For many billions of years, humans spread throughout the entire Milky Way. They are able to live all their dreams, but to their great disappointment, no other intelligent species has ever been encountered. Now, humanity itself is on the brink of extinction.
They have only one hope: The ‘Rescue Project’ was designed to feed the black hole in the center of the galaxy until it becomes a quasar, delivering much-needed energy to humankind during its last breaths. But then something happens that no one ever expected—and humanity is forced to look at itself and its existence in an entirely new way.
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The Enceladus Mission (Ice Moon 1)
In the year 2031, a robot probe detects traces of biological activity on Enceladus, one of Saturn’s moons. This sensational discovery shows that there is indeed evidence of extraterrestrial life. Fifteen years later, a hurriedly built spacecraft sets out on the long journey to the ringed planet and its moon.
The international crew is not just facing a difficult twenty-seven months: if the spacecraft manages to make it to Enceladus without incident it must use a drillship to penetrate the kilometer-thick sheet of ice that entombs the moon. If life does indeed exist on Enceladus, it could only be at the bottom of the salty, ice covered ocean, which formed billions of years ago.
However, shortly after takeoff disaster strikes the mission, and the chances of the crew making it to Enceladus, let alone back home, look grim.
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Ice Moon – The Boxset
All four bestselling books of the Ice Moon series are now offered as a set, available only in e-book format.
The Enceladus Mission: Is there really life on Saturn's moon Enceladus? ILSE, the International Life Search Expedition, makes its way to the icy world where an underground ocean is suspected to be home to primitive life forms.
The Titan Probe: An old robotic NASA probe mysteriously awakens on the methane moon of Titan. The ILSE crew tries to solve the riddle—and discovers a dangerous secret.
The Io Encounter: Finally bound for Earth, ILSE makes it as far as Jupiter when the crew receives a startling message. The volcanic moon Io may harbor a looming threat that could wipe out Earth as we know it.
Return to Enceladus: The crew gets an offer to go back to Enceladus. Their mission—to recover the body of Dr. Marchenko, left for dead on the original expedition. Not everyone is working toward the same goal.
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Proxima Rising
Late in the 21st century, Earth receives what looks like an urgent plea for help from planet Proxima Centauri b in the closest star system to the Sun. Astrophysicists suspect a massive solar flare is about to destroy this heretofore-unknown civilization. Earth’s space programs are unequipped to help, but an unscrupulous Russian billionaire launches a secret and highly-specialized spaceship to Proxima b, over four light-years away. The unusual crew faces a Herculean task—should they survive the journey. No one knows what to expect from this alien planet.
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The Hole
A mysterious object threatens to destroy our solar system. The survival of humankind is at risk, but nobody takes the warning of young astrophysicist Maribel Pedreira seriously. At the same time, an exiled crew of outcasts mines for rare minerals on a lone asteroid.
When other scientists finally acknowledge Pedreira’s alarming discovery, it becomes clear that these outcasts are the only ones who may be able to save our world, knowing that The Hole hurtles inexorably toward the sun.
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Mars Nation 1
NASA finally made it. The very first human has just set foot on the surface of our neighbor planet. This is the start of a long research expedition that sent four scientists into space.
But the four astronauts of the NASA crew are not the only ones with this destination. The privately financed ‘Mars for Everyone’ initiative has also targeted the Red Planet. Twenty men and women have been selected to live there and establish the first extraterrestrial settlement.
Challenges arise even before they reach Mars orbit. The MfE spaceship Santa Maria is damaged along the way. Only the four NASA astronauts can intervene and try to save their lives.
No one anticipates the impending catastrophe that threatens their very existence—not to speak of the daily hurdles that an extended stay on an alien planet sets before them. On Mars, a struggle begins for limited resources, human cooperation, and just plain survival.
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Impact: Titan
How to avoid killing Earth if you don't even know who sent the killer
250 years ago, humanity nearly destroyed itself in the Great War. Shortly before, a spaceship full of researchers and astronauts had found a new home on Saturn's moon, Titan, and survived by having their descendants genetically adapted to the hostile environment.
The Titanians, as they call themselves, are proud of their cooperative and peaceful society, while unbeknownst to them, humanity is slowly recovering back on Earth. When a 20-mile-wide chunk of rock escapes the asteroid belt and appears to be on a collision course with Earth, the Titanians fear it must look as if they launched the deadly bombardment. Can they prevent the impact and thus avoid an otherwise inevitable war with the Earthlings?
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The Life and Death of the Stars
There are amazing parallels between humans and stars: While birth is basically the same for all of them, the further course of life depends on different conditions. One of these is the starting conditions: Those who are born in a cloud richer in gas tend to have a more brilliant, but also shorter life. On the other hand, living conditions also play a role: Star babies from multiple births, for example, often have a different fate than single children.
