A search for biogenic trace gases in the atmosphere of Mars

The detection of certain trace gases in the atmosphere of Mars may serve as a possible indicator of microbial life on the surface of Mars. Candidate biogenic gases include methane CH4, ammonia NH3, nitrous oxide N2O, and several reduced sulfur species. Chemical thermodynamic equilibrium and photochemical calculations preclude the presence of these gases in any measurable concentrations in the atmosphere of Mars in the absence of biogenic production. A search for these gases utilizing either high resolution (spectral and spatial) spectroscopy from a Mars orbiter, such as the Observer, and or in situ measurements from a Mars lander or rover, is proposed

Thirty Years After: The Science of the Viking Program and the Discovery of a 'New Mars'

Viking discovered a Mars that was very different from the Mars found by Mariner 4, 6 and 7. The new, exciting, more Earth-like Mars was hinted at by the Mariner 9 orbiter and confirmed by Viking. Viking discovered some very fundamental things about Mars. Viking discovered the presence of nitrogen in the atmosphere. A key ingredient needed for life. Viking made the first measurements of the isotopic composition of carbon, oxygen, nitrogen and the noble gases in the atmosphere of Mars. The ratio of 15N to 14N suggested that Mars may have lost more than 99% of the total mass of its atmosphere. The denser atmosphere in the past may explain the presence of flowing water earlier in the history of Mars first discovered by Mariner 9 with additional and higher spatial resolution examples provided by the Viking Orbiters. Viking did not measure organics or life at the surface of Mars. But, Viking did discover a surface unlike any other on the Solar System--a surface exhibiting very high chemical reactivity, most probably formed by the deposition of chemically active atmospheric gases, like hydrogen peroxide (H2O2) and ozone (O3), onto the surface of Mars

The Exploration of Mars by Humans: Why Mars? Why Humans?

As we commemorate the 50th anniversary of Yuri Gagarin's historic flight in 1961, the first flight of a human in space, plans are underway for another historic human mission. Plans are being developed for a human mission to Mars. Once we reach Mars, the human species will become the first two-planet species. Both the Bush Administration (in 2004) and the Obama Administration (in 2010) proposed a human mission to Mars as a national goal of the United States

Titan Explorer: The Next Step in the Exploration of a Mysterious World

The Titan Explorer Mission outlined in this report is a proposed next step in the exploration of Titan, following the highly successful Huygens Titan probe of 2005. The proposed Titan Explorer Mission consists of an Orbiter and an Airship that traverses the atmosphere of Titan and can land on its surface. The Titan Explorer Mission is science driven and addresses some of the fundamental questions about the atmosphere, surface and evolution of Titan, which will add to our understanding of the origin and evolution of life on Earth and assess the likelihood of life elsewhere in the Solar System

Humans to Mars: The Greatest Adventure in Human History

The reasons for a human mission to Mars are many and include (1) World technological leadership, (2) Enhanced national security, (3) Enhanced economic vitality, (4) The human urge to explore new and distant frontiers, (5) Scientific discovery (how did Mars evolve from an early Earth-like, hospitable planet to its present inhospitable state? Is there life on Mars?) (6) Inspiring the American public and the next generation of scientists and engineers (following the launch of Sputnik I by the USSR on October 4, 1957, the U. S. and the rest of the world witnessed a significant increase in the number of students going into science and engineering), (7) Develop new technologies for potential non-space spin-off applications, and, (8) Enhanced national prestige, etc. Other reasons for colonizing the Red Planet are more catastrophic in nature, including Mars as a safe haven for the survival of the human species in the event of an impact with a large asteroid (remember the demise of the dinosaurs 65-million years as a result of an asteroid impact!). Some have also suggested that the colonization of Mars may be a solution to the global exponential population explosion on our planet! A human mission to and the colonization of the Red Planet requires multi-disciplined expertise in many areas including engineering, technology, science, human health and medicine and the human psychological and behavior. To capture the relevant areas of needed expertise, we have invited a group of more than 70 U. S. and foreign experts in these areas, including astronauts, scientists, engineers, technologists, medical doctors, psychologists and economists to share their views and thoughts on a human mission to Mars

The Dust in the Atmosphere of Mars and Its Impact on the Human Exploration of Mars: A NESC Workshop

The NASA Engineering and Safety Center (NESC) Chief Scientist provided support to produce an NESC final report on the "Dust in the Atmosphere of Mars and Its Impact on Human Exploration" workshop held June 1315, 2017, in Houston, TX. This report follows the standard NESC report format to describe the findings, observations, and NESC recommendations developed by the workshop participants. The key stakeholders for the final report are the Mars mission designers and engineers for the precursor missions and the crewed mission, and the NESC. Further stakeholders are the mission planners deciding on the payload selections for the Mars missions

