1. Introduction

Life is unique in Nature. Biology possess unique complexities and a unique drive for self-perpetuation. Also, the various constants of physics precisely allow biology to exist. In this sense, the universe came to a unique point in Life.

We are part of Life. We share with all cellular organisms the complex pathways of genetic reproduction, enzyme catalysis, energy use and membrane transport. Belonging to the family of organic gene/protein life is our basic human identity.

Our common identity with all life suggests a human purpose to safeguard and expand life in the universe. This enterprise can be guided by biotic ethics that values the basic patterns of organic gene/protein life, and panbiotic ethics that seeks to expand life in the universe.

To secure and expand life, we can settle the Solar System, and seed with life new solar systems in the nearby galaxy. These programs can start presently with existing technologies. This is imperative because our space-faring society may be fragile, but if confined to Earth, life will end with the Red Giant Sun. If we are alone, the fate of all life is in our hands.

Can we expand life in the Solar System and throughout the galaxy? Astroecology experiments with carbonaceous meteorites showed that asteroids materials can serve as fertile soils for microorganisms, algae and plants. Nutrients in meteorites showed that similar asteroid materials can support populations of trillions. (Mautner,1997b, Mautner et al., 1997, Mautner, 2002) Similar materials and stellar energy may support life in other solar systems. Beyond our Solar System, we can therefore use directed panspermia to seed with life extrasolar planets, accreting solar nebulae, and star-forming interstellar clouds. (Mautner and Matloff, 1979, Mautner, 1995,1997a, 2000; Zuckerman, 1981).

These programs can lead to immense future life in the galaxy, whose amounts may be quantified in terms of biomass integrated over time available (Biomass Integrated Over Time Available, BIOTAint , measured in kilogram-years) (Mautner, 2005). This expansive life can explore many diverse forms, including intelligent species who enjoy conscious existence and who may expand life further in the galaxy. By securing the immense potentials of life, our human existence can find a cosmic purpose. Zuckerman, 1981, Along these lines, we studied samples of extraterrestrial soils formed from meteorites, and found them to biologically fertile (Mautner, 2002). We also evaluated the technologies and ethics of directed panspermia to new planetary systems. The technologies of launch, navigation, capture and biological payload, and the cosmological outlook for this expanding life, were studied in some detail (Mautner and Matloff, 1979, Mautner, 1995, 1997a) . The discoveries of extrasolar planets and extremophile microorganisms can help these programs. These subjects will be reviewed here and in the companion article. Zuckerman, 1981,

2. Strategies of Directed Panspermia

Directed panspermia aims to preserve and expand our family of gene/protein life. Fortunately, the main features of organic gene/protein life are present in every cell, from microorganisms to humans. Therefore, microorganisms can carry the seed our family of gene/protein life, which can develop into many diverse new life-forms. Zuckerman, 1981, Directed panspermia was suggested as a possible origin of life on Earth started by an earlier civilisation, and sending directed panspermia missions from Earth was also discussed briefly (Shklovskii and Sagan, 1966; Crick and Orgel, 1973). The technical requirements and ethics of such missions were developed in more detail (Mautner and Matloff, 1979; Zuckerman, 1981, Mautner, 1995, 1997a) Zuckerman, 1981, Panspermia missions may be aimed at extrasolar planets, at accretion disks about new stars, or at star-forming interstellar clouds. Once these environments are seeded with microorganisms, life may expand there through natural panspermia ( Mautner et al., 2004, Napier 2004; Wikramsinghe et al., 2003).

The biological payload may be divided into large numbers of small capsules to increase the chances of capture. For example, each capsule of about 20 micron radius may contain 100,000 microorganisms weighing altogether 0.1 micrograms. The panspermia capsules may be bundled in shielded containers and dispersed at the target. They may be sent also directly as large swarms of small capsules that are easier and cheaper to launch. The panspermia missions need to be:

- Launched at sufficient velocities to assure survivable transit times. This can be achieved with present technology using solar sails.

- Aimed or navigated to reach the capture zones, whose positions need to be predicted with sufficient accuracy. The probability to arrive at the targets increases with the resolution of proper star motion and with the area of the target (see Appendix).

