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VENUS BEFORE THE NEW ERA OF DISCOVERY Featured Story | From the Desk of Lori Glaze | News from Space | Meeting Highlights | Opportunities for Students Spotlight on Education | In Memoriam | Milestones | New and Noteworthy | Calendar LUNAR AND PLANETARY INFORMATION BULLETIN October 2021 Issue 166
F E AT U R E D S TO RY
VENUS BEFORE THE NEW
ERA OF DISCOVERY
Justin Filiberto (NASA Johnson Space Center/Lunar and Planetary Institute),
Matthew Weller (Brown University), Walter Kiefer (Lunar and Planetary Institute),
and Allan H. Treiman (Lunar and Planetary Institute)
Venus is often considered Earth’s hellish 2030s, respectively. Collectively, these
twin due to its thick caustic atmosphere, missions aim to constrain long-standing
high surface pressure, and hot dry surface questions about the geologic history
environment. Venus has a thick omnipresent of our divergent and hellish twin.
cloud layer that is opaque to most orbital To prepare for the coming decade
sensing methods, which — along with the of Venus exploration, the Lunar and
hellish surface conditions — has prevented Planetary Institute’s (LPI) new Venus
it from receiving the attention that Mars or Science Initiative is a four-workshop series
the Moon have had. dedicated to discussing and summarizing
some of the critical unanswered questions
Many fundamental questions about before the procession of spacecraft begin
the Venus surface environment remain arriving. The topics at the workshops
unanswered, which will be addressed will be (1) Ancient Venus, (2) Venus
in the coming decade as a fleet of Surface and Atmosphere, (3) Venus as
As it sped away from Venus, NASA’s Mariner 10
spacecraft approach Venus. NASA a System, and (4) Venus-Like Planets spacecraft captured this seemingly peaceful view
will send the Venus Emissivity, Radio and Exoplanets; the first of these of a planet the size of Earth, wrapped in a dense,
Science, InSAR, Topography, and workshops (Ancient Venus) will be held global cloud layer. But, contrary to its serene
Spectroscopy (VERITAS) orbiter mission in May 2022. Here, we describe some appearance, the clouded globe of Venus is a world
of intense heat, crushing atmospheric pressure, and
in 2028 and the Deep Atmosphere Venus outstanding questions about Venus. clouds of corrosive acid. This image was processed
Investigation of Noble gases, Chemistry, from archived Mariner 10 data by JPL engineer
and Imaging (DAVINCI) atmospheric The surface of Venus is covered with Kevin M. Gill. Credit: NASA/JPL-Caltech.
probe in 2029, and the European Space volcanoes, including some of the
Agency (ESA) will send the EnVision largest volcanoes in our solar system.
orbiter mission in 2032. In addition, the Based on orbital spectroscopic and work has shown that basaltic rocks and
Indian Space Research Organization’s radar measurements, some of the associated minerals should alter very
Shukrayaan-I and Russian Space associated lava flows appear to be quickly when exposed to the hot and
Agency’s Venera-D orbiter and probe fresh unweathered basalt rock and are caustic venusian atmosphere. Models
missions are also under consideration thought to be geologically quite young. based on these experiments suggest
for flight in the late 2020s and early Recent and ongoing experimental that these unweathered lava flows
may be very young — only years to
decades old! Geophysical studies also
“ The surface of Venus is covered with suggest active or very recently active
volcanism for coronae structures (a
volcanoes, including some of the diverse set of circular volcano-tectonic
features), which are thought to be
largest volcanoes in our solar system.” supported by active deep-seated mantle
plumes. Furthermore, investigations of
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F E AT U R E D S TO RY
the geology of Idunn Mons, a volcano
in Imdr Regio, suggest that there have
been alternating periods of both volcanic
and tectonic activity in the very recent
geologic past. Similarly, portions of the
venusian crust may be in motion today,
with many blocks (hundreds of kilometers
to a side) jostling and sliding against
each other, somewhat like chunks of
pack ice on Earth. The questions remain
of the exact timing of these volcanic
and tectonic events, including which,
if any, volcanoes are active today.
The debate about the age of lava
flows plays into two other debates
about volcanism on Venus: so-called
“catastrophic” vs. gradual resurfacing,
and the water concentration of the Venus
interior. The surface of Venus is thought
to be geologically young, based on the
number, distribution, and degradation
state of impact craters on the surface. Venus’ surface is younger than other planets like Mercury and Mars. It’s clear that the planet stayed warmer
Constraining the age of lava flows longer than the other two and was resurfaced with lava flows more recently than the other two. But for the
most part, scientists think that Venus is volcanically inactive in our present day. There’s some evidence of recent
on Venus, as well as the rate at which
volcanic activity, mostly in the form of coronae, which are ring-like structures on the surface caused by plumes
new lava flows are produced, will help of hot material flowing from the depths of the planet through the mantle and the crust. Credit: Universe Today.
determine if lava gradually poured
out of volcanoes to cover (resurface)
the planet in dribs and drabs, or if of the venusian interior. Gradual ongoing targeting volcanic regions to constrain
there were periods of more extreme volcanism would support some amount the age and evolution of volcanoes
eruptions with lava pouring out in large of water (and other volatile species) still on Venus. DAVINCI will measure the
volumes (akin to flood basalts on Earth), being trapped in the Venus interior, while chemistry of the atmosphere including
covering the planet in large swaths. catastrophic resurfacing would support a trace gases that could be spewing
drier and more volatile-free Venus interior. from ongoing or previous volcanic
There is no liquid water on the surface of activity, as well as noble gas isotopes
Venus today because the surface is too To address these uncertainties, the (such as argon-40) that can be used
hot and the atmosphere is thought to have VERITAS and EnVision missions to constrain the rate of volcanic
largely lost its water; however, there is an will analyze the surface using both outgassing through geologic time.
ongoing debate about the water content radar and spectroscopy, specifically
The composition of Venus’ atmosphere
“ A current debate about also gives evidence for active volcanism.
