WHO guidelines on gaming disorder

This curated set answers which official WHO documents define gaming disorder, place it in ICD-11, and provide the detailed clinical diagnostic guidance needed to assess it.^[1][2][3]

Space Settlements: A Design Study 1977

The study asks how humans could build a permanent community beyond Earth, and its central answer is that settlement is technically plausible but depends on solving social, economic, ecological, and organizational problems as carefully as engineering problems.^[1] The proposed colony is meant to be a real community where people work, raise families, live ordinary lives, and generate enough value to maintain itself and expand.^[2]

The baseline colony

The reference design is a settlement for 10,000 permanent residents in a rotating torus, located near the Earth-Moon L5 libration point. L5 is a gravitationally favorable region selected for comparatively practical connections to both Earth and the Moon.^[3][4]

How the colony would work

The design is therefore more than a pressure vessel. It links mining, transport, energy, agriculture, recycling, manufacturing, habitation, and social organization into one operating system.^[22]

Key assumptions and trade-offs

The study deliberately makes conservative choices where evidence was limited. It assumes near-Earth gravity, a general-population radiation limit of no more than 0.5 rem per year, and a reduced-pressure atmosphere of about 50.8 kPa with normal oxygen partial pressure, nitrogen as buffer gas, low carbon dioxide, and controlled humidity.^[23][24][25]

Its agricultural model is highly demanding: year-round cultivation with controlled carbon dioxide, lighting, temperature, water, and nutrients is assumed to feed 10,000 people using about 61 hectares.^[26] At the same time, the first settlement is not expected to be fully self-sufficient. It would remain dependent on Earth for some materials, advanced equipment, expertise, and replacement goods for an extended period.^[27][28]

The torus is presented as a compromise. Other forms could offer advantages in volume or structural mass, but the study considered them less satisfactory for psychological reasons, including shorter sightlines, reduced apparent openness, more complicated circulation, and a stronger sense of confinement.^[29] The Moon itself is rejected as the principal habitat location because it lacks continuous sunlight, imposes one-sixth Earth gravity, and is less well placed for sending solar power satellites to geosynchronous orbit.^[30]

Major insights

Overall assessment

The report's deepest insight is that space settlement should be understood as the beginning of an industrial and cultural civilization, not as the construction of a single spacecraft. Its L5 torus is a conservative demonstration case: technically ambitious, dependent on lunar resources and highly productive ecological systems, initially tied to Earth, and economically justified through space-based energy production.^[39]

The authors consequently call for further systems research on radiation, artificial gravity, closed ecology, intensive agriculture, lunar processing, transportation, human factors, governance, environmental effects, and the economics of space-based energy.^[40] The lasting lesson is that keeping people alive in space is only the first requirement. A viable settlement must also support health, meaning, economic exchange, cultural growth, and the ability to create new communities.

Humans to Mars: Fifty Years of Mission Planning, 1950-2000

David S. F. Portree's history shows that Mars mission planning was never simply an engineering exercise. Across five decades, designers repeatedly found technically credible ways to reach Mars, yet politics, cost, changing priorities, scientific discoveries, and institutional continuity usually determined whether those plans advanced. ^[1][2]

The central lesson is practical: successful human exploration would require a clear purpose, disciplined mission scope, sustained political support, intelligent cooperation between robots and astronauts, and technologies that reduce dependence on Earth. ^[3][4]

Why Mars remained compelling

Mars attracted planners because it is relatively Earth-like, preserves evidence of past water and climate, may contain signs of ancient life, and offers resources that could support exploration or eventual settlement. These scientific possibilities gave human missions a purpose beyond simply repeating the achievement of reaching another world. ^[5]

At the same time, the rationale for sending people was repeatedly questioned. Robots could often conduct reconnaissance and collect samples more cheaply and with less risk, while human crews faced radiation, isolation, long-duration life support, planetary-protection concerns, complex logistics, and extraordinary cost. ^[6]

How mission concepts changed

The technical problems that shaped every plan

Propellant mass was the recurring systems problem. Every mission had to pay for departure from Earth, arrival at Mars, movement around or from the planet, and the return journey. This made trajectories, propulsion systems, staging, aerobraking, and local resource production tightly connected design choices. ^[19]

