California State University, Sacramento
Analyzing Europa’s Surface Topography Using
Stereo Photogrammetry
El-iza El Henson
Faculty Mentor: Dr. Vera Margoniner
McNair Scholars Journal s Volume 16
ranges with a variety of different altitudes. Occasionally these ridges all form in close
vicinity to one another, and it is this compilation of ridges in close proximity that
composes chaos terrain. Europa remains one of the main focal points of an emerging
discipline known as astrobiology, because of its hypothesized oceans; which
scientists theorize to reside beneath about 150 to 200 km of ice (Carr et al., 1998).
Although Europa’s actual icy depths may vary widely from a few kilometers to ten
or more kilometers (Schenk, 2002). Understanding the topography of Europa is an
essential step in thoroughly evaluating the moon’s potential to harbor life.
Abstract
Mankind has, for as long as we know, tried to understand its place in the universe. Is life exclusive
to Earth or is there life throughout the universe? Where did life originate? Jupiter’s moon Europa
has the potential to help us start to answer these questions because scientists believe that a large ocean
exists under its icy surface. In this study, attention is focused on Europa’s topography and what it
tells us about the oceans underneath. Stereo photogrammetry is the method used to construct threedimensional maps by piecing together the information from pictures taken from different angles.
Introduction
Europa is known as a one of the four Galilean moons because it was discovered
by Galileo Galilee in 1610 along with Io, Callisto, and Ganymede. Since then,
astronomers have discovered 63 other moons; giving Jupiter a grand total of 67
moons (Moratto, 2010). Although this may seem like an excessive amount of mass
orbiting the Jovian planet, the other 63 moons are significantly less massive than
their Galilean counterparts. Just to give a little bit of perspective, Europa has a radius
of 1560.8 km, or about a quarter of Earth’s radius (Moratto, 2010). However, when
it comes to surface area, Europa has approximately only 6 percent of Earth’s total
surface area. And when it comes to mass, Europa accounts for 4.79 x 1022 kg which
is less than 1 percent of Earth’s mass. In total Jupiter itself is a massive 1.9 x 1027
kg and the Jovian moons ac­count for 3.93 x 1023 kg, for some perspective all the
moons combined are only 0.0002 percent of Jupiter’s mass (Moratto, 2010).
Another contrasting measure between Earth and Europa is its albedo. In this
context albedo refers to the potential of a surface to reflect radioactive waves or in
other words, light. A planet with a high albedo means that its surface can reflect a
large amount of light, and a planet with a low albedo can only reflect a small amount
of light back into space. Europa’s high albedo of 0.67 was the first indication of an
icy surface. This moon possesses a variety of surface topography that ranges from flat
lands, to craters, ridges, and chaos terrain (Schmidt et al., 2011).
The flat lands are for the most part composed of relatively smooth vast open
environments (see Figure 1). While the ridges can be thought of as icy mountain
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Figure 1: Flat lands. Ridges and Chaos Terrain (S.E. T l. Institute), Figure 2: Cilix Crator (S.E. T l. Institute)
Europa consists of an iron core estimated to be 1250 km in diameter (see Figure
3). The satellite Galileo also detected a magnetic field surrounding the small
moon. Scientists are almost certain that Europa has an induced magnetosphere
due to Jovian forces as opposed to an intrinsic magnetosphere like we experience
on Earth (Kivelson et al., 2000). This magnetosphere is critical when it comes to
protecting life from harmful radioactive waves from space.
Astronomer’s current models suggest that above Europa’s iron core exists a Silicate
(rocky) mantle; enveloping its Silicate mantle is about 150 km of an icy/water
crust (see Figure 3). This ice shell and homogenous liquid ocean is theorized to be
the product of tidal flexing.
Jovian gravitational forces give European oceans thermal energy that allows
Europa to maintain its oceans in a liquid state. The potential for liquid water
greatly increases Europa’s appeal in the search for extraterrestrial life, which makes
this study particularly exciting. In this analysis, the researcher primarily focuses
their attention on ridges and craters. Specifically the researcher will be discussing
a region on Europa’s surface near Cilix Crater (see Figure 2). The objective of this
project is to produce a 3-Dimensional representation of Europa’s surface; in effect
evaluating if the measurements corroborate or contradict measurements made by
previous astronomers. The comparison will help one determine whether stereo
photogrammetry is a reliable method when it comes to analyzing the surface
topography of Earth-like planets. Such insight will lead to the most efficient
method in the analyzation of potential life forms.