Over the last few decades, the sulfur
content of the upper atmosphere has
the venusian atmosphere spiked and gradually declined several
times — the spikes could represent
massive eruptions with sulfur-rich gas
is whether the thick cloud plumes that penetrated Venus’ cloud
deck. But the spikes in atmospheric sulfur
could have also been produced by other
deck could be a habitable mechanisms. Much of this uncertainty
stems largely from our lack of data of
Venus’ lower atmosphere, below the
environment for life as we opaque cloud deck. The Venera and
Vega probes analyzed the chemical
composition of the lower atmosphere, but
know it.” those missions were decades ago. More
recent orbital missions, such as ESA’s
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F E AT U R E D S TO RY
The clouds of Venus can actually reach the pleasant temperature of 30°C (86°F). Credit: Jurik Peter via Shutterstock/HDR tune by Universal-Sci.
Venus Express and Japan Aerospace for life as we know it. The surface is too of phosphine and suggest that it either is
Exploration Agency’s (JAXA) Akatsuki, hot and caustic for known Earth-life to not in the clouds at all or is at much lower
measured the composition of the upper exist (let alone thrive), but the clouds concentrations than the original report.
atmosphere, providing a wealth of data, could be more hospitable. Unlike clouds
but could not see beneath the clouds, and on Earth, which are a transient feature, There is, therefore, still substantial debate
therefore the chemistry and oxidation clouds on Venus are more stable and as to whether the clouds of Venus could
state (oxygen and sulfur fugacity) of the long-lasting. The temperatures in venusian be a habitable environment, and if
lower atmosphere remains a mystery. clouds are reasonable for many terrestrial they are habitable, are they inhabited?
life forms, sunlight could provide DAVINCI will directly address these
A current debate about the venusian energy (both directly as photosynthesis questions by measuring the chemistry
atmosphere is whether the thick cloud and indirectly through photochemical and isotopic composition of the Venus
deck could be a habitable environment disequilibria), and the clouds contain atmosphere, including measuring for
essential nutrients. However, life phosphine, and will determine whether
in Venus’ clouds would have to be they in fact constitute a habitable
adapted to a highly acidic environment environment. DAVINCI will also
(the cloud particles are mostly sulfuric measure the composition and oxidation
acid) and limited available water, state of the lower atmosphere.
more akin to extremophiles on Earth.
Tessera terrain areas are thought to be the
The hypothesis that Venus’ clouds could oldest exposed crust on Venus and so are
be habitable gained significant traction among the best targets for understanding
last year with a reported Earth-based ancient Venus (a time period that is all but
detection of abundant phosphine wiped out in Earth’s rock record). They are,
gas (PH3). On Earth, phosphine can however, some of the least-understood
be produced both abiotically and regions in our solar system. They are
A portion of Alpha Regio is displayed in this three-
dimensional perspective view of the surface of Venus. by biological activity, but at the high highly deformed (faulted and folded) so
Alpha Regio, a topographic upland approximately concentrations originally described in that original structures are not clear, and
1300 kilometers across, is centered on 25°S latitude, the clouds of Venus were suggestive of even what kind of rock they are (igneous
4°E longitude. In 1963, Alpha Regio was the first
biological activity. Subsequent studies did vs. sedimentary) remains uncertain.
feature on Venus to be identified from Earth-based
radar. Credit: NASA/JPL. not fully reproduce the original detections Tessera terrain are characterized by
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F E AT U R E D S TO RY
high elevations, extensive and multiple models suggest and may point toward a better than achieved by the Magellan
deformations, and high radar backscatter. more Mars-like early Venus dominated mission and high-resolution topography,
by volcanic activity of basaltic lava. which will enable new modeling to
The current data available are consistent constrain faulting and folding processes
with both highly altered basaltic lava Another question about tessera are their that formed the tessera. The DAVINCI
flows and evolved granitic rocks like mountain tops. The highest elevations of probe will enter the atmosphere above
continents on Earth. many tessera are bright in reflected radar, Alpha Regio, imaging the surface from
which suggests that they may be coated below the clouds, enabling scientists
The difference in these interpretations has in a semi-conductor material. Different to (1) determine if they are granitic
enormous implications for early Venus. minerals, from very common minerals on or basaltic in composition and (2)
Granitic contents on Venus would imply Earth like pyrite and apatite to incredibly constrain what minerals are forming
that early Venus was much more like rare minerals like tellurobismuthite (Bi2Te3) during weathering of the rocks.
the early Earth with water in the interior and coloradoite (HgTe), have been
and crustal recycling remelting water- suggested to cause these anomalies.
bearing rocks. On the other hand, if
tessera are altered basaltic lava flows, VERITAS and EnVision will explore the
this could imply that early Venus may early history of the tessera with radar
not have been as Earth-like as some imagery that is an order of magnitude
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F ROM T H E D ES K
O F LO R I G L A Z E
LOOKING BACK,
MOVING FORWARD
Lori S. Glaze
Director, NASA’s Planetary Science Division, October 2021
As I write, in early October, our Lucy the Lucy mission is set to revolutionize our commitment to IDEA and added inclusion
mission is just days away from launch. understanding of planetary origins and to the Agency’s core values (safety,
The next in our line of Discovery missions, the formation of the solar system. integrity, teamwork, excellence) last July.
Lucy will journey to the Trojan asteroids
that have been trapped in stable But while I anticipate the Lucy launch As such, I’d like to take this opportunity to
Lagrange Points, along Jupiter’s orbit, for and am thinking about our origins, I can’t update you on some of the many IDEA-
billions of years. Starting in 2027, Lucy help but also contemplate the evolution focused initiatives we are working on at
will fly by seven of these Trojan asteroids of our planetary science community over NASA, the Science Mission Directorate
and, in doing so, will allow us to survey the past year, and what the planetary (SMD), and the Planetary Science
their diversity and gain new insights science landscape will look like in the Division (PSD).
