Venus is very hot and all other planets and moons are very cold. There are some natural places on Earth, where humans have explored, that are similar to the conditions on Mars. The highest altitude reached by a balloon that was carrying humans, was 34,668 meters (113,740 feet), a record set in May 1961.[3] The pressure at that altitude is about the same as on the surface of Mars.[4] Extreme cold in the Arctic and Antarctic match all but the most extreme temperatures on Mars. It may be possible to terraform Mars to allow a wide variety of living things.[5] In April 2012, it was reported that lichen and bacteria survived for 34 days in conditions like those on Mars.[6][7][8] This experiment was maintained by the German Aerospace Center (DLR). Organizations Many organizations support the colonization of Mars. They have also given different reasons and ways humans can live on Mars. One of the oldest organizations is the Mars Society. They promote a NASA program that supports human colonies on Mars. The Mars Society have set up Mars analog research stations in Canada and the United States. Conditions on the surface of Mars are closer to the conditions on Earth in terms of temperature and sunlight than on any other planet or moon, except for the cloud tops of Venus. However, the surface is not hospitable to humans or most known life forms due to the radiation, greatly reduced air pressure, and an atmosphere with only 0.16% oxygen. In 2012, it was reported that some lichen and cyanobacteria survived and showed remarkable adaptation capacity for photosynthesis after 34 days in experiments that partially simulated Martian conditions in the Mars Simulation Laboratory maintained by the German Aerospace Center. Some scientists think that cyanobacteria could play a role in the development of self-sustainable crewed outposts on Mars. They propose that cyanobacteria could be used directly for various applications, including the production of food, fuel and oxygen, but also indirectly: products from their culture could support the growth of other organisms, opening the way to a wide range of life-support biological processes based on Martian resources. Humans have explored parts of Earth that match some conditions on Mars. Based on NASA rover data, temperatures on Mars (at low latitudes) are similar to those in Antarctica. The atmospheric pressure at the highest altitudes reached by piloted balloon ascents (35 km (114,000 feet) in 1961, 38 km in 2012) is similar to that on the surface of Mars. However, the pilots were not exposed to the extremely low pressure, as it would have killed them, but were seated in a pressurized capsule. Human survival on Mars would require living in artificial Mars habitats with complex life-support systems. One key aspect of this would be water processing systems. Being made mainly of water, a human being would die in a matter of days without it. Even a 5–8% decrease in total body water causes fatigue and dizziness, and with a 10% decrease comes physical and mental impairment (See Dehydration). A person in the UK uses 70–140 litres of water per day on average. Through experience and training, astronauts on the International Space Station (ISS) have shown it is possible to use far less, and that around 70% of what is used can be recycled using the ISS water recovery systems. (For instance, half of all water is used during showers.) Similar systems would be needed on Mars but would need to be much more efficient, since regular robotic deliveries of water to Mars would be prohibitively expensive (the ISS is supplied with water four times per year). Potential access to on-site water (frozen or otherwise) via drilling has been investigated by NASA. Robotic spacecraft to Mars are required to be sterilized, to have at most 300,000 spores on the exterior of the craft—and more thoroughly sterilized if they contact "special regions" containing water, otherwise there is a risk of contaminating not only the life-detection experiments but possibly the planet itself. It is impossible to sterilize human missions to this level, as humans are host to typically a hundred trillion microorganisms of thousands of species of the human microbiome, and these cannot be removed while preserving the life of the human. Containment seems the only option, but it is a major challenge in the event of a hard landing (i.e. crash). There have been several planetary workshops on this issue, yet no final guidelines have been produced. Human explorers would also be vulnerable to back contamination to Earth if they become carriers of microorganisms should Mars have life. Space colonization in general has been discussed as a continuation of imperialism and colonialism, especially regarding Mars colonial decision making, reasons for colonial labor and land exploitation have been questioned with postcolonial critique. Seeing the need for inclusive and democratic participation and implementation of any space and Mars exploration, infrastructure, or colonialization, many have called for dramatic sociological reforms and guarantees to prevent racism, sexism, and other forms of prejudice. The narrative of space exploration as a "New Frontier" has been criticized as an unreflected continuation of settler colonialism and manifest destiny, continuing the narrative of colonial exploration as fundamental to the assumed human nature. The predominant perspective of territorial colonization in space has been called surfacism, especially comparing advocacy for colonization of Mars opposed to Venus. Mars colonization is advocated by several non-governmental groups for a range of reasons and with varied proposals. One of the oldest groups is the Mars Society that promotes a NASA program to accomplish human exploration of Mars and has set up Mars analog research stations in Canada and the United States. Mars to Stay advocates recycling emergency return vehicles into permanent settlements as soon as initial explorers determine