Space Sciences

Crystals of the hydrogenase maturation factor HypF N-terminal domain grown in microgravity, display improved internal order

by Camillo Rosano

Dynamical effects of internal gravity waves in the equinoctial thermosphere

by Erdal Yigit

Identification of Kinetic Alfven Wave Turbulence in the Solar Wind

by Christopher Chen

C. S. Salem, G. G. Howes, D. Sundkvist, S. D. Bale, C. C. Chaston, C. H. K. Chen, F. S. Mozer
Astrophys. J. Lett. 745 L9 (2012)

Anisotropy in Space Plasma Turbulence: Solar Wind Observations

by Christopher Chen

T. S. Horbury, R. T. Wicks, C. H. K. Chen
Space Sci. Rev. (online first), (2011)

Astronomy and Space Science in Portuguese Popular Newspapers at the End of the 20th Century

by Rui Brito Fonseca

Recent aeolian dune changes on Mars

by Ken Edgett

(2008)
M. C. Bourke, K. S. Edgett, and B. A. Cantor
Geomorphology, 94, 247–255. doi:10.1016/j.geomorph.2007.05.012

Previous comparisons of Martian aeolian dunes in satellite images have not detected any change in dune form or... more Previous comparisons of Martian aeolian dunes in satellite images have not detected any change in dune form or position. Here, we show dome dunes in the north polar region that shrank and then disappeared over a period of 3.04 Mars years (5.7 Earth years), while larger, neighboring dunes showed no erosion or movement. The removal of sand from these dunes indicates that not only is the threshold wind speed for saltation exceeded under present conditions on Mars, but that any sand that is available for transport is likely to be moved. Dunes that show no evidence of change could be crusted, indurated, or subject to infrequent episodes of movement.

Mars Global Surveyor Mars Orbiter Camera: Interplanetary Cruise through Primary Mission

by Ken Edgett

(2001)
M. C. Malin and K. S. Edgett
Journal of Geophysical Research, 106(E10), 23,429–23,570. doi:10.1029/2000JE001455

More than 3 years of high-resolution (1.5–20 m/pixel) photographic observations of the surface of Mars have... more More than 3 years of high-resolution (1.5–20 m/pixel) photographic observations of the surface of Mars have dramatically changed our view of that planet. Among the most important observations and interpretations derived therefrom are that much of Mars, at least to depths of several kilometers, is layered; that substantial portions of the planet have experienced burial and subsequent exhumation; that layered and massive units, many kilometers thick, appear to reflect an ancient period of large-scale erosion and deposition within what are now the ancient heavily cratered regions of Mars; and that processes previously unsuspected, including gully-forming fluid action and burial and exhumation of large tracts of land, have operated within near-contemporary times. These and many other attributes of the planet argue for a complex geology and complicated history.

Mars landscape evolution: Influence of stratigraphy on geomorphology in the north polar region

by Ken Edgett

(2003) **SELF ARCHIVED PDF AVAILABLE HERE**
K. S. Edgett, R. M. E. Williams, M. C. Malin, B. A. Cantor, and P. C. Thomas
Geomorphology, 52(3–4), 289–297. doi:10.1016/S0169-555X(02)00262-3

Lithology and physical properties of strata exposed at the Earth's surface have direct influence on the erosion and... more Lithology and physical properties of strata exposed at the Earth's surface have direct influence on the erosion and geomorphic expression of landforms. While this is well known on our planet, examples on Mars are just coming to light among the tens of thousands of airphoto-quality images (resolutions 1.5–12 m/pixel) acquired since 1997 by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC). Specific examples occur among martian north polar layered materials, which MOC images reveal are divided into two distinct stratigraphic units: a lower, dark-toned layered unit and a younger, upper, lighter-toned layered unit. The lower unit is less resistant to wind erosion than the upper unit. The upper unit most likely consists of stratified dust and ice, while the lower unit contains abundant, poorly cemented sand. Sand is more easily mobilized by wind than dust; the lower resistance to erosion of the lower unit results from the presence of sand. Where wind erosion in polar troughs has penetrated to the lower unit, geomorphic change has proceeded more rapidly: sand has been liberated from the lower unit, and arcuate scarps have formed as the upper unit has been undermined. Wind erosion of the lower unit thus influences the geomorphology of the north polar region; this result likely explains the genesis of the large polar trough, Chasma Boreale, and the relations between dunes and arcuate scarps that have puzzled investigators for nearly three decades. The properties of the stratigraphic units suggest that the upper limit for the amount of water contained in the north polar layered materials may be 30–50% less than previously estimated.