A Comparison of Platforms for the Aerial Exploration of Titan

Exploration of Titan, envisioned as a follow-on to the highly successful Cassini-Huygens mission, is described in this paper. A mission blending measurements from a dedicated orbiter and an in-situ aerial explorer is discussed. Summary description of the science rationale and the mission architecture, including the orbiter, is provided. The mission has been sized to ensure it can be accommodated on an existing expendable heavy-lift launch vehicle. A launch to Titan in 2018 with a 6-year time of flight to Titan using a combination of Solar Electric Propulsion and aeroassist (direct entry and aerocapture) forms the basic mission architecture. A detailed assessment of different platforms for aerial exploration of Titan has been performed. A rationale for the selection of the airship as the baseline platform is provided. Detailed description of the airship, its subsystems, and its operational strategies are provided

Role of chondroitin sulfate proteoglycans (CSPGs) in synaptic plasticity and neurotransmission in mammalian spinal cord.

Chronic unilateral hemisection (HX) of the adult rat spinal cord diminishes conduction through intact fibers in the ventrolateral funiculus (VLF) contralateral to HX. Intraspinal injections of Chondroitinase-ABC, known to digest chondroitin sulfate proteoglycans (CSPGs) in the vicinity of injury, prevented this decline of axonal conduction. This was associated with improved locomotor function. We further injected three purified CSPGs into the lateral column of the uninjured cord at T10: NG2 and neurocan, which increase in the vicinity of a spinal injury, and aggrecan, which decreases. Intraspinal injection of NG2 acutely depressed axonal conduction through the injection region in a dose dependent manner. Similar injections of saline, aggrecan, or neurocan had no significant effect. These results identify a novel acute action of CSPGs on axonal conduction in spinal cord, and suggest that antagonism of proteoglycans reverses or prevents the decline of axonal conduction, in addition to stimulating axonal growth

Measuring Humidity in Sealed Glass Encasements

A technique has been devised for measuring the relative humidity levels in the protective helium/water vapor atmosphere in which the Declaration of Independence, the United States Constitution, and the Bill of Rights are encased behind glass panels on display at the National Archives in Washington, DC. The technique is noninvasive: it does not involve penetrating the encasements (thereby risking contamination or damage to the priceless documents) to acquire samples of the atmosphere. The technique could also be applied to similar glass encasements used to protect and display important documents and other precious objects in museums. The basic principle of the technique is straightforward: An encasement is maintained at its normal display or operating temperature (e.g., room temperature) while a portion of its glass front panel is chilled (see Figure 1) until condensed water droplets become visible on the inside of the panel. The relative humidity of the enclosed atmosphere can then be determined as a known function of the dew point, the temperature below which the droplets condense. Notwithstanding the straightforwardness of the basic principle, careful attention to detail is necessary to enable accurate determination of the dew point. In the initial application, the affected portion of the glass panel was cooled by contact with an aluminum plate that was cooled by a thermoelectric module, the exhaust heat of which was dissipated by a heat sink cooled by a fan. A thermocouple was used to measure the interior temperature of the aluminum plate, and six other thermocouples were used to measure the temperatures at six locations on the cooled outer surface of the glass panel (see Figure 2). Thermal grease was applied to the aluminum plate and the thermocouples to ensure close thermal contact. Power was supplied to the thermoelectric module in small increments, based on previous laboratory tests. A small flashlight and a magnifying glass were used to look for water droplets condensing on the inner surface of the glass. The temperature readings of the thermocouples were taken during cool-down and upon observing condensation. In determining the dew point, it was necessary to make a correction for the differences between the temperatures measured on the chilled outer surface of the glass and the temperature of the inner surface, where the condensation took place. The correction was derived from a laboratory test on a measurement setup that was nearly identical, except that the dew location on the inner surface was also instrumented with a thermocouple. The test showed that the temperature at the dew location on the inner surface of the glass panel was 0.9 C above the temperature determined from the measurements on the chilled outer surface of the panel

Biomass Burning

Biomass burning may be the overwhelming regional or continental-scale source of methane (CH4) as in tropical Africa and a significant global source of CH4. Our best estimate of present methane emissions from biomass burning is about 51.9 Tg/yr, or 10% of the annual methane emissions to the atmosphere. Increased frequency of fires that may result as the Earth warms up may result in increases in this source of atmospheric methane