into this unique, never-before-explored, coming decades. The events of 2020
population of early solar system remnants. and 2021 have been a wakeup call to
us as individuals, as scientists, and as SMD IDEA
Lucy is named for the fossilized skeleton members of a worldwide community. But
of an early hominid found in Ethiopia in as hard as these times have been, I am Working Group
1974. The name of that find was inspired grateful that important issues — namely
by The Beatles’ song “Lucy in the Sky with those relating to inclusion, diversity, I am pleased to share that earlier this
Diamonds,” and by naming our mission equity, and accessibility (IDEA) — have year we officially chartered an Inclusion,
for the skeleton, we come full circle and come to the fore, and that individuals Diversity, Equity, and Accessibility
are taking Lucy back to the sky! Just as and organizations alike are trying to Working Group within SMD. This Group
the Lucy skeleton provided fundamental foster positive and long-lasting change. (comprised of SMD staff and advisors)
insights into the evolution of our species, Indeed, NASA has been increasing its will seek to advocate for and promote
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F R O M T H E D E S K O F LO R I G L A Z E
inclusive values and efforts, and will carefully and submit comments before the and we are currently in the process of
develop viable, actionable solutions November 3, 2021, deadline. matching each of these students with
that are impactful, sustainable, and mentors from the mission teams. The
measurable for SMD to implement. Dual-Anonymous students will participate in the mission
Reporting to the SMD Associate science team meetings as well as other
Administrator (Dr. Thomas Zurbuchen), Peer Review planetary science community meetings.
the IDEA Working Group is responsible In addition, participants in the program
for the development and implementation As you are hopefully aware, we are now will be offered supplemental activities
of an IDEA Strategic Implementation deep into the second ROSES cycle where such as seminars, social events (including
Plan, to focus current and future IDEA we are implementing Dual-Anonymous an upcoming Lucy launch party), career
activities for a five-year period (and Peer Review (DAPR) for several of our panels, and more. I am keen to see the
renewable five-year increments research programs. Under this system, outcomes of this pilot, and if it proves
thereafter). The Working Group currently neither are proposers told the identity of successful, we will plan to scale the
consists of several subgroups that are their reviewers nor are reviewers told the program up to include all PSD missions
focused on various aspects of SMD identity of the proposers until they have and other institutions.
activities, including recruitment and completed the evaluation of the scientific
hiring; missions, programs, and projects; merit of the anonymized proposals. The In SMD we are also pleased to be
science engagement; leadership results of SMD’s pilot implementation partnering with several societies
development; research and analysis; and demonstrated improvements in both the (e.g., AGU, GSA) to support the new
inclusion and culture. I am so glad to see overall quality of the review process as Mentoring365 platform. With programs
SMD developing IDEA initiatives in this well as in the demographics of awardees. such as this we are investing in early-
strategic manner, and I am excited to see After the successful pilot year, during career researchers and students working
what this group achieves. which PSD’s Habitable Worlds program within Earth and space science, which
was run under DAPR, we are using this in turn helps us foster a robust, diverse,
process in ROSES-2021 for all our data equitable, and inclusive workforce that is
Proposed Changes analysis programs (Cassini, Discovery, equipped to address the challenges our
Lunar, New Frontiers, and Mars Data environment and planet are facing and
to Announcements Analysis Programs), as well as the cross- the science and exploration goals we
divisional Exoplanets Research Program. have. This program is highly customizable
of Opportunity Please refer to our DAPR webpage to and free to use. Please take a look at the
read more. website and sign up to be a mentor and/
As another example of NASA’s or mentee!
commitment to IDEA values, SMD is
undertaking a comprehensive effort to Mentorship Programs These are just a few of the activities we
ensure NASA programs are accessible are undertaking to create a more diverse,
to all Americans, especially underserved Lastly, I want to highlight two new inclusive, and fruitful planetary science
and underrepresented communities. To mentorship programs we are supporting community — one that is welcoming to
that end, a Request for Information (RFI) at the PSD and SMD level. Within PSD, all. I am incredibly proud to see how my
was released on September 22, 2021, we have recently started a pilot program, colleagues within PSD, SMD, and the
for public comments on draft language known as “Here to Observe” (H2O). larger planetary science community have
that SMD plans to add to future The goal of this initiative is to spark and taken IDEA issues to heart, and I know
Announcements of Opportunity [and to maintain an interest for underrepresented that these efforts will allow us to achieve
amend the open Stand-Alone Mission students considering STEM careers, and long-term changes. After all, our efforts
of Opportunity Notice (SALMON)]. The so far we have assembled three PSD to study the origins and workings of our
proposed amendments would require mission/Minority-Serving Institution solar system — and our place within
proposers to describe how the processes (MSI) pairs: Europa Clipper and the it — will only truly be worthwhile if we
used to assemble the proposed team and University of Puerto Rico; Dragonfly and continue to use the lessons we learn to
to execute the proposed project would Virginia State University; and Lucy and strive for a better future.
align with NASA’s core value of inclusion Howard University. We already have
and NASA’s IDEA values. If you have not 30 undergraduate students from these
already, I urge you to read the RFI text universities signed up to participate
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N E WS FROM S PAC E
LUCY BEGINS ITS TRAVELS TO THE
FOSSIL ASTEROIDS OF JUPITER
loose groups, with one into humanity’s evolution. Likewise,
group leading ahead of the Lucy mission will revolutionize our
Jupiter in its path, the other knowledge of planetary origins and
trailing behind. Clustered the formation of the solar system.
around the two Lagrange
points equidistant from Lucy launched in October 2021 and,
the Sun and Jupiter, the with boosts from Earth’s gravity, will
Trojans are stabilized by complete a 12-year journey to eight
the Sun and its largest different asteroids — a main-belt asteroid
planet in a gravitational and seven Trojans, four of which are
balancing act. These members of “two-for-the-price-of-one”
primitive bodies hold vital binary systems. Lucy’s complex path
This diagram illustrates Lucy’s orbital path. The spacecraft’s path (green) clues to deciphering the will take it to both clusters of Trojans
is shown in a frame of reference where Jupiter remains stationary, giving solar system’s history, and and give us our first close-up view of
the trajectory its pretzel-like shape. Credit: Southwest Research Institute. perhaps even the origins of all three major types of bodies in the
organic material on Earth. swarms (so-called C-, P- and D-types).