Oceans or seas in the martian northern lowlands: High resolution imaging tests of proposed coastlines

by Ken Edgett

(1999) **SELF ARCHIVED PDF AVAILABLE HERE**
M. C. Malin and K. S. Edgett
Geophysical Research Letters, 26(19), 3049–3052. doi:10.1029/1999GL002342

Mars Global Surveyor Mars Orbiter Camera images that were targeted specifically to observe locations where published... more Mars Global Surveyor Mars Orbiter Camera images that were targeted specifically to observe locations where published accounts argue for the presence of landforms created by the interaction of a large body of water with Martian topography fail to reveal any evidence to support the hypothesis that the northern lowlands were once the site of oceans or seas. Given the difficulty of identifying ancient coastlines on Earth from orbital and aerial photography in the absence of field work, this result does not preclude the possibility that Mars once had large standing bodies of water on its surface, but calls into question shorelines previously proposed.

AVIATR—Aerial Vehicle for In-situ and Airborne Titan Reconnaissance A Titan airplane mission concept

by Ken Edgett

(2012) **OPEN ACCESS**
J. W. Barnes, L. Lemke, R. Foch, C. P. McKay, R. A. Beyer, J. Radebaugh, D. H. Atkinson, R. D. Lorenz, S. Le Mouélic, S. Rodriguez, J. Gundlach, F. Giannini, S. Bain, F. M. Flasar, T. Hurford, C. M. Anderson, J. Merrison, M. Ádámkovics, S. A. Kattenhorn, J. Mitchell, D. M. Burr, A. Colaprete, E. Schaller, A. J. Friedson, K. S. Edgett, A. Coradini, A. Adriani, K. M. Sayanagi, M. J. Malaska, D. Morabito, K. Reh
Experimental Astronomy. doi:10.1007/s10686-011-9275-9

We describe a mission concept for a stand-alone Titan airplane mission: Aerial Vehicle for In-situ and Airborne Titan... more We describe a mission concept for a stand-alone Titan airplane mission: Aerial Vehicle for In-situ and Airborne Titan Reconnaissance (AVIATR). With independent delivery and direct-to-Earth communications, AVIATR could contribute to Titan science either alone or as part of a sustained Titan Exploration Program. As a focused mission, AVIATR as we have envisioned it would concentrate on the science that an airplane can do best: exploration of Titan’s global diversity. We focus on surface geology/hydrology and lower-atmospheric structure and dynamics. With a carefully chosen set of seven instruments—2 near-IR cameras, 1 near-IR spectrometer, a RADAR altimeter, an atmospheric structure suite, a haze sensor, and a raindrop detector—AVIATR could accomplish a significant subset of the scientific objectives of the aerial element of flagship studies. The AVIATR spacecraft stack is composed of a Space Vehicle (SV) for cruise, an Entry Vehicle (EV) for entry and descent, and the Air Vehicle (AV) to fly in Titan’s atmosphere. Using an Earth-Jupiter gravity assist trajectory delivers the spacecraft to Titan in 7.5 years, after which the AVIATR AV would operate for a 1-Earth-year nominal mission. We propose a novel ‘gravity battery’ climb-then-glide strategy to store energy for optimal use during telecommunications sessions. We would optimize our science by using the flexibility of the airplane platform, generating context data and stereo pairs by flying and banking the AV instead of using gimbaled cameras. AVIATR would climb up to 14 km altitude and descend down to 3.5 km altitude once per Earth day, allowing for repeated atmospheric structure and wind measurements all over the globe. An initial Team-X run at JPL priced the AVIATR mission at FY10 $715M based on the rules stipulated in the recent Discovery announcement of opportunity. Hence we find that a standalone Titan airplane mission can achieve important science building on Cassini’s discoveries and can likely do so within a New Frontiers budget.

An overview of the 1985–2006 Mars Orbiter Camera science investigation

by Ken Edgett

(2010) **OPEN ACCESS**
M. C. Malin, K. S. Edgett, B. A. Cantor, M. A. Caplinger, G. E. Danielson, E. H. Jensen, M. A. Ravine, J. L. Sandoval, K. D. Supulver
Mars, 5, 1–60. doi:10.1555/mars.2010.0001

The Mars Observer Camera (MOC) investigation was proposed in 1985 and selected in 1986 for the Mars Observer mission,... more The Mars Observer Camera (MOC) investigation was proposed in 1985 and selected in 1986 for the Mars Observer mission, a spacecraft that was lost enroute to Mars in 1993. Re-named the Mars Orbiter Camera, MOC was re-flown on Mars Global Surveyor and successfully provided more than 4 Mars years (between September 1997 and October 2006) of daily global meteorological observations and observed ancient, water-lain sedimentary rock, present-day impact cratering, and youthful gullies (some of which may be showing evidence for present-day liquid water), among many other results from its more than 243,000 images.

