360 research outputs found
Characterizing of a Mid-Latitude Ice-Rich Landing Site on Mars to Enable in Situ Habitability Studies
We suggest an ice-rich landing site at 188.5E 46.16N within Amazonis Planitia as a candidate location to support a Mars lander mission equipped to study past habitability and regions capable of preserving the physical and chemical signs of life and organic matter. Studies of the ice-rich subsurface on Mars are critical for several reasons. The subsurface environment provides protection from radiation to shield organic and biologic compounds from destruction. The ice-rich substrate is also ideal for preserving organic and biologic molecules and provides a source of H2O for biologic activity. Examination of martian ground ice can test several hypotheses such as: 1) whether ground ice supports habitable conditions, 2) that ground ice can preserve and accumulate organic compounds, and 3) that ice contains biomolecules evident of past or present biological activity on Mars. This Amazonis site, located near the successful Viking Lander 2, shows indirect evidence of subsurface ice (ubiquitous defined polygonal ground, gamma ray spectrometer hydrogen signature, and numerical modeling of ice stability) and direct evidence of exposed subsurface ice. This site also provides surface conditions favorable to a safe landing including no boulders, low rock density, minimal rough topography, and few craters
Ice Dragon: A Mission to Address Science and Human Exploration Objectives on Mars
We present a mission concept where a SpaceX Dragon capsule lands a payload on Mars that samples ground ice to search for evidence of life, assess hazards to future human missions, and demonstrate use of Martian resources
Water induced sediment levitation enhances downslope transport on Mars
On Mars, locally warm surface temperatures (~293 K) occur, leading to the possibility of (transient) liquid water on the surface. However, water exposed to the martian atmosphere will boil, and the sediment transport capacity of such unstable water is not well understood. Here, we present laboratory studies of a newly recognized transport mechanism: “levitation” of saturated sediment bodies on a cushion of vapor released by boiling. Sediment transport where this mechanism is active is about nine times greater than without this effect, reducing the amount of water required to transport comparable sediment volumes by nearly an order of magnitude. Our calculations show that the effect of levitation could persist up to ~48 times longer under reduced martian gravity. Sediment levitation must therefore be considered when evaluating the formation of recent and present-day martian mass wasting features, as much less water may be required to form such features than previously thought
Neutron Spectrometer Prospecting in the Mojave Volatiles Project Analog Field Test
We know that volatiles are sequestered at the poles of the Moon. While we have evidence of water ice and a number of other compounds based on remote sensing, the detailed distribution, and physical and chemical form are largely unknown. Additional orbital studies of lunar polar volatiles may yield further insights, but the most important next step is to use landed assets to fully characterize the volatile composition and distribution at scales of tens to hundreds of meters. To achieve this range of scales, mobility is needed. Because of the proximity of the Moon, near real-time operation of the surface assets is possible, with an associated reduction in risk and cost. This concept of operations is very different from that of rovers on Mars, and new operational approaches are required to carry out such real-time robotic exploration. The Mojave Volatiles Project (MVP) was a Moon-Mars Analog Mission Activities (MMAMA) program project aimed at (1) determining effective approaches to operating a real-time but short-duration lunar surface robotic mission, and (2) performing prospecting science in a natural setting, as a test of these approaches. Here we describe some results from the first such test, carried out in the Mojave Desert between 16 and 24 October, 2014. The test site was an alluvial fan just E of the Soda Mountains, SW of Baker, California. This site contains desert pavements, ranging from the late Pleistocene to early-Holocene in age. These pavements are undergoing dissection by the ongoing development of washes. A principal objective was to determine the hydration state of different types of desert pavement and bare ground features. The mobility element of the test was provided by the KREX-2 rover, designed and operated by the Intelligent Robotics Group at NASA Ames Research Center. The rover-borne neutron spectrometer measured the neutron albedo at both thermal and epithermal energies. Assuming uniform geochemistry and material bulk density, hydrogen as either hydroxyl/water in mineral assemblages or as moisture will significantly enhance the return of thermalized neutrons. However, in the Mojave test setting there is little uniformity, especially in bulk material density. We find that lighter toned materials (immature pavements, bar and swale, and wash materials) have lower thermal neutron flux, while mature, darker pavements with the greatest desert varnish development have higher neutron fluxes. Preliminary analysis of samples from the various terrain types in the test area indicates a prevailing moisture content of 2-3 wt% H2O. However, soil mineralogy suggests that the welldeveloped Av1 soil horizon beneath the topmost dark pavement clast layer contains the highest clay content. Structural water (including hydroxyl) in these clays may explain the enhanced neutron albedo over dark pavements. On the other hand, surface and subsurface bulk density can also play a role in neutron albedo - lower density of materials found in washes, for example, can result in a reduction in neutron flux. Analysis is ongoing
From oil field to geothermal reservoir: assessment for geothermal utilization of two regionally extensive Devonian carbonate aquifers in Alberta, Canada
The Canadian province of
Alberta has one of the highest per capita CO2-equivalent emissions
in Canada, predominantly due to the industrial burning of coal for the
generation of electricity and mining operations in the oil sands deposits.