Time capsules from the birth of our solar
system more than 4 billion years ago, the NASA’s Lucy will be the first space mission
swarms of Trojan asteroids associated with to study the Trojans. The mission takes its
Jupiter are thought to be remnants of the name from the fossilized human ancestor
primordial material that formed the outer (called “Lucy” by her discoverers)
planets. The Trojans orbit the Sun in two whose skeleton provided unique insight
NASA’S PERSEVERANCE ROVER
COLLECTS FIRST MARS ROCK SAMPLE
NASA’s Perseverance rover recently Earth for closer study. These samples and dust) while searching for signs of
completed the collection of the first would be the first set of scientifically ancient microscopic life, Perseverance’s
sample of martian rock, a core from identified and selected materials mission includes studying the Jezero
Jezero Crater slightly thicker than a returned to our planet from another. region to understand the geology and
pencil. Mission controllers at NASA ancient habitability of the area, as well
Jet Propulsion Laboratory (JPL) in “NASA has a history of setting ambitious as to characterize the past climate.
Southern California received data that goals and then accomplishing them,
confirmed the historic milestone. reflecting our nation’s commitment to “For all of NASA science, this is truly a
discovery and innovation,” said NASA historic moment,” said Thomas Zurbuchen,
The core is now enclosed in an airtight Administrator Bill Nelson. “This is a Associate Administrator for Science at
titanium sample tube, making it available momentous achievement and I can’t NASA Headquarters in Washington,
for retrieval in the future. Through the wait to see the incredible discoveries DC. “Just as the Apollo Moon missions
Mars Sample Return campaign, NASA produced by Perseverance and our team.” demonstrated the enduring scientific value
and the European Space Agency (ESA) of returning samples from other worlds
are planning a series of future missions Along with identifying and collecting for analysis here on our planet, we will
to return the rover’s sample tubes to samples of rock and regolith (broken rock be doing the same with the samples
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and transmit the results back to Earth. “Getting the first sample under our belt
After mission controllers confirmed is a huge milestone,” said Perseverance
the cored rock’s presence in the tube, Project Scientist Ken Farley of Caltech.
they sent a command to complete “When we get these samples back on
the processing of the sample. Earth, they are going to tell us a great
deal about some of the earliest chapters
On September 6, Perseverance transferred in the evolution of Mars. But however
sample tube serial number 266 and its geologically intriguing the contents of
martian cargo into the rover’s interior to sample tube 266 will be, they won’t tell
measure and image the rock core. It then the complete story of this place. There
hermetically sealed the container, took is a lot of Jezero Crater left to explore,
This sealed titanium sample tube contains Persever-
ance’s first cored sample of Mars rock. The rover’s
another image, and stored the tube. and we will continue our journey in
Sampling and Caching System Camera (known as the months and years ahead.”
CacheCam) captured this image. Credit: NASA. “With over 3000 parts, the Sampling
and Caching System is the most complex The rover’s initial science foray, which
Perseverance collects as part of our Mars mechanism ever sent into space,” said spans hundreds of sols (martian days),
Sample Return program. Using the most Larry D. James, Interim Director of will be complete when Perseverance
sophisticated science instruments on Earth, JPL. “Our Perseverance team is excited returns to its landing site. At that
we expect jaw-dropping discoveries and proud to see the system perform point, Perseverance will have traveled
across a broad set of science areas, so well on Mars and take the first step between 2.5 and 5 kilometers (1.6
including exploration into the question for returning samples to Earth. We also and 3.1 miles) and may have filled as
of whether life once existed on Mars.” recognize that a worldwide team of many as 8 of its 43 sample tubes.
NASA, industry partners, academia, and
international space agencies contributed After that, Perseverance will travel
First Sample to and share in this historic success.” north, then west, toward the location of
its second science campaign: Jezero
Crater’s delta region. The delta is the
The sample-taking process began First Science fan-shaped remains of the spot where
on Wednesday, September 1, when an ancient river met a lake within the
the rotary percussive drill at the Campaign crater. The region may be especially
end of Perseverance’s robotic arm rich in clay minerals. On Earth, such
cored into a flat, briefcase-size minerals can preserve fossilized signs of
Mars rock nicknamed “Rochette.” Perseverance is currently exploring ancient microscopic life and are often
the rocky outcrops and boulders associated with biological processes.
After completing the coring process, the of “Artuby,” a ridgeline of more than
arm maneuvered the corer, bit, and 900 meters (0.5 miles) bordering two For more about Perseverance, visit
sample tube so the rover’s Mastcam-Z geologic units believed to contain www.nasa.gov/perseverance.
camera instrument could image the Jezero Crater’s deepest and most
contents of the still-unsealed tube ancient layers of exposed bedrock.
TRACES OF CERES’ ICY CRUST
FOUND AT OCCATOR CRATER
Anomalies in the distribution of hydrogen concentration of hydrogen in the vicinity Letters. PSI scientists Yuki Yamashita,
at Occator Crater on the dwarf planet of Occator was derived from observations Norbert Schorghofer, Carle Pieters, and
Ceres reveal an icy crust, says a new study from elliptical orbits that brought the Hanna Sizemore are co-authors.
led by Tom Prettyman, a senior scientist spacecraft very close to the surface during
at the Planetary Science Institute (PSI). the final mission phase, said Prettyman. The GRaND’s neutron spectrometer found
paper, entitled “Replenishment of near- elevated hydrogen concentrations in
The evidence comes from data acquired surface water ice by impacts into Ceres’ the outermost 1 meter (3.2 feet) of the
by the Gamma Ray and Neutron volatile-rich crust: Observations by Dawn’s surface of Occator, a large, young crater
Detector (GRaND) onboard NASA’s Gamma Ray and Neutron Detector,” 92 kilometers (57 miles) in diameter, the
Dawn spacecraft. A detailed map of the appears in Geophysical Research paper says. The paper argues that the
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miles). So, observed enhancements in
the concentration of hydrogen within
the crater and ejecta blanket support
our interpretation that the crust is ice
rich. The findings reinforce the emerging
consensus that Ceres is a differentiated
body in which ice separated from
rock to form an icy outer shell and
subcrustal ocean,” Prettyman said.
“Smaller, water-rich bodies, including
the parent bodies of the carbonaceous
chondrite meteorites, may not have
experienced differentiation. So, the
findings could have implications for
the evolution of icy bodies, small
The study focused on Occator Crater (left), which contains Ceres’ most prominent bright spots. The newly and large,” Prettyman said. “More
reported map (right) reveals higher concentrations of hydrogen than expected if the near sub-surface within broadly, as an ocean world, Ceres
Occator Crater and its ejecta blanket was ice-free. Results indicate that the crustal materials excavated by the could be habitable and is therefore an
crater-forming impact were rich in water ice. Credit: NASA/JPL-CalTech/UCLA/MPS/DLR/IDA; Prettyman
et al. (2021).
attractive target for future missions.”