- Decelerated at the target zones, by solar sails approaching the target stars or by drag in the gas and dust at the targets.

- Captured into orbit about target stars, or into gas and dust and accreting comets in accreting solar nebulae and interstellar clouds.

- Delivered to planets along with meteoritic dust or by cometary impact. The probability of delivery depends on the mixing ratio of the panspermia capsules and the dust, and on the fraction of this dust that is delivered to planets.

- Survive and evolve on the target planets.

Each of these steps have been considered in detail, and the probability of success has been evaluated (Mautner, 1997a). If the probability of capture of the panspermia capsules is small, large numbers of capsules may be sent to achieve success.

The next sections will illustrate missions to specific targets. More detailed mission parameters are described in the Appendix.

3. Missions to Extrasolar Planets

The main benefit is that the missions will aim at known Earth-like planets in habitable zones about Sun-like stars with favourable environments. Such planets may be identified the Kepler mission. However, these missions require high precision.

A mission to a target planet is illustrated in Fig.1. The sail-ship is first placed into solar orbit, then the sail is unfurled to cancel gravitation and the ship carries on in an outward path. Missions by solar sails can achieve velocities up to 0.0005 times the velocity of light. This can be achieved by thin solar sails that present large areas to the propelling solar radiation while having a small mass (Tsu, 1959).

The direction is defined by the position in orbit when the sail is unfurled. To achieve sufficient accuracy, the launch window is 0.2 seconds. For a target at 10 ly this will allow entry into an orbit defined with 0.024 au about the target star if the position of the star was defined accurately.

However, it is important to predict the position of the target star when the mission arrives after hundreds of thousands or millions of years of travel. The present resolution of proper star motion of 1 milliarcsecond/year needs to be increased for missions to extarsolar planets.

At the target, the panspermia capsules will be dispersed into an orbit intersecting the orbit of the target planet (Fig. 1). From this orbit they will captured along with meteoritic dust (Kyte and Wasson, 1989; Weatherill, 1997). The probability of capture depends on the size, orbital inclination and density of the panspermia ring and on the gravitational capture radius of the planet (see Appendix).

Missions to individual planets will benefit from the Kepler space telescope program that will identify Earth-like extrasolar planets. It is expected to find about 50 planets of 12.0 Earth radius, 185 planets with 1.3 Earth radius, and 640 planets with 2.2 Earth radius, or a combination of these. Any such planet in a habitable zone will be a suitable target for panspermia missions.

4. Missions to Accretion Disks

These missions will target planet-forming accretion disks about young stars. These accretion disks have diameters of several light-years (Safranov and Ruskol, 1994), requiring smaller targeting accuracy than targeting planets. However, aiming specifically at a habitable zone in the accretion disk requires an accuracy similar to aiming at planets.

Microbial capsules sent to these accretion disks can be decelerated by the gas and dust in the colder outer zones where they are also shielded from radiation. They will be captured, frozen and protected in comets until they are delivered to planets as cometary or asteroid dust, or by impacts of comets and cometary meteorites. This delivery will occur gradually over geological times when habitable conditions arise on the planet (Anders, 1989, Bailey et al., 1990, Chyba and McDonald, 1995).

The microbial capsules can be sent bundled in one sail-ship and dispersed after capture. Alternatively, a swarm of capsules can be launched directly, for example, each with about 20 micron radius weighing 0.1 micrograms and carrying 100,000 microorganisms. They can be attached to miniature 1.8 mm radius solar sails that may be envelopes of thin reflective films enclosing the payload.

Some potential targets are Beta Pictoris at a distance of 22.6 light years, or AU Microscopium, a new red dwarf star only 12 million years old at a distance of 33 ly, or alpha PsA (Fomalhout) at 52 ly. All have dust rings suggesting potential planet formation.

The probability of arriving at the targets (P_target) in the habitable zone of Beta Pictoris is 0.25, and to Fomalhaut is 1.2 (see Appendix). Assuming a probability of capture by planets from these orbits as 0.00001 yields probabilities for capture of one capsule by planets in the habitable zones as 0.0000025 and 0.00001, respectively.

