About

Kerri Cahoy is a professor and the head of the Space Sector at MIT AeroAstro's STAR Lab. Her role involves leading research efforts in space-related technologies and exploration. The page indicates her position and leadership within the lab, emphasizing her contributions to the field of aerospace engineering and space research. Specific details about her research focus, background, or key contributions are not provided in the text.

Research topics

• Physics
• Astronomy
• Artificial Intelligence
• Computer Science
• Remote sensing
• Algorithm
• Computer vision
• Astrobiology
• Optics
• Geography
• Aerospace engineering
• Engineering

Selected publications

• Leveraging photometry for deconfusion of directly imaged multiplanet systems

  Journal of Astronomical Telescopes Instruments and Systems · 2026-05-05

  articleOpen access

  Future missions, including the Habitable Worlds Observatory, will aim to image Earth-like exoplanets around Sun-like stars in reflected light. Determining whether an exoplanet is in the habitable zone of its star may be difficult in multiplanet systems when the observer does not know in advance which detection corresponds to which planet. This “confusion” problem will be a concern for future missions due to the high occurrence rate of multiplanet systems and will be exacerbated by the lack of prior knowledge about planets’ orbital parameters or characteristics. We address the exoplanet confusion problem by applying a photometry model to update an orbit ranking scheme for a “deconfuser” tool. This helps to account for the phase variation of planets throughout their orbits. We demonstrate the updated ranking scheme as a proof-of-concept on a subset of known to be confused simulated multiplanet systems among three inclination groupings (i.e., low, medium, and high). We find that incorporating photometry improves correctly interpreting previously confused orbits in more than half of these particularly challenging cases. These results emphasize that photometry is useful for orbit discrimination and deconfusion of directly imaged multiplanet systems, providing a framework for including photometry alongside astrometry when fitting orbits to detections.

  PublisherOA PDFDOI

• A NN approach for precipitation retrieval using TROPICS data

  2025-08-03

  articleSenior author

  In this work a precipitation retrieval scheme based on neural networks (NNs) using data from the TROPICS (Time-Resolved Observations of Precipitation structure and storm Intensity with a Constellation of Smallsats) constellation is presented. High time-resolved microwave TROPICS observations are used as input to an NN model with the scope of estimating precipitation rates, using data from the Global Precipitation Measurement (GPM) mission as training dataset. The NN algorithm is developed and tested on a dataset composed of several storm events. The results show a good level of agreement between NN prediction and reference precipitation values, with a R<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> of about 0.9.

  PublisherDOI

• The NASA Time-Resolved Observations of Precipitation Structure and Storm Intensity with a Constellation of Smallsats (TROPICS) Mission: Results from the Pathfinder Demonstration and Look Ahead to the Constellation Mission

  Digital Commons - USU (Utah State University) · 2025-05-16

  otherOpen access

  The NASA Time-Resolved Observations of Precipitation structure and storm Intensity with a Constellation of Smallsats (TROPICS) mission will provide nearly all-weather observations of 3-D temperature and humidity, as well as cloud ice and precipitation horizontal structure, at high temporal resolution to conduct high-value science investigations of tropical cyclones. TROPICS will provide rapid-refresh microwave measurements (median refresh rate of approximately 50 minutes for the baseline mission) over the tropics that can be used to observe the thermodynamics of the troposphere and precipitation structure for storm systems at the mesoscale and synoptic scale over the entire storm lifecycle. The TROPICS constellation mission comprises six CubeSats in three low-Earth orbital planes. Each CubeSat will host a high-performance radiometer to provide temperature profiles using seven channels near the 118.75 GHz oxygen absorption line, water vapor profiles using three channels near the 183 GHz water vapor absorption line, imagery in a single channel near 90 GHz for precipitation measurements (when combined with higher resolution water vapor channels), and a single channel at 205 GHz that is more sensitive to precipitation-sized ice particles. TROPICS spatial resolution and measurement sensitivity is comparable with current state-of-the-art observing platforms. Launches for the TROPICS constellation mission are planned in 2022. NASA’s Earth System Science Pathfinder (ESSP) Program Office approved the separate TROPICS Pathfinder mission, which launched into a sun-synchronous orbit (2:00pm LTDN, 530 km) on June 30, 2021, in advance of the TROPICS constellation mission as a technology demonstration and risk reduction effort. The TROPICS Pathfinder mission has provided an opportunity to checkout and optimize all mission elements prior to the primary constellation mission. In this paper, we describe the instrument checkout and calibration/validation plans and progress for the TROPICS Pathfinder mission and discuss first light mission results. All spacecraft and radiometer systems are fully operational as of Launch + 11 months.

