planetary science institute

Sara Seager

(born 1971) Astronomer and planetary scientist

Sara Seager is a full professor of physics and planetary science at MIT. She is perhaps best known for the Seager equation which identifies potentially habitable planetary systems through gas analysis. She has been awarded countless honors, including being recognized as an honorary fellow with the Royal Astronomical Society of Canada and was awarded the “Genius Grant” from the MacArthur Foundation in September 2013.

Number 85 in an ongoing series celebrating remarkable women in science, technology, engineering, and mathematics.


A Fresh Look at Older Data Yields a Surprise Near the Martian Equator

Scientists taking a new look at older data from NASA’s longest-operating Mars orbiter have discovered evidence of significant hydration near the Martian equator – a mysterious signature in a region of the Red Planet where planetary scientists figure ice shouldn’t exist.

Jack Wilson, a post-doctoral researcher at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, led a team that reprocessed data collected from 2002 to 2009 by the neutron spectrometer instrument on NASA’s Mars Odyssey spacecraft. In bringing the lower-resolution compositional data into sharper focus, the scientists spotted unexpectedly high amounts of hydrogen – which at high latitudes is a sign of buried water ice – around sections of the Martian equator.

An accessible supply of water ice near the equator would be of interest in planning astronaut exploration of Mars. The amount of delivered mass needed for human exploration could be greatly reduced by using Martian natural resources for a water supply and as raw material for producing hydrogen fuel.

By applying image-reconstruction techniques often used to reduce blurring and remove “noise” from medical or spacecraft imaging data, Wilson’s team improved the spatial resolution of the data from around 320 miles to 180 miles (520 kilometers to 290 kilometers). “It was as if we’d cut the spacecraft’s orbital altitude in half,” Wilson said, “and it gave us a much better view of what’s happening on the surface.”
The neutron spectrometer can’t directly detect water, but by measuring neutrons, it can help scientists calculate the abundance of hydrogen – and infer the presence of water or other hydrogen-bearing substances.

Mars Odyssey’s first major discovery, in 2002, was abundant hydrogen just beneath the surface at high latitudes. In 2008, NASA’s Phoenix Mars Lander confirmed that the hydrogen was in the form of water ice.

But at lower latitudes on Mars, water ice is not thought to be thermodynamically stable at any depth. The traces of excess hydrogen that Odyssey’s original data showed at lower latitudes were initially explained as hydrated minerals, which other spacecraft and instruments have since observed.
Wilson’s team concentrated on those equatorial areas, particularly with a 600-mile (1,000-kilometer) stretch of loose, easily erodible material between the northern lowlands and southern highlands along the Medusae Fossae Formation. Radar-sounding scans of the area have suggested the presence of low-density volcanic deposits or water ice below the surface, “but if the detected hydrogen were buried ice within the top meter of the surface, there would be more than would fit into pore space in soil,” Wilson said. The radar data came from both the Shallow Radar on NASA’s Mars Reconnaissance Orbiter and the Mars Advanced Radar for Subsurface and Ionospheric Sounding on the European Space Agency’s Mars Express orbiter and would be consistent with no subsurface water ice near the equator.

How water ice could be preserved there is a mystery. A leading theory suggests an ice and dust mixture from the polar areas could be cycled through the atmosphere when Mars’ axial tilt was larger than it is today. But those conditions last occurred hundreds of thousands to millions of years ago. Water ice isn’t expected to be stable at any depth in that area today, Wilson said, and any ice deposited there should be long gone. Additional protection might come from a cover of dust and a hardened “duricrust” that traps the humidity below the surface, but this is unlikely to prevent ice loss over timescales of the axial tilt cycles.

“Perhaps the signature could be explained in terms of extensive deposits of hydrated salts, but how these hydrated salts came to be in the formation is also difficult to explain,” Wilson added. “So for now, the signature remains a mystery worthy of further study, and Mars continues to surprise us.”

Wilson led the research while at Durham University in the U.K. His team - which includes members from NASA Ames Research Center, the Planetary Science Institute and the Research Institute in Astrophysics and Planetology - published its findings this summer in the journal Icarus.

