Skip to main content

About RaD-X

The Project

The Earth is continuously bombarded by high-energy cosmic rays, the primary source of ionizing radiation in the atmosphere that increases the risk of cancer and other health effects. Commercial aircrews are classified as radiation workers, and are among the most exposed occupational group. In any given year, a pilot absorbs as much radiation as a worker in a nuclear power plant. Yet, the dose of radiation they receive during a cosmic storm or during the span of their career is not quantified or documented.

NASA’s Radiation Dosimetry Experiment, or RaD-X, is a high-altitude balloon project that took place in 2015.
It provided first-time indications of how cosmic rays deposit energy at the top of atmosphere – which produce showers of additional particles that increase the energy deposited where commercial airlines fly. This experiment will improve NASA’s Nowcast of Atmospheric Ionizing Radiation for Aviation Safety (NAIRAS) model, which is currently used by public and private entities for informed decision-making about radiation exposure safety for flight crews, the general public, and commercial space operations.

Low-cost missions, like RaD-X, provide NASA with valuable opportunities to test emerging technologies and economical commercial off-the-shelf components which may be useful in future space missions. Developed at NASA’s Langley Research Center, it will launch from New Mexico and will fly on a scientific research balloon for 24 hours at approximately 110,000 feet. The flight will validate low-cost sensors for future missions and will provide data to improve the health and safety of all future commercial and military aircrews that transit the poles.

In addition, RaD-X will host the first Cubes in Space (CiS) balloon flight opportunity. CiS is a global Science, Technology, Engineering, Art, and Mathematics (STEAM)-based education program for students (ages 11-18) that provides a no-cost opportunity to design and compete to launch an experiment into space. The small cubes are placed on sounding rockets and scientific balloons in cooperation with NASA’s Wallops Flight Facility and the Earth Systems Science Pathfinder Program Office.

RaD-X, one of two hosts for CiS experiments this year, will carry more than 100 small cubes filled with experiments created by students around the US.

In 2013, RaD-X was competitively selected as NASA’s Hands-On Project Experience (HOPE) program, a cooperative workforce development program sponsored by NASA’s Science Mission Directorate (SMD) and the Academy of Program/Project and Engineering Leadership (APPEL). The program gives early career or transitional employees hands-on experience to fast track project development learning, ultimately benefiting the Agency on future missions they will serve. RaD-X is managed at NASA’s Langley Research Center in Hampton, VA and the team includes participation from the Wallops Flight Facility (WFF) and Ames Research Center (ARC).


1 TEPC Microdosimeter
The TEPC Environmental Monitor model FW-AD1 is built by Far West Technologies, Inc., and is referred to as the “HAWK” TEPC (see Figure I.5-2). The HAWK TEPC measures mixed-field radiation environments, such as those found in space, commercial airlines, and many nuclear reactors. The sensitive volume of the TEPC is a spherical cavity surrounded by the tissue equivalent plastic A-150 and filled with propane gas in order to emulate a tissue volume with a diameter of 2 µm. The TEPC design enables direct measurement of the energy deposition of charged particles in tissue from the ambient mixed-field radiation environment, which may include neutrons and gamma rays in addition to charges particles. The detector provides a spectral measurement of the lineal energy by accumulating a pulse height spectrum, which can be transformed into the ambient dose equivalent as the operational quantity. The TEPC is considered the de facto standard measurement technique in microdosimetry.

The detector’s design was developed under contract to NASA and has been in use for more than 10 years. It has been calibrated in numerous laboratory beam sources (Los Alamos Nuclear Science Center, Loma Linda Medical University, Brookhaven National Laboratory, and more) and used on the Mir Space Station, the Space Shuttle Discovery, other NASA spacecraft, and airplanes.

Figure I.5-2 TEPC microdosimeter

Figure I.5-2 TEPC microdosimeter

2 RaySure® Silicon Diode Microdosimeter Emulator
The RaySure®, which is manufactured by QinetiQ, is a compact radiation sensor designed for use in aircraft (see Figure I.5-3). The detector utilizes solid-state pin diode technology to measure energy depositions in silicon from mixed-field radiation environments, which may include charged particles, gamma rays, and neutrons. The detector measures dose equivalent and accumulated dose equivalent every 2 minutes. The absorbed dose in silicon is converted to dose in tissue using a pre-determined calibration curve, which is further converted to ambient dose equivalent using a quality factor derived from the measured LET spectra. Hence, the RaySure® is a microdosimeter emulator. The RaySure® has been extensively calibrated via numerous airline flights and ground tests (e.g., CERN, WNR, and TRIUMF particle beams).

Figure I.5-3 RaySure® silicon diode microdosimeter emulator.

Figure I.5-3 RaySure® silicon diode microdosimeter emulator.