With these probabilities, Table 1 below shows that a few grams of microorganisms, dispersed in ten million 20 micron capsules, can assure probable success. These capsules can be mass manufactured and launched at a small cost, possibly by small groups or even individuals. Once the nebula is seeded, life can expand there through collisions between asteroids. The asteroids undergo a period of aqueous alteration when they contain liquid water and dissolved organics and nutrients. Microbes inside these objects can use these nutrients to achieve high populations, and then disperse by collisions to seed other asteroids and comets and eventually planets. Therefore a successful mission that seeds one asteroid can seed the entire nebula and all of its forming planets (Mautner et al., 2004).

5. Missions to Star-Forming Clouds

These missions target interstellar clouds where star formation occurs. A potential target is the Rho Ophiuchus cloud 520 ly away. As illustrated in Fig. 2, such clouds contain zones with various densities along the path to star formation (Mezger, 1994) , while Fig. 3 shows a section with young stars.

The missions may target entire clouds, or dense cores in the clouds to seed clusters of new solar systems; or the protosolar condensations that form each star; or accretion disks about new stars in these clouds. The payload of microbial capsules can be bundled and protected and dispersed on arrival, possibly by collisions with dust or small aggregates. Alternatively, swarms of microscopic capsules can be sent directly.

Selective penetration to various target zones can be achieved by choosing the mass of the vehicles, since heavier projectiles can penetrate into increasingly dense zones. For example, for objects injected into the cloud with a velocity of 0.0005 times the velocity of light, a 35 micron spherical object will penetrate a dense cloud fragment and stop in a dense cloud core, while a 1 mm object will penetrate further and will be stopped in a more dense protostellar condensation (Mautner, 1997a). Heating and ablation by the gas would be significant only at relativistic speeds (Powell, 1975).

It is desirable to target smaller dense zones that are closer to star formation, where the payload will mix with less dust and a larger fraction of its mass will be eventually delivered to planets. However, these smaller targets require higher precision.

At the target zones the payload will be dispersed into 20 micron, 0.1 microgram capsules each carrying 100,000 microorganisms. They will mix with dust, and along with it undergo accretion, some into comets and asteroids. From there, a small fraction of the original capsules will be delivered later to planets. The Appendix describes a mission to the Rho Ophiuchus cloud in more detail.

All of these factors affect the probability of eventual capture of the microbial capsules by planets. If the probability is small, more capsules and biomass need to be sent for success. Table 1 summarizes these data, and the Appendix describes how these data were calculated. According the required biomass in Table 1, a few hundred tons of microbial biomass with launch costs of $10,000/kg, costing about $1 billion can seed dozens of new solar systems with life for eons. These programs can be achieved with existing technologies and may be easy to implement as a space infrastructure develops and launch costs decrease.

6. The Biological Payload

Directed panspermia aims to preserve and expand our family of gene/protein life. The main features of organic biological life are present in every cell including microorganisms, which can seed new habitats with our family of gene/protein life.

As humans, we may also want to induce evolution toward conscious intelligent life. For this purpose we can include, along with the first colonizer cyanobacteria, also hardy multicellular organisms such as rotifer eggs, that have the basic body-plans of higher organisms with differentiated organs. This will bypass a bottleneck to higher evolution that on Earth took eons to occur.

The colonizing organisms may find diverse environments on new planets, including wide ranges of temperature, pressure, pH and salinity. Fortunately, extremophile microorganisms survive in a wide range of these conditions, from anaerobic to oxygen-rich conditions, from below 0 C to over 140 C, from low pressures at high altitudes to hundreds of atmospheres in deep sea, from basic pH to concentrated sulphuric acid, from fresh water to concentrated brine, and also under intense radiation (Horikoshi and Grant, 1998). The microbial payloads should contain a variety of microbes with various tolerances.

Genetic engineering may develop microorganisms with further environmental tolerances, and combine various features in one colonizing organism. For example, cyanobacteria can be equipped with various extremophile features, making them suitable as first colonizers in diverse environments. Like on Earth, these cyanobacteria may then establish oxygen-rich atmospheres for higher evolution.