ASSESSMENT OF EVALUATION METHODS FOR SPACE TECHNOLOGY CONCEPTS

by Egbert Jan van der Veen

This paper identifies, analyses and appraises a range of technology evaluation methods for their applicability in... more This paper identifies, analyses and appraises a range of technology evaluation methods for their applicability in evaluating space technologies concepts. Evaluation methods are mostly used to support and enhance decisions regarding investments in technology development projects. Examples of evaluation methods include: Delphi Method, S-Curve Extrapolation, Decision Trees, Analogy- and Patent Analysis and many others. The paper identifies methods which are most suitable for evaluating space technologies in order to improve investment decisions in the space sector. Investments in space technologies can be categorized according to a mission-focused (“pull”) and transformational (“push”) influenced decisions. Especially the push technology investments require a great deal of strategic planning, as their time horizon is longer than that of pull investments. Because of the presence of breakthrough innovations (also named Game Changing Technologies or Disruptive Space Technologies), the need for the usage of the most accurate evaluation methods is apparent. In literature many evaluation methods exist, however these methods are just partially applicable to the space sector, because of its different market dynamics. This difference causes the factors influencing the diffusion of innovations (agents’ decision-making process, the product characteristics and the structure of interactions between agents) to be different from the non-space sector. For example, because of a relative low frequency of space technology usage, the method of extrapolating trends is deemed impractical for evaluating space technology concepts. This paper identifies which factors influence the effectiveness of evaluation methods within the space market structure and assesses which methods show the highest potential to be an accurate tool for space technology investment decisions. The application of the results of this paper will lead to more informed investment decisions and thus, improvement of the technological capabilities of the space sector as a whole.

Trajectories of charged particles trapped in Earth's magnetic field

by Kaan Öztürk

Submitted to American Journal of Physics.
Source code of programs can be downloaded from the ArXiv site, or from https://sites.google.com/site/mkaanozturk/programs

I outline the theory of relativistic charged-particle motion in the magnetosphere in a way suitable for undergraduate... more I outline the theory of relativistic charged-particle motion in the magnetosphere in a way suitable for undergraduate courses. I discuss particle and guiding center motion, derive the three adiabatic invariants associated with them, and present particle trajectories in a dipolar field. I provide twelve computational exercises that can be used as classroom assignments or for self-study. Two of the exercises, drift-shell bifurcation and Speiser orbits, are adapted from active magnetospheric research. The Python code provided in the supplement can be used to replicate the trajectories and can be easily extended for different field geometries.

Some alternatives in the sociology of space colonization: The kibbutz as a space colony

by Michael Ashkenazi

Interstellar Spaceflight Using Nuclear Propulsion And Advanced Techniques

by Dr Ugur Guven

International Astronautical Congress, 2011 Proceedings, South Africa

Our present space technology has just put its first step outside our heliopause. With 2012, Voyager will be the first... more Our present space technology has just put its first step outside our heliopause. With 2012, Voyager will be the first
manmade object to exit our Solar System for the first time. As space technology develops and as the future of
humanity demands more and more; the only way that the humanity can expand would be toward the stars. Even
though this may seem to be a dream at this point, the continuing trend in the technology suggests that this will be
possible in the next century or towards the end of the 21st century. Thus, the modes of transportation for interstellar
distances need to be considered now, so that the necessary technology can be developed correspondingly. In terms of
specific impulse, conventional methods are totally useless for any distances that are outside our solar system. Thus,
more exotic means of space transport conditions need to be realized in order to make interstellar travel a reality. With
current technology, using advanced nuclear propulsion techniques seem to be the best way, as they possess the
ability to create high specific impulses in a short period of time. Continued acceleration will be a key to success in
such an endeavor and more importantly, with advanced nuclear propulsion, it can be possible to meet the necessary
power requirements for the mission. In addition, combination of antimatter propulsion as well as fusion propulsion
can be combined to give even a higher specific impulse, as well as an ability to meet power demands for decades,
which will be necessary for travelling even at those high speeds. This paper will examine the most probable
possibilities regarding interstellar travel based upon the available science and technology that we have today. In
addition, this paper will treat some advanced but hypothetical forms of interstellar travel by the utilization of space
curvature to some extent. In the end, the humanity has nowhere to go but to the stars. In this paper, we will try to
demonstrate with calculations, the most probable way of achieving these objectives.

MISSE 2 PEACE polymers atomic oxygen erosion experiment on the international space station

by Catherine McCarthy

MISSE 2 PEACE Polymers Experiment Atomic Oxygen Erosion Yield Error Analysis

by Catherine McCarthy

Analysis of the MISSE PEACE Polymers International Space Station Environmental Exposure Experiment

by Catherine McCarthy

Solar Effects on Tensile and Optical Properties of Hubble Space Telescope Silver-Teflon Insulation

by Catherine McCarthy

ARGOS: HYPER AMPLIFICATION MANIFOLD FOR ENHANCING GROUND STATION RECEPTION

by Ronnie Nader