ALTUS II
ALTUS II

The Dual Optical Pulse Sensor (DOPS) is an airborne optical sensor used to study lightning in the atmosphere. It is an improved version of the Optical Pulse Sensor (OPS). DOPS measures lightning's duration, intensity, and waveform features. It operates on two channels centered at 500 and 777.4 nm with a sample duration of 0.328 seconds. It has a wide field of view (60 degrees) and can detect lightning during daylight conditions.

The Parallel Plate Antenna is a passive device used to measure the vertical electric fields generated by lightning. It consists of two or more horizontal flat plates separated by a few meters to detect electromagnetic radiation emitted by lightning. The antenna can be adjusted for either slow-field or fast-field measurements. The slow-field antenna has a longer decay time constant and is used to measure lightning flashes over a longer period, while the fast-field antenna has a shorter decay time and captures rapid changes in the electric field from individual lightning strikes. The slow-field antenna operates in the 1 Hz to 100 kHz frequency range, whereas the fast-field antenna operates from 1 Hz to 3 MHz.

Accelerometers are in situ sensors that measure the acceleration experienced by an object. Accelerometers utilize electromagnetic sensing to detect the vibration of an object. The force of vibration causes the sensor to produce an electrical charge, indicating how much force was exerted, which can be used to determine the acceleration. Accelerometers are typically used on aircraft when collecting flight navigation information. Accelerometers have also been deployed on research vessels and other water-based platforms such as buoys.

The Gerdien Probe is an in situ airborne conductivity device. It measures atmospheric electrical conductivity by recording the time it takes for a sample of air to discharge after being exposed to a capacitor. The Gerdien probe can detect both positive and negative ions. It can be mounted on aircraft, uncrewed aerial systems (UAS), and rockets.

An Electric Field Mill (EFM) is a ground-based and airborne electric sensor developed at NASA Marshall Space Flight Center (MSFC). It measures the full vector components of the atmospheric electric field and provides information about the electrical structure within and around storms. EFMs can detect both intracloud and cloud-to-ground lightning and can operate in large thunderstorm fields (thousands of volts per meter). An EFM typically has a response time of about 10 Hz.

A Search Coil Magnetometer (SCM) is a passive, remote magnetometer used to detect lightning and rapid changes in the magnetic field. It operates based on Faraday’s law of induction. When the magnetic field changes, it induces a current in the coil, which is then amplified and recorded. SCMs generally operate within the 100 Hz to 100 kHz frequency range and are suitable for airborne, spaceborne, and ground-based uses.

The Electric Field Change Meter (EFCM) is an airborne in situ electric meter. It uses a two-channel (fast and slow) antenna system to measure electric field changes caused by lightning. The fast channel samples at 10 MHz and detects the radiative component of lightning discharges. The slow channel samples at 1 MHz and observes the electrostatic field component. The EFCM operates across a frequency range of 1 Hz to 100 kHz and has a detection radius of 25 km.

Magnetometers are passive instruments that measure the variations in Earth’s magnetic field. There are two types of magnetometers: a vector magnetometer, which measures the vector components of a magnetic field, and a total field magnetometer, which measures the magnitude. Magnetometers are used for geophysical surveys and ocean exploration. They can be used for airborne, ground-based, or water-based operations.