Even if sent in one mission, the various organisms may be delivered to planets gradually as the environment develops. Microbial capsules will be captured, frozen and preserved in accreting comets in the outer regions of the solar nebulae. They will be then delivered by cometary and meteorite impacts gradually as the planets evolve. Cyanobacteria delivered by early impacts will be the first colonizers and extablish an oxygen-containing atmosphere, where multi-cellular rotifers will survive and evolve when delivered by later impacts. Life planted in the target nebulae or interstellar clouds may then expand further through natural panspermia (Mautner et al., 2004; Napier, 2004; Joseph and Schild, 2010).

7. Astroecology and the Future of Life

Having planted life in space, what is its outlook for life in the Solar System and on cosmological scales?

Life can develop in many new directions in these new habitats through natural and directed evolution. The potential amounts of this future life can be estimated based on the available resources. For these purposes, the amount of life in a habitat of finite duration can be quantified in terms of time-integrated biomass (Biomass Integrated Over Times Available (BIOTA_int), measured in kg-years. For example, the amount of life on Earth to date has been about 1e15 kg x 3e9 years = 3e24 kg-years (Mautner, 2005).

Life in the Solar System can be based on accessible resources in carbonaceous asteroids and comets. Samples of these materials are available in carbonaceous chondrite meteorites. Miniaturized soil science experiments confirmed the fertilities of these materials. Millions of other solar systems in the galaxy should contain similar resources for life.

Beyond the Solar System, immense amounts of life can exist about various stars for cosmological times. The amounts of sustainable life can be calculated based on the power output of the stars, their duration and their number in the galaxy, and on the power requirements of biomass. These calculations show that red and white dwarf stars can sustain 1046 kg-years of BIOTA during the trillions of eons in the galaxy. (Mautner, 2005) These subjects are discussed in more detail in the companion article (Mautner, 2010).

These immense amounts of life will allow many new forms of biological and social complexity, including intelligent civilisations that may expand life further in the universe.

May life last indefinitely? The habitable lifetime of the galaxy may depend on dark matter and energy. These forces may need to be observed for many more eons to predict their future behaviour. During those cosmological times our descendants may understand nature more deeply and seek to extend life indefinitely.

8. Motivation and a Panbiotic Ethics

Directed panspermia to expand life is altruistic, bearing results after eons. It must be therefore motivated by ethics. In turn, our ethics may shape the future of the universe.

We belong to the family of organic gene/protein life. All life seeks self-propagation as if actively pursuing this purpose. Intrinsic to life there is therefore purpose, and a universe that contains life, contains purpose. Belonging to life then implies a human purpose to safeguard and expand life in space. This purpose suggests a biotic ethics that value the basic patterns of gene/protein life. This in turn implies panbiotic ethics that seek to secure and expand life in the universe. (Mautner and Matloff, 1979, Mautner, 1995, 2009).

These ethics also define basic values: that which sustains life is good, and that which destroys life is evil. Expanding life in space is highly moral by these principles.

Can panspermia missions perturb existing extraterrestrial life? At present, there is no conclusive scientific evidence for extraterrestrial life; though admittedly not all scientists share this opinion (Joseph and Schild, 2010; Levin 2010). Every living cell needs thousands of complex components as DNA, proteins and membranes, and the probability of these components coming together to originate life may be very small even on billions of planets (see Joseph and Schild, 2010, for an extended discussion of these isssues).

If we still detect extraterrestrial life, we can avoid these targets. In any case, we can target new solar systems where life could not have evolved yet. We may seed a few hundred new solar systems, that will secure the future of our family of gene/protein life but will leave all the other hundred billion stars in the galaxy and their possible indigenous life unperturbed.

If there is local life there that is fundamentally different, it will not be affected; if it is gene/protein life, it may be enriched and we can induce higher evolution. The new biospheres may prepare the way for human colonization if interstellar human travel becomes possible.

Should we risk our future for the fear of interfering with putative alien life? We may detect such life with certainty only with interstellar probes, taking thousands of years. We cannot be sure that our technology will still exist when we receive the answers. We alone are capable to secure the future of life that is threatened if confined to Earth and will end otherwise with the red giant Sun. We should therefore proceed promptly.

Our commitment is first to secure and expand our family of gene/protein life. We should do this by seeding other solar systems now while our space-faring technology exists. If we are alone, then the fate of all life is in hands. We must then secure and expand life in space where it has immense potentials. In securing this future for life, our human existence can find a cosmic purpose.

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