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Figure 3: Theorized internal structure of Europa (image found at Maung-Science.com)
Figure 4: Visual representation (Stereo Photogrammetry image found on computamaps.com )
Literature Review
Europa has become very popular in the study of Astronomy and more specifically
Astro­biology. New studies and more advanced techniques have lead astronomers
among other scientists alike into viewing the universe in an entirely different
light (Akos and Zsolt, 2013). Many factors govern a planet’s potential to harbor
life, some of these factors include: chemical composition, surface pressure, and
whether or not the planet resides within what is known as the habitable zone of a
star (Schmidt et al., 20 11).
Scientists use methods such as Spectroscopy, which is the study of the interaction
be­tween energy and matter. Spectroscopy was first utilized for the study of visible
light transmitted according to its wavelength, by a prism. Since then, the process
has been expanded enormously to comprise any interaction with radiative energy
as a function of its frequency or wavelength.
This technique proved useful in practice, however if astronomers hope to land
a probe that can physically scan for potential life on Europa, it is necessary to
know more than just the composition of the moon. It is essential that we develop
a working model that accurately depicts Europa’s surface. Only then will they be
able to predict and eventually analyze the most probable regions that may contain
liquid water. In order to properly analyze the topography of Europa, the re­
searcher utilized the method known as Stereo Photogrammetry (Moratto, 2010).
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Figure 4 is a visual demonstration of photogrammetry, which is the process
of deducing the geometric properties of objects from photographic images.
Photogrammetry uses methods from many disciplines, including optics and
projective geometry (Moratto, 2010). Specifically, Stereo Photogrammetry
involves estimating the three dimensional coordinates of points on an object.
These points are determined by measurements made in two or more photographic
images taken from different positions. Points of commonality are identified on
each image. A line of sight or ray can be constructed from the camera’s location
to the point on the object (Moratto, 2010). It is the intersection of these rays or
triangulation that determines the three-dimensional location of the point. More
sophisticated algorithms can exploit other information about the scene that are
known a priori, for instance symmetries, in some cases allowing reconstructions of
3D coordinates from only one camera position (Moratto et al., 2010).
Astronomers theorize that if there is in fact liquid water on Europa, then there is
a high probability that there will be organic life in some form as well (Hinman,
2013). This kind of analysis will assist in the finding of extraterrestrial liquid
water. After much review, the results from multiple authors have led to the
consensus that there is an ice crust enveloping the majority of Europa’s surface,
coupled with the presence of an internal ocean (Schenk, 2002). Moreover chaos
terrains and other lenticulae regions may be related to submarine geothermal
centers (Akos and Zsolt, 2013). A thermal center is a concept used in applied
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physics and engineering, which asserts that when a solid object is exposed to
thermal variance an expansion will occur. This ex­pansion tends to change the
dimensions and potentially the shape of the body and or the position of its points.
On the other hand, pull-apart terrains among other linear regions are likely in con­
nection with submarine oceanic processes. Therefore, if scientists were to rank
the surface features in relation to deep submarine processes, chaos terrain is more
important than tidal related linear features (Akos and Zsolt, 2013).
After evaluating the dimensions of blocks in the terrain of Conamara Chaos,
scientists have found strong evidence that suggests the thickness of the ice crust
during its formation is roughly around 2 km at the rafts (segments of flat icy
surface that supports icy matrix) and 0.5 km at the matrix, which is in agreement
with multiple other authors estimated values (Akos and Zsolt, 2013). Researchers
calculated the hydrostatic pressure at the bottom of an approximately 25 km
thick ice crust to be on the order of 10,000 to 20,000 kPa, and at the bottom of
a 100 km deep ocean, pressures were found at the order of 150,000 kPa (101 kPa
corresponds to 1 atm). Clathrates are any chemical substances that consists of a
lattice that traps or contains molecules. Taking into account such pressure and
assumed temperature, volcanic gases will become dissolved in the water, although
clathrates might also form, and could be released later as gaseous bubbles (Alrns
and Zsolt, 2013). It is this excess of clathrates in conjunction with underwater
volcanic activity that allows chaos terrain to form.