Conjunction-class missions generally reduced propellant and spacecraft mass by using relatively low-energy transfers, but they required missions lasting roughly 900 to 1,100 days and a long stay on Mars. Opposition-class missions offered a shorter stay, but demanded a much more energetic return and therefore more propellant. ^[20][21]

The recurring tension between ambition and affordability

The late 1960s represented a technical and conceptual high point. NASA and industry studied piloted flybys, nuclear-rocket landings, and very large spacecraft. Yet Vietnam, domestic unrest, budget pressure, the Apollo 1 fire, and the termination of Saturn V and NERVA halted that momentum. ^[27]

Later proposals responded by making the mission smaller, more modular, or more dependent on technologies that could be developed incrementally. Private groups and individuals revived the subject through the Case for Mars conferences, The Planetary Society, base studies, cyclers, Lagrange-point staging, and possible US-Soviet cooperation. ^[28]

This evolution did not mean that the fundamental difficulties had disappeared. It meant that planners increasingly treated affordability and continuity as design requirements rather than as questions to be addressed after the ideal mission had been defined. ^[29][30][31]

What the history ultimately teaches

Mars knowledge repeatedly changed mission architecture. Early telescope-based assumptions about canals, atmosphere, landing conditions, and life were overturned by spacecraft observations, while later evidence of ancient water and possible biological traces renewed scientific interest. ^[32][33]

The history also shows that technological ideas tend to recur. Later planners repeatedly rediscovered concepts such as aerobraking, artificial gravity, cyclers, local resource use, and split mission architectures. Preserving earlier studies therefore has practical value, because it prevents future programmes from paying to reinvent solutions already explored. ^[34]

By 2000, the direction of travel was clear: robotic precursor missions, Earth-based technology development, demonstrations of local resource production, human-factors research, realistic surface operations, and reference architectures that could be refined over time. NASA had begun integrating robotic and human Mars planning and recognised that people might eventually reach Mars without another Apollo-scale national mobilisation. ^[35]

Conclusion

Portree's overall conclusion is measured rather than triumphalist. Human Mars flight was neither shown to be imminent nor judged impossible. The past fifty years demonstrated that credible technical routes could be identified, but also that cost, infrastructure, institutional weakness, shifting national priorities, and fragile political commitment could stop them. ^[36]

The enduring insight is that Mars exploration must be designed as a sustained programme, not a one-off gesture. A durable effort would need a clear reason for sending people, controlled scope and cost, continuity across political cycles, early attention to planetary protection, effective use of robots and Martian resources, and a realistic account of what astronauts can do that machines cannot. ^[37]

Walking to Olympus: An EVA Chronology

Walking to Olympus: An EVA Chronology presents human extravehicular activity, or EVA, as the history of learning how to perform useful work outside a spacecraft. Covering March 1965 to April 1997, the book follows the transition from hazardous demonstrations of survival to lunar exploration, satellite repair, orbital construction, and preparation for the International Space Station (ISS).^[1]

Its central insight is that progress did not come from suits alone. EVA matured through the combined development of life-support systems, mobility aids, restraints, tools, procedures, training, crew coordination, and the ability to respond intelligently when hardware or circumstances behaved unexpectedly.^[2][3]

The chronology: from demonstration to permanent orbital work

Suit and life-support development

The U.S. progression runs from Gemini's G4C suit and chest-mounted equipment to Apollo's lunar suit and Portable Life Support System (PLSS), which supplied astronauts with the life support and mobility needed for surface EVA. Apollo 9 tested the lunar suit, PLSS, and contingency movement between the lunar module and command module before lunar operations began.^[12]

The Shuttle era introduced the Extravehicular Mobility Unit (EMU) as a reusable system for orbital work. Unlike Apollo's surface-oriented equipment, the Shuttle EMU supported repeated payload-bay operations, satellite servicing, and later Hubble and station work. The MMU added powered free-flight capability, while SAFER provided a smaller emergency self-rescue system for an astronaut who became separated from the spacecraft.^[13][14]

