A model of habitability within the Milky Way galaxy

We present a model of the galactic habitable zone (GHZ), described in terms of the spatial and temporal dimensions of the Galaxy that may favor the development of complex life. The Milky Way galaxy was modeled using a computational approach by populating stars and their planetary systems on an individual basis by employing Monte Carlo methods. We began with well-established properties of the disk of the Milky Way, such as the stellar number density distribution, the initial mass function, the star formation history, and the metallicity gradient as a function of radial position and time. We varied some of these properties and created four models to test the sensitivity of our assumptions. To assess habitability on the galactic scale, we modeled supernova rates, planet formation, and the time required for complex life to evolve. Our study has improved on other literature on the GHZ by populating stars on an individual basis and modeling Type II supernova (SNII) and Type Ia supernova (SNIa) sterilizations by selecting their progenitors from within this preexisting stellar population. Furthermore, we considered habitability on tidally locked and non-tidally locked planets separately and studied habitability as a function of height above and below the galactic midplane. In the model that most accurately reproduces the properties of the Galaxy, the results indicate that an individual SNIa is ～5.6× more lethal than an individual SNII on average. In addition, we predict that ～1.2% of all stars host a planet that may have been capable of supporting complex life at some point in the history of the Galaxy. Of those stars with a habitable planet, ～75% of planets are predicted to be in a tidally locked configuration with their host star. The majority of these planets that may support complex life are found toward the inner Galaxy, distributed within, and significantly above and below, the galactic midplane.     

Delayed gratification habitable zones: when deep outer solar system regions become balmy during post-main sequence stellar evolution

Like all low- and moderate-mass stars, the Sun will burn as a red giant during its later evolution, generating of solar luminosities for some tens of millions of years. During this post-main sequence phase, the habitable (i.e., liquid water) thermal zone of our Solar System will lie in the region where Triton, Pluto-Charon, and Kuiper Belt objects orbit. Compared with the 1 AU habitable zone where Earth resides, this "delayed gratification habitable zone" (DGHZ) will enjoy a far less biologically hazardous environment - with lower harmful radiation levels from the Sun, and a far less destructive collisional environment. Objects like Triton, Pluto-Charon, and Kuiper Belt objects, which are known to be rich in both water and organics, will then become possible sites for biochemical and perhaps even biological evolution. The Kuiper Belt, with >10(5) objects > or =50 km in radius and more than three times the combined surface area of the four terrestrial planets, provides numerous sites for possible evolution once the Sun's DGHZ reaches it. The Sun's DGHZ might be thought to only be of academic interest owing to its great separation from us in time. However, approximately 10(9) Milky Way stars burn as luminous red giants today. Thus, if icy-organic objects are common in the 20-50 AU zones of these stars, as they are in our Solar System (and as inferred in numerous main sequence stellar disk systems), then DGHZs may form a niche type of habitable zone that is likely to be numerically common in the Galaxy.     

Space exploration goals for the 21st century

This paper addresses, with examples, the essential need to devise important scientific research questions in order to set the objectives of space missions. However, the crucial objective of the human race is to survive the numerous hazards, both natural and anthropogenic, which may be expected to occur on Earth during the 21st century. With some experts believing that human civilisation may not survive to the end of the century, the main goals for space exploration should first be the preservation of planet Earth as a human habitat and, second, for human beings to settle in another haven, e.g. to colonise Mars. Treating this as an insurance policy, the annual premium for which could be around $16 billion, a globally cooperative plan should now be prepared and agreed. The fundamental message of this article echoes Zubrin's belief that, in order to survive, humanity must become a spacefaring species.     

World economics for mankind's frontier

In Acta Astronautica, Vol. 56, No. 5, March 2006, at ISSN0094-5765 there appears the article entitled “Will space actually be the Final Frontier of humankind?” written by Giancarlo Genta, and Michael Rycroft. This Acta Astronautica article requires amplification on the economic side. The writer of this article was personally present at the Apollo 11th launchings for the first landing on the Moon, by Buzz Aldrin and others. The Apollo 11 take off to the Moon, from Cape Carnival, did not leave the situation “so humankind seems forever to be bound to its own planet!” There was nothing pessimistic about the launch of Apollo 11. It is written that there was a lack of vision at that time, which is also not correct. The ‘Final Frontier’ myth was never mentioned on that occasion. At Apollo 11 we did take planet earth's “first faltering step for mankind” on the path towards a space faring civilization, exactly as these two authors later correctly mention. Now with the US Presidential initiatives “Moon, Mars and Beyond,” the authors suggested that it “will depend on social, political and economic issues rather than technological and scientific ones.” This Academy Note respectfully submits that all of these factors social, political and economic issues, plus psychological and scientific ones, instead of, “rather than technical and scientific ones” are going to be the determining factors of the speed of progress of the exploration of the entire universe, and particularly the sun in our Milky Way Galaxy. Russia and Ukraine are now on same, deep-space policy directions. The attention of the readers of this Academy Note is called to the current “Cosmic Collision” excellent presentation at the Hayden Planetarium, located at the Museum of National History in the City of New York. It shows the past, the present and the future of international humankind in exploring space and the creation of the universe, with particular reference to the protons of our sun, for our Milky Way Galaxy.     

