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by Ken Kremer
May 26, 2015
from
UniverseToday Website
The
fascinating surface of Jupiter's icy moon Europa looms large in this
newly-reprocessed color view,
made from images
taken by NASA's Galileo spacecraft in the late 1990s.
This is the color
view of Europa from Galileo that shows
the largest portion
of the moon's surface at the highest resolution.
Credits:
NASA/JPL-Caltech/SETI Institute
In a major move forward on a long
dreamed of mission to investigate the habitability of the subsurface
ocean of Jupiter's mysterious
moon Europa, top NASA officials
announced today, Tuesday, May 26, the selection of nine science
instruments that will fly on the agency's long awaited planetary
science mission to an intriguing world that many scientists suspect
could support
life.
"We are on our way to Europa,"
proclaimed John Grunsfeld, associate administrator for NASA's
Science Mission Directorate in Washington, at a media briefing
today outlining NASA's plans for a mission dedicated to
launching in the early to mid-2020s.
"It's a mission to inspire. We are
trying to answer big questions.
Are we
alone?"
"The young surface seems to be in
contact with an undersea ocean."
The Europa mission goal is to
investigate whether the tantalizing icy Jovian moon, similar in size
to Earth's moon, could harbor conditions suitable for the evolution
and sustainability of life in the suspected ocean.
It will be equipped with high resolution
cameras, radar and spectrometers, several generations beyond
anything before to map the surface in unprecedented detail and
determine the moon's composition and subsurface character.
And it will search for subsurface lakes
and seek to sample erupting vapor plumes like those occurring today
on Saturn's tiny moon Enceladus.
"Europa has tantalized us with its
enigmatic icy surface and evidence of a vast ocean, following
the amazing data from 11 flybys of the Galileo spacecraft over a
decade ago and recent Hubble observations suggesting plumes of
water shooting out from the moon," says Grunsfeld.
"We're excited about the potential
of this new mission and these instruments to unravel the
mysteries of Europa in our quest to find evidence of life beyond
Earth."
Planetary scientists have long desired a
speedy return on Europa, ever since the groundbreaking discoveries
of NASA's
Galileo Jupiter orbiter in the
1990s showed that the alien world possessed a substantial and deep
subsurface ocean beneath an icy shell that appears to interact with
and alter the surface in recent times.
This 12-frame mosaic
provides the highest resolution view ever obtained
of the side of
Jupiter's moon Europa that faces the giant planet.
It was obtained on
Nov. 25, 1999 by the camera onboard the Galileo spacecraft,
a past NASA mission
to Jupiter and its moons.
Credit:
NASA/JPL/University of Arizona
NASA's Europa mission would blastoff
perhaps as soon as 2022, depending on the budget allocation and
rocket selection, whose candidates include the heavy lift Space
Launch System (SLS).
The solar powered probe will go into
orbit around Jupiter for a three year mission.
"The mission concept is that it will
conduct multiple flyby's of Europa," said Jim Green. director,
Planetary Science Division, NASA Headquarters, during the
briefing.
"The purpose is to determine if
Europa is a habitable place. It shows few craters, a brown gum
on the surface and cracks where the subsurface meet the surface.
There may be organics and nutrients among the discoloration at
the surface."
Europa is at or near the top of the list
for most likely places in our solar system that could support life.
Mars is also near the top of the list and currently being
explored by a fleet of NASA robotic probes including surface rovers
Curiosity and
Opportunity.
"Europa is one of those critical
areas where we believe that the environment is just perfect for
potential development of life," said Green. "This mission will
be that step that helps us understand that environment and
hopefully give us an indication of how habitable the environment
could be."
The exact thickness of Europa's ice
shell and extent of its subsurface ocean is not known.
The ice shell thickness has been
inferred by some scientists to be perhaps only 5 to 10 kilometers
thick based on data from Galileo, the Hubble Space Telescope, a
Cassini flyby and other ground and space based observations.
The global ocean might be twice the
volume of all of Earth's water. Research indicates that it is salty,
may possess organics, and has a rocky sea floor.
Tidal heating from Jupiter could provide
the energy for mixing and chemical reactions, supplemented by
undersea volcanoes spewing heat and minerals to support living
creatures, if they exist.
This artist's
rendering shows a concept for a future NASA mission to Europa
in which a spacecraft
would make multiple close flybys of the icy Jovian moon,
thought to contain a
global subsurface ocean.
