Spitzer Space Telescope Begins 'Beyond' Phase

[baa...@earthlink.net]

http://www.jpl.nasa.gov/news/news.php?feature=6602

Spitzer Space Telescope Begins 'Beyond' Phase
Jet Propulsion Laboratory
August 25, 2016

Celebrating the spacecraft's ability to push the boundaries of space science
and technology, NASA's Spitzer Space Telescope team has dubbed the next
phase of its journey "Beyond."

"Spitzer is operating well beyond the limits that were set for it at the
beginning of the mission," said Michael Werner, the project scientist
for Spitzer at NASA's Jet Propulsion Laboratory in Pasadena, California.
"We never envisioned operating 13 years after launch, and scientists are
making discoveries in areas of science we never imagined exploring with
the spacecraft."

NASA recently granted the spacecraft a two-and-a-half-year mission extension.
This Beyond phase of the Spitzer mission will explore a wide range of
topics in astronomy and cosmology, as well as planetary bodies in and
out of our solar system.

Because of Spitzer's orbit and age, the Beyond phase presents a variety
of new engineering challenges. Spitzer trails Earth in its journey around
the sun, but because the spacecraft travels slower than Earth, the distance
between Spitzer and Earth has widened over time. As Spitzer gets farther
away, its antenna must be pointed at higher angles toward the sun to communicate
with Earth, which means that parts of the spacecraft will experience more
and more heat. At the same time, Spitzer's solar panels point away from
the sun and will receive less sunlight, so the batteries will be under
greater stress. To enable this riskier mode of operations, the mission
team will have to override some autonomous safety systems.

"Balancing these concerns on a heat-sensitive spacecraft will be a delicate
dance, but engineers are hard at work preparing for the new challenges
in the Beyond phase," said Mark Effertz, the Spitzer spacecraft chief
engineer at Lockheed Martin Space Systems Company, Littleton, Colorado,
which built the spacecraft.

Spitzer, which launched on Aug. 25, 2003, has consistently adapted to
new scientific and engineering challenges during its mission, and the
team expects it will continue to do so during the "Beyond" phase, which
begins Oct. 1. The selected research proposals for the Beyond phase, also
known as Cycle 13, include a variety of objects that Spitzer wasn't originally
planned to address -- such as galaxies in the early universe, the black
hole at the center of the Milky Way and exoplanets.

"We never even considered using Spitzer for studying exoplanets when it
launched," said Sean Carey of NASA's Spitzer Science Center at Caltech
in Pasadena. "It would have seemed ludicrous back then, but now it's an
important part of what Spitzer does."

Spitzer's exoplanet exploration

Spitzer has many qualities that make it a valuable asset in exoplanet
science, including an extremely accurate star-targeting system and the
ability to control unwanted changes in temperature. Its stable environment
and ability to observe stars for long periods of time led to the first
detection of light from known exoplanets in 2005. More recently, Spitzer's
Infrared Array Camera (IRAC) has been used for finding exoplanets using
the "transit" method -- looking for a dip in a star's brightness that
corresponds to a planet passing in front of it. This brightness change
needs to be measured with exquisite accuracy to detect exoplanets. IRAC
scientists have created a special type of observation to make such measurements,
using single pixels within the camera.

Another planet-finding technique that Spitzer uses, but was not designed
for, is called microlensing. When a star passes in front of another star,
the gravity of the first star can act as a lens, making the light from
the more distant star appear brighter. Scientists are using microlensing
to look for a blip in that brightening, which could mean that the foreground
star has a planet orbiting it. Spitzer and the ground-based Polish Optical
Gravitational Lensing Experiment (OGLE) were used together to find one
of the most distant planets known outside the solar system, as reported
in 2015. This type of investigation is made possible by Spitzer's increasing
distance from Earth, and could not have been done early in the mission.

Peering into the early universe

Understanding the early universe is another area where Spitzer has broken
ground. IRAC was designed to detect remote galaxies roughly 12 billion
light-years away -- so distant that their light has been traveling for
roughly 88 percent of the history of the universe. But now, thanks to
collaborations between Spitzer and NASA's Hubble Space Telescope, scientists
can peer even further into the past. The farthest galaxy ever seen, GN-z11,
was characterized in a 2016 study using data from these telescopes. GN-z11
is about 13.4 billion light-years away, meaning its light has been traveling
since 400 million years after the big bang.

"When we designed the IRAC instrument, we didn't know those more distant
galaxies existed," said Giovanni Fazio, principal investigator of IRAC,
based at the Harvard Smithsonian Center for Astrophysics in Cambridge,
Massachusetts. "The combination of the Hubble Space Telescope and Spitzer
has been fantastic, with the telescopes working together to determine
their distance, stellar mass and age."

Closer to home, Spitzer advanced astronomers' understanding of Saturn
when scientists using the observatory discovered the planet's largest
ring in 2009. Most of the material in this ring -- consisting of ice and
dust -- begins 3.7 million miles (6 million kilometers) from Saturn and
extends about 7.4 million miles (12 million kilometers) beyond that. Though
the ring doesn't reflect much visible light, making it difficult for Earth-based
telescopes to see, Spitzer could detect the infrared glow from the cool
dust.

The multiple phases of Spitzer

Spitzer reinvented itself in May 2009 with its warm mission, after the
depletion of the liquid helium coolant that was chilling its instruments
since August 2003. At the conclusion of the "cold mission," Spitzer's
Infrared Spectrograph and Multiband Imaging Photometer stopped working,
but two of the four cameras in IRAC persisted. Since then, the spacecraft
has made numerous discoveries despite operating in warmer conditions (which,
at about minus 405 Fahrenheit or 30 Kelvin, is still cold by Earthly standards).

"With the IRAC team and the Spitzer Science Center team working together,
we've really learned how to operate the IRAC instrument better than we
thought we could," Fazio said. "The telescope is also very stable and
in an excellent orbit for observing a large part of the sky."

Spitzer's Beyond mission phase will last until the commissioning phase
of NASA's James Webb Space Telescope, currently planned to launch in October
2018. Spitzer is set to identify targets that Webb can later observe more
intensely.

"We are very excited to continue Spitzer in its Beyond phase. We fully
expect new, exciting discoveries to be made over the next two-and-a-half
years," said Suzanne Dodd, project manager for Spitzer, based at JPL.

JPL manages the Spitzer Space Telescope mission for NASA's Science Mission
Directorate, Washington. Science operations are conducted at the Spitzer
Science Center at Caltech in Pasadena, California. Spacecraft operations
are based at Lockheed Martin Space Systems Company, Littleton, Colorado.
Data are archived at the Infrared Science Archive housed at the Infrared
Processing and Analysis Center at Caltech. Caltech manages JPL for NASA.
For more information about Spitzer, visit:

http://spitzer.caltech.edu

http://www.nasa.gov/spitzer

News Media Contact
Elizabeth Landau
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-6425
elizabet...@jpl.nasa.gov

2016-221