Project Overview

In 2007, a Space Act Agreement between NASA Ames Research Center and H211, LLC began a relationship that ultimately led to the formation of the Alpha Jet Atmospheric eXperiment (AJAX) Project. atmospheric measurement flights began in 2011 and AJAX is currently performing regular missions to measure ozone and greenhouse gases, such as carbon dioxide (CO₂) and methane (CH₄) over California and Nevada.

The crew prepares for take off of an AJAX flight
from NASA Ames Research Center

Unlike most atmospheric airborne research missions, NASA's flexible relationship with the aircraft provider allows Ames Research Center to collect data on a regular basis over multiple seasons, which will complement surface and tower-based observations collected elsewhere in the region. It also allows AJAX to provide validation data for satellite sensors over months and years, to help assess the sensor health and calibration over its lifetime.

AJAX supports NASA's Orbiting Carbon Observatory (OCO-2) Science Team and is developing collaborations with the California Air Resources Board (CARB).

The AJAX project provides hands-on training for Ames personnel in the areas of instrument development, systems engineering, science mission development, and project management.

Science Flights

Ozone mixing ratios measured along
a typical flight track originating from
NASA Ames Research Center.

AJAX has recently begun a series of upwind/downwind ozone profile measurements intended to address the inflow of ozone during a variety of weather patterns and seasonal cycles. Vertical profiles of ozone over the San Joaquin Valley, coupled with upwind profiles over the Pacific Ocean, provide direct mapping of the vertical and horizontal ozone concentrations offshore and inland, to better understand trans-Pacific pollution transport and its effects on air quality in California.

In a second type of science flight, vertical profiles of greenhouse gases over Railroad Valley, NV, are collected in support of the Greenhouse gases Observing Satellite (GOSAT) total column measurements. AJAX provides calibrated, in-situ altitude-resolved vertical profiles of CO₂ and CH₄ from 25,000 ft down to the surface. These data are converted into a format comparable to satellite findings before being compared to the column measurements provided by GOSAT.

Carbon dioxide (left) and methane (right) mixing ratios measured during descent over Railroad Valley, NV on 25 June 2011.

Regular vertical profiles of CO2 and CH4 continue to be collected over Railroad Valley, and the AJAX team is evaluating future collaborations with the JPL Atmospheric Infrared Sounder (AIRS) satellite team as well.

Instrumentation

Ozone measurements are made with a 2B-Tech ultraviolet (UV) absorption instrument that has been packaged to withstand the conditions of flight and to meet airworthiness standards. Multiple vertical profiles of ozone mixing ratios have been collected in coincidence with standard balloon-borne (electrochemical) measurements performed by the National Oceanic and Atmospheric Administration (NOAA), and excellent agreement is obtained.

The first measurements with the Greenhouse Gas Sensor (Picarro model 2301-m cavity ring down spectrometer, repackaged and modified for conditions on the Alpha Jet) were collected in collaboration with a June 2011 intensive measurement period at Railroad Valley, Nevada. A variety of laboratory, environmental chamber, and flight tests have been performed, and AJAX data have been compared to standard measurements made at the tall tower at Walnut Grove.

AJAX team members mount the instru-
mented wing pod onto the Alpha Jet in
preparation for a research flight.

Both instruments are housed in the starboard external wing pod. Each has a separate inlet and has been tested under a wide variety of flight maneuvers.