Such processes are magnified during the formation of chaos terrains if the
ice crust thick­ness is only 2 km at the active phase (volcanically active) and
the pressure is approximately be­tween 2400 to 3100 kPa at its base. The
decomposition of clathrates and bubble formation may be the most intensive at
chaos regions, and bubbles may be trapped between ice grains or inside clathrate
structures (Akos and Zsolt, 2013). Based on similar terrestrial analogs, scientists
deduced that trapped bubbles might be detectable remotely by analysis of the
difference in albedo in the infrared and visual parts of the spectrum, as well as
other scattering properties (Akos and Zsolt, 2013). The possibility of detecting
gas bubbles or other material floating upward in the warm rising plume is of high
interest at chaos terrains since this is a potential theory contributing to their
own origin. Therefore the development of topography detecting methods for
the next Europa mission is useful. This study, among other similar studies, will
ideally assist the European Space Agency (ESA) with Project JUICE ( Jupiter Icy
Moons Explorer). This will be the first large scale mission in ESA’s Cosmic Vision
2015-2025 program planned for launch in 2022 and will arrive at Jupiter in 2030
(Dougherty, M.K. et al., 2012). This probe will spend at least three years making
detailed observations of the gaseous red planet Jupiter, along with three of its
largest moons, Europa, Ganymede, and Callisto.
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Methods
In this process the researcher used images from the Galileo satellite, the AMES
Stereo Pipeline: NASA’s Open Source Automated Stereogrammetry Software
Version 2.2.2 (Moratto, 2010), and ISIS 3 software. ISIS is the Integrated System
for Imagers and Spectrometers, essentially a specialized, digital image processing
software package developed by the United States Geological Survey (USGS) for
NASA. ISIS’s main feature is the ability to place many types of data in the correct
cartographic location, enabling different types of data to be co-analyzed. ISIS
also includes standard image processing applications such as contrast, stretch,
image algebra, filters, and statistical analysis. ISIS can process two-dimensional
images as well as three dimensional cubes derived from imaging spectrometers.
The production of USGS topographic maps of extraterrestrial landing sites relies
on ISIS software processing of data from NASA and International spacecraft
missions including Lunar Orbiter, Apollo, Voyager, Mariner 10, Viking, Galileo,
Magellan, Clementine, Mars Global Surveyor, Cassini, Mars Odyssey, Mars
Reconnaissance Orbiter, MESSENGER, Lunar Reconnaissance Orbiter,
Chandrayaan, Dawn, and Kaguya.
The first step in the Photogrammetric process is to use the JMARS ( Java MissionPlan­ning and Analysis for Remote Sensing) software to identify high resolution
images of Europa’s surface that overlap each other. It is a geospatial information
system (GIS) developed by Arizona State University’s Mars Space Flight
Facility to provide mission planning and data-analysis tools to NASA’s orbiters,
instrument team members, students, and the general public. This step is par­
ticularly challenging because the grid that determines overlap does not account
for parallax, which is an effect where the position or direction of an object appears
to differ when viewed from different positions. An elementary example of parallax
could be the perceived difference in the position of an object when an individual
is viewing it exclusively from one eye, as opposed to the other. Matching the
images requires thorough visual evaluation of whether there was actual overlap
between the two photographs, or simply an error in computed parallax. After
determining that the pair of images are of similar resolutions, the researcher
became able to begin using the ISIS software to input points of commonality.
The researcher was instructed to find 4 to 5 points of commonality in order to help
the ISIS software successfully re-project the two images. The researcher speculated
that this failure to produce a comprehensive DEM using the two images was a
product of insufficient image resolution coupled with lack of surface overlap.
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Conclusion
The researcher was able to determine that Europa has ridges whose heights range
from fifty to one hundred meters high. Moreover these ridges can stretch for as
long as 20km. Also Cilix Crater has a unique central peak that makes it unusual
when compared to other craters in its size range. This central peak is anywhere
from 300-350m taller than the crater floor. The crater floor is relatively level,
and from rim to floor the heights range from 250-300m. Cilix Crater has an
estimated diameter of 16-17km, making it one of the larger visible impact craters
on Europa. Moreover due to the complex activity associated with chaos terrain,
this makes Europa more appealing to scientists when it comes to the search for
extraterrestrial life. This is why topographical analysis of Europa’s surface is of the
utmost importance for future explorations.
Figure 5: DEM (Digital Elevation Map) Profiles
Finally after extracting topographic profiles from successful DEM ‘s the
researcher was able to begin creating a 3-Dimensional rendition of Europa’s
surface topography. To verify the findings, the researcher and his collaborators
took several profiles of the same region (as seen in figure 5 and 6), which allowed
them to evaluate the consistency of all of their measurements compared to prior
research done in the region.