Alberta's geothermal potential could reduce CO2 emissions by
substituting at least some fossil fuels with geothermal energy.The Upper Devonian carbonate aquifer systems within the Alberta Basin are
promising target formations for geothermal energy. To assess their
geothermal reservoir potential, detailed knowledge of the thermophysical and
petrophysical rock properties is needed. An analogue study was conducted on
two regionally extensive Devonian carbonate aquifers, the Southesk-Cairn
Carbonate Complex and the Rimbey-Meadowbrook Reef Trend, to furnish a
preliminary assessment of the potential for geothermal utilization. Samples
taken from outcrops were used as analogues to equivalent formations in the
reservoir and correlated with core samples of the reservoir. Analogue
studies enable the determination and correlation of facies-related rock
properties to identify sedimentary, diagenetic, and structural variations,
allowing for more reliable reservoir property prediction.Rock samples were taken from several outcrops of Upper Devonian carbonates
in the Rocky Mountain Front Ranges and from four drill cores from the
stratigraphically equivalent Leduc Formation and three drill cores of the slightly
younger Nisku Formation in the subsurface of the Alberta Basin. The samples
were analyzed for several thermophysical and petrophysical properties, i.e.,
thermal conductivity, thermal diffusivity, and heat capacity, as well as
density, porosity, and permeability. Furthermore, open-file petrophysical
core data retrieved from the AccuMap database were used for correlation.The results from both carbonate complexes indicate good reservoir conditions
regarding geothermal utilization with an average reservoir porosity of about
8 %, average reservoir permeability between 10−12 and
10−15 m2, and relatively high thermal conductivities
ranging from 3 to 5 W m−1 K−1. The most promising target
reservoirs for hydrothermal utilisation are the completely dolomitized reef
sections. The measured rock properties of the Leduc Formation in the
subsurface show no significant differences between the Rimbey-Meadowbrook
Reef Trend and the Southesk-Cairn Carbonate Complex. Differences between the
dolomitized reef sections of the examined Leduc and Nisku Formation are also
minor to insignificant, whereas the deeper basinal facies of the Nisku
Formation differs significantly.In contrast, the outcrop analogue samples have lower porosity and
permeability, likely caused by low-grade metamorphism and deformation during
the Laramide orogeny that formed the Rocky Mountains. As such, the outcrop
analogues are not valid proxies for the buried reservoirs in the Alberta
Basin.Taken together, all available data suggest that dolomitization enhanced the
geothermal properties, but depositional patterns and other diagenetic
events, e.g., fracturing, also played an important role.</p
Red Dragon: Low-cost Access to the Surface of Mars using Commercial Capabilities
We will discuss the feasibility of using a minimally-modified variant of a SpaceX Dragon capsule as a low-cost, large-capacity, near-term, Mars lander for scientific and human-precursor missions. We have been evaluating such a Red Dragon platform as an option for a Discovery Program mission concept. A Red Dragon lander has the potential to be low cost primarily because it would be derived from a routinely-flying spacecraft. Dragon is being developed to ferry cargo and crew to and from the International Space Station (ISS). The cargo variant is currently undergoing test flights, which will be followed by standard ISS cargo missions and, eventually, crewed flights. The human variant, unlike other Earth-return vehicles, appears to also have most of the capabilities necessary to land on Mars. In particular, it has a set of high-thrust, throttleable, storable bi-propellant Super- Draco engines integrated directly into the capsule which are intended for launch abort and powered landings on Earth. These thrusters suggest the possibility of a parachute-free, fully-propulsive deceleration at Mars from supersonic speeds to the surface. Concepts for large, human-relevant landers (see, e.g., [1]) also often employ supersonic retro-propulsion; Red Dragon's entry, descent, and landing approach would scale to those landers. Further, SpaceX's Falcon Heavy launch vehicle, currently under development and expected to have its first flight in 2013, will be capable of sending Dragon on a trajectory to Mars. We will discuss our motivation for exploring a Red Dragon lander, the primary technical questions which determine its feasibility, and the current results of our analysis. In particular, we will examine entry, descent, and landing (EDL) in detail. We will describe the modifications to Dragon necessary for interplanetary cruise, EDL, and operations on the Martian surface
BASALT A: Basaltic Terrains in Idaho and Hawaii as Planetary Analogues for Mars Geology and Astrobiology
Probing for Invisible Higgs Decays with Global Fits
We demonstrate by performing a global fit on Higgs signal strength data that
large invisible branching ratios Br_{inv} for a Standard Model (SM) Higgs
particle are currently consistent with the experimental hints of a scalar
resonance at the mass scale m_h ~ 124 GeV. For this mass scale, we find
Br_{inv} < 0.64 (95 % CL) from a global fit to individual channel signal
strengths supplied by ATLAS, CMS and the Tevatron collaborations. Novel tests
that can be used to improve the prospects of experimentally discovering the
existence of a Br_{inv} with future data are proposed. These tests are based on
the combination of all visible channel Higgs signal strengths, and allow us to
examine the required reduction in experimental and theoretical errors in this
data that would allow a more significantly bounded invisible branching ratio to
be experimentally supported. We examine in some detail how our conclusions and
method are affected when a scalar resonance at this mass scale has couplings
deviating from the SM ones.Comment: 32pp, 15 figures v2: JHEP version, ref added & comment added after
Eq.
