Architecture

Puzzle pieces - all pieces emphasized

ACCP is designing architectures for candidate observing systems. We are evaluating each system's ability to meet science and applications objectives within a prescribed cost.

A full architecture includes:
  • Launch vehicles
  • Spacecraft buses
  • Suborbital campaigns
  • Instruments
  • Mission operations
  • Ground systems
  • Science team (data analysis and algorithms)
Puzzle pieces - launch vehicles, spacecraft buses and suborbital campaigns pieces emphasized

Launch Vehicles, Spacecraft Buses and Suborbital Campaigns

Puzzle pieces - instruments piece emphasized

Instruments

How it Works

Radar sends out radio waves and picks them up again after the waves strike another object and bounce back.

Mission Role

Radar helps identify the size, type, and concentration of hydrometeors – liquid and solid water particles – in the atmosphere. Doppler radar can measure the vertical motion of hydrometeors. ACCP radars will include W, Ka, Ku microwave bands including Doppler and non-Doppler, scanning and nadir only.
Radar diagram

Lidar can provide profiles of optically thin clouds. Radar can provide profiles of optically thick clouds and precipitation. Co-located radar and lidar observations allow the vertical structure of cloud occurrence and heating to be characterized.

How it Works

Lidar is similar to radar, but instead of bouncing radio waves off its target, lidar uses short pulses of laser light. Some of that light reflects off of tiny particles in the atmosphere and back to a telescope aligned with the laser.

Mission Role

By precisely timing the lidar's "echo," and by measuring how much laser light is received by the telescope, scientists can accurately determine the location, distribution and nature of particles. The result is a tool for studying constituents in the atmosphere, from cloud droplets to industrial pollutants that are difficult to detect by other means. ACCP lidars will include two and three frequencies, backscatter and High Spectral Resolution Lidar (HSRL).

Radar can provide profiles of optically thick clouds and precipitation. Lidar can provide profiles of optically thin clouds. Co-located radar and lidar observations allow the vertical structure of cloud occurrence and heating to be characterized.

Lidar diagram
This lidar image is from CALIPSO and a similar system will be deployed with ACCP.

How it Works

A radiometer measures the intensity of radiation emitted at specific wavelengths. Radiometers are often combined with radar and lidar to derive meteorological parameters such as temperature, humidity, and water vapor.

Mission Role

ACCP radiometers will include cross-track and conically scanning, with frequencies ranging from 10 to 833 GHz. The 874 - 883 GHz wavelength range, for example, will be utilized for detecting ice content in clouds.
Radiometer diagram
Overview of how radiometry at various wavelengths is used to understand clouds and precipitation. Source: NASA.

How it Works

A spectrometer is used to separate and measure wavelengths of light as it interacts with materials, in this case trace gases and particulates.

Mission Role

A spectrometer covers several bandwidths in the Visible (VIS), Near Infrared (NIR) and Short Wave Infrared (SWIR), Long Wave Infrared (LWIR), and Thermal Infrared (TIR) spectral ranges and can provide ozone profiles and columns, monitors various trace gases and air quality, and supports climate monitoring.
Images from the Airborne PRISM Experiment (APEX).

How it Works

As the satellite orbits, the polarimeter measures the angle of rotation of different angles of sunlight scattering off substances such as aerosols. The polarimeter uses the information of how substances affect light to identify their characteristics. For example, some substances are optically active, and polarized light will rotate either to the left (counter-clockwise) or right (clockwise) when light passes through them. The amount by which the light is rotated is known as the angle of rotation or observed angle.

Mission Role

A polarimeter helps identify the size, type, concentration, and orientation of hydrometeors – liquid and solid water particles – and aerosols in the atmosphere. ACCP polarimeters will include varying channels (5 to hyperspectral) and angles (5° to 255°).
Polarimeter diagram
Puzzle pieces - mission ops and ground systems pieces emphasized

Mission Ops & Ground Systems

The diagram below is an example of typical NASA earth science mission elements including Launch, Space, Ground, and Science Data Segments. These work together to control earth-orbiting satellites, upload / download data, and ensure that high-quality data are available to the science community.
Mission OPS and ground systems
Puzzle pieces, science piece emphasized

Science

Key science drivers to balance:
  • High latitude coverage
  • Diurnal cycle
  • Continuity of the climate data record
  • Radiation measurements
  • Consideration of new approaches such as time-differencing of satellite measurements