TOP IMAGE….Taking advantage of Mars’s closest approach to Earth in eight years, astronomers using NASA’s Hubble Space Telescope have taken the space-based observatory’s sharpest views yet of the Red Planet. NASA is releasing these images to commemorate the second anniversary of the Mars Pathfinder landing. The lander and its rover, Sojourner, touched down on the Red Planet’s rolling hills on July 4, 1997, embarking on an historic three-month mission to gather information on the planet’s atmosphere, climate, and geology.
The telescope’s Wide Field and Planetary Camera 2 snapped images between April 27 and May 6, when Mars was 54 million miles (87 million kilometers) from Earth. From this distance the telescope could see Martian features as small as 12 miles (19 kilometers) wide. The telescope obtained four images(see PIA01587), which, together, show the entire planet.
This image is centered on the region of the planet known as Tharsis, home of the largest volcanoes in the solar system. The bright, ring-like feature just to the left of center is the volcano Olympus Mons, which is more than 340 miles (550 kilometers) across and 17 miles(27 kilometers) high. Thick deposits of fine-grained, windblown dust cover most of this hemisphere. The colors indicate that the dust is heavily oxidized (“rusted”), and millions (or perhaps billions) of years of dust storms have homogenized its composition. Prominent late afternoon clouds along the right limb of the planet can be seen.
This color composite is generated from data using three filters: blue (410 nanometers), green (502 nanometers), and red (673 nanometers).

LOWER IMAGE….Re-analysis of 2002-2009 data from a hydrogen-finding instrument on NASA’s Mars Odyssey orbiter increased the resolution of maps of hydrogen abundance. The reprocessed data (lower map) shows more “water-equivalent hydrogen” (darker blue) in some parts of this equatorial region of Mars. Puzzingly, this suggests the possible presence of water ice just beneath the surface near the equator, though it would not be thermodynamically stable there.
The upper map uses raw data from Odyssey’s neutron spectrometer instrument, which senses the energy state of neutrons coming from Mars, providing an indication of how much hydrogen is present in the top 3 feet (1 meter) of the surface. Hydrogen detected by Odyssey at high latitudes of Mars in 2002 was confirmed to be in the form of water ice by the follow-up NASA Phoenix Mars Lander mission in 2008.
A 2017 reprocessing of the older data applied image-reconstruction techniques often used to reduce blurring from medical imaging data. The results are shown here for an area straddling the equator for about one-fourth the circumference of the planet, centered at 175 degrees west longitude. The white contours outline lobes of a formation called Medusae Fossae, coinciding with some areas of higher hydrogen abundance in the enhanced-resolution analysis. The black line indicates the limit of a relatively young lava plain, coinciding with areas of lower hydrogen abundance in the enhanced-resolution analysis.
The color-coding key for hydrogen abundance in both maps is indicated by the horizontal bar, in units expressed as how much water would be present in the ground if the hydrogen is all in the form of water. Units of the equivalent water weight, as a percentage of the material in the ground, are correlated with counts recorded by the spectrometer, ranging from less than 1 weight-percent water equivalent (red) to more than 30 percent (dark blue).
Odyssey’s neutron spectrometer, provided by Los Alamos National Laboratory in New Mexico, is part of the mission’s Gamma Ray Spectrometer suite overseen by the University of Arizona, Tucson. NASA’s Jet Propulsion Laboratory, a division of Caltech in Pasadena, California, manages the Mars Odyssey mission for the NASA Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, built the Odyssey spacecraft, which has been studying Mars from orbit since 2001.

anonymous asked:

How does one find internships? Unfortunately, many of my peers are having trouble finding science-related internships, mainly ones relating to lab work, and I myself don't know where to start.

Google is your friend. Get intimate with it. There are a lot of databases/lists of internships floating around, but you usually have to dig a bit to find them.

Here’s an incomplete list of ones I’ve personally taken note of. Most are in the US or the UK, and they’re mostly available to international students. There are MANY more programs open to US and EU citizens; you guys have a lot more options.

LISTS of STEM internships/programs in all fields:

Specific STEM fields:

Astronomy and Physics

Environmental Science

Australian Programs

LISTS of Science Writing Internships:

Specific Science Writing Internships

Basically, do your research, because this is a hugely incomplete list, but hopefully this gets you started.

Spread this around! My extensive Googling skills have to be good for something.

Earth's moon wandered off axis billions of years ago

A new study published today in Nature reports discovery of a rare event – that Earth’s moon slowly moved from its original axis roughly 3 billion years ago. Ancient lunar ice indicates the moon’s axis slowly shifted by 125 miles, or 6 degrees, over 1 billion years. Earth’s moon now a member of solar system’s exclusive ‘true polar wander’ club, which includes just a handful of other planetary bodies.

Planetary scientist Matt Siegler at Southern Methodist University, Dallas, and colleagues made the discovery while examining NASA data known to indicate lunar polar hydrogen. The hydrogen, detected by orbital instruments, is presumed to be in the form of ice hidden from the sun in craters surrounding the moon’s north and south poles. Exposure to direct sunlight causes ice to boil off into space, so this ice – perhaps billions of years old – is a very sensitive marker of the moon’s past orientation.