Searching for WR stars in I Zw 18 -- The origin of HeII emission
I Zw 18 is the most metal poor star-forming galaxy known and is an ideal
laboratory to probe stellar evolution theory at low metallicities. Using
archival HST WFPC2 imaging and FOS spectroscopy we were able to improve
previous studies. We constructed a continuum free HeII map, which was used to
identify Wolf-Rayet (WR) stars recently found by ground-based spectroscopy and
to locate diffuse nebular emission. Most of the HeII emission is associated
with the NW stellar cluster, clearly displaced from the surrounding shell-like
[OIII] and Halpha emission. We found evidence for HeII sources, compatible with
5--9 WNL stars and/or compact nebular HeII emission, as well as residual
diffuse emission. Only one of them is outside the NW cluster. We have
calculated evolutionary tracks for massive stars and synthesis models at the
appropriate metallicity (Z ~ 0.02 Zsun). These single star models predict a
mass limit M_WR ~ 90 Msun for WR stars to become WN and WC/WO. For an
instantaneous burst model with a Salpeter IMF extending up to M_up ~ 120-150
Msun our model predictions are in reasonable agreement with the observed
equivalent widths. Our model is also able to fully reproduce the observed
equivalent widths of nebular HeII emission due to the presence of WC/WO stars.
This quantitative agreement and the spatial correlation of nebular HeII with
the stellar cluster and the position of WR stars shown from the ground-based
spectra further supports the hypothesis that WR stars are responsible for
nebular HeII emission in extra-galactic HII regions. (Abridged abstract)Comment: Accepted by ApJ. LaTeX using aas2pp4, psfigs macros. 23 pages
including 6 figures. Paper and figures also separately available at
http://www.obs-mip.fr/omp/astro/people/schaerer
Scientific Goals and Objectives for the Human Exploration of Mars: 1. Biology and Atmosphere/Climate
To prepare for the exploration of Mars by humans, as outlined in the new national vision for Space Exploration (VSE), the Mars Exploration Program Analysis Group (MEPAG), chartered by NASA's Mars Exploration Program (MEP), formed a Human Exploration of Mars Science Analysis Group (HEM-SAG), in March 2007. HEM-SAG was chartered to develop the scientific goals and objectives for the human exploration of Mars based on the Mars Scientific Goals, Objectives, Investigations, and Priorities.1 The HEM-SAG is one of several humans to Mars scientific, engineering and mission architecture studies chartered in 2007 to support NASA s plans for the human exploration of Mars. The HEM-SAG is composed of about 30 Mars scientists representing the disciplines of Mars biology, climate/atmosphere, geology and geophysics from the U.S., Canada, England, France, Italy and Spain. MEPAG selected Drs. James B. Garvin (NASA Goddard Space Flight Center) and Joel S. Levine (NASA Langley Research Center) to serve as HEMSAG co-chairs. The HEM-SAG team conducted 20 telecons and convened three face-to-face meetings from March through October 2007. The management of MEP and MEPAG were briefed on the HEM-SAG interim findings in May. The HEM-SAG final report was presented on-line to the full MEPAG membership and was presented at the MEPAG meeting on February 20-21, 2008. This presentation will outline the HEM-SAG biology and climate/atmosphere goals and objectives. A companion paper will outline the HEM-SAG geology and geophysics goals and objectives
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