Too small: brown dwarfs
In the beginning there is always the nebula. Although astronomers have not yet completely recorded all biographies, it is assumed that the path to a brown dwarf also begins with an interstellar gas cloud. This clusters together under the influence of gravity to form a protostar until the temperatures inside are high enough to ignite nuclear fusion. However, it can happen that there is simply not enough raw material. Either because the gas cloud itself was too small or because a giant star in the vicinity has blown away too much fuel. It is also possible that the protostar was formed as part of a multiple system and its brothers secured a larger share of the primary supply.
Exactly how much nuclear fuel is needed depends on its composition - just as alcohol burns more easily than diesel. However, the heavier the raw material, the better stars can ignite. If the composition corresponds to our sun, then about 75 Jupiter masses are needed for the ignition (thousand Jupiter masses correspond approximately to a sun mass), in the young universe however still 90 Jupiter masses were needed. If the protostar is lighter, nevertheless fusion reactions can occur: from 65 Jupiter masses for example the lithium fusion starts, already from 13 Jupiter masses deuterium nuclei fuse with protons to helium. But because usually neither lithium nor heavy hydrogen (deuterium) belong to the main components of a baby star, it glows only very weakly, it only glows.
Brown dwarfs usually reach about the size of Jupiter, the lighter stars are bigger than the heavier ones, because the gravitation is weaker here. The mini-stars age relatively fast. Shortly after ignition of the fusion reactions they start to cool down. The heaviest known representatives have a surface temperature of 2900 Kelvin. On the surface of the so far coolest observed brown dwarf WISE 1828+2650 it is summery warm with 27° Celsius. The fate of a brown dwarf is relatively unspectacular: It cools down more and more with time until it wanders through space as an ice ball after a few billion years.
Luhman 16 is the closest brown dwarf to the solar system. The system is about 6.5 light years away from the sun. This makes it the third closest star system to our solar syst
em, after Alpha Centauri and Barnard's Star. The fact that the objects were discovered so late, despite their comparatively large proximity to our Earth, is due to their extremely low apparent brightness, which is very typical for brown dwarfs.
Average Joe's of the Universe: Red Dwarfs
If the protostar is heavy enough to ignite hydrogen fusion, but lighter than about half a solar mass, then a so-called red dwarf is formed. Red dwarfs are basically the Otto normal of the universe. About 70 percent of the stars in the Milky Way belong to this type. The ordinary red dwarf has one tenth of the mass of the sun, its radius is 15 percent of the sun's radius. Because of the low mass (and thus the low pressure) the nuclear fusion proceeds slowly, red dwarfs are comparatively cold with 2200 to 3800 Kelvin surface temperature (the sun is 5800 Kelvin hot at the surface).
As their name suggests, they emit mainly long-wavelength light, which has a low intensity. Therefore they are hardly noticeable in the sky, although they make up the bulk of the stellar population.
However, their cozy character gives them a great advantage: they are enormously long-lived. Since the generated heat is completely dissipated to the outside by convection, no helium (as waste) accumulates in their interior. Red dwarfs can therefore make optimal use of their hydrogen supply. Depending on their mass they reach a lifetime of tens of billions up to trillions of years.
But even this time will eventually come to an end. The red dwarf then shrinks. Since this releases energy, it can also burn the remaining hydrogen in its outer shell, where otherwise the pressure would not have been sufficient. When finally no more fusion reactions are possible, the star cannot resist its own gravitation and shrinks to a white dwarf about the size of the Earth. The process of contraction initially releases a larger amount of energy, which heats up the surface: The former red dwarf now glows white before it eventually cools down completely.
The closest red dwarf to the solar system is Proxima Centauri. We have already visited it together in the Proxima trilogy.
Relatives of the Sun: Main Sequence Stars
A protostar that is at least half as heavy as the Sun evolves (as does the Sun) into a main sequence star. This stage is characterized by the fusion of hydrogen to helium in a central region of the star, which is spatially limited to a few percent of the total volume. Only the resulting energy is transported to the outside, the fusion products remain in the core.
The star spends about 90 percent of its lifetime in this state (which is currently also the state of our Sun). The heavier the star is, the more violent the fusion processes are. This results in the paradox that the lifetime decreases with increasing fuel supply. The heaviest stars shine very bright, but die very young. Independent of the mass, however, the main sequence stars become brighter, hotter and bigger during their lifetime. Even our sun shines about two fifths brighter than after its birth.
The end of a star is initiated by the fact that it runs out of hydrogen as fuel. With enough pressure inside, helium fusion now begins. This is not a smooth transition, however, but a self-reinforcing, dramatic process called a helium flash: within seconds, the amount of energy produced increases dramatically. Under the pressure of the helium flash, the star expands and becomes a red giant, often increasing its diameter a hundredfold. This can cause the outer shells to be ejected - astronomers can then observe these as planetary nebulae.
Among the sunlike main sequence stars Alpha Centauri is the closest to us. It is a yellow dwarf of the spectral type G2 V. Thus it belongs to the hotter G-stars like the Sun. The luminosity class V indicates that it belongs to the main sequence stars. With an apparent magnitude of 0.00 mag it is the fourth brightest star in the night sky after Sirius (-1.46 mag), Canopus (-0.72 mag) and Arcturus (-0.05 mag) before Vega (0.03 mag).