Future Work
As previously mentioned, JUICE will be the first large scale mission in ESA’s
Cosmic Vision 2015-2025 program. Some potential follow up research can be
done after the planned JUICE mission of ESA, since there will probably be two
Europa flybys (satellite will pass by Europa twice). Scientists aim to include the
understanding of the formation and composition of non-water-ice material, the
subsurface exploration with radar, and to identify and characterize candidate sites
for future exploration (Akos and Zsolt, 2013). Currently scientists are planning
on utilizing Narrow Angle Cameras (NAC), Wide Angle Cameras (WAC),
Visible Infrared Hyper­spectral Imaging Spectrometers (VIRHIS), UV Imaging
Spectrometers (UVIS), Sub-mm Wave Instruments (SWI), Laser Altimeters
(LA), and Ice Penetrating Radar (Dougherty and Grasset, 2012) detectors to
analyze imaging and radar activity of selected regions.
Figure 6: 3-Dimensional Model of Ci/ix Crater (S.E.T l. Institute )
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References
Akos, K. & Zsolt, K. “Astrobiological implications of chaos terrains on Europa to
help targeting future missions, Planetary and Space Science.” Volume 77, Pages 7490, (2013)
Carr, M.H. et al. “Evidence for a subsurface ocean on Europa Nature.” 391, 363-365
(1998)
Dougherty, M.K. et al. “Jupiter Icy moons Explorer (JUICE): An ESA mission to
orbit Ganymede and to characterize the Jupiter system, Planetary and Space Science.”
Volume 78, Pages 1- 21 (2012)
Hinman, N.W. “Water-Rock Interaction and Life.” Procedia Earth and Planetary
Science 7, 354- 359 (2013)
Ivanov, M.A. et al. “Landforms of Europa and selection of landing sites.” Advances
in Space Research Volume 48, Issue 4, Pages 661-677 (2011)
Kivelson, M.G. et al. “Galileo magnetometer measurements: a stronger case for a
sub-surface ocean at Europa.” Science 289, 1340-1343 (2000)
Moratto, Z.M. AMES. “Stereo Pipeline: NASA’s Open Source Automated
Stereogrammetry.” Software Version 2.2.2 (2010)
Schenk, P. M. Thickness constraints on the icy shells of the galilean satellites from a
comparison of crater shapes. Nature 417, 419-421 (2002)
Schmidt, B. E., et al. “Active formation of ‘chaos terrain’ over shallow subsurface
water on Europa.” Nature 479, 502-505 (2011)
McNair Scholars Journal s Volume 16
The Effect of Lomatium Californicum
on Mouse Embryonic Cell Line NIH-3T3
Margaret Johnson
Faculty Mentor: Dr. Mary McCarthy-Hintz
Abstract
The plant species Lomatium Californicum has authentic spiritual and therapeutic aspects
that are well known in the Native American communities of California, such as the Chumash,
Karuk, Yuki, and Kawaiisu. Historically, the customary name for L. Californicum is oshá,
whose root is used to make chuchupate. Chuchupate is a sacred medicine used in medical treatments
for various ailments, including colds, fever, and upper respiratory conditions. In stronger doses,
it has been used in women’s medicine as an abortifacient. To better understand the medicinal
properties of L. Californicum, scientists have studied it from a Western perspective. The purpose
of this research is to understand the pharmaceutical uses and safety concerns of this alternative
medicine and to convey awareness of it to non-Traditional health practitioners who work with
Native American communities. In previous research, an ethanolic extract of L. Californicum
roots showed cytotoxicity toward breast cancer cells and normal human peripheral blood
mononuclear cells. Because of its use as an abortifacient, it was hypothesized that it would also
have cytotoxic effects on embryonic cells. Therefore, a dilution series of an L. Californicum root
extract was tested on a mouse embryonic cell line, NIH-3T3. The results were inconclusive due to
the low number of cells that were used in the assay. Therefore, future experiments will be conducted
using a higher quantity of cells.
Introduction
There is a growing interest in medicinal botanicals as part of therapeutic
alternatives in the United States (Borchers et al. 2000). In particular,
pharmaceutical companies are becoming more aware of the use of herbals by
Native American societies. In addition, there is a high demand from consumers
seeking alternative medicines that are natural, rather than using prescription
medicines. Many anthropologists have studied California Indian communities, to
try to understand how Native Americans have used medicinal plants (Timbrook
1987). One must understand traditional practices to understand their context in
the society and culture (Strike 1994). Native Americans believe that everything
has a spirit: earth, animals, trees, roots, and rocks, as well as elements such as
lightning and wind (Martin 1981; Zigmond 1977).
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