P-3 Orion
Associated content: 

P-3 Upper cockpit escape hatch

P-3 Proposed AATS-14 location from the interior

NASA P-3 at Thule, Greenland

TSI 3563 Integrating Nephelometer

TSI Integrating Nephelometers are designed specifically for studies of direct radiative forcing of the Earth’s climate by aerosol particles, or studies of ground-based or airborne atmospheric visual air quality in clean areas. They may also be used as an analytical detector for aerosol particles whenever the parameter of interest is the light-scattering coefficient of the particles after a pretreatment step, such as heating, humidification, or segregation by size. The light-scattering coefficient is a highly variable aerosol property. Integrating Nephelometers measure the angular integral of light scattering that yields the quantity called the aerosol scattering coefficient, which is used in the Beer-Lambert Law to calculate total light extinction.


P-3 Orion - WFF

NASA P-3 Orion

The NASA Goddard Space Flight Center’s (GSFC) Wallops Flight Facility (WFF) Aircraft Office operates the NASA Airborne Science Program's P-3 Orion (N426NA) research aircraft to support airborne science research. Wallops Flight Facility has operated the P-3 since 1991 in support of a variety of scientific studies including ecology, meteorology, atmospheric chemistry, cryospheric research, oceanography, soil science, biology, and satellite calibration/validation. The P-3 is also used as a technology test bed for new airborne and satellite instrumentation. The P-3 is a self-sufficient global reaching aircraft that can operate from civilian and military airports to remote areas of the world in support of scientific studies.

The P-3 is a four-engine turboprop aircraft designed for endurance and range and is capable of long duration flights. The P-3 has been extensively modified to support airborne science related activities. Aircraft features include zenith ports, three nadir ports (aft of the wings), and seven P-3 and DC-8 style windows to mount experiments, a tail cone, nose radome and ten mounting locations on the wings. Most of the fuselage ports are contained within the pressurized cabin environment. The unpressurized bomb bay can be converted into experimenter ports via a custom fairing. This fairing creates two large nadir ports and several oblique ports for installation of large sensors and antennas. A dropsonde deployment system is also available for use.

A project data system is located on the aircraft and provides aircraft data and video throughout the cabin. This system is also connected to two satellite constellations and provides uplink/downlink capability, internet access, flight tracking, and instant messaging between other aircraft and ground assets. Several sensors are connected to the project data system to provide meteorological and aircraft positional data to experimenters.

The GSFC/WFF Aircraft Office is committed to providing safe, reliable, and cost-effective platforms for airborne research.

Current Status:
Open (Next Activity 10/04/21: P-3 Flight and Simulator Training)
NASA GSFC Wallops Flight Facility
Conventional Aircraft
14 hours (payload and weather dependent)
Useful Payload: 
14 700 lbs
Gross Take-off Weight: 
135 000 lbs
Onboard Operators: 
24 (including flight crew)
Max Altitude: 
28,000 MSL
Air Speed: 
400 knots
3 800 Nmi
115V 60Hz single phase; 115V 400Hz 3 phase; 28V DC
NASA SMD User Fee per Hour: 
Point(s) of Contact: 

Mike Cropper

Work: (757) 824-2140
Fax: (757) 854-4616

Lidar Atmosphere Sensing Experiment

The Differential Absorption Lidar uses the backscatter of two simultaneous laser wavelengths through zenith and nadir windows to measure the vertical profiles of H2O and aerosols/clouds.

NASA's Lidar Atmospheric Sensing Experiment (LASE) system is an airborne DIAL (Differential Absorption Lidar) system used to measure water vapor, aerosols, and clouds throughout the troposphere. LASE probes the atmosphere using lasers to transmit light in the 815-nm absorption band of water vapor. Pulses of laser light are fired vertically below the aircraft. A small fraction of the transmitted laser light is reflected from the atmosphere back to the aircraft and collected with a telescope receiver. The received light indicates the amount of water vapor along the path of the laser beam.