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Scientists have long held the belief that planets – including Earth – were built from rocky asteroids, but new research challenges that view.

Published in Science Advances, a journal of the American Association for the Advancement of Science, the research suggests that many of the original planetary building blocks in our solar system may actually have started life, not as rocky asteroids, but as gigantic balls of warm mud.

Phil Bland, Curtin University planetary scientist, undertook the research to try and get a better insight into how smaller planets, the precursors to the larger terrestrial planets we know today, may have come about.

Planetary Science Institute Senior Scientist Bryan Travis is a co-author on the paper “Giant Convecting Mud Balls of the Early Solar System” that appears in Science Advances.

“The assumption has been that hydrothermal alteration was occurring in certain classes of rocky asteroids with material properties similar to meteorites,” Travis said. “However, these bodies would have accreted as a high-porosity aggregate of igneous clasts and fine-grained primordial dust, with ice filling much of the pore space. Mud would have formed when the ice melted from heat released from decay of radioactive isotopes, and the resulting water mixed with fine-grained dust.”

Travis used his Mars and Asteroids Global Hydrology Numerical Model (MAGHNUM) to carry out computer simulations, adapting MAGHNUM to be able to simulate movement of a distribution of rock grain sizes and flow of mud in carbonaceous chondrite asteroids.

The results showed that many of the first asteroids, those that delivered water and organic material to the terrestrial planets, may have started out as giant convecting mud balls and not as consolidated rock.

The findings could provide a new scientific approach for further research into the evolution of water and organic material in our solar system, and generate new approaches to how and where we continue our search for other habitable planets.

IMAGES….These images show temperature maps as simulated by MAGHNUM as a result of mud convection, in a medium sized asteroid (above) and a large asteroid (below). Temperatures are shown in degrees Celcius.



Images acquired by NASA’s MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft show geologic features that indicate Mercury is likely still contracting today, joining Earth as a tectonically active planet in our solar system.

Previously undetected small fault scarps were observed in images collected during the MESSENGER mission’s final 18 months in orbit around Mercury, according to a new paper in Nature Geoscience []. During these last months of the mission, the spacecraft’s altitude was lowered allowing the surface to be imaged at higher resolutions than ever before possible.

Planetary Science Institute Research Scientist Maria Banks is a co-author on “Recent Tectonic Activity on Mercury Revealed by Small Thrust Fault Scarps.” Smithsonian senior scientist Thomas R. Watters is lead author and principal investigator of the research.

“These small-scale thrust fault scarps are orders of magnitude smaller, only a few kilometers in length and tens of meters of relief, than larger scarps previously known to exist on the surface of Mercury,” said Banks, who analyzed MESSENGER images to find and analyze these small-scale tectonic structures. “Steady meteoroid bombardment quickly degrades and destroys structures this small, indicating that they must have formed relatively recently. They are comparable in size to very young fault scarps identified on the lunar surface attributed to shrinking of the Moon.”

Fault scarps appear as cliff-like landforms. Larger, older scarps were identified in both MESSENGER and Mariner 10 images and are evidence of the global contraction of Mercury as its interior cooled causing the crust to shrink.

“The young age of the small scarps means that Mercury joins Earth as a tectonically active planet in our solar system, with new faults likely forming today as Mercury’s interior continues to cool.” said Watters, of the Center for Earth and Planetary Studies at the National Air and Space Museum.

Active faulting, paired with evidence for ancient faulting and also the recent discovery by PSI Senior Scientist Catherine Johnson that Mercury’s global magnetic field was present billions of years ago, offer consistent support for long-lived slow cooling of Mercury’s still hot outer core.

Slip along thrust faults associated with small lunar scarps is possibly connected with shallow moonquakes detected by seismometers deployed during the Apollo missions. Some of these moonquakes reached magnitudes of near 5 on the Richter scale. Seismometers deployed on Mercury in future missions would likely detect Mercury-quakes associated with ongoing slip events on small faults and reactivated older large faults.

Banks’s funding for this project came from a grant from NASA’s Mercury MESSENGER mission.

LOWER IMAGE…. A cluster of small lobate scarp thrust faults on Mercury’s intercrater plains (~38.90° N, 27.93° E). The longest scarp in the cluster (upper arrows) is ~4.3 km in length. (MESSENGER Mercury Dual Imaging System (MDIS) image frame number EN1029769395M). B. Close up view of small scarp shown in A. Inset: A small impact crater ~90m in diameter (lower arrow) is potentially disturbed or crosscut (note the lack of a well-defined rim on the scarp face) by the scarp segment, and another crater ~135m in diameter (upper arrow) may be horizontally shortened. The box in B shows the location of the inset. Figure modified from Watters et al., 2016.