The Soviet and Russian line developed from Leonov's Berkut, whose tendency to balloon severely restricted movement, through Yastreb articulation systems and successive Orlan designs. Orlan suits evolved towards harder torsos, rear entry, improved mobility, longer endurance, autonomous communications, and protection against glove punctures.^[15]

The overlooked engineering problem: controlling the body

A spacewalker must not only survive in a vacuum but also remain positioned well enough to work. Without a stable point of contact, an astronaut can spend more effort stopping unwanted motion than turning a tool or handling a component. The book therefore treats mobility and restraint systems as central EVA technologies, not accessories.^[16]

What the early missions revealed

The first spacewalks were demonstrations, but they also exposed the conditions that made EVA difficult. The chronology identifies suit stiffness, overheating, visor fogging, poor restraint, tether-management problems, limited visibility, hand fatigue, dust, and inadequate tools as recurring obstacles. Later missions incorporated lessons from failures and near-failures into equipment, procedures, and training.^[22]

Leonov's first EVA became especially important in retrospect because later knowledge revealed hazards that were not apparent from the public success narrative. The event showed that an EVA could be threatened by interactions between suit pressure, movement, spacecraft geometry, and the astronaut's ability to return through the airlock. Its historical value lies partly in demonstrating how much risk was being managed despite the appearance of a simple technological first.^[23]

The same pattern recurred in the U.S. programme. Cernan's difficulties during Gemini 9 contributed to improved restraints and training, while Hubble servicing and Shuttle-Mir operations converted equipment failures, unexpected geometry, and operational surprises into revised procedures and hardware.^[24]

Expertise, improvisation, and international convergence

One of the book's most important historical insights is that EVA expertise is not automatically preserved. It had to be developed, allowed to decay when missions changed, and deliberately rebuilt when new operational demands arose. The move from Gemini to Apollo, from Apollo to Skylab, from Shuttle servicing to station construction, and from separate U.S. and Soviet systems to Shuttle-Mir cooperation each required organisations to recover and adapt practical knowledge.^[25][26][27]

Real-time human judgement remained indispensable. Procedures and hardware could reduce risk, but astronauts and ground teams still had to interpret unexpected motion, suit behaviour, tool problems, visibility limits, and structural geometry. Failures were therefore productive historical events, because crews and controllers used improvisation to complete tasks and then converted that experience into better designs and procedures.^[28]

The U.S.-Soviet rivalry accelerated the early chronology: Voskhod 2 was intended to precede the United States, while Gemini was organised to acquire the capabilities required for Apollo.^[29] Over time, however, the two programmes increasingly converged. Their approaches differed in suits, airlocks, training, documentation, and crew coordination, but Shuttle-Mir cooperation helped create shared techniques and expectations for ISS operations.^[30]

Key takeaways

The book's lasting message is that spacewalking became reliable not through a single breakthrough, but through repeated encounters with danger and difficulty. Each mission added practical knowledge, and that knowledge gradually turned EVA from a spectacular test of human survival into an organised form of construction and maintenance in orbit.

Beyond Earth: The Making of Deep-Space Exploration, 1958-2016

Asif A. Siddiqi presents deep-space exploration as a cumulative human enterprise: spacecraft gradually became better at leaving Earth, reaching other worlds, surviving hostile environments, returning data, and working together across national boundaries. The book’s value lies not only in the discoveries, but in showing how engineering setbacks, institutional choices, and persistent operations made those discoveries possible.^[1][2]

The Book’s Central Argument

The chronicle is primarily a history of missions and capabilities rather than a catalogue of scientific results. Siddiqi emphasizes launches, trajectory changes, orbital insertion, atmospheric entry, landing, surface operations, communications, and mission recovery, stating that the focus is on “what happened rather than what was discovered.”^[3]

This approach reveals exploration as an engineering system. Launch vehicles, guidance, power, thermal control, software, instruments, communications, and human operations had to work together, often across enormous distances and with little opportunity for repair. A failure in one apparently minor component could determine whether an entire mission succeeded, partially succeeded, or failed.^[4][5]

