News and Highlights:

_____________

HARP Overview

HARP (Hyper-Angular Rainbow Polarimeter) is a CubeSat satellite funded by the NASA ESTO InVest Program designed to measure the properties of aerosols and cloud particles from space. Aerosols are solid and liquid particles in suspension in the atmosphere (like dust, smoke, pollen, particulate pollution from industry, cars, etc.) originating from natural or man-made sources. The HARP science objectives includes the detailed characterization of aerosol particles and the measurements of the properties of cloud particles including their thermodynamic phase (ice or water) and the size of cloud water droplets.

The HARP payload, a hyperangular imaging polarimeter that can see Earth from multiple viewing angles, 4 wavelengths, and three polarization angles was developed and is being built at the Laboratory for Aerosol, Clouds and Optics (LACO) in the Physics Department at UMBC with support from the Joint Center of Earth Systems and Technology (JCET) and NASA Goddard. The HARP spacecraft was designed and is being built at the Space Dynamics Lab (SDL) in Utah. The HARP science algorithms will be developed in collaboration between UMBC and Science and Technology Corporation (STC). The main characteristics of the HARP payload are described in the table below.

HARP Polarimeter Specs

• One hyper-angular channel with up to 60 viewing angles per pixel at 670nm (for cloudbow measurements)

• Three channels with up to 20 viewing angles per pixel at 440, 550, 670nm

• Goal of one additional channel with up to 20 viewing angles at 870nm

• 2.5km nadir resolution (from 650km orbit)

• 94 deg FOV X-track

• 110 deg FOV along track

The HARP payload is fully programmable and will allow for the selection of different spatial resolutions and combinations of wavelengths and viewing angles depending on the science interest and total amount of data to downlink. The different along track viewing angles from HARP will allows the observations of targets on the ground from different viewing perspectives. These different viewing observations of the same target allow for additional information from the target facilitating the quantitative retrieval of information from the atmosphere and surface properties such as the aerosol particle amount, the cloud droplet sizes, and specific characteristics of Earth’s surface. The figure below shows a series of pictures of the coast of California taken during the PODEX experiment by the PACS multi-angle imaging polarimeter taken from the NASA ER-2 aircraft. PACS serves as an airborne simulator for the HARP imaging polarimeter. The different perspectives in the images emphasize the variation of the reflection of the sun on the ocean surface as a function of the viewing angle. In some along track viewing angles this reflection disappears while in other angles this reflections appear very intensively.

HARP is expected to be launched by the NASA CSLI program in the International Space Station orbit with potential opportunities beginning in early 2016. This orbit has the advantage of allowing HARP to cross many other Earth Science Satellites (including Terra, Aqua, Aura, VIIRS, Calipso, etc.) and produce intercomparisons and a synergistic use of the HARP data together with data from these other platforms.