By Gary R. SwensonElectrical and Computer EngineeringUniversity of Illinois,Champaign-Urbana, Illinois

LEO -Low Earth Orbit Environment-Summary

-Launch -vibration

-On orbit

Low atmospheric density (no convection)

(Affects orbital mechanics)

Exposure to solar UV

(Solar Radiation Flux=1.3 kW/m2)

(Affects exposed materials)

Exposure to some energetic particles (trapped)

(Affects electronic, Single Event Upsets

and damage to semiconductors.)

Spacecraft charging

Meteors

System Environmental TestingION vibration test in test PPOD

Thermal-vacuum chamber

DNPER High level Vibration Test Response Data, Long Axis

PPOD Integration of ION (Cal-Poly)

Reference:Schunk and Nagy, 2000.

http://uap-www.nrl.navy.mil/models_web/msis/msis_home.htm

Our Faculty Study the Atmosphere Using Remote Sensing Methods

The upperatmosphere

is rich intracers includingmetal atoms andthe ionosphere

Reference: Schunk and Nagy, 2000.

Earth Horizon Sensors, CO2 15μ

Earth Radius, Mean 6563 km

Earth Radius, Mean 6563 km

The Earth is pear shape

6371 km, EQUATOR; 6349 km AT 90o

Reference: Schunk and Nagy, 2000.

Presentation Outline

• Background (The auroral particle source)

• Earth’s magnetic field

• Aurora

• Spectroscopic experiments in Greenland

Reference: Schunk and Nagy, 2000.

The Earth actually has two radiation belts of different origins. The inner ring is called the Van Allen belt after its discoverer James Van Allen of the University of Iowa. This atmospheric radiation was first detected by Geiger counters onboard the Explorer 1 satellite during the International Geophysical Year and was substantiated by data from later Explorer satellites. ﾊ

The Van Allen belt extends above the equator at an altitude of about 4,000 miles (6437 kilometers). This belt is populated by very energetic protons in the 10-100 MeV range (a byproduct of collisions by cosmic rays with atoms of the atmosphere). The cosmic radiation has a rather low intensity (comparable to starlight) and only by accumulating particles over the span of years does the inner belt reach its high intensity. These particles can readily penetrate spacecraft and prolonged exposure can damage instruments and be a hazard to astronauts.

ﾊ The space probes Pioneer 3 and 4 detected the outer radiation belt. It is nowadays seen as part of the plasma trapped in the magnetosphere. The name radiation belt is usually applied to the more energetic part of the plasma population (e.g., ions of about 1 MeV of energy). The more numerous lower-energy particles are known as the "ring current," since they carry the current responsible for magnetic storms. Most of the ring current energy resides in the ions (typically with 0.05 MeV), but energetic electrons can also be found.

How does it effect us?

• Communications (wave propagation)

• Satellites (electrical, GPS, lifetime)

• Upper atmosphere heating

• Influences upper atmospheric composition (noctilucent clouds? ozone? other?)

http://www.sec.noaa.gov/NOAAscales/index.html#GeomagneticStorms

http://www.sec.noaa.gov/Data/index.html#model

Ref: SMAaD, Wertz&Larson,

Barnes and Silva, Ch 10.

Ref: http://leonid.arc.nasa.gov/meteor.html

METEORS: Meteors are better known as "shooting stars": startling streaks of light that suddenly appear in the sky when a dust particle from outer space evaporates high in the Earth's atmosphere. We call the light phenomenon in the atmosphere a "meteor", while the dust particle is called a "meteoroid".

* Size: Most visible Leonids are between 1 mm and 1 cm in diameter. For example, a Leonid meteor of magnitude +5, which is barely visible with the naked eye in a dark sky, is caused by a meteoroid of 0.5 mm in diameter and weights only 0.00006 gram. * Speed That tiny particle can cause a light so bright that it can be seen over distances of hundreds of kilometers. The reason is the astronomical speed of the meteoroids. Just before they enter the Earth's atmosphere, Leonid meteoroids travel at 71 kilometers per second, or some 2,663 times as fast as a fast pitch in baseball, or, equivalent to around the Earth in 3.8 minutes! * Source of light When meteoroids enter the Earth's atmosphere, they collide with numerous air molecules. Those collisions sputter away the outer layers of the particle, creating a vapor of sodium, iron and magnesium atoms. In subsequent collisions, electrons are knocked into orbits at larger mean distances from the nucleus of the atoms. When the electrons fall back to their rest positions, light is emitted. This is the same process as in gas discharge lamps.

* colors of a meteor Colors of meteors The color of many Leonids is caused by light emitted from

metal atoms from the meteoroid (blue, green, and yellow) and light emitted by atoms and molecules of the air (red). The metal atoms emit light much like in our sodium discharge lamps: sodium (Na) atoms give an orange-yellow light, iron (Fe) atoms a yellow light, magnesium (Mg) a blue-green light, ionized calcium (Ca+) atoms may add a violet hue, while molecules of atmospheric nitrogen (N2) and oxygen atoms (O) give a red light. The meteor color depends on whether the metal atom emissions or the air plasma emissions dominate.

AF-GEOSPACE

Posted Printable Fact Sheet

AF-GEOSPACE is a user-friendly, graphics-intensive software program bringing together many of the space environment models, applications, and data visualization products developed by the Air Force Research Laboratory and others in the space weather community. AF-GEOSPACE currently serves as a platform for rapid prototyping of operational products,

scientific model validation, environment specification for spacecraft design, mission planning, frequency and antenna

management for radar and HF communications, and post-event anomaly resolution.

AF-GEOSPACE provides common input data sets, application modules, and 1-D, 2-D, and 3-D visualization tools to all of its models. Available graphical tools include animation, annotation, axes, coordinate probes, coordinate slices, detector cones (e.g., from satellites), Earth, emitters (e.g., radar fans and communication domes), field-lines (e.g., geomagnetic), global inputs (e.g., Kp and Dst indices), grids, isosurfaces, links (e.g., ground-to-satellite), orbit probe (data along orbit tracks), orbit slice (data in orbit plane), plane slice (data in arbitrary plane), ray trace (through ionosphere electron densities), satellites, stars, stations, and volume (global 3-D rendering of data sets). The software's "dynamic" mode enables the simultaneous display of output from multiple environment models as a function of time over user-specified intervals.

SEEhttp://www.kirtland.af.mil/library/factsheets/factsheet.asp?id=7899

References:

Larson, W. J. and J. R. Wertz, Space Mission Analysis and Design, Microcosm, Inc. Kluwer Academic Publishers, ISN 1-881883-01-09 (pb)

Barnes, C. and L. Selva, Radiation effects in MMIC devices, from JPL Publication 96-25: Ed Jet Propulsion Laboratory, 1996, pp. 203-243 (Ch 10).

Valley, S. L. (Editor), Handbook of Geophysics and Space Environments, Air Force Cambridge Research Laboratories, 1965.

Schunk, R. W. and A. F. Nagy, Ionospheres; Physics, Plasma Physics, and Chemistry,Cambridge University Press, 2000. ISBN 0 521 63237 4

Kivelson, M. G., and C. T. Russell (Editors) , Introduction to Space Physics, Cambridge University Press, 1995. ISBN 0-521-45714-9 (Paperback)