The closest red giant to us with a distance of 37 light-years is Arcturus. It is a red giant of orange-red color. Arcturus is at least 110 times brighter than the Sun. Since the star emits much more radiation in the infrared spectrum than in the visible spectrum, the total radiation is about 210 times that of the Sun. The lower radiant power in the visible range compared to the Sun is due to the cooler surface.
The future of the sun: White dwarfs
How a star's life continues depends again on the mass of the star: At less than 2.3 solar masses, the helium burning eventually finishes - typically after a million years. The star then collapses under its own gravity and becomes a white dwarf. This fate also awaits the Sun. White dwarfs usually consist of a core of oxygen, followed by a carbon and finally a helium layer. The fact that the star does not collapse further and further is due to the equilibrium that builds up between gravity and the counterpressure of the core. Up to about 1.44 solar masses of residual mass, the so-called Chandrasekhar limit, the star's interior can withstand the pressure of gravity to such an extent that evolution stops at the white dwarf.
If, on the other hand, the mass of the star is between 2.3 and 3 solar masses, carbon burning can begin after helium burning. In this process, elements up to iron are formed. After that, it's over, because iron can no longer be fused exothermically: Further fusion reactions swallow energy instead of giving some away. If also, after some 10,000 years, the carbon as fuel runs out, such stars usually blow a part of their shell as planetary nebula into space. Eventually, they share the fate of the Sun and turn into a white dwarf.
This white dwarf cools over time and eventually becomes a black dwarf - unless it suffers a Type I supernova: this can happen to it in binary systems where two (or even more) suns orbit each other. If the companion eventually inflates into a red giant, the white dwarf's gravity may succeed in pulling its matter away. The influx of fresh material unbalances the white dwarf - and it explodes in a supernova.
The closest white dwarf to the solar system is Sirius B. It is only about the size of the Earth and, because of its proximity, one of the best-studied white dwarfs around. Observation is complicated by the fact that it is outshone by the great brightness of Sirius A. Sirius B has 98 percent of the mass of the sun, but only 2.7 percent of its luminosity.
Extremely dense: neutron stars
Stars that are at least about three times heavier than the sun suffer a spectacular end. They manage to use all elements up to iron as fuel in different shells in their interior. Their core, which is only 10,000 kilometers across, then usually consists of iron and heavier elements.
What happens to the dying star now depends mainly on this core. When it crosses the Chandrasekhar limit described above, its matter can no longer resist its own gravity and collapses into a neutron star. Its matter is compressed so much that the electrons of the atomic shell fuse with the protons of the nucleus to form neutrons (releasing electron neutrinos). The nucleus simultaneously ejects its shell in a gigantic explosion, a supernova.
A neutron star is a very compact object - up to 3 solar masses are contained in a sphere 20 kilometers in diameter. One cubic centimeter of it weighs about as much as an iron cube with one kilometer edge length. At its surface, gravity is 200 billion times stronger than on Earth. If an object fell to the ground from a height of one meter, it would hit the ground after a microsecond at 7.2 million kilometers per hour.
Neutron stars no longer shine by themselves. Because of their often unusual properties, however, they were discovered early on. During the sudden contraction of the star, for example, its magnetic field is also frozen. If the neutron star now also rotates, the star emits radio radiation, which astronomers can pick up as a pulsar.
Of course, researchers have not yet been able to verify the structure of a neutron star. But from the theory a shell structure emerges: The outer crust consists of iron atoms and ions, which form a crystal lattice. At a depth of ten meters, the inner crust begins - the pressure here is already so high that even free neutrons can survive. From a depth of two kilometers the outer core begins, which is dominated by neutrons, but also contains protons and electrons. According to the theory, it should be both superconducting and superfluid
- there is no more internal friction. What the inner core looks like can only be speculated. Either it is composed of more exotic particles such as pions and kaons, which form a Bose-Einstein condensate there, i.e. they all assume the same quantum state, or there are even free quarks, the building blocks of elementary particles.
The Strange Ones: Quark Stars
If this is the case, one also speaks of a quark star. Theoretically - because no such objects has been detected so far - every neutron star could become a quark star, if its mass approaches the so-called Tolman-Oppenheimer-Volkoff limit without exceeding it. This limit is between 1.5 and 3 solar masses.
Physicists are interested in quark stars because they should be one of the few places where hypothetical strange matter can exist. It consists of the strange quarks belonging to the standard model of physics. Strange matter, if it is heavy enough with more than 1000 proton masses, should be stable.
True, it should be difficult to distinguish quark stars directly from ordinary neutron stars. However, when two objects of this type merge to form a black hole, computer simulations at MPA Garching show clear differences. The gravitational waves emitted in this process should have higher frequencies than those of neutron stars - this would make it possible to detect the strange stars indirectly.
Where space and time are meaningless: Black holes
Proxima Logfiles 1: Marchenko's Children: Hard Science Fiction Page 16
