The Beacon: Hard Science Fiction by Brandon Morris (heaven official's blessing novel english .txt) 📗

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.

3.99 $ – hard-sf.com/links/762824

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?

3.99 $ – hard-sf.com/links/1433312

A Guided Tour of Multi-Messenger Astronomy

For millennia, humans looked at the sky with their naked eyes.

Then came the telescope. Celestial bodies looked closer and clearer, but in principle, one still gained the same information. Next, scientists discovered that there is a continuous electromagnetic spectrum. Gamma and X-ray radiation, microwave radiation, ultraviolet and visible light, infrared, and radio emissions are all of the same nature, but have different frequencies, and thus transmit different information.

Electromagnetism is not the only source of data from space. Other fundamental forces also convey information about cosmic objects. Today, therefore, we speak of ‘multi-messenger astronomy.’ It is based on the coordinated observation and interpretation of different messenger signals. Interplanetary probes can visit objects within the solar system, but beyond that, scientists must rely on special ‘extrasolar’ messengers. These four extrasolar messengers include the aforementioned electromagnetic radiation, plus gravitational waves, neutrinos, and cosmic rays. They are generated by different astrophysical processes, and therefore reveal different information about their sources.

The most important multi-messenger research subjects outside the heliosphere are expected to include compact binary pairs (black holes and neutron stars), supernovae, irregular neutron stars, gamma-ray bursts (GRBs), active galactic nuclei (AGNs), and relativistic jets. Just about any object reveals more about itself when observed in all available wavelengths and with all messengers.

In the following pages, I describe individual measurement methods and their special features.

Gamma Astronomy

Gamma rays represent the most energetic form of electromagnetic radiation. Their photons (light particles) reach energies of more than 100 keV. The cosmic processes that emit gamma rays are diverse, but mostly identical to those that emit X-rays, except that they occur at higher energies. Thus, where gamma rays are found, X-rays are often encountered as well. These include electron-positron annihilation, the inverse Compton effect, and in some cases, the decay of radioactive material (gamma decay) in space, which is possible in extreme events such as supernovae and hypernovae, and when matter comes under extreme conditions, such as in pulsars and blazars.

The highest photon energies measured so far are in the TeV range, the record being held by the Crab Nebula, which delivered photons of up to 80 TeV in 2004.

Long before experiments could detect gamma rays emitted by cosmic sources, scientists knew that the universe must produce them. These processes include interactions of cosmic rays with interstellar gas, supernova explosions, and interactions of energetic electrons with magnetic fields. However, it took until the 1960s before we were able to detect these emissions.

Indeed, most gamma rays coming from space are absorbed by the Earth’s atmosphere, so gamma-ray astronomy could not develop until it was possible to get detectors beyond most of the atmosphere using balloons and spacecraft. The first gamma-ray telescope, launched into orbit on the U.S. Explorer 11 satellite in 1961, caught fewer than 100 cosmic gamma-ray photons. They appeared to come from all directions in the universe, suggesting some sort of uniform gamma-ray background. Such a background would be expected from the interaction of cosmic rays with interstellar gas.

The first true astrophysical gamma-ray sources were solar flares that revealed a strong 2.223 MeV line. This line is developed during the formation of deuterium by the union of a neutron with a proton. Significant gamma-ray emissions from the Milky Way were first registered in 1967 by the detector aboard the OSO 3 satellite. It found 621 events attributable to cosmic gamma rays.

The field of gamma-ray astronomy made great leaps forward with the SAS-2 (1972) and Cos-B (1975-1982) satellites. These two satellites provided a glimpse into the high-energy universe. They confirmed earlier findings regarding the gamma-ray background, produced the first detailed map of the sky at gamma-ray wavelengths, and discovered a number of point sources. However, the instruments’ resolutions were not sufficient to identify most of these point sources as specific visible stars or star systems.

An important discovery in gamma-ray astronomy came from military satellites in the late 1960s and early 1970s. Detectors aboard the Vela series of satellites, designed to detect gamma-ray bursts from atomic bomb explosions, began recording gamma-ray bursts in space instead. Later detectors found that these GRBs last from fractions of a second to minutes, can appear suddenly and from unexpected directions, flicker, and then fade after briefly dominating the gamma-ray sky.

To this day, the sources of these mysterious high-energy flashes remain a mystery. In any case, they appear to come from far across the universe. The most plausible theory at present is that at least some of them come from so-called hypernova explosions—supernovas that produce black holes rather than neutron stars.

X-ray astronomy

X-ray astronomy, of course, deals with the observation of X-rays coming from astronomical objects. However, the Earth’s atmosphere absorbs X-rays, so instruments to detect them must be carried to high altitudes by balloons, sounding rockets, and satellites.

X-rays are emitted