A glimpse from the inside of a space suit: What is it really like to train for an EVA?

The beauty of the view from the office of a spacewalking astronaut gives the impression of simplicity, but few beyond the astronauts, and those who train them, know what it really takes to get there. Extravehicular Activity (EVA) training is an intense process that utilizes NASA’s Neutral Buoyancy Laboratory (NBL) to develop a very specific skill set needed to safely construct and maintain the orbiting International Space Station. To qualify for flight assignments, astronauts must demonstrate the ability to work safely and efficiently in the physically demanding environment of the space suit, possess an acute ability to resolve unforeseen problems, and implement proper tool protocols to ensure no tools will be lost in space. Through the insights and the lessons learned by actual EVA astronauts and EVA instructors, this paper will take you on a journey through an astronaut’s earliest experiences working in the space suit, termed the Extravehicular Mobility Unit (EMU), in the underwater training environment of the NBL. This work details an actual Suit Qualification NBL training event, outlines the numerous challenges the astronauts face throughout their initial training, and the various ways they adapt their own abilities to overcome them. The goal of this paper is to give everyone a small glimpse into what it is really like to work in a space suit.     

The data compression problem for the “GAIA” astrometric satellite of ESA

Space-based astrometry has a great tradition at ESA. The first space-based astrometric satellite in history, “Hipparcos”, was launched by ESA in 1989 and, in spite of orbital problems, was able to accomplish almost all of its tasks until it was finally shut down in 1993. The results of the Hipparcos mission were published by ESA in 1997 in the form of six CD-ROMs: the Hipparcos Catalogue contains 118,218 entries with median astrometric precision of around 1 milliarcsec, and specific results for double and multiple systems. In practice, Hipparcos drew for the first time the three-dimensional “map” of the spherical region of the Galaxy surrounding the Sun and having a radius of roughly 1,000 light years.

Then, in 1995, ESA launched the study of a new astrometric satellite, named “GAIA” and about a hundred times more powerful than Hipparcos, i.e. with median astrometric precision of around 10 microarcsec. This new satellite is intended to measure the parallaxes of over 50 million stars in the Galaxy, at least for the brightest stars, and this would mean to “draw” the three-dimensional map of the whole Galaxy, reaching out even to the Magellanic Clouds, 180,000 light years away.

The team of European scientists and engineers now designing GAIA, however, is facing hard technological difficulties. One of these is the design and coding of radically new and ultra-powerful mathematical algorithms for the on-board compression of the 50-million-stars data that GAIA will send to Earth from its intended geostationary orbit. Preliminary estimates of the raw data rates from the GAIA focal plane, in fact, are of the order of a few Gigabits per second. To reduce the data stream to the envisaged telemetry link of 1 Megabit per second, on-board data compression with a 1 to 1,000 ratio is the target. Clearly, this is far beyond the capabilities of any lossless compression technique (enabling compression ratios of 1 to some tens), and so some “wise” lossy compression mathematical procedure must be adopted.

In this paper a GAIA-adapted lossy data compression technique is presented, based on the Karhunen-Loève Transform (KLT). The essence of this method was already used by NASA for the Galileo mission when the large antenna got stuck and the mission was rescued by re-programming the on-board computer in terms of the KLT. That transform was officially named ICT — “Integer Cosine Transform” — by the NASA-JPL team led by Dr. Kahr-Ming Cheung. But the KLT here described for GAIA will of course differ from the JPL one in many regards, owing to the advances in computer technology.

Finally, estimates are also given about the possibility of using the KLT for onboard data compression in case GAIA is going to be put into orbit around the Lagrangian point L2 of the Earth-Sun system, and, above all, in case the number of stars to be observed is actually raised from 50 millions to one billion, as ESA currently appears to be likely to pursue.     