Credits:
NASA/JPL-Caltech
"Europa could be the best place in
the solar system to look for present day life beyond our home
planet," says NASA officials.
The instruments chosen today by NASA
will help answer the question of habitability, but they are not life
detection instruments in and of themselves.
That would require a follow on mission.
"They could find indications of
life, but they're not life detectors," said Curt Niebur, Europa
program scientist at NASA Headquarters in Washington.
"We currently don't even have
consensus in the scientific community as to what we would
measure that would tell everybody with confidence this thing
you're looking at is alive. Building a life detector is
incredibly difficult."
"During the three year mission, the
orbiter will conduct 45 close flyby's of Europa," Niebur told
Universe Today.
"These will occur about every two to
three weeks."
The close flyby's will vary in altitude
from 16 miles to 1,700 miles (25 kilometers to 2,700 kilometers).
"The mass spectrometer has a range
of 1 to 2000
daltons", Niebur told me.
"That's a much wider range than
Cassini. However there will be no means aboard to determine
chirality."
The presence of Chiral compounds could
be an indicator of life.
Right now the Europa mission is in the
formulation stage with a budget of about $10 million this year and
$30 Million in 2016. Over the next three years the mission concept
will be defined.
The mission is expected to cost in the
range of at least $2 Billion or more.
Jupiter Moon Europa,
Ice Rafting View
Here's a NASA description of the 9
instruments selected:
-
Plasma Instrument for Magnetic Sounding (PIMS)
- principal investigator Dr. Joseph Westlake of Johns
Hopkins Applied Physics Laboratory (APL), Laurel, Maryland.
This instrument works in
conjunction with a magnetometer and is key to determining
Europa's ice shell thickness, ocean depth, and salinity by
correcting the magnetic induction signal for plasma currents
around Europa.
-
Interior Characterization
of Europa using Magnetometry (ICEMAG)
- principal investigator Dr. Carol Raymond of NASA's
Jet Propulsion Laboratory (JPL), Pasadena, California.
This magnetometer will measure
the magnetic field near Europa and – in conjunction with the
PIMS instrument – infer the location, thickness and salinity
of Europa's subsurface ocean using multi-frequency
electromagnetic sounding.
-
Mapping Imaging Spectrometer for Europa (MISE)
- principal investigator Dr. Diana Blaney of JPL.
This instrument will probe the
composition of Europa, identifying and mapping the
distributions of organics, salts, acid hydrates, water ice
phases, and other materials to determine the habitability of
Europa's ocean.
-
Europa Imaging System (EIS)
- principal investigator Dr.
Elizabeth Turtle of APL.
The wide and narrow angle
cameras on this instrument will map most of Europa at 50
meter (164 foot) resolution, and will provide images of
areas of Europa's surface at up to 100 times higher
resolution.
-
Radar for Europa Assessment and Sounding:
Ocean to Near-surface (REASON)
- principal investigator Dr. Donald Blankenship of
the University of Texas, Austin.
This dual-frequency ice
penetrating radar instrument is designed to characterize and
sound Europa's icy crust from the near-surface to the ocean,
revealing the hidden structure of Europa's ice shell and
potential water within.
-
Europa Thermal Emission Imaging System (E-THEMIS)
- principal investigator Dr. Philip Christensen of
Arizona State University, Tempe.
This "heat detector" will
provide high spatial resolution, multi-spectral thermal
imaging of Europa to help detect active sites, such as
potential vents erupting plumes of water into space.
-
Mass SPectrometer for Planetary EXploration/Europa
(MASPEX)
- principal investigator Dr. Jack (Hunter)
Waite of the Southwest Research Institute (SwRI), San
Antonio.
This instrument will determine
the composition of the surface and subsurface ocean by
measuring Europa's extremely tenuous atmosphere and any
surface material ejected into space.
-
Ultraviolet Spectrograph/Europa (UVS)
- principal investigator Dr. Kurt Retherford of SwRI.
This instrument will adopt the
same technique used by the Hubble Space Telescope to detect
the likely presence of water plumes erupting from Europa's
surface. UVS will be able to detect small plumes and will
provide valuable data about the composition and dynamics of
the moon's rarefied atmosphere.
-
Surface
Dust Mass Analyzer (SUDA)
- principal investigator Dr. Sascha Kempf of the
University of Colorado, Boulder.
This instrument will measure the
composition of small, solid particles ejected from Europa,
providing the opportunity to directly sample the surface and
potential plumes on low-altitude flybys.
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