Funding for the study was provided by
excess hydrogen is in the form of water ice. of Occator. Similarities between the a grant from NASA’s Discovery Data
Results confirm Ceres’ outer crust is ice- global distribution of hydrogen and the Analysis Program, the NASA Dawn
rich and that water ice can survive within pattern of large craters suggest impact Mission, and the SSERVI TREX project.
impact ejecta on airless, icy bodies. The processes have delivered ice to the
data imply partial control of the distribution surface elsewhere on Ceres. This process
of near-surface ice by large impacts is accompanied by the loss of ice by
and provide constraints on surface age sublimation caused by heating of the
and regolith thermophysical properties. surface by sunlight,” Prettyman said.
“We think that ice has survived in the “The impact that formed Occator would
shallow subsurface during the roughly have excavated crustal materials
20 million years following the formation as deep as 10 kilometers (about 6
NEW EVIDENCE OF RECENT
(GEOLOGICALLY SPEAKING)
VENUSIAN VOLCANISM
New data analysis techniques allow Science Institute (PSI) researchers than its cousins Mars and Mercury. The
evidence of recent volcanism to be Megan Russell and Catherine Johnson. craters that it does have are randomly
found in old Magellan spacecraft scattered across the planet. Craters build
data. It is unclear if this activity is In the 31 years since NASA’s Magellan up over time, and Venus’ low number
occurring today or occurred within tens spacecraft entered orbit around Venus, of craters means it has a surface that
of millions of years, but geologically researchers have been using the mission’s was somehow wiped clean roughly
speaking, either case is recent. This adds radar images, topography, and gravity 300 million to 1 billion years ago. It is
to the growing body of evidence that mapping to understand the surface history unclear whether this was a catastrophic
volcanoes on Venus didn’t go extinct of this cloud-covered world. Early results event that resurfaced the entire planet
as long ago as many had thought. This made it clear that Venus has significantly at once, randomly distributed ongoing
work was conducted by Planetary fewer impact craters on its surface events that systematically resurfaced
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the ground around it bends, like flexing
a plastic ruler,” said Megan Russell, a
research associate at PSI and lead
author of the article “Evidence for a
locally thinned lithosphere associated
with recent volcanism at Aramaiti
Corona, Venus,” which appears in
Journal of Geophysical Research —
Planets. “The same kind of deformation
is seen in the bending of the seafloor
around the Hawaiian Islands. From this
deformation, we can infer properties
like heat flow local to the volcano.”
Using complex computer models
to model the surface deformation
is necessary to go beyond simply
indicating older vs. younger. It is from
this modeled deformation that properties
like heat flow can be inferred.
Over time, these kinds of structures can
evolve, and the observed degree of
deformation hints at how old or young
a feature might be and how much heat
might be flowing under the surface.
Russell goes on to explain, “Modeling
studies suggest that the shape and
topography of this corona indicate
that it is also geologically young, and
would have similarly geologically
young volcanism associated with it.”
Magellan SAR image of Aramaiti Corona. Narina Tholus (center left) appears as two adjacent domes that are This particular structure seems to be
superposed on the west outer fracture ring. Credit: Russell et al. (2021).
unique in Magellan’s limited dataset.
Only seven other coronae in the 20%
Venus over time, or a combination the edge of the 350-kilometer-diameter of Venus that Magellan studied with
of both options. To understand what (217.5-mile-diameter) Aramaiti Corona. SAR have steep-sided volcanoes on
happened, it is necessary to understand or near their fractured ring like that
when volcanoes have been active. Coronae are roughly circular features, studied by Russell and Johnson. In
surrounded by a ring of cracks that addition, the stereo topography data
“The question of whether Venus has appear roughly like a crown and are on the feature in this study was of
had geologically recent or ongoing thought to be large faults. At some particularly high quality. With three
volcanism has been an enduring enigma coronae, like Aramaiti, volcanoes and upcoming missions planned for Venus,
from the Magellan mission: we still lava flows are observed close to or on this team looks forward to exploring this
have no smoking gun regarding this, these fractures. The volcano studied by question in greater detail in the future.
but more and more lines of evidence the PSI researchers was part of the lucky
suggest a recently, and potentially 20% of Venus’ surface to be imaged in For Johnson, Venus has already played
currently, active planet,” said PSI stereo with synthetic aperture radar (SAR), a multi-decade role; she worked on
Senior Scientist Catherine Johnson. which revealed the elevations across the her Ph.D. from 1984–1989 as a guest
three-dimensional structure, providing investigator on Magellan. For Russell, this
As computers have improved, it has a better view than a simple image. work is a great start to her career. This
become possible to do more and more research was performed while Russell was
with Magellan’s finite dataset. Russell “Instead of looking at the surface of the a graduate student at the Department of
and Johnson used a high-resolution volcano or flows, we look at how the Earth, Ocean, and Atmospheric Sciences
stereo topography dataset generated by volcano deforms the ground around it. at the University of British Columbia.
other researchers to look at a volcano at In response to the weight of the volcano,
11 Issue 166 October 2021 © Copyright 2021 Lunar and Planetary InstituteN E W S F R O M S PAC E
“COOL” KIDS IN THE COSMOS
MAY NOT BE SO UNIQUE
G, K, and M — which gave information
about their sizes and temperatures.
They compared the properties of the
Sun, a G-type star, with what they knew
of other cool stars through its Rossby
number, a measure of stellar activity
that combines its speed of rotation with
its subsurface fluid flows that influence
the distribution of magnetic flux on a
star’s surface. Their models suggest
that each star’s “space weather” works
in much the same way, influencing
conditions on their respective planets.