Formaldehyde in the far outer galaxy: constraining the outer boundary of the galactic habitable zone

We present results from an initial survey of the 2(12)-1(11) transition of formaldehyde (H2CO) at 140.8 GHz in giant molecular clouds in the far outer Galaxy (RG >or= 16 kpc). Formaldehyde is a key prebiotic molecule that likely plays an important role in the development of amino acids. Determining the outermost extent of the H2CO distribution can constrain the outer limit of the Galactic Habitable Zone, the region where conditions for the formation of life are thought to be most favorable. We surveyed 69 molecular clouds in the outer Galaxy, ranging from 12 to 23.5 kpc in galactocentric radius. Formaldehyde emission at 140.8 GHz was detected in 65% of the clouds. The H2CO spectral line was detected in 26 of the clouds with RG > 16 kpc (detection rate of 59%), including 6 clouds with RG > 20 kpc (detection rate of 55%). Formaldehyde is readily found in the far outer Galaxy-even beyond the edge of the old stellar disk. Determining the relatively widespread distribution of H2CO in the far outer Galaxy is a first step in establishing how favorable an environment this vast region of the Galaxy may be toward the formation of life.     

An international relations perspective on the consequences of SETI

Can we envision what the laws of politics and the laws of ethics will be in extraterrestrial civilizations? The laws of physics and chemistry will be the same. Presumably, if there are biospheres in other solar systems, the nature of biology will be the same. Over time evolution may produce the same forms of consciousness and intelligence as we see on earth. However, the political and ethical systems on earth are diverse. Often our images of extraterrestrial civilizations are mere projections of earthly patterns of conflict and cooperation. Perhaps over time the many civilizations and patterns on earth will evolve into one global civilization with harmonious political and ethical norms. These may be the same in universal civilizations if evolution is a cosmic process.     

Odyssey: Principles for enduring space exploration

As the USA, Europe and other nations embark on a new voyage of exploration to the Moon, Mars and beyond, they should lay the foundations and establish precedents that invite a host of participants and followers. We argue that international cooperation, driven by foreign-policy and cost-sharing considerations, has taken a prominent role but must be pragmatically and flexibly balanced with economic and strategic self-interest. Since exploration visions are likely to differ, the steps each country will pursue, the funding provided, and schedules followed will also differ. To support an enduring exploration vision, it will be important to remain flexible to changing priorities and amenable to the inclusion of new, non-traditional participants. Open-systems principles and metaprinciples should be employed at all levels—hardware, software, programmatic, political and cultural. Equally important, national leadership and decision makers should be mindful of the potential pitfalls that might undermine the venture. While the new vision inspires us all, it will take creativity, resourcefulness, hard work and cooperation to succeed.     

Mars scientific investigations as a precursor for human exploration.

In the past two years, NASA has begun to develop and implement plans for investigations on robotic Mars missions which are focused toward returning data critical for planning human missions to Mars. The Mars Surveyor Program 2001 Orbiter and Lander missions will mark the first time that experiments dedicated to preparation for human exploration will be carried out. Investigations on these missions and future missions range from characterization of the physical and chemical environment of Mars, to predicting the response of biology to the Mars environment. Planning for such missions must take into account existing data from previous Mars missions which were not necessarily focused on human exploration preparation. At the same time, plans for near term missions by the international community must be considered to avoid duplication of effort. This paper reviews data requirements for human exploration and applicability of existing data. It will also describe current plans for investigations and place them within the context of related international activities.     

Searching for alien artifacts on the moon

The Search for Extraterrestrial Intelligence (SETI) has a low probability of success, but it would have a high impact if successful. Therefore it makes sense to widen the search as much as possible within the confines of the modest budget and limited resources currently available. To date, SETI has been dominated by the paradigm of seeking deliberately beamed radio messages.However, indirect evidence for extraterrestrial intelligence could come from any incontrovertible signatures of non-human technology. Existing searchable databases from astronomy, biology, earth and planetary sciences all offer low-cost opportunities to seek a footprint of extraterrestrial technology. In this paper we take as a case study one particular new and rapidly-expanding database: the photographic mapping of the Moon's surface by the Lunar Reconnaissance Orbiter (LRO) to 0.5 m resolution. Although there is only a tiny probability that alien technology would have left traces on the moon in the form of an artifact or surface modification of lunar features, this location has the virtue of being close, and of preserving traces for an immense duration.Systematic scrutiny of the LRO photographic images is being routinely conducted anyway for planetary science purposes, and this program could readily be expanded and outsourced at little extra cost to accommodate SETI goals, after the fashion of the SETI@home and Galaxy Zoo projects.     

