INCREASED LEVEL OF UV AND X-RAY RADIATION

Transcription

1 INCREASED LEVEL OF UV AND X-RAY RADIATION By Senem ÜNAL Page 1

2 WHAT IS UV AND X-RAY? The sun radiates energy in a wide range of wavelengths, most of which are invisible to human eyes. The shorter the wavelength, the more energetic the radiation, and the greater the potential for harm For example, Ultraviolet (UV) radiation that reaches the Earth s surface is in wavelengths between 290 and 400 nm (nanometers, or billionths of a meter). This is shorter than wavelengths of visible light, which are 400 to 700 nm. Page 2

3 WHAT ABOUT X-RAY? Page 3

4 X-RAY ON HUMANBEING UV radiation from the sun has always played important roles in our environment, and affects nearly all living organisms. Biological actions of many kinds have evolved to deal with it. UV-A plays a helpful and essential role in formation Vitamin D by the skin, and harmful role in that it causes sunburn and cataracts in our eyes. Page 4

5 X-RAY ON HUMANBEING UV-B causes damage at the molecular level to the fundamental building block of life deoxyribonucleic acid (DNA). DNA readily absorbs UV-B radiation, which commonly changes the shape of the molecule in one of several ways. Changes in the DNA molecule often mean that protein-building enzymes cannot read the DNA code at that point on the molecule. As a result, distorted proteins can be made, or cells can die. Page 5

6 DNA But living cells are smart. Over millions of years of evolving in the presence of UV- B radiation, cells have developed the ability to repair DNA. Page 6

7 X-RAY ON SATELLITES Space radiation can have serious effects on satellite operation. Some particle radiation is so energetic that it can penetrate to the interior of a satellite and interact with its electronic circuitry. This can cause a wide variety of effects that range from unimportant ones to the shutdown of a vital system. For example, if the circuitry controls the way the satellite is pointing its antenna, the satellite can veer out of contact with ground-based receivers and be temporarily lost. Page 7

8 X-RAY ON SATELLITES Page 8

9 X-RAY ON ELECTRONICS It is important to understand the space radiation environment so that reliable satellites can be designed at a reasonable cost. Underestimating the radiation environment leads to excessive risk for the satellite. This can result in degraded performance and a shorter mission lifetime. On the other hand, overestimating the radiation environment can result in over-design by engineers. This can increase the cost of the satellite and even limit its capabilities. Page 9

10 X-RAY ON ELECTRONICS Radiation effects in the interior of satellites are often grouped into three categories Total Ionizing Dose Displacement Damage Single Event Effects Page 10

11 X-RAY ON ELECTRONICS Total Ionizing Total ionizing dose effects in electronics are the result of damage that usually builds up over a long period of time in an insulating region of an electronic device. This changes the device properties, which results in performance degradation and eventually can cause the device to fail completely. Displacement Damage Displacement damage is also a cumulative effect but this occurs in the electronic device s semiconductor material. These effects also cause the device to deteriorate at first and possibly fail if it is exposed to enough radiation. Page 11

12 X-RAY ON ELECTRONICS Single event effects are caused by the passage of a single particle through a sensitive region in an electronic device. There are many types of single event effects, which can be either non-destructive or destructive to the device. The severity of the effect can be so small that it can go unnoticed. At the other extreme it could cause a system in a satellite to shut down. Page 12

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14 X-RAY ON GPS, AIR TRAVEL AND ELECTRIC POWER GRIDS Since space radiation can affect our satellites it can also adversely affect our society by causing problems in communication systems, GPS navigation systems and other high technology systems in space. It can also affect air travel in the Earth s polar regions, which are less protected by the Earth s magnetic field than the equatorial region. A large coronal mass ejection from our sun can also cause serious effects in electric power grids. The particle radiation ejected from the sun disturbs the Earth s magnetic field, causing a magnetic storm. Page 14

15 Due to our growing dependence on high technology systems, an extreme radiation event like this can now potentially cause more economic hardship than other extreme events on our planet such as hurricanes and earthquakes. THANK YOU FOR LISTENING Page 15