“The study suggests that stars — at least
Rice University scientists have shown that “cool” stars like the Sun share dynamic surface behaviors that cool stars — are not too dissimilar from
influence their energetic and magnetic environments. Stellar magnetic activity is key to whether a given star each other,” Alexander said. “From
can host planets that support life. Credit: NASA.
our perspective, Alison’s model can be
applied without fear or favor when we
Stars scattered throughout the cosmos “All stars spin down over their lifetimes look at exoplanets around M or F or K
look different, but they may be more as they shed angular momentum, and stars, as well, of course, as other G stars.”
alike than once thought, according they get less active as a result,” Farrish
to Rice University researchers. said. “We think the Sun in the past “It also suggests something much
was more active, and that might more interesting for established stellar
New modeling work by Rice scientists have affected the early atmospheric physics, that the process by which a
shows that “cool” stars like the Sun share chemistry of Earth. So thinking about magnetic field is generated may be
the dynamic surface behaviors that how the higher-energy emissions from quite similar in all cool stars. That’s a
influence their energetic and magnetic stars change over long timescales is bit of a surprise,” he said. This could
environments. This stellar magnetic pretty important to exoplanet studies.” include stars that, unlike the Sun, are
activity is key to whether a given star convective down to their cores.
hosts planets that could support life. “More broadly, we’re taking models
that were developed for the Sun “All stars like the Sun fuse hydrogen and
The work by Rice postdoctoral researcher and seeing how well they adapt helium in their cores, and that energy is
Alison Farrish and astrophysicists David to stars,” said Johns-Krull. first carried in the radiation of photons
Alexander and Christopher Johns-Krull toward the surface,” Johns-Krull said.
appears in a published study in The The researchers set out to model what “But it hits a zone about 60% to 70%
Astrophysical Journal. The research far-flung stars are like based on the of the way that’s just too opaque, so
links the rotation of cool stars with the limited data available. The spin and flux it starts to undergo convection. Hot
behavior of their surface magnetic flux, of some stars have been determined, matter moves from below, the energy
which in turn drives the star’s coronal along with their classification — types F, radiates away, and the cooler matter
X-ray luminosity in a way that could
help predict how magnetic activity
affects any exoplanets in their systems. “ More broadly, we’re taking models
The study follows another led by Farrish that were developed for the Sun and
and Alexander that showed a star’s
“space weather” may make planets in seeing how well they adapt to stars.”
their “Goldilocks zone” uninhabitable.
12 Issue 166 October 2021 © Copyright 2021 Lunar and Planetary InstituteN E W S F R O M S PAC E
times more active than the Sun may not
“ It also reinforces the idea be a G-class star, it’s still captured by
the analysis that Alison has done.”
that even though a star “We do have to be clear that we’re
not simulating any specific star or
system,” he said. “We are saying that
that is 30 times more active statistically, the magnetic behavior of
a typical M star with a typical Rossby
number behaves in a similar fashion to
than the Sun may not that of the Sun, which allows us to assess
its potential impact on its planets.”
be a G-class star, it’s still A critical wild card is a star’s activity
cycle, which can’t be incorporated into
the models without years of observation.
captured by the analysis (The Sun’s cycle is 11 years, evidenced
by sunspot activity when its magnetic
field lines are most distorted.)
that Alison has done.” Johns-Krull said the model will still be
useful in many ways. “One of my areas
falls back down. But stars with less than a certain point, an increase in magnetic of interest is studying very young stars,
a third of the mass of the Sun don’t have activity stops showing the associated many of which are, like low-mass stars,
a radiative zone; they’re convective increase in high energy X-ray emission. fully convective,” he said. “Many of these
everywhere,” he said. “A lot of ideas The reason that dumping more magnetism have disk material around them and are
about how stars generate a magnetic onto the star’s surface doesn’t give you still forming planets. How they interact
field rely on there being a boundary more emission is still a mystery. Conversely, is mediated, we think, by the stellar
between the radiative and the convection the Sun is in the unsaturated regime, magnetic field. So, Alison’s modeling
zones, so you would expect stars that where we do see a correlation between work can be used to learn about the
don’t have that boundary to behave magnetic activity and energetic emission,” large-scale structure of very magnetically
differently. This paper shows that in many she said. “That happens at a more active stars, and that can then allow
ways, they behave just like the Sun, once moderate activity level, and those stars us to test some ideas about how these
you adjust for their own peculiarities.” are of interest because they might provide young stars and their disks interact.”
more hospitable environments for planets.”
Farrish, who recently earned her doctorate Minjing Li, a visiting undergraduate
at Rice and will begin a postdoctoral “The bottom line is the observations, from the University of Science and
research assignment at NASA Goddard which span four spectral types including Technology of China, is a co-author of
Space Flight Center soon, noted the both fully and partially convective stars, the paper. Alexander is a professor of
model applies only to unsaturated stars. can be reasonably well represented physics and astronomy and the director
by a model generated from the Sun,” of the Rice Space Institute. Johns-Krull is
“The most magnetically active stars are the Alexander said. “It also reinforces the a professor of physics and astronomy.
ones we call ‘saturated,’” Farrish said. “At idea that even though a star that is 30
SPACE SCIENTISTS REVEAL SECRET
BEHIND JUPITER’S ENERGY CRISIS
New research published in Nature has re- Goddard Space Flight Center, and the have created the most detailed yet global
vealed the solution to Jupiter’s energy crisis, National Institute of Information and map of the gas giant’s upper atmosphere,
which has puzzled astronomers for decades. Communications Technology (NICT) to confirming for the first time that Jupiter’s
reveal the mechanism behind Jupiter’s powerful aurorae are responsible
Space scientists at the University of atmospheric heating. for delivering planet-wide heating.
