The NearEarth Space Environment

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The Near-Earth Space Environment

• Professor Greg Earle
• The University of Texas at Dallas

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THE GEOSPACE ENVIRONMENT

• The energy that controls the physics of space
  throughout our solar system comes from our local
  star, the sun.
• Radiation heat, light, X-rays
• Energetic particles associated with solar
  flares, etc.
• Space scientists study these
• processes their effects on
• planetary environments.

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A MORE DYNAMIC VIEW
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NEAR EARTH SPACE WEATHER EFFECTS
Auroras are the most easily observed effect of
energetic particles streaming into the atmosphere
along magnetic field lines.
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THE GLOBAL VIEW
When viewed from satellites in space, the auroras
occur in oval shaped regions centered around the
magnetic poles
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Formation of the Quiescent Ionosphere
Even in geomagnetically quiet condtions when
there is no visible aurora, short wavelength
radiation creates an ionized plasma in the upper
atmosphere this is the ionosphere.
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THE NEAR-EARTH SPACE PLASMA ENVIRONMENT
C/NOFS operating altitude range
The neutral density is far greater than the
plasma density in the ionosphere. UTDs latest
satellite (C/NOFS) orbits in a region dominated
by O and O. Note the characteristic shape of
the electron density profile.
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EFFECTS OF THE SPACE ENVIRONMENT
Space weather produced by solar and magnetic
storms can affect telecom systems, power grids,
GPS, computer chip fault rates, and orbiting
satellites.
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WHAT DO WE WANT TO KNOW?
Most of these plasma and neutral parameters can
be measured directly.
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WHAT IS A CUBESAT?
1-Unit Board Stack
Power Board
Transceiver Board
Patch Antenna
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VECTOR VELOCITY INSTRUMENTATION C/NOFS SATELLITE

• Sensors shown measure neutral and ion gas
  velocities in 3D from a satellite platform
• 6 ruler shown (bottom center)
• Total mass for both instruments is 11 kg
• These instruments alone are bigger than a CubeSat!

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SERIOUS SHRINKAGE IS REQUIRED

• Each of the unit-cubes comprising a CubeSat
  element measures only 10 cm on a side.
• Each CubeSat must have attitude control,
  telemetry, and power systems, which together
  occupy about 2 units with OTS technology.
• In a 3-unit CubeSat (called
• a pea-pod) this leaves
• only 1-unit for
• instrumentation.

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DOWNSIZING ISNT ALWAYS BAD
Leadless and surface mount component packages
help to minimize the size of circuit boards in
CubeSat designs, but introduce higher risks from
radiation damage.

• Hypothesis what CubeSats give up in
  instrumentation complexity can be made up by
  flying lots of simple systems.
• Each CubeSat may carry only 1-2 instruments, and
  serious volume and power reductions must be
  realized even in this case (10x10x30 cm, 3 kg,
  2-3 W).
• On a CubeSat all systems, circuit boards, and
  components must therefore be low power, and must
  occupy very small volumes.
• Lots of innovative instrument development is
  needed.
• NSF is leading the way on CubeSats, and they
  strongly encourage student involvement, even at
  the undergraduate level.

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STUDENTS ARE INVOLVED IN INSTRUMENT DEVELOPMENT
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What Is the Optimal Orbit Scenario?
Multiple inclinations provide great global
coverage, but are not feasible w/o multiple
launches!
Even if an entire constellation has the same
inclination, we would like separation in either
altitude or time.
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OUR MISSION

• Fly a satellite with at 600-800 km altitude
• Fly at an inclination that will cover both low
  and middle latitudes
• Fly an RPA instrument to measure ion temperature,
  heavy/light ion composition, ion density, and
  estimate one component of the ion velocity.
• More on all this later