ARCADE is a high altitude balloon payload designed to study the early universe. It measured the frequency spectrum of the Cosmic Microwave Background (CMB) at centimeter wavelengths, to search for signals from the first stars to form after the Big Bang. ARCADE's science goals were to observe the formation of structure from the first stars and galaxies, search for particle physics relics from the Big Bang, and understand the large-scale structure and energetics of our Galaxy. ARCADE flew in 2001, 2003, 2005 and 2006.
The Solar Isotope Spectrometer provides isotopically resolved measurements of the elements from lithium to zinc over the energy range 10 - 100 MeV/nucleon. The SIS dectector system consists of two identical telescopes composed of stacks of large-area solid-state detectors.
The Active Cavity Irradiance Monitor Satellite, or AcrimSat, mission spent 14 years in orbit monitoring Earth's main energy source, radiation from the sun, and its impacts on our planet.
The ASCENDS mission will make global atmospheric column carbon dioxide (CO2) measurements without a seasonal, latitudinal, or diurnal bias. The mission will also measure ambient air pressure and temperature. The measurements made by ASCENDS will allow the mission to: 1) quantify global spatial distributions of atmospheric CO2 on scales of weather models in the 2010-2020 era; 2) quantify the current global spatial distribution of terrestrial and oceanic sources and sinks of CO2 on 1x1 degree grids at weekly resolution; and 3) provide a scientific basis for future projections of CO2 sources and sinks through data-driven enhancements of Earth system process modeling.
The Advanced Composition Explorer (ACE) studies energetic particles from the sun as well as sources within and outside our galaxy. ACE observations contribute to our understanding of the formation and evolution of the solar system as well as the astrophysical processes involved. NASA's Goddard Space Flight Center provided detectors and telescopes for several of ACE's instruments. The mission launched in 1997.
The Advanced Earth Observing Satellite (ADEOS), Japanese name MIDORI, was the first international space platform dedicated to Earth environmental research. It was developed and managed by the National Space Development Agency of Japan (NASDA). The TOMS (Total Ozone Mapping Spectrometer) instrument, along with NSCAT (a NASA spectrometer designed to study wind speed and direction) were the major US components of the platform. ADEOS launched on August 17, 1996 into a sun-synchronous subrecurrent orbit of an altitude of approximately 830 km by an H-II launch vehicle from the Tanegashima Space Center. After an equipment malfunction, NASDA declared the spacecraft and the two NASA instruments aboard lost on June 30, 1997.
The ADEOS II mission was an international satellite mission led by the Japan Aerospace Exploration Agency (JAXA) - formerly the National Space Development Agency (NASDA) of Japan - with U.S. (NASA) and French Centre Nationale d'Etudes Spatiales (CNES) participation. Midori-II is the Japanese name for the mission.
Advanced Energetic Pair Telescope
(AdEPT)
AdEPT is a space observatory that will probe the medium-energy gamma-ray
band (5 - 200 MeV) with unprecedented sensitivity and high angular
resolution, allowing for detailed observations in this energy band for the
first time. The AdEPT telescope will also, for the first time, have the
capability to detect polarization at MeV energies. This capability will
provide new probes of the structures of astrophysical sources, such as
blazars, star-forming galaxies, gamma-ray binaries, gamma-ray bursts,
pulsars, and magnetars, as well as tests of fundamental physics such as
quantum gravity models. Thus, AdEPT will explore new scientific and
technological frontiers of gamma-ray astrophysics. Launch is anticipated in
2020.
The Advanced Microwave Scanning Radiometer for EOS (AMSR-E) was a twelve-channel, six-frequency, total power passive-microwave radiometer system. It measured brightness temperatures at 6.925, 10.65, 18.7, 23.8, 36.5, and 89.0 GHz. Vertically and horizontally polarized measurements were taken at all channels. The Earth-emitted microwave radiation was collected by an offset parabolic reflector 1.6 meters in diameter that scanned across the Earth along an imaginary conical surface, maintaining a constant Earth incidence angle of 55° and providing a swath width array of six feedhorns which then carried the radiation to radiometers for measurement. Calibration was accomplished with observations of cosmic background radiation and an on-board warm target. Spatial resolution of the individual measurements varied from 5.4 km at 89.0 GHz to 56 km at 6.9 GHz.
The Advanced Satellite for Cosmology and Astrophysics (ASCA), formerly Astro-D, was Japan's fourth X-ray astronomy mission. ASCA carried four X-ray telescopes and was optimized for X-ray spectroscopy. The spacecraft conducted more than 3,000 observations covering a broad range of astronomical objects. These included supernova remnants, galaxies and galaxy clusters, X-ray binary stars, active galactic nuclei, and variable stars. The satellite was successfully launched in February 1993. After suffering damage on July 14, 2000 during a geomagnetic storm, ASCA reentered the atmosphere on March 2, 2001, after more than 8 years in orbit.
