NASA’s SPHEREx mission will survey the Milky Way
galaxy looking for water ice and other key ingredients for life. In the search
for these frozen compounds, the mission will focus on molecular clouds —
collections of gas and dust in space — like this one imaged by the agency’s
James Webb Space Telescope.
NASA, ESA, CSA
Where is all the water that may form oceans on distant planets and moons?
The SPHEREx astrophysics mission will search the galaxy and take stock.
Every living organism on Earth
needs water to survive, so scientists searching for life outside our solar
system, are often guided by the phrase “follow the water.” Scheduled to launch
no earlier than Thursday, Feb. 27, NASA’s SPHEREx (Spectro-Photometer for the
History of the Universe, Epoch of Reionization, and Ices Explorer) mission will
help in that quest.
After its ride aboard a SpaceX
Falcon 9 from Vandenberg Space Force base in California, the observatory will
search for water, carbon dioxide, carbon monoxide, and other key ingredients
for life frozen on the surface of interstellar dust grains in the clouds of gas
and dust where planets and stars eventually form.
While there are no oceans or lakes
floating freely in space, scientists think these reservoirs of ice, bound to
small dust grains, are where most of the water in our universe forms and
resides. Additionally, the water in Earth’s oceans as well as those of other
planets and moons in our galaxy likely originated in such locations.
The Perseus Molecular Cloud, located about 1,000
light-years from Earth, was imaged by NASA’s retired Spitzer Space Telescope.
NASA’s SPHEREx mission will search the galaxy for water ice and other frozen
compounds in clouds of gas and dust in space like this one.
NASA/JPL-Caltech
The mission will focus on massive regions of gas and dust called molecular
clouds. Within
those, SPHEREx will also look at some newly formed stars and
the disks of material around them from which new planets are born.
Although space telescopes such as NASA’s James Webb and retired Spitzer have detected water, carbon dioxide, carbon monoxide, and other compounds in hundreds of targets, the SPHEREx observatory is the first to be uniquely equipped to conduct a large-scale survey of the galaxy in search of water ice and other frozen compounds.
Rather than taking 2D images of a target like a star, SPHEREx will gather
3D data along its line of sight. That enables scientists to see the amount of
ice present in a molecular cloud and observe how the composition of the ices
throughout the cloud changes in different environments.
By making more than 9 million of
these line-of-sight observations and creating the largest-ever survey of these
materials, the mission will help scientists better understand how these
compounds form on dust grains and how different environments can influence
their abundance.
Tip of the
Iceberg
It makes sense that the composition
of planets and stars would reflect the molecular clouds they formed in.
However, researchers are still working to confirm the specifics of the planet
formation process, and the universe doesn’t always match scientists’
expectations.
For example, a NASA mission
launched in 1998, the Submillimeter Wave Astronomy Satellite (SWAS), surveyed the galaxy for water in gas form —
including in molecular clouds — but found far less than expected.
BAE Systems employees work on NASA’s SPHEREx
observatory in the Astrotech Space Operations facility at Vandenberg Space
Force Base in California on Jan. 16. Targeting a Feb. 27 launch, the mission
will map the entire sky in infrared light.
NASA/JPL-Caltech
“This puzzled us for a while,” said Gary Melnick, a senior astronomer at
the Center for Astrophysics | Harvard & Smithsonian and a member of the
SPHEREx science team. “We eventually realized that SWAS had detected gaseous
water in thin layers near the surface of molecular clouds, suggesting that
there might be a lot more water inside the clouds, locked up as ice.”
The mission team’s hypothesis also
made sense because SWAS detected less oxygen gas (two oxygen atoms bound
together) than expected. They concluded that the oxygen atoms were sticking to
interstellar dust grains, and were then joined by hydrogen atoms, forming
water. Later research confirmed this. What’s more, the clouds shield molecules
from cosmic radiation that would otherwise break those compounds apart. As a
result, water ice and other materials stored deep in a cloud’s interior are
protected.
As starlight passes through a
molecular cloud, molecules like water and carbon dioxide block certain
wavelengths of light, creating a distinct signature that SPHEREx and other
missions like Webb can identify using a technique called absorption spectroscopy.
In addition to providing a more
detailed accounting of the abundance of these frozen compounds, SPHEREx will
help researchers answer questions including how deep into molecular clouds ice
begins to form, how the abundance of water and other ices changes with the
density of a molecular cloud, and how that abundance changes once a star forms.
Powerful
Partnerships
As a survey telescope, SPHEREx is
designed to study large portions of the sky relatively quickly, and its results
can be used in conjunction with data from targeted telescopes like Webb, which
observe a significantly smaller area but can see their targets in greater
detail.
“If SPHEREx discovers a
particularly intriguing location, Webb can study that target with higher
spectral resolving power and in wavelengths that SPHEREx cannot detect,” said
Melnick. “These two telescopes could form a highly effective partnership.”
More About
SPHEREx
SPHEREx is managed by NASA’s Jet
Propulsion Laboratory in Southern California for the Astrophysics Division
within the Science Mission Directorate at NASA Headquarters in Washington. BAE
Systems (formerly Ball Aerospace) built the telescope and the spacecraft bus.
The science analysis of the SPHEREx data will be conducted by a team of
scientists located at 10 institutions in the U.S., two in South Korea, and one
in Taiwan. Data will be processed and archived at IPAC at Caltech, which manages JPL for NASA. The mission principal
investigator is based at Caltech with a joint JPL appointment. The SPHEREx
dataset will be publicly available at the NASA/IPAC Infrared Science Archive.
For more information about the
SPHEREx mission visit:
https://www.jpl.nasa.gov/missions/spherex/
By: Jet Propulsion Laboratory
Source: NASA’s SPHEREx Space Telescope Will Seek Life’s Ingredients - NASA
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