Introduction
People have watched these worlds for thousands of years.
Babylonian priests read the Moon, Mars and Jupiter as signs of the gods. Indian and Chinese astronomers measured their motions, and writers from the 2nd century onward imagined travelling to them.
None of the ancient sources reviewed describes how to build a home there. That work began with Kepler in the 17th century and with the engineers and storytellers who followed. This guide places the real conditions, and the measures a habitat needs, next to what each culture recorded.
1. At a glance
The three destinations compared.
| Moon | Mars | Jupiter system | |
|---|---|---|---|
| Gravity | About one-sixth of Earth's | 3.73 m/s2, about 0.38 of Earth's | Callisto: 0.126 of Earth's |
| Length of day | Rotation 27.3 Earth days; day and night each last about two weeks | 24.66 hours (24 h 39 min 35 s) | Not covered here |
| Temperature | Mean +107 C by day, -153 C by night | Mean -59 C; -89 C to -31 C over a day at the Viking 1 site | Not covered here |
| Air | No long-lasting atmosphere | 6.4 millibars (Earth about 1,013); 95% carbon dioxide, 0.16% oxygen | Not covered here |
| Radiation (dose equivalent) | Not measured in the sources used | 0.67 mSv per day on the surface; 1.8 mSv per day in transit | Callisto about 0.1 mSv per day; Europa about 5,400; Io about 36,000 |
| Main hazards | Sharp, electrically charged dust; temperature swings; low gravity | Radiation; fine dust with perchlorate; thin air; long radio delay | Radiation near Jupiter; low gravity; distance; no tidal heating at Callisto |
Sources: NASA Mars fact sheet; NASA/JPL Moon facts; SwRI surface radiation; Universe Today on Jupiter's moons. Europa and Io figures come from a secondary article and are indicative only.
2. Getting there
Most of the danger begins before arrival.
NASA's Curiosity rover measured an average of 1.8 millisieverts per day inside its spacecraft on the way to Mars. The transit phases of a round trip with current propulsion would add up to about 0.66 sieverts, and a 500-day stay on the surface brings the total to around 1 sievert.
Dose equivalent in millisieverts per day, logarithmic scale: each step is ten times the last. Grey bars are levels people could plan around; copper bars are levels no unshielded habitat could tolerate. Sources: SwRI (transit and Mars surface); Universe Today (Jupiter system, secondary and indicative). 1 rem = 10 mSv.
The research team notes that 1 sievert is linked to roughly a 5 percent increase in fatal cancer risk, and that keeping crews inside agency standards means staying below that level (SwRI).
Shielding and a storm shelter
Radiation shielding and a storm shelter sized for the worst solar events, plus crew dose monitoring. There is still no approved drug that protects against deep-space cosmic radiation.
Food and medicine that last
Mars plans call for food that lasts five years, and most medicines flown to the space station have a shelf life under 24 months.
Medical self-sufficiency
A signal from Mars takes about 3 minutes to reach Earth at closest approach (54.6 million km) and about 22 minutes at the farthest (401.4 million km), so the crew cannot wait for advice. Delay figures are calculated from NASA distances.
Body and mind
Astronauts lose roughly 1 to 2 percent of bone density a month in microgravity, and gut, skin and mouth microbes shift in flight.
3. The Moon
Measures a lunar habitat needs.
Pressure and temperature control
There is no lasting atmosphere, and surface temperatures swing between roughly +107 C and -153 C.
Dust control
Lunar dust is mostly under 5 micrometres, sharp and electrically charged. In Apollo it irritated eyes and noses, scored suit zippers and spread through the cabin. NASA's technical brief lists HEPA filtration, wipeable and antistatic surfaces, an airlock separate from the habitat, suits cleaned before and after entry, dust masks and goggles during heavy exposure, and a stored-dust area, with a time-weighted limit of 0.3 mg per cubic metre for particles under 10 micrometres in cabin air.
Low-gravity countermeasures
Measures for bone and muscle, and a plan for a lunar night that lasts about two weeks.