The Advanced Technology Large Aperture Space Telescope (ATLAST) is a NASA strategic mission concept study for the next generation of UVOIR space observatory. ATLAST will have a primary mirror diameter in the 8m to 16m range that will allow us to perform some of the most challenging observations to answer some of our most compelling astrophysical questions.
ATHENA is an ESA large mission that is slated to launch in the early 2030s. The main science goals of ATHENA address the questions:
* How and why does ordinary matter assemble into the galaxies and galaxy clusters that we see today?
* How do black holes grow and influence their surroundings?
These will be accomplished thanks to a large X-ray mirror with a 5” point spread function that pivots to focus on onto one of two instruments: the X-ray Integral Field Unit (X-IFU) which is an X-ray calorimeter with ~ 2 eV spectral resolution and the Wide-Field Imager (WFI) which is a large field of view (40’ x 40’) active pixel sensor.
ICESat-2 carries a single instrument – the Advanced Topographic Laser Altimeter System, or ATLAS. Like the altimeter on the first ICESat mission, ATLAS measures the travel times of laser pulses to calculate the distance between the spacecraft and Earth’s surface. ATLAS features new technologies that allow it to collect a more detailed, precise picture of the heights of the planet’s ice, vegetation, land surface, water and clouds. As it orbits over the poles, ATLAS has three major tasks: Send pulses of laser light to the ground, collect the returning photons in a telescope, and record the photon travel time.
The AIM satellite mission is designed to explore Polar Mesospheric Clouds (PMCs), also called noctilucent clouds, to find out why they form and why they are changing.
Four multi-angle polarimeters and two atmosphere profiling lidar instruments were deployed on NASA's high altitude ER-2 aircraft in late 2017 from the Armstrong Flight Research Center in Palmdale, California. A collaboration between NASA (ACE mission) and the Netherlands Institute for Space Research (SRON), ACEPOL targeted a wide variety of scene types in order to test and validate ocean, aerosol and cloud observations. ACEPOL also was supported by the CALIPSO mission for validation purposes. ACEPOL is particularly relevant for PACE because of the participation of airborne versions of the HARP2 and SPEXone instruments, and provides valuable data for algorithm development and instrument characterization.
The AERONET (AErosol RObotic NETwork) program is a federation of ground-based remote sensing aerosol networks established by NASA and PHOTONS (PHOtométrie pour le Traitement Opérationnel de Normalisation Satellitaire; Univ. of Lille 1, CNES, and CNRS-INSU) and is greatly expanded by networks (e.g., RIMA, AeroSpan, AEROCAN, and CARSNET) and collaborators from national agencies, institutes, universities, individual scientists, and partners. The program provides a long-term, continuous and readily accessible public domain database of aerosol optical, microphysical and radiative properties for aerosol research and characterization, validation of satellite retrievals, and synergism with other databases. The network imposes standardization of instruments, calibration, processing and distribution.
In response to the 2007 NRC Decadal Survey, the ACE mission brings together aerosol, cloud, ocean ecosystem and other earth system scientists in a multiple-sensor, multiple-platform, low earth orbit, sun-synchronous satellite
mission that combines active and passive sensors to observe the Earth at microwave, infrared, visible and ultraviolet wavelengths. The ACE Final Study report was published in September 2020.
Accurate retrievals of aerosol and cloud properties from space-borne sensors have been achieved with certain degrees of confidence. One of the most difficult tasks remaining to be resolved is when aerosols and clouds co-exist and interact with each other.
The Airborne Earth Science Microwave Imaging Radiometer (AESMIR) is a passive microwave airborne imager covering the 6-100 GHz bands that are essential for observing key Earth System elements such as precipitation, snow, soil moisture, ocean winds, sea ice, sea surface temperature, vegetation, etc.
The Airborne Topographic Mapper (ATM) is a scanning LIDAR developed and used by NASA for observing the Earth’s topography for several scientific applications, foremost of which is the measurement of changing arctic and antarctic icecaps and glaciers. It typically flies on aircraft at an altitude between 400 and 800 meters above ground level, and measures topography to an accuracy of better than 10 centimeters by incorporating measurements from GPS (global positioning system) receivers and inertial navigation system (INS) attitude sensors.
AMEGO, the All-sky Medium Energy Gamma-ray Observatory, is an Astrophysics Probe mission concept designed to explore the MeV sky. AMEGO will consist of four hardware subsystems: a double-sided silicon strip tracker with analog readout, a segmented CZT calorimeter, a segmented CsI calorimeter and a plastic scintillator anticoincidence detector. AMEGO provides three new capabilities in MeV astrophysics: sensitive continuum spectral studies, polarization, and nuclear line spectroscopy. The primary optimization for AMEGO is continuum sensitivity across a broad energy range.
The Apache Point Lunar Laser Ranging Station utilizes the Astrophysical Research Consortium 3.5-meter telescope at the Apache Point Observatory in Sunspot, New Mexico. The large collecting area of the Apache Point 3.5 m diameter telescope, good atmospheric conditions at the site, and the efficient avalanche photodiode arrays used by the station result in a high-detection rate (even multiple detections per laser pulse) leading to millimeter-level range precision.