  PublisherOA PDFDOI

• A feasibility study to reconstruct atmospheric rivers using space- and ground-based GNSS observations

  Atmospheric measurement techniques · 2025-11-18

  articleOpen accessCorresponding

  Abstract. Atmospheric rivers (ARs) are long filaments that transport large amounts of water vapor from the Tropics to mid- and high latitudes. They are directly related to heavy precipitation and extreme weather leading to flooding and mud slides. Accurate identification of AR structures over the ocean is important to improve the forecast of their landfall location and timing. Global Navigation Satellite Systems (GNSS) radio occultation (RO) is a space-based technique that can measure meteorological variables with high vertical resolution. While RO can observe structures like ARs in individual RO profiles, RO observations have non-uniform and sparse spatial and temporal sampling, so it is not yet possible to fully characterize AR morphology using RO alone. In this work, we use previous research in which we applied machine learning (ML) to enhance the spatial and temporal resolution of RO observations. Here, we train neural networks (NNs) to map RO observations and help resolve ARs. Analyses using existing RO data, such as from the COSMIC-2 mission, showed that the sampling density is insufficient to resolve and geo-locate ARs. Adding observations from the other available missions (for example METOP) improved matters, but was still insufficient to reliably reconstruct AR structure. We undertake a study to determine how many LEO RO satellites would be needed to quantify the structure, location, and timing of ARs. We simulate RO observations as would be obtained with Walker constellations of 12, 24, 36, 48 and 60 LEO RO satellites. First, we investigate possible constellations for proper AR monitoring. We aim for constellations that lead to hourly RO counts that change as little as possible during the AR (up to several days). This allows us to resolve ARs with similar accuracy during the scenario. We conclude that 3 or 6 orbital planes and inclinations between 85 and 90° perform best. Second, we make use of 12 h forecasts of the European Centre for Medium-range Weather Forecasts (ECMWF) system to interpolate the forecasts to the simulated RO constellation sampling coordinates. Third, we use the ECMWF-based RO observations to train ML models and map them to the ECMWF grid. We compare ML-mapped RO sampled grids to ECMWF products in a closed-loop validation. Initially, we map RO refractivity at 2 km geopotential height, where small-scale structures related to water vapor are visible. We find that at least 36 RO satellites are needed to characterize the morphology of ARs in the Pacific basin with useful precision and accuracy (from the ML produced maps). Then, we use a framework with two consecutive NNs to map column-integrated water vapor (IWV) from profiles of RO. The first NN maps the refractivity into IWV, and the second NN maps the IWV spatially. In this case, we find that a constellation of 48 satellites is needed to continuously map IWV fields accurately and thus reconstruct the morphology of ARs with useful precision and accuracy. Finally, when using RO, we find that mapping refractivity into IWV is less accurate over land than over oceans. To further improve the AR mapping over land, we made use of IWV from ground-based (GB) GNSS. The significantly higher spatial and temporal resolutions of GB data compared to RO lead to much improved IWV fields and thus AR path and shape over land.

  PublisherDOI

• Improving Cloud Observations by Autonomously Pointing Satellites

  2025-08-03

  articleSenior author

  One of the largest sources of uncertainty in climate research is aerosol-cloud interaction. Our capabilities to increase our understanding are limited by the quantity and quality of cloud measurements we can make. Traditional, nadir-pointing satellites waste time and power by measuring clear skies while potentially missing high-value cloud measurements just off-nadir. With the conclusion of the CloudSat and CALIPSO missions, there is a need for new satellites to monitor clouds. New satellites have an opportunity to take advantage of advanced remote sensing techniques such as autonomy to improve the yield of high-value cloud measurements. In this paper, we present a proof of concept for an autonomously pointing satellite that can dynamically target off-nadir clouds. We develop a simulation environment that evaluates the capabilities of different algorithms and satellites to complete this task while managing power and memory storage. We build this simulation with MODIS cloud masks, which contain data for cloud cover percentages, existence of cirrus clouds, and light/eclipse status. We analyze data from January 2010, when the CloudSat mission was in full operation. We compare the number of clouds measured by algorithms we developed (binary toggle, greedy, nearest greedy, and distance weighted) to CloudSat’s performance during the same period. Our best performing algorithm measures, on average, 60 percent of cloud cells with low variance, compared with CloudSat’s less than 40 percent with high variance. Dynamic targeting satellites can substantially enhance cloud monitoring and improve our ability to understand aerosol-cloud interactions for climate research.

