 centimeters with a 3.5° x 11° field of view and six 2k x 2k
arrays.
Each 2K x 2K focal plane array is covered with a linear variable filter, providing narrow-band response with a band center that varies along one axis of the array. SPHEREx obtains spectra through multiple exposures, placing a given source at multiple positions in the field of view, where it is measured at multiple wavelengths by repointing the spacecraft.