DESIGN: THE INSTRUMENT
 
 
What Are the Parts to the SDC?
How Does the SDC Measure Dust?
 
       
 
 
What Are the Parts to the SDC?
The Student Dust Counter consists of three major pieces:

The Detector Assembly is 18 inches x 12 inches. This is the piece of equipment that is mounted on the outside of the spacecraft and is exposed to the dust particles. The detector is thermally isolated from the New Horizons Spacecraft and lies outside its Thermal Blanket.

The Electronics Box is approximately 5.4 inches x 8.25 inches x 1.825 inches. This is the brains of the Dust Counter; when a hit occurs on the detector the electronics box will decipher the data and determine the mass and speed of the dust particle. The electronics box is actually located within the spacecraft and is thermally and electronically bonded to the New Horizons Spacecraft.

The Intra-Harness is the "bridge" between the detector assembly and the electronics box. It serves a similar purpose as the cable which allows your home computer to communicate with your printer.
 
 
How Does the SDC Measure Dust?
The space environment through which the New Horizons Mission will be traveling contains a large variety of conditions which can negatively affect spacecraft materials. The dust collector must be made of a substance which is not affected by changes in the temperature, radiation environment, or quantity of high-energy particles surrounding it.

To meet these challenges, a simple, reliable substance called PVDF (PolyVinyliDine Fluoride film) has been chosen. When PVDF is manufactured, it is polarized. This means all of the molecules in the material are aligned so that they are pointing in the same direction.

When a dust particle impacts on the detector, it randomly aligns some of these previously organized molecules. This depolarization generates an electric signal which is then detected. The pulse height of the signal will tell us the mass of the dust particle using the relative velocity of the spacecraft.