Instrument Type: 
Point(s) of Contact: 
Syed Ismail (Prev PI)

Langley Aerosol Research Group Experiment

Langley Aerosol Research Group Experiment (LARGE).  The "classic" suite of instrumenation measures in-situ aerosol micrphysical and optical properties. The package can be tailored for specific science objectives and to operate on a variety of aircraft. Depending on the aircraft, measurments are made from either a shrouded single-diffuser "Clarke" inlet, from a BMI (Brechtel Manufacturing Inc.) isokinetic inlet, or from a HIML inlet. Primary measurements include:

1.) total and non-volatile particle concentrations (3nm and 10nm nominal size cuts),
2.) dry size distributions from 3nm to 5µm diameter using a combination of mobilty-optical-aerodynamic sizing techniques,
3.) dry and humidified scattering coefficients (at 450, 550, and 700nm wavelength), and
4.) dry absorption coefficients (470, 532, and 670nm wavelength). 

LARGE derived products include particle size statistics (integrated number, surface area, and volume concentrations for ultrafine, accumulation, and coarse modes), dry and ambient aerosol extinction coefficients, single scattering albedo, angstrom exponent coefficients, and scattering hygroscopicity parameter f(RH).

DC-8 - AFRC, C-130H - WFF, P-3 Orion - WFF, HU-25 Falcon - LaRC, King Air B-200 - LaRC
Point(s) of Contact: 

High Volume Precipitation Spectrometer

SPEC previously built the Version 1 and Version 2 HVPS probes that have now been discontinued due to obsolete parts and significant advances in technology. The HVPS-3 uses the same 128-photodiode array and electronics that are used in the 2D-S and 2D-128 probes. The optics are configured for 150 micron pixel resolution, resulting in a maximum field of view of 1.92 cm (i.e., particles up to 1.92 cm are completely imaged, although even larger particles can be sized in the direction of flight).

Sample volume of the HVPS-3 is 400 L s-1 at 100 m s-1. The 2D-S or 2D-128 and HVPS make an excellent pair of probes that completely image particles from 10 microns to 1.92 cm.

Point(s) of Contact: 

Cloud Droplet Probe

The Cloud Droplet Probe (CDP), manufactured by Droplet Measurement Technologies, measures the concentration and size distribution of cloud droplets in the size range from 2-50 µm. The instrument counts and sizes individual droplets by detecting pulses of light scattered from a laser beam in the near-forward direction, using a sample area of 0.24 mm2 or a sample rate of 48 cm3 at a flight speed of 200 m/s. The probe is mounted in an underwing canister and is designed to operate at up to 200 m/s; the G-V often exceeds this flight speed, but usually not in penetrations of clouds containing cloud droplets. Droplet sizes are accumulated in 30 bins with variable sizes, as specied in the header of the netCDF data files. Measurements are usually provided at a rate of 1 Hz in the standard data files but can be made available at 10 Hz in special high-rate processing. The instrument is similar to, and might be considered a high-speed replacement for, the Forward Scattering Spectrometer Probe. At high droplet concentration (> 500 cm-3), coincidence losses have been observed with this probe, and these are especially serious at G-V flight speeds. The probe is designed for cloud droplets, and its response to ice crystals is not intended to be quantitative; measurements in ice clouds should not be used except as qualitative indications of cloud.

Instrument Type: 
Point(s) of Contact: 

Langley Wideband Integrated Bioaerosol Sensor

Wideband Integrated Bioaerosol Sensor (WIBS-4A) - Droplet Measurement Technologies.  Dectection of Fluorescent Biological Aerosol Particle (FBAP) number concentrations.  Single particle analysis using dual wavelength (280nm and 370nm by xenon lamps) excitation on two parallel broadband visible-wavelength detectors (310-400nm and 420-650nm). Particles are classified by a combination of fluorescence excitation and emission characteristics, as well as their optical size measured by forward-scattering using a 635nm continuous-wave diode laser.    

Instrument Type: 
Point(s) of Contact: 


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