What makes space extreme

However, on returning to Earth, the spacecraft will re-enter the atmosphere. While the air itself may not seem dense, travelling very fast through air creates very high frictional forces generating extremely high temperatures. To protect astronauts from these high temperatures, the spacecraft must be able to:. Spacecraft have heatproof tiles on the underside.

But points in space removed from heat sources aren't cold in the sense that they would quickly make you cold. Quick heat transfer requires contact or air, both lacking in space. As a result objects cool very slowly through the much slower mechanism of thermal radiation. A human exposed to outer space in shadow without a space suit does not instantly freeze to a block of ice.

Acidity and alkalinity are measures of the concentration of protons; the units used are pH units. The lower the number down to zero , the higher the acidity. The higher up to 14 , the more alkaline. A neutral pH near 7 is optimal for many biological processes, although some — such as the light reactions of photosynthesis — depend on pH gradients.

In nature, pH can be high, such as in soda lakes or drying ponds, or as low as 0 and below. Organisms that live at either extreme do this by maintaining the near-neutral pH of their cytoplasm i. The extreme acidophiles are microbes. Several algae, such as the unicellular red alga Cyanidium caldarium and the green alga Dunaliella acidophila , are exceptional acidophiles both of which can live below pH 1.

Three fungi, Acontium cylatium , Cephalosporium sp. Another species, Ferroplasma acidarmanus , has been found growing at pH 0 in acid mine drainage in Iron Mountain in California. These polyextremophiles tolerant to multiple environmental extremes thrive in a brew of sulfuric acid and high levels of copper, arsenic, cadmium, and zinc with only a cell membrane and no cell wall. Temperature is a critical parameter because it determines whether liquid water is present.

If temperature is too low, enzymatic activity slows, membrane fluidity decreases. Below freezing ice crystals form that slice through cell membranes.

High temperatures can irreversibly alter the structure of biomolecules such as proteins, and increase membrane fluidity. The solubility of gasses in water is correlated with temperature, creating problems at high temperature for aquatic organisms requiring oxygen or carbon dioxide.

As it happens, organisms can outwit theory. Geysers, hotsprings, fumaroles and hydrothermal vents all house organisms living at or above the boiling point of water. The stability of nucleic acids is enhanced by the presence of salts which protect the DNA from being destroyed.

Thermophily living in hot places is more common than living in scalding, ultra-hot locales, and includes phototrophic bacteria i. Octopus Spring, an alkaline pH 8. In this environment the pink filamentous Thermocrinis ruber thrives. Think winter, think polar waters. Freezing of water located within a cell is almost invariably lethal. The only exception to this rule known from nature is the nematode Panagrolaimus davidi which can withstand freezing of all of its body water. In contrast, freezing of extracellular water — water outside of cells — is a survival strategy used by a small number of frogs, turtles and one snake to protect their cells during the winter.

The other method to survive freezing temperatures is to avoid freezing in the first place. Fish in Antarctic seas manage to employ these mechanisms to their advantage. The fluidity of cell membranes decreases with temperature. In response, organisms that are able to adapt to cold environments simply increase the ratio of unsaturated to saturated fatty acids thus retaining the required flexibility of membranes.

Radiation is a hazard even on a comfortable planet like Earth. Sunlight can cause major damage unless mechanisms are in place to repair — or at least limit — the damage.

Humans lacking the capacity to repair ultraviolet UV damage have xeroderma pigmentosa. This disease is so serious that suffers cannot leave their house during the day unless completely covered, and must even shade the windows in their homes.

Once you leave the protected surface of Earth, things can get more hostile. One of the major problems that organisms might face during interplanetary transfer inside a rock blasted off of a planet by a large impact event for example , living on Mars, or even at high altitudes on Earth is the high levels of UV ultraviolet radiation. In space there is cosmic and galactic radiation to contend with as well.

The dangers of UV and ionizing radiation range from inhibition of photosynthesis up to damage to nucleic acids. Direct damage to DNA or indirect damage through the production of reactive oxygen molecules can alter the sequence or even break DNA strands. Several bacteria including two Rubrobacter species and the green alga Dunaliella bardawil , can endure high levels of radiation. Deinococcus radiodurans , on the other hand, is a champ and can withstand up to 20 kGy of gamma radiation and up to 1, joules per square meter of UV radiation.

Indeed, D. This extraordinary tolerance is accomplished through a unique repair mechanism which involves reassembling damaged fragmented DNA. Scientists at the Department of Energy are looking to augment the D. So eager are biotechnologists to understand just how D. Gravity is a constant force in our lives; who has not imagined what it would be like to be an astronaut escaping gravity even temporarily?

Gravitational effects are more pronounced as the mass of an organism increases. That being said, flight experiments have revealed that even individual cells respond to changes in gravity. Cell cultures carried aboard various spacecraft including kidney cells and white blood cells showed marked alterations in their behavior, some of which is directly due to the absence of the effects of a strong gravity field.

Indeed, recent work conducted aboard Space Shuttle missions has shown that there is a genetic component as yet understood to kidney cell responses to microgravity exposure. Pressure increases with depth, be it in a water column or in rock.

Hydrostatic water pressure increases at a rate of about one-tenth of an atmosphere per meter depth, whereas lithostatic rock pressure increases at about twice that rate.

Electronics built from the semiconductor silicon carbide SiC have been in use on high-power devices for some time now and are well known for operating at high temperatures. This 1. The rig can also be adapted for other environments, including those in the atmospheres of Jupiter and Saturn, and it can achieve even higher pressures than those found on Venus, albeit at lower temperatures.

His group had access to the GEER chamber for a straight run of 21 days and at the end the SiC electronics were still operating at full capacity. The ultimate aim, Neudeck says, is to develop more complex electronics that can function indefinitely.

The chambers at its facility in Oxfordshire range from 0. A second 5 m diameter, 6 m long chamber is being manufactured by the Spanish firm Cadinox, which won the tender from Added Value Solutions, a Spanish firm that has offices near RAL Space. Several even larger vacuum chambers, up to 8 m in diameter, are also being considered for the future, according to Giles Case, manager of the assembly, integration and verification facility at RAL Space.

The specifications for chambers intended for spacecraft and instrumentation testing can vary, he explains, but in general they are constructed from electro-polished stainless steel that reduces outgassing.

Beyond that, individual specifications may include how much weight it can carry, how many instruments can be adorned within it and how many doors and viewing points it has. Once inside the chamber, SPICE was mounted on a platform that acts as a temperature interface, controlled by a black-painted thermal shroud that surrounds the instrument under testing.

In addition to a bright lamp to simulate sunlight, the temperature interface mimics the operating temperatures that SPICE will experience in space. This set-up is capable of producing temperatures as low as 93 K or as high as K. Setting an instrument up inside a vacuum chamber is complicated, so to save time and effort, Caldwell explains that thermal tests are generally conducted alongside other performance trials.

The vacuum chamber itself had to be extremely clean because even the smallest amount of organic molecules sticking to the optics could cause darkening when exposed to ultraviolet light. To that end, the instrument had to undergo constant gas purges to keep the optics clear of contamination.