What cultures wrote about the Moon
| Culture | What was recorded | Source |
|---|---|---|
| Hindu | Chandra, also Soma, is the lunar deity, son of the sage Atri and Anasuya. The Moon is lit by the Sun and holds the 'nectar of immortality'. Its abode is Chandraloka. The Mahabharata explains waxing and waning through Daksha's curse. | Chandra |
| Mesopotamian | The Moon is the god Sin. Its movements were read alongside the five planet-gods as omens in Enuma Anu Enlil (70 tablets, about 7,000 omens, compiled by the 16th century BCE). | Babylonian astrology |
| Chinese | Shi Shen (4th century BCE) predicted eclipses from Sun and Moon positions. Jing Fang held that moonlight is reflected sunlight, and Zhang Heng explained eclipses that way in 120 CE. | Chinese astronomy |
| Greek and Roman | Lucian's True History (2nd century CE) sends a ship to an inhabited Moon, as satire. It is often called an early work of science fiction. | Public Domain Review |
| Islamic world | Ibn al-Haytham (965 to 1040) wrote on the nature of the Moon's light. Al-Razi (1149 to 1209) argued for 'a thousand thousand worlds' beyond ours. | Muslim cosmology |
| Aztec and Maya | Coyolxauhqui (Aztec, 'Golden Bells') and Ix Chel (Maya) are the Moon goddesses. | Windows to the Universe |
Johannes Kepler wrote Somnium in 1608/09 and it was published in 1634. His Moon, Levania, has a day and night of about two weeks each: intense heat, then intense cold. His travellers are sedated for the journey and hold damp sponges to their noses to breathe, and the giant inhabitants of the far side hide under water to escape the day's heat. He also correctly places the Earth fixed in the lunar sky. Four centuries later, the same problems of heat, cold, breathing and a two-week night sit at the centre of lunar habitat design.
4. Mars
Measures a Mars habitat needs.
Pressure and oxygen
The air is 6.4 millibars of mostly carbon dioxide with 0.16 percent oxygen, so everything inside must be sealed and supplied.
Radiation protection on the surface
The surface dose is 0.67 mSv per day, about 245 mSv per year by our calculation. Shielding with soil or water ice is under study.
Dust and perchlorate
Martian dust is very fine and contains about 0.5 to 1 percent perchlorate, which interferes with thyroid function.
A different day
A sol is 39 minutes and 35 seconds longer than an Earth day. Rover teams who lived on Mars time found it exhausting, and a 2008 Phoenix crew of 19 volunteers used blue light and timed caffeine, with 87 percent reporting they could adjust (a small study with no control group).
Food, water and medicine
Systems that can be made or kept for years, and a crew that can run its own medical care.
What cultures wrote about Mars
| Culture | What was recorded | Source |
|---|---|---|
| Hindu | Mangala ('the auspicious one'), also Lohita (the red one), Bhauma and Angaraka. He rules Tuesday, rides a ram and is the god of anger and war. His abode is Mangalaloka. In one account he is the son of the earth goddess Bhumi and Vishnu; in another he formed from drops of Shiva's sweat. | Mangala |
| Indian astronomy | The Surya Siddhanta gave Mars's orbital period as 686 days 23 h 56 min; the modern value is 686 days 23 h 30 min. The estimate was within about 26 minutes over almost two years. | Mangala |
| Mesopotamian | Mars was linked to the god Nergal, and its appearance was read as a sign of the gods' will concerning the king and the state. | Babylonian astrology |
| Chinese | Gan De and Shi Shen made detailed observations of the five planets in the 4th century BCE. | Gan De |
| Modern fiction | 1877 Schiaparelli reports 'canali'. 1895 to 1908 Lowell argues they are irrigation canals. 1897 Wells, The War of the Worlds. 1912 Burroughs, A Princess of Mars. 1950 Bradbury, The Martian Chronicles. 1951 Clarke, The Sands of Mars (early terraforming). 1953 Miller, 'Crucifixus Etiam' (colonists need blood-oxygenating machines). 1955 Alien Dust (colonists with dust-related lung disease and muscle loss). 1965 Mariner 4 shows the canals were an illusion. 1992 to 1996 Robinson's Mars trilogy. | Mars in fiction |
The fiction of the 1950s already named problems that mission planners still work on: thin air, oxygen, dust that damages lungs, and muscle loss in low gravity.
5. Jupiter and its moons
Choose the site by radiation first.
Jupiter itself is a gas giant with no solid surface, so the discussion is about its moons. Jupiter's magnetic environment makes the inner moons deadly: Io's surface dose is about 36,000 mSv per day and Europa's about 5,400, while Callisto, far enough out to escape most of it, is about 0.1 mSv per day, lower than the Mars surface.
Callisto as base site
A 2003 NASA study (HOPE) chose Callisto. Its gravity is 0.126 of Earth's, lower than the Moon (0.165) and Mars (0.376), so bone and muscle loss would be a serious concern.
Isolation and supply
Plan for long isolation, long supply lines and a very long delay in communication. Distance, advanced propulsion and the lack of tidal heating are the other hurdles.
Life support for years
Counter bone and muscle loss in very low gravity, and keep food, air and medicine systems running for years.