3 Liulin-6SA1 LET Spectrometer
The Liulin-6SA1 semiconductor LET spectrometer was manufactured at the Solar-Terrestrial Influences Laboratory of the Bulgarian Academy of Sciences (see
Figure I.5-4). The detector consists of a silicon diode. Pulse height analysis technique is used to measure the energy deposition of charged particles in the detector. This detector is mostly insensitive to neutrons. The amplitude of the pulses after the preamplifier is proportional to the energy loss in the detector and hence to the dose and LET by a factor of 240 mV/MeV. The amplitudes are digitized by an analog-to-digital converter (ADC) and arranged in a 256-channel spectrum in order to provide the energy deposition spectrum. Calibration factors are used to derive ambient total charged particle fluence and to convert the measured radiation dose in silicon to ambient dose equivalent for tissue. Different modifications of the Liulin LET spectrometer have been built and used on spacecraft (e.g., the Mir Space Station and ISS), aircraft, and calibrated on the ground (e.g., Indiana University proton test facility, Belgium cyclotron facility, CERN, HIMAC, and more).

Figure I.5-4 Liulin-6SA1 LET spectrometer.

Figure I.5-4 Liulin-6SA1 LET spectrometer.

4 TID Detector
The TID detector, manufactured by Teledyne, measures energy absorbed in a silicon hybrid microcircuit from charged particles and gamma rays (see Figure I.5-5). The output of this device is intended to be directly connected to most ADCs or payload housekeeping analog inputs, which makes minimal demands on the host vehicle. The TID has been calibrated at Lawrence Berkley National Laboratory and is successfully operating on the NASA Lunar Reconnaissance Orbiter. The TID is also planned to fly on NASA experimental aircraft.

Figure I.5-5 Teledyne TID detector.

Figure I.5-5 Teledyne TID detector.

Historical Program Events

  • 09.15.15 – RaD-X Successfully Launched!
  • 09.10.15 – Project Launch Window Begins
  • 08.31.15 – Team Flies Out.
  • 06.19.15 – Pre-ship Review Completed.

Related Program Links

  • CAPABLE/CRAVE Full Site Photo from left to right site enclosures: 1196A NASA LaRC, MPLnet, Virginia DEQ
    CAPABLE/CRAVE Full Site Photo from left to right site enclosures: 1196A NASA LaRC, MPLnet, Virginia DEQ

  • NASA LaRC NAST-I and HU ASSIST side-by-side for intercomparison
    NASA LaRC NAST-I and HU ASSIST side-by-side for intercomparison

  • Virginia DEQ, NASA and Penn State-NATIVE Enclosures (from right to left)
    Virginia DEQ, NASA and Penn State-NATIVE Enclosures (from right to left)

  • Ozone-sonde away.
    Ozone-sonde away.
  • About to lift.
    About to lift.
PurpleAir PA-II-SD Air Quality Sensor
Laser Particle Counters
Type (2) PMS5003
Range of measurement 0.3, 0.5, 1.0, 2.5, 5.0, & 10 μm
Counting efficiency 50% at 0.3μm & 98% at ≥0.5μm
Effective range
(PM2.5 standard)*
0 to 500 μg/m³
Maximum range (PM2.5 standard)* ≥1000 μg/m³
Maximum consistency error (PM2.5 standard) ±10% at 100 to 500μg/m³ & ±10μg/m³ at 0 to 100μg/m³
Standard Volume 0.1 Litre
Single response time ≤1 second
Total response time ≤10 seconds
Pressure, Temperature, & Humidity Sensor
Type BME280
Temperature range -40°F to 185°F (-40°C to 85°C)
Pressure range 300 to 1100 hPa
Humidity Response time (τ63%): 1 s
Accuracy tolerance: ±3% RH
Hysteresis: ≤2% RH

Pandora capabilities










Total Column O3, NO2, HCHO, SO2, H2O, BrO

0.01 DU

0.1 DU



Virginia Department of Environment Quality in-situ instrumentation






Thermo Scientific 42C (Molybdenum converter)

60 s

NO and NOx

50 pptv


Teledyne API 200EU w/ photolytic converter
(EPA) PI-Szykman

20 s


50 pptv


Thermo Scientific 49C (VADEQ)

20 s


1 ppbv


Thermo Scientific 48i (VADEQ)

60 s


40 ppbv


Thermo Scientific 43i (VADEQ)

80 s


0.2 ppbv


Thermo Scientific 1400AB TEOM (VADEQ)

600 s

PM2.5 (continuous)


1 3%

Thermo Scientific Partisol Plus 2025 (VADEQ)

24 hr

PM2.5 (filter-based FRM)- 1/3 days



Large area view.
Latitude: 37.1038
Longitude: -76.3872
Elevation: 3 m Above sea level
Scenes: urban, marsh, bay, river and farm.