From Escaping Earth to Reaching the Moon

Between 1958 and 1962, the first challenge was transportation itself. Launchers, upper stages, attitude control, telemetry, and deep-space tracking were still experimental, and many probes failed before reaching Earth orbit or escape velocity. The successful missions established the basic possibility of deep-space operations.^[9][10]

The period also demonstrates why partial success mattered. Pioneer III missed the Moon but returned radiation measurements that helped define Earth’s Van Allen belts. Its result did not satisfy the headline objective, yet it contributed to the knowledge and technical base needed for later missions.^[15]

From Reconnaissance to Fieldwork

From 1964 to 1970, spacecraft moved beyond brief encounters. They began taking close images, landing on other worlds, transmitting from hostile surfaces, collecting samples, and moving across another celestial body. This was a decisive change: other worlds became places where instruments could perform sustained work rather than distant targets seen only during a flyby.^[16][17][18]

Planetary Systems Come into View

During the 1970s, exploration matured from isolated encounters into planetary-system investigations. Orbiters mapped entire worlds, landers conducted surface experiments, rovers extended mobility, and solar-monitoring spacecraft studied environments far from Earth.^[24][25]

Mariner 9’s orbit around Mars was especially important. Its observations revealed volcanoes, vast canyons, and evidence of geological activity, showing that Mars was not simply a Moon-like body. Pioneer 10 and 11 crossed the asteroid belt and explored Jupiter and Saturn, while Viking combined Mars orbiters and landers with biological experiments. Helios 1 and 2 expanded the study of the near-Sun environment.^[26][27]

The Voyager missions extended this logic to the outer Solar System. Gravity assists, in which a spacecraft gains or redirects momentum during a close planetary encounter, enabled Voyager 2 to continue from Jupiter to Saturn, Uranus, and Neptune. Together, the Voyagers transformed knowledge of the outer planets, their moons, and their rings.^[28][29]

Cooperation, Longevity, and Adaptation

The exploration enterprise became increasingly networked. Orbiters relayed data for landers and rovers, multiple spacecraft observed the same events, and agencies coordinated instruments, tracking, launches, and scientific analysis. The 1985-1986 Halley missions showed how international cooperation could work in practice: Soviet Vega spacecraft, Japan’s Sakigake and Suisei, and ESA’s Giotto contributed to a coordinated comet investigation, with Giotto benefiting partly from tracking data supplied by Vega.^{[30][31][32][33]}

Mission duration also became a major source of scientific return. Pioneer VI operated for about twenty years despite a planned six-month lifetime, Ulysses worked for more than four times its design life, and Mars rovers designed for roughly three months continued operating for years. These extended missions were not merely lucky bonuses: they became important ways to increase the scientific value of existing hardware.^[34][35][36]

Adaptability was equally important. Missions such as ISEE-3, Dawn, Deep Impact, and the repurposed THEMIS satellites were redesigned after launch, sometimes turning an original project into a longer or substantially different investigation. Backup systems, alternate trajectories, and improvised operating modes repeatedly helped recover useful science after failures.^{[37][38][39][40]}

The 1990s to 2016: Precision and Habitability

From the 1990s onward, exploration diversified. Smaller and more focused missions, including Discovery-class projects, operated alongside major international programs. Spacecraft increasingly combined high-resolution mapping, atmospheric chemistry, autonomous navigation, electric propulsion, sample return, and targeted searches for water and habitable conditions.^{[41][42][43][44]}

Key Lessons and Lasting Insights

Conclusion

Taken as a whole, Beyond Earth describes a transformation from experimental attempts to escape Earth into a durable, multinational system for investigating the Solar System. The progression ran from impacts and flybys to orbiters, landers, rovers, sample-return vehicles, gravity-assist trajectories, Lagrange-point operations, and coordinated spacecraft networks.^[59][60][61]

The deepest lesson is that exploration advanced through persistence rather than a smooth sequence of victories. By 2016, its achievements rested on accumulated engineering knowledge, extended mission operations, institutional learning, and international cooperation. The result was not simply a larger map of space, but a more capable and more evidence-based understanding of planetary environments, habitability, the Sun, and the origins of the Solar System.^[62][63][64]