What cultures wrote about Jupiter
| Culture | What was recorded | Source |
|---|---|---|
| Hindu | Brihaspati or Guru, one of the nine grahas, ruling Thursday. | Navagraha |
| Mesopotamian | Jupiter was identified with Marduk, the patron god of Babylon. | Babylonian astrology |
| Chinese | Gan De (4th century BCE) wrote a Treatise on Jupiter. He gave a 12-year period against the modern 11.86 years. A fragment quoted in an 8th-century text describes a small reddish star beside Jupiter; in 1981 Xi Zezong proposed it was a Galilean moon seen with the naked eye. This is disputed, and the accepted discovery date remains 1610. | Gan De |
No historical text was found that describes living near Jupiter. Ideas about Jupiter's moons are modern. Figures are from a secondary article and are indicative.
6. A long human conversation
About other worlds.
| When | What happened |
|---|---|
| 4th century BCE | Epicurus teaches an unlimited number of worlds (Epistle to Herodotus); Plato and Aristotle argue Earth is unique. |
| 2nd century CE | Lucian writes a satirical voyage to the Moon and Sun. |
| 676 to 733 | Imam Muhammad al-Baqir writes that God created thousands of worlds with thousands of humankinds. |
| 1149 to 1209 | Fakhr al-Din al-Razi argues for 'a thousand thousand worlds'. |
| 1584 | Giordano Bruno publishes on innumerable suns and earths; he is later executed. |
| 1608/09; 1634 | Kepler writes and publishes Somnium. |
| 1656 | Kircher's Itinerarium exstaticum is the first fictional tour of the planets. |
| 1686; 1862 | Fontenelle and Flammarion popularise the idea of a plurality of worlds. |
| 1903 to 1977 | Tsiolkovsky (1903, rotating cylindrical settlements), Bernal (1929, spherical settlement), O'Neill (1974 and 1976, cylinders up to 8 km across and 32 km long) and the NASA settlement studies of 1975 and 1977. |
Sources: Cosmic pluralism; Space settlement; Mars in fiction.
7. How our work connects
From the conditions to the products.
Each product is under research and development. This table links the stresses above to the Aeginis work that addresses them.
| Challenge | Where it matters | Related work | Status |
|---|---|---|---|
| Radiation | All destinations | Radiation Recovery Vesicles; MycoShell for the habitat | Research programme; TRL 4 |
| Bone loss in low gravity | Moon, Mars, Callisto | Bone-Support Probiotic | Research programme |
| Changed gut, skin and mouth microbes | All journeys | SpaceBiotic Spore Capsule | In development |
| Vitamins and food that must last years | Mars, transit | Stabilised Vitamin System | In development |
| Medicines that expire | Mars, transit | On-Demand Peptide Library | Research programme |
| Dust and perchlorate | Mars; Moon (dust) | Mars Dust and Perchlorate Defence Kit | Concept |
| A longer day | Mars | Circadian Planning Module | Concept |
| Choosing what to test first | All | Cosmion | In development |
Questions
Living beyond Earth FAQ.
What is gravity like on the Moon, Mars and Callisto?
The Moon's gravity is about one-sixth of Earth's, Mars's is 3.73 m/s2 or about 0.38 of Earth's, and Callisto, a moon of Jupiter, is 0.126 of Earth's, lower than both the Moon and Mars.
How hot and cold is the Moon?
Surface temperatures swing between a mean of about +107 C by day and -153 C by night, and a lunar day and night each last about two weeks, so a habitat needs strong thermal control and a plan for the long night.
Is there air on Mars?
Mars has a thin atmosphere of about 6.4 millibars, compared with about 1,013 on Earth. It is 95% carbon dioxide and only 0.16% oxygen, so everything inside a Mars habitat must be sealed and supplied.
Which moon of Jupiter is best for a base?
Because radiation is the deciding factor, Callisto is the only Galilean moon whose surface dose, about 0.1 mSv per day, is below that of the Mars surface. A 2003 NASA study (HOPE) chose Callisto as the base site. Europa and Io are far more dangerous.
What did ancient Indian astronomers record about Mars?
The Surya Siddhanta gave Mars's orbital period as 686 days 23 hours 56 minutes, within about 26 minutes of the modern value. In the Hindu tradition Mars is Mangala, also called Lohita, the red one, who rules Tuesday.
Who first imagined settling the Moon?
Johannes Kepler's Somnium, written in 1608/09 and published in 1634, describes a Moon with a two-week day and night and travellers who must be sedated and breathe through damp sponges. Lucian's satire of a voyage to the Moon, in the 2nd century CE, is far older but not a habitat design.
Is this guide a design standard?
No. It summarises published sources, mostly summaries and agency pages, and gives indicative figures. The cultural entries describe what texts recorded and do not claim that ancient writers planned settlements.
About this guide: it summarises published sources, mostly summaries and agency pages, and is not a design standard. Conditions and dose figures are indicative. The cultural entries describe what texts recorded and do not claim that ancient writers planned settlements. Aeginis products are under research and development, are not approved or cleared by any regulator and are not available for sale. Nothing here is medical advice.
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