  • The inner red circle is a 20km CERES foot print centered on the BSRN-LRC site.
  • The pink circle represents a possible tangential 20km foot print.
  • The middle red circle represents the area in which a 20km foot print could fall and still see the site.
  • Yellow is a sample 40 deg off nadir foot print.
  • The outer red circle is the region which would be seen by a possible 40 deg off nadir foot print.
The BSRN-LRC sun tracker at the NASA Langley Research Center on a snowy day (02/20/2015) The BSRN-LRC sun tracker at the NASA Langley Research Center on a snowy day (02/20/2015)
CAPABLE-BSRN Google Site Location Image

Team Satellite Sensor G/L Dates Number of obs Phase angle range (°)
CMA FY-3C MERSI LEO 2013-2014 9 [43 57]
CMA FY-2D VISSR GEO 2007-2014
CMA FY-2E VISSR GEO 2010-2014
CMA FY-2F VISSR GEO 2012-2014
JMA MTSAT-2 IMAGER GEO 2010-2013 62 [-138,147]
JMA GMS5 VISSR GEO 1995-2003 50 [-94,96]
JMA Himawari-8 AHI GEO 2014- -
EUMETSAT MSG1 SEVIRI GEO 2003-2014 380/43 [-150,152]
EUMETSAT MSG2 SEVIRI GEO 2006-2014 312/54 [-147,150]
EUMETSAT MSG3 SEVIRI GEO 2013-2014 45/7 [-144,143]
EUMETSAT MET7 MVIRI GEO 1998-2014 128 [-147,144]
CNES Pleiades-1A PHR LEO 2012 10 [+/-40]
CNES Pleiades-1B PHR LEO 2013-2014 10 [+/-40]
NASA-MODIS Terra MODIS LEO 2000-2014 136 [54,56]
NASA-MODIS Aqua MODIS LEO 2002-2014 117 [-54,-56]
NASA-VIIRS NPP VIIRS LEO 2012-2014 20 [50,52]
NASA-OBPG SeaStar SeaWiFS LEO 1997-2010 204 (<10, [27-66])
NASA/USGS Landsat-8 OLI LEO 2013-2014 3 [-7]
NOAA-STAR NPP VIIRS LEO 2011-2014 19 [-52,-50]
NOAA GOES-10 IMAGER GEO 1998-2006 33 [-66, 81]
NOAA GOES-11 IMAGER GEO 2006-2007 10 [-62, 57]
NOAA GOES-12 IMAGER GEO 2003-2010 49 [-83, 66]
NOAA GOES-15 IMAGER GEO 2012-2013 28 [-52, 69]
VITO Proba-V VGT-P LEO 2013-2014 25 [-7]
KMA COMS MI GEO 2010-2014 60
AIST Terra ASTER LEO 1999-2014 1 -27.7
ISRO OceanSat2 OCM-2 LEO 2009-2014 2

The NASA Prediction Of Worldwide Energy Resources (POWER) Project improves the accessibility and usage NASA Earth Observations (EO) supporting community research in three focus areas: 1) renewable energy development, 2) building energy efficiency, and 3) agroclimatology applications. The latest POWER version enhances its distribution systems to provide the latest NASA EO source data, be more resilient, support users more effectively, and provide data more efficiently. The update will include hourly-based source Analysis Ready Data (ARD), in addition to enhanced daily, monthly, annual, and climatology ARD. The daily time-series now spans 40 years for meteorology available from 1981 and solar-based parameters start in 1984. The hourly source data are from Clouds and the Earth's Radiant Energy System (CERES) and Global Modeling and Assimilation Office (GMAO), spanning 20 years from 2001.

The newly available hourly data will provide users the ARD needed to model the energy performance of building systems, providing information directly amenable to decision support tools introducing the industry standard EPW (EnergyPlus Weather file). One of POWER’s partners, Natural Resource Canada’s RETScreen™, will be simultaneously releasing a new version of its software, which will have integrated POWER hourly and daily ARD products. For our agroclimatology users, the ICASA (International Consortium for Agricultural Systems Applications standards) format for the crop modelers has been modernized.

POWER is releasing new user-defined analytic capabilities, including custom climatologies and climatological-based reports for parameter anomalies, ASHRAE® compatible climate design condition statistics, and building climate zones. The ARD and climate analytics will be readily accessible through POWER's integrated services suite, including the Data Access Viewer (DAV). The DAV has been improved to incorporate updated parameter groupings, new analytical capabilities, and the new data formats. Updated methodology documentation and usage tutorials, as well as application developer specific pages, allow users to access to POWER Data efficiently.

+Visit the POWER Program Site to Learn More.