Odd Showers: Nature’s Strange Falls Explained

Odd Showers is a nineteenth-century popular-science account of unusual substances reported to fall from the sky, from insects, frogs, and fish to sand, ash, coloured rain, and meteorites. Its central lesson is that extraordinary appearances should be examined through observation and ordinary physical laws rather than assumed to be supernatural events.^[1]

The book’s most useful distinction is between an event and its interpretation: something may genuinely descend from above without having formed in a cloud or arrived with ordinary rain. The chapters therefore move from living organisms to earthly materials and finally to objects believed to have come from beyond Earth.^[2][3]

The book’s central method

The author begins with a personal experience near Montreal, where he encountered thousands of small frogs and initially assumed that they had fallen with the rain. He later presents that assumption as a common error, while allowing that violent weather, including waterspouts and hurricanes, could lift animals from water and carry them elsewhere.^[4]

Major examples and explanations

Key insights

The book shows that the phrase “shower from the sky” can describe several different processes. Insects may emerge together from soil or water; animals may be carried by violent air movements; coloured precipitation may contain biological or mineral matter; and volcanic or desert dust may be transported by atmospheric currents.^[21]

This approach preserves the observable part of a strange report while challenging its explanation. The author does not simply dismiss accounts of fish, frogs, lizards, or stones. Instead, he asks whether the material was lifted from the ground or water, transported through the atmosphere, generated by a local emergence, or delivered from space.^[22][23][24]

Conclusion

The lasting message of Odd Showers is that nature can be astonishing without being disorderly. By comparing eyewitness accounts with mechanisms such as wind, water, volcanic action, biological emergence, and gravity, the book replaces folklore and fear with a habit of investigation: observe carefully, distinguish evidence from interpretation, and seek the simplest physical explanation that fits the event.^[25][26]

Curious Facts in the History of Insects, Spiders, and Scorpions

Frank Cowan’s 1865 book is less a conventional zoological survey than a history of how people have imagined, feared, used, worshiped, and studied small creatures. Its central purpose is to collect memorable “extra-scientific” facts from chronicles, travel writing, medicine, folklore, religion, art, and everyday custom, while asking where belief ends and observation begins.^[1]

For a first-time reader, the main lesson is simple: insects, spiders, and scorpions matter not only because of what they do in nature, but also because human societies have made them symbols, resources, omens, dangers, and objects of scientific curiosity.

The book’s major themes

Memorable examples and insights

Recurring insights

Overall perspective

Cowan’s perspective is curious, broad, and cautiously sceptical. He does not treat folklore as worthless: it reveals how people tried to interpret an unfamiliar natural world. At the same time, he frequently separates testimony from proof and exposes magical, medical, and prophetic claims as uncertain, exaggerated, or false.^[18]

The book’s lasting insight is that insects, spiders, and scorpions are mirrors of human practical life and imagination. They can be worshiped as sacred figures, feared as omens, eaten in scarcity, used in manufacture and medicine, admired for beauty and social organisation, or investigated as natural phenomena. Their history is therefore also a history of human attempts to explain, control, benefit from, and live alongside the small creatures around us.^[19]

Freaks and Marvels of Plant Life: Key Points and Insights

M. C. Cooke’s book presents plants as active, responsive organisms rather than passive scenery. Through examples of carnivory, movement, mimicry, unusual growth and cultural symbolism, it shows how apparently strange structures often have practical biological functions, while reminding readers to distinguish demonstrated facts from speculation.^[1][2]

The book’s central themes

Striking examples

Broader insights

The book’s most important lesson is methodological: unusual botanical claims should be tested through observation, measurement and comparison. A claim should not be accepted simply because it is marvellous, nor rejected simply because it conflicts with familiar ideas about what plants can do.^[23]

Summary

Overall, Freaks and Marvels of Plant Life turns botanical curiosities into evidence of adaptation, responsiveness and ecological relationships. Its lasting insight is that plants are neither inert nor uniform: they sense conditions, alter their forms and movements, interact with animals and people, and reveal their abilities most clearly when observation replaces assumption.^[28]