Russian space programmes and industry: Defining the new institutions for new conditions

The aim of this article is to define the major elements of the institutional design process for the Russian rocket and space industry, a process which must take account of the changed economic conditions in the country and provide for the industry's integration into the wider national economy. The article does this by demonstrating the features that need to be understood, highlighting the problems that need to be resolved, and arguing that an institutional design process will have to be based on compromise and accommodation of all the different actors involved. The article deals with a number of particular problems challenging the managers and methodologists of the Russian national space programme of today.     

Astromedicine and astrolaw: Emerging issues for advanced missions beyond Earth orbit

It is generally agreed within the scientific community that provision of appropriate medical facilities and administration of quality health care to astronauts are of great importance. However, for the more complex and remote missions envisaged for the future, issues of liability, responsibility and damage relating to medical practice may take on a greater significance and will need to be addressed. The author briefly reviews potential issues which may arise in the context of medical emergencies, crew autonomy and environmentally altered physiological status which characterize some projected advanced space missions and argues that the law of outer space will need to be expanded to take account of them.     

Architectural design for space tourism

The paper describes the main issues for the design of an appropriately planned habitat for tourists in space.Due study and analysis of the environment of space stations (ISS, MIR, Skylab) delineate positive and negative aspects of architectonical design. Analysis of the features of architectonical design for touristic needs and verification of suitability with design for space habitat.Space tourism environment must offer a high degree of comfort and suggest correct behavior of the tourists. This is intended for the single person as well as for the group. Two main aspects of architectural planning will be needed: the design of the private sphere and the design of the public sphere.To define the appearance of environment there should be paid attention to some main elements like the materiality of surfaces used; the main shapes of areas and the degree of flexibility and adaptability of the environment to specific needs.     

Search for high-proper motion objects with infrared excess

The possibility of interstellar migration has been theorized during the past thirty years in the form of “Dysonships” that, using non-relativistic propulsion systems, are able to colonize the Galaxy in a relatively short time compared to the age of the Galaxy and consequently penetrate inside our solar system too. Observational evidence of this can be potentially obtained using the present state of the art of telescopes and related sensors, by following aimed searches and an expanded SETI protocol. Some transient and unrepeated radio signals recorded during standard SETI observations might be due to the transit of high-proper motion artificial sources of extraterrestrial origin, which are expected to show a very weak optical emission, a strong infrared excess and occasional high-energy bursts in the X and Gamma-ray wavelength ranges. Such artificial sources might show an interest to Earth by sending probes to visit it: such a possibility can be investigated scientifically as well.     

Developing new launch vehicle technology: The case for multi-national private sector cooperation

Space is now a global business, yet the cost of getting to space is still high. Developing new launch vehicles that are cheaper, safer, and more reliable is the key to both rapid commercial growth and to more and better government uses of space. However, the R&D process leading to new launch vehicles is expensive and technically challenging; the past 50 years have seen many government development programs, but no major technological breakthroughs. Perhaps, it is therefore time to think about other ways of developing new launch vehicles. The best expertise in this field resides primarily with private companies and is spread across many actors and nations. A consortium led by space firms might be a better approach to opening up space in the 21st century. Governments will have to develop new policies treating space as though it were a commercial industry, in particular, relaxing export trade restrictions wherever possible. Issues of dual-use may be outweighed by the rapidly growing widespread availability of launch capabilities. Since new launch vehicles will require large up-front R&D expenditures, government support will continue to be needed to supplement private capital funds. Contributions to this effort should be international. However, difficult it might be in today's security conscious environment to reorient government policy, doing so may offer the most efficient and successful way to break the technological and economic barriers to more reliable access to space.     

Got life? Hours of boredom followed by moments of sheer terror (and that's just with the press)

It may be hoped that an initial discovery of extraterrestrial life and its disclosure will be done by accident. An event of that kind would have its own dynamic, and while communications about the discovery might be strained at times, there would be less likelihood that lines of inquiry and discourse would have already been taken by the participants and the press. In an ideal world (or worlds), the discovery would come ready-made with a picture or pictures that would be useful as an immediate verification of its reality. But such is not the way of the real world (or worlds, apparently). Lessons learned from the publication of the ALH84001 results in Science magazine are indicative of what may be a more likely scenario. Nonetheless, even that publication was held in confidence for much of the time leading up to NASA's press conference, and the science team doing the work was accordingly insulated from press inquiry while the work was underway. Envisioning a Mars sample return mission, or other, similar sort of endeavor that may involve a dedicated team of scientists—working under continual public scrutiny—it is clear that the circumstances that surround any fundamental discovery about life in the sample would be quite different. Planning for a communications strategy to support the operations of a Mars sample receiving facility (or facilities) must take those circumstances into account. An optimization of the time spent communicating the results of the facility's work should acknowledge the time and effort required, and make provisions for the work to proceed without extensive interruptions—and without being influenced by the expectations of the press or the public. This paper will discuss some of the initial planning associated with the communications strategy surrounding such a facility.     

