The blog of Xeno, a slightly mad scientist
The one-year International Space Station mission successfully launched to orbit today (March 27). Read the full story here – Liftoff! US, Russia Launch Historic One-Year Space Mission An epic and unprecedented one-year mission to the International Space Station will begin Friday (March 27). NASA astronaut Scott Kelly and Russian cosmonaut Mikhail Kornienko are scheduled to launch toward the orbiting lab aboard a capsule at 3:42 p.m. EDT (1942 GMT) Friday from Baikonur Cosmodrome in Kazakshtan. You can watch the launch here at Space.com, courtesy of NASA TV.
Studying how Kelly and Kornienko cope during their 12 months aloft should shed light on the physiological and psychological effects of long-term spaceflight, paving the way for eventual journeys to Mars and other deep-space destinations, officials have said. (Kelly and Kornienko will travel to the orbiting lab Friday with cosmonaut Gennady Padalka, who will stay in space for the normal six months.)
The ISS is in low earth orbit below the Van Allen radiation belts. Other than lunar flights Low Earth Orbit, which is sea level up to 2,000km high, defines the boundary of all human space exploration. Here’s the statement on how much radiation the Apollo missions encountered going through the radiation belts on the way to the moon:
Missions beyond low Earth orbit leave the protection of the geomagnetic field, and transit the Van Allen belts. Thus they may need to be shielded against exposure to cosmic rays, Van Allen radiation, or solar flares. The region between two to four Earth radii lies between the two radiation belts and is sometimes referred to as the “safe zone”.
Solar cells, integrated circuits, and sensors can be damaged by radiation. Geomagnetic storms occasionally damage electronic components on spacecraft. Miniaturization and digitization of electronics and logic circuits have made satellites more vulnerable to radiation, as the total electric charge in these circuits is now small enough so as to be comparable with the charge of incoming ions. Electronics on satellites must be hardened against radiation to operate reliably. The Hubble Space Telescope, among other satellites, often has its sensors turned off when passing through regions of intense radiation A satellite shielded by 3 mm of aluminium in an elliptic orbit (200 by 20,000 miles (320 by 32,190 km)) passing the radiation belts will receive about 2,500 rem (25 Sv) per year. Almost all radiation will be received while passing the inner belt.
The Apollo missions marked the first event where humans traveled through the Van Allen belts, which was one of several radiation hazards known by mission planners. The astronauts had low exposure in the Van Allen belts due to the short period of time spent flying through them. The command module’s inner structure was an aluminum “sandwich” consisting of a welded aluminium inner skin, a thermally bonded honeycomb core, and a thin aluminium “face sheet”. The steel honeycomb core and outer face sheets were thermally bonded to the inner skin.
In fact, the astronauts’ overall exposure was dominated by solar particles once outside Earth’s magnetic field. The total radiation received by the astronauts varied from mission to mission but was measured to be between 0.16 and 1.14 rads (1.6 and 11.4 mGy), much less than the standard of 5 rads (50 mSv) per year set by the United States Atomic Energy Commission for people who work with radioactivity.