Leicester worked with colleagues from
the Japan Aerospace Exploration Now, using data from the Keck Dr. James O’Donoghue is a
Agency (JAXA), Boston University, NASA Observatory in Hawaii, astronomers researcher at JAXA and completed
13 Issue 166 October 2021 © Copyright 2021 Lunar and Planetary InstituteN E W S F R O M S PAC E
Jupiter is shown in visible light for context underneath an artistic impression of the jovian upper atmosphere’s infrared glow. The brightness of this upper atmosphere layer
corresponds to temperatures, from hot to cold, in this order: white, yellow, bright red, and lastly, dark red. The aurorae are the hottest regions, and the image shows how
heat may be carried by winds away from the aurora and cause planet-wide heating. Credit: J. O’Donoghue (JAXA)/Hubble/NASA/ESA/A. Simon/J. Schmidt.
his Ph.D. at Leicester. He is the lead Dr. Tom Stallard and Dr. Henrik Melin spewing from its volcanic moon, Io,
author for the research paper. are part of the School of Physics and leads to the most powerful aurora
Astronomy at the University of Leicester. in the solar system and enormous
O’Donoghue said, “We first began trying heating in the planet’s polar regions.
to create a global heat map of Jupiter’s Dr. Stallard added, “There has been a
uppermost atmosphere at the University very long-standing puzzle in the thin Although the jovian aurorae have long
of Leicester. The signal was not bright atmosphere at the top of every giant planet been a prime candidate for heating
enough to reveal anything outside of within our solar system. With every Jupiter the planet’s atmosphere, observations
Jupiter’s polar regions at the time, but with space mission, along with groundbased have previously been unable to
the lessons learned from that work, we observations, over the past 50 years, we confirm or deny this until now.
managed to secure time on one of the have consistently measured the equatorial
largest, most competitive telescopes on temperatures as being much too hot. This Previous maps of the upper atmospheric
Earth some years later.” ‘energy crisis’ has been a long-standing temperature were formed using images
issue — do the models fail to properly consisting of only several pixels. This
He continued, “Using the Keck telescope, model how heat flows from the aurora, or is not enough resolution to see how
we produced temperature maps of is there some other unknown heat source the temperature might be changed
extraordinary detail. We found that near the equator? This paper describes across the planet, providing few clues
temperatures start very high within the how we have mapped this region in as to the origin of the extra heat.
aurora, as expected from previous work, unprecedented detail and have shown
but now we could observe that Jupiter’s that, at Jupiter, the equatorial heating is Researchers created five maps of the
aurora, despite taking up less than 10% directly associated with auroral heating.” atmospheric temperature at different
of the area of the planet, appear to be spatial resolutions. The highest-
heating the whole thing. This research Aurorae occur when charged particles resolution map shows an average
started in Leicester and carried on at are caught in a planet’s magnetic temperature measurement for squares
Boston University and NASA before field. These spiral along the field lines 2° longitude high by 2° latitude wide.
ending at JAXA in Japan. Collaborators toward the planet’s magnetic poles,
from each continent working together striking atoms and molecules in the The team scoured more than 10,000
made this study successful, combined atmosphere to release light and energy. individual data points, only mapping
with data from NASA’s Juno spacecraft points with an uncertainty of less than 5%.
in orbit around Jupiter and JAXA’s Hisaki On Earth, this leads to the characteristic
spacecraft, an observatory in space.” light show that forms the Aurora Borealis Models of the atmospheres of gas
and Australis. At Jupiter, the material giants suggest that they work like a
14 Issue 166 October 2021 © Copyright 2021 Lunar and Planetary InstituteN E W S F R O M S PAC E
giant refrigerator, with heat energy which could be interpreted as evidence Telescope. Leicester also plays a leading
drawn from the equator toward the of the process driving heat transfer. role in science and instrumentation
pole and deposited in the lower on the European Space Agency
atmosphere in these pole regions. Planetary research at the University (ESA)’s JUpiter ICy moons Explorer
of Leicester spans the breadth of (JUICE), due for launch in 2022.
These new findings suggest that fast- the jovian system, from the planet’s
changing aurorae may drive waves magnetosphere and atmosphere to “Global upper-atmospheric heating on
of energy against this poleward flow, its diverse collection of satellites. Jupiter by the polar aurorae” is available
allowing heat to reach the equator. in the August 2021 issue of Nature.
Leicester researchers are members
Observations also showed a region of of the Juno mission, a global team of
localized heating in the sub-auroral region astronomers observing the giant planet
that could be interpreted as a limited and leading Jupiter observations from
wave of heat propagating equatorward, the forthcoming James Webb Space
FROZEN SMECTITE CLAYS, NOT
WATER, DETECTED BENEATH MARS
SOUTH POLAR REGION
What lies beneath the frozen surface papers has made the presence of
of Mars’ south polar region has been underground lakes in the martian south
a recent hot topic among researchers, polar region less likely, including a recent
and a new paper by Planetary Science paper on which PSI Senior Scientist
Institute (PSI) Research Scientist Isaac Nathanial Putzig was a co-author.
Smith refines the answer, pouring cold
water on the subglacial lake theory. “To date, all previous papers were only
able to suggest holes in the lakes argument.
The bright radar reflectors detected at the We’re the first paper to demonstrate that
martian south pole are not liquid water, another material is the most likely cause
but clays, specifically frozen-solid smectite of the observations,” said Smith, who is
minerals, said Smith, the lead author of “A also affiliated with York University, Toronto,
solid interpretation of bright radar reflectors Canada. “Now, our paper offers the
under the Mars south polar ice,” which first plausible, and considerably more
appears in Geophysical Research Letters. likely, alternative hypothesis to explain the
MARSIS observations. Specifically, solid
Using the Mars Advanced Radar for clays frozen to cryogenic temperatures
Subsurface and Ionosphere Sounding can make the reflections. Considering the
(MARSIS) radar instrument onboard recent work on this topic finding faults Mars south polar layered deposits on top of martian
smectites. Top: The multi-kilometer-thick south
the European Space Agency’s Mars with the lake theory, this is like a 1-2-3 polar ice cap has a base that is composed, at least
Express orbiter, previous work detected punch combination that puts big holes in partially, of a common type of clays. These clays
areas of high radar reflectivity deep the lake interpretation and then solves the are found over nearly half of the planet’s surface
beneath martian south polar ice deposits. riddle. In my opinion, it’s a knockout.” and now at the edges of the ice cap. Credit: ESA/
DRL/FU Berlin. Bottom: Radar measurements of the
That team said the bright reflections clays from a lab led by Smith show that they can
indicated that several bodies of water, Subglacial lakes were first reported in explain the bright reflections observed by MARSIS,
commonly reported as lakes, were 2018 and caused a big stir because of a simpler explanation than bodies of liquid water.
found. But a recent flurry of journal the potential for habitability on Mars. Credit: NASA.
