Tech Tree

	* Structural
	* Power Supply & Distribution
	* Communications
	* Attitude & Articulation Control
	* First Stage Engines & Fuel Tanks
	* Upper Stage Engines & Fuel Tanks
	* Solid Rocket Boosters
	* Aerodynamics
	* RCS Thrusters
	* Decouplers
	* Landing Systems
	* Spacecraft Bus
	* Crew Support
	* Science Instruments
		* Direct-Sensing Instruments
			* High-energy particle detector: A device for measuring the energy spectra of trapped energetic electrons, and the energy and composition of atomic nuclei.
			* Low-energy charged particle detector: A device designed to characterize the composition, energies, and angular distributions of charged particles in interplanetary space and within planetary systems.
			* Plasma detector: A device for measuring the density, composition, temperature, velocity and three-dimensional distribution of plasmas that exist in interplanetary regions and within planetary magnetospheres.
			* Dust detector: A device for measuring the velocity, mass, charge, flight direction and number of dust particles striking the instrument.
			* Magnetometer: A device for measuring the strength and direction of the interplanetary and solar magnetic fields. They typically detect the strength of magnetic fields in three planes.
			* Plasma wave detector: A device for measuring the electrostatic and electromagnetic components of local plasma waves in three dimensions.

		* Remote-Sensing Instruments
			* Imaging instruments: Optical imaging is performed by two families of detectors: vidicons and the newer charged coupled devices. Although the detector technology differs, in each case an image in focused by a telescope onto the detector where it is converted to digital data.
			* Vidicon: An imaging device consisting of a vacuum tube, which produces a video signal based on the varying electrical potential measured as an electron beam is swept across a phosphor coating on the glass where the image is focused.
			* Charged coupled device: An imaging device consisting of a large-scale integrated circuit which has a two-dimensional array of hundreds of thousands of charge-isolated wells, each representing a pixel.
			* Infrared radiometer: An optical instrument that measures the intensity of infrared energy radiated by its targets.
			* Polarimeter: An optical instrument that measures the direction and extent of the polarization of light reflected from its targets.
			* Photometer: An optical instrument that measures the intensity of light from a source.
			* Spectrometer: An optical instrument that splits the light received from an object into its component wavelengths by means of a diffraction grating; then measuring the amplitudes of the individual wavelengths.
			* Scan platform: An articulated, powered appendage to the spacecraft bus which points in commanded directions, allowing optical observations to be taken independently of the spacecraft's attitude.

		* Active Sensing Instruments
			* Synthetic aperture radar: A radar imaging instrument which provides a penetrating illumination of radio waves, and is capable of imaging surfaces covered by clouds and haze. SAR images are constructed of a matrix where lines of constant distance or range intersect with lines of constant Doppler shift.
			* Altimeter: A device that measures altitude above the surface of a planet or moon. Spacecraft altimeters work by timing the round trip of radio signals bounced off the surface.