Got life? Hours of boredom followed by moments of sheer terror (and that''s just with the press)

It may be hoped that an initial discovery of extraterrestrial life and its disclosure will be done by accident. An event of that kind would have its own dynamic, and while communications about the discovery might be strained at times, there would be less likelihood that lines of inquiry and discourse would have already been taken by the participants and the press. In an ideal world (or worlds), the discovery would come ready-made with a picture or pictures that would be useful as an immediate verification of its reality. But such is not the way of the real world (or worlds, apparently). Lessons learned from the publication of the ALH84001 results in Science magazine are indicative of what may be a more likely scenario. Nonetheless, even that publication was held in confidence for much of the time leading up to NASA's press conference, and the science team doing the work was accordingly insulated from press inquiry while the work was underway. Envisioning a Mars sample return mission, or other, similar sort of endeavor that may involve a dedicated team of scientists—working under continual public scrutiny—it is clear that the circumstances that surround any fundamental discovery about life in the sample would be quite different. Planning for a communications strategy to support the operations of a Mars sample receiving facility (or facilities) must take those circumstances into account. An optimization of the time spent communicating the results of the facility's work should acknowledge the time and effort required, and make provisions for the work to proceed without extensive interruptions—and without being influenced by the expectations of the press or the public. This paper will discuss some of the initial planning associated with the communications strategy surrounding such a facility.     

Radiation protection guidelines for space activities

At the beginning of the space age the dangers of hurtling into space were considerable. Despite this fact, radiation risks were examined in the U.S.S.R. and the U.S.A. and recommendations were made to limit the exposure of the crews to radiation. To date the radiation exposures of crews on missions in low-Earth orbits have been low. Now that missions in low-Earth orbit are becoming longer in duration and new missions into deep space are being considered, radiation protection guidelines become more important. Recently the estimates of the risks of radiation-induced cancer have been increased and new guidelines on radiation exposure limits for crew members must be developed. For deep space missions the guidelines take into account the risks posed by heavy ions. Unfortunately, knowledge about these risks is insufficient. If the new risk estimates are applied, current career dose limits may have to be reduced by a factor of two.     

Societal Statistics by virtue of the Statistical Drake Equation

The Drake equation, first proposed by Frank D. Drake in 1961, is the foundational equation of SETI. It yields an estimate of the number N of extraterrestrial communicating civilizations in the Galaxy given by the product N=Ns×fp×ne×fl×fi×fc×fL, where: Ns is the number of stars in the Milky Way Galaxy; fp is the fraction of stars that have planetary systems; ne is the number of planets in a given system that are ecologically suitable for life; fl is the fraction of otherwise suitable planets on which life actually arises; fi is the fraction of inhabited planets on which an intelligent form of life evolves; fc is the fraction of planets inhabited by intelligent beings on which a communicative technical civilization develops; and fL is the fraction of planetary lifetime graced by a technical civilization.The first three terms may be called “the astrophysical terms” in the Drake equation since their numerical value is provided by astrophysical considerations. The fourth term, fl, may be called “the origin-of-life term” and entails biology. The last three terms may be called “the societal terms” inasmuch as their respective numerical values are provided by anthropology, telecommunication science and “futuristic science”, respectively.In this paper, we seek to provide a statistical estimate of the three societal terms in the Drake equation basing our calculations on the Statistical Drake Equation first proposed by this author at the 2008 IAC. In that paper the author extended the simple 7-factor product so as to embody Statistics. He proved that, no matter which probability distribution may be assigned to each factor, if the number of factors tends to infinity, then the random variable N follows the lognormal distribution (central limit theorem of Statistics). This author also proved at the 2009 IAC that the Dole (1964) [7] equation, yielding the number of Habitable Planets for Man in the Galaxy, has the same mathematical structure as the Drake equation. So the number of Habitable Planets follows the lognormal distribution as well. But the Dole equation is described by the first FOUR factors of the Drake equation. Thus, we may “divide” the 7-factor Drake equation by the 4-factor Dole equation getting the probability distribution of the last-3-factor Drake equation, i.e. the probability distribution of the SOCIETAL TERMS ONLY. These we study in detail in this paper, achieving new statistical results about the SOCIETAL ASPECTS OF SETI.