15 Issue 166 October 2021 © Copyright 2021 Lunar and Planetary InstituteN E W S F R O M S PAC E
Astrobiologists and non-scientists were demonstrate that the materials are present measured them, nor had they identified
equally attracted to the exciting news. at the site of the observation,” Smith said. these minerals at the south pole.”
Now, the solution to this question, with
great import to the planetary science Smith puts the clays in perspective, saying The paper could put to rest the question
community, may be much more mundane “Smectites are a type of clay that is of what lies beneath Mars’ south polar
than bodies of water on Mars. extremely abundant on Mars, covering region. “Lakes under the ice leave more
nearly 50% of the surface, especially questions unanswered than answered. A
The strength of this new study is the focused in the southern hemisphere. I simpler answer is that a material we now
diversity of techniques employed. “Our call them solid-state to reinforce the know exists at the south pole of Mars
study combined theoretical modeling with idea that these materials are solid. explains the anomalous observations
laboratory measurements and remote There is no unbound water. Further, our better than an extraordinary claim of
sensing observations from the Compact experiments show that when the clays are bodies of liquid water,” Smith said. “In
Reconnaissance Imaging Spectrometer for frozen to cryogenic temperatures, they my opinion, the liquid water interpretation
Mars (CRISM) instrument on NASA’s Mars become brittle, rather than a soft clay is hard to support at this point.”
Reconnaissance Orbiter. All three agreed like you might use for pottery. Recent
that smectites can make the reflections theoretical work had suggested that
and that smectites are present at the south clays could make bright reflections, but
pole of Mars. It’s the trifecta: Measure the no one had frozen them to temperatures
material properties, show that the material we would see on Mars — namely
properties can explain the observation, and 40° to 50° below freezing — and
NASA SPACECRAFT PROVIDES
INSIGHT INTO ASTEROID
BENNU’S FUTURE ORBIT
In a recent study, NASA researchers reducing uncertainties related to its future OSIRIS-REx data,” was published in the
used precision-tracking data from the orbit, and improving scientists’ ability to November issue of the journal Icarus.
agency’s Origins, Spectral Interpretation, determine the total impact probability
Resource Identification, Security-Regolith and predict orbits of other asteroids. “NASA’s Planetary Defense mission is to
Explorer (OSIRIS-REx) spacecraft to find and monitor asteroids and comets
better understand movements of the The study, entitled “Ephemeris and that can come near Earth and may pose
potentially hazardous asteroid Bennu hazard assessment for near-Earth a hazard to our planet,” said Kelly Fast,
through the year 2300, significantly asteroid (101955) Bennu based on Program Manager for the Near-Earth
Object Observations Program at NASA
Headquarters in Washington, DC. “We
“ NASA’s Planetary Defense carry out this endeavor through continuing
astronomical surveys that collect
data to discover previously unknown
mission is to find and objects and refine our orbital models
for them. The OSIRIS-REx mission has
provided an extraordinary opportunity
monitor asteroids and to refine and test these models, helping
us better predict where Bennu will be
when it makes its close approach to
comets that can come Earth more than a century from now.”
In 2135, asteroid Bennu will make a
near Earth and may pose
close approach with Earth. Although
the near-Earth object will not pose
a danger to our planet at that time,
a hazard to our planet.”
scientists must understand Bennu’s exact
trajectory during that encounter in order
16 Issue 166 October 2021 © Copyright 2021 Lunar and Planetary InstituteN E W S F R O M S PAC E
This mosaic of Bennu was created using observations made by NASA’s OSIRIS-REx spacecraft, which was in close proximity to the asteroid for over two years.
Credit: NASA/Goddard/University of Arizona.
to predict how Earth’s gravity will alter mass, and composition while monitoring its during its 2135 close approach. These
the asteroid’s path around the Sun — and spin and orbital trajectory. The spacecraft keyholes are areas in space that would
affect the hazard of Earth impact. also scooped up a sample of rock and set Bennu on a path toward a future
dust from the asteroid’s surface, which impact with Earth if the asteroid were to
Using NASA’s Deep Space Network it will deliver to Earth on September 24, pass through them at certain times due
and state-of-the-art computer models, 2023, for further scientific investigation. to the effect of Earth’s gravitational pull.
scientists were able to significantly
shrink uncertainties in Bennu’s “The OSIRIS-REx data give us so To calculate exactly where the asteroid will
orbit, determining its total impact much more precise information, we be during its 2135 close approach — and
probability through the year 2300 can test the limits of our models and whether it might pass through a gravita-
is about 1 in 1750 (or 0.057%). The calculate the future trajectory of Bennu tional keyhole — Farnocchia and his team
researchers also identified September to a very high degree of certainty evaluated various types of small forces
24, 2182, as the most significant through 2135,” said study lead Davide that may affect the asteroid as it orbits the
single date in terms of a potential Farnocchia of the Center for Near Sun. Even the smallest force can signifi-
impact, with an impact probability Earth Object Studies (CNEOS), which cantly deflect its orbital path over time,
of 1 in 2700 (or about 0.037%). is managed by NASA Jet Propulsion causing it to pass through or completely
Laboratory (JPL) in Southern California. miss a keyhole.
Although the chances of it hitting Earth “We’ve never modeled an asteroid’s
are very low, Bennu remains one trajectory to this precision before.” Among those forces, the Sun’s heat plays
of the two most hazardous known a crucial role. As an asteroid travels
asteroids in our solar system, along with Gravitational around the Sun, sunlight heats its dayside.
another asteroid called 1950 DA. Because the asteroid spins, the heated
Keyholes surface will rotate away and cool down
Before leaving Bennu on May 10, 2021, when it enters the nightside. As it cools, the
OSIRIS-REx spent more than two years in The precision measurements on Bennu surface releases infrared energy, which
close proximity to the asteroid, gathering help to determine better how the asteroid’s generates a small amount of thrust on
information about its size (it is about 500 orbit will evolve over time and whether it the asteroid — a phenomenon called the
meters or one-third of a mile wide), shape, will pass through a “gravitational keyhole” Yarkovsky effect. Over short timeframes,
17 Issue 166 October 2021 © Copyright 2021 Lunar and Planetary InstituteYou can also read