  PublisherDOI

• Demonstrations of adjoint electric field conjugation for a vortex coronagraph

  Journal of Astronomical Telescopes Instruments and Systems · 2025-07-21

  articleOpen accessSenior author

  Focal plane wavefront sensing and control (FPWFSC) will be required for coronagraph instruments attempting to reach the high contrasts needed to discover and characterize exoplanets. The most commonly implemented method of FPWFSC has been electric field conjugation (EFC), which uses a precomputed model-based Jacobian. This can require extensive computation times and memory resources, particularly for coronagraphs utilizing a large number of actuators and a focal plane mask (FPM) needing a combination of large spatial extent and high resolution to model. However, the more recent adjoint EFC (aEFC) approach demonstrated on the High-contrast Imager for Complex Aperture Telescopes used algorithmic differentiation and nonlinear optimization to solve for the actuator commands without the use of a Jacobian. We derive the adjoint model for a vortex coronagraph and demonstrate aEFC both with simulations and with a laboratory experiment using the Space Coronagraph Optical Bench (SCoOB). The simulations use an independent Fresnel model of a vortex coronagraph instrument, which captures the Talbot effect between propagations from optic to optic. These simulations include the first demonstration of broadband aEFC where a contrast below 10−10 is achieved between 3 λ/D−36 λ/D and over a 10% bandpass. An additional broadband simulation with the presence of model errors is performed to demonstrate that model errors can be overcome with aEFC using a regularization bumping scheme similar to that of EFC. Finally, we experimentally test this aEFC method on the SCoOB where a contrast of 8.1×10−9 is achieved between 3 λ/D and 10 λ/D with a 632.8-nm laser source.

  PublisherOA PDFDOI

• Performance and modelling of a deployed diffractive optical element for space-based LiDAR

  2025-09-16

  articleSenior author

  SPECIES (Smart Polyimide Expandable Collector to enable Investigations for Earth Science) is a NASA Earth Science Technology Office (ESTO) project that explores the use of a deployable diffractive optical element (DOE) in a space-based LiDAR instrument for a 12–24U small satellite operating in low Earth orbit (LEO). The DOE is a 0.6-meter hybrid multi-level Fresnel zone plate (MLFZP), constructed from a tessellation of hexagonal polyimide membranes, each with a distinct number of diffractive levels. It is stowed for launch and deployed on orbit using a 3-meter-long extendible boom, which positions the optic at the correct distance from the spacecraft, while guy wires provide tensioning to maintain a flat profile. This architecture enables the DOE to achieve high diffractive efficiency and optical performance while significantly reducing mass and cost compared to traditional refractive or reflective optics of comparable size. This work presents methods and results to model the performance of a deformed DOE. A custom optical model is employed to propagate the beam through the deformed DOE and characterize the optical response and system performance. Using deformation inputs from mechanical stresses due to packing and deployment and thermal variations in orbit, the model evaluates key optical performance parameters, including the focal point spread function, beam quality, diffraction efficiency, and wavefront aberrations. The model extends traditional Fourier optics principles to enable field propagation from a non-planar diffractive optic, maintaining computational efficiency through Fourier transforms. These results are then used to assess the effects on LiDAR performance, including measurement uncertainties and overall system efficiency. We present the implementation of this model, including numerical wave propagation techniques for deformed diffractive optical elements. By addressing these challenges, SPECIES demonstrates the viability of large-format, lightweight DOEs for high-performance, space-based LiDAR applications. The findings offer broader insights into the practical implementation of diffractive optics for compact, deployable, and cost-effective optical systems, with potential applications in Earth observation and beyond.

  PublisherDOI

• On-Orbit Results From the NASA Time-Resolved Observations of Precipitation Structure and Storm Intensity With a Constellation of Smallsats (TROPICS) Mission

  Digital Commons - USU (Utah State University) · 2025-08-04

  otherOpen access

  The NASA TROPICS Earth Venture (EVI-3) CubeSat constellation mission will provide nearly all-weather observations of 3-D temperature and humidity, as well as cloud ice and precipitation horizontal structure, at high temporal resolution to conduct high-value science investigations of tropical cyclones. TROPICS will provide rapid-refresh microwave measurements (median refresh rate better than 60 minutes for the baseline mission) over the tropics that can be used to observe the thermodynamics of the troposphere and precipitation structure for storm systems at the mesoscale and synoptic scale over the entire storm lifecycle. The TROPICS constellation mission comprises four 3UCubeSats (5.4 kg each) in two low-Earth orbital planes. Each CubeSat contains a Blue Canyon Technologies bus and a high-performance radiometer payload to provide temperature profiles using seven channels near the 118.75 GHz oxygen absorption line, water vapor profiles using three channels near the 183 GHz water vapor absorption line, imagery in a single channel near 90 GHz for precipitation measurements (when combined with higher resolution water vapor channels), and a single channel at 205 GHz that is more sensitive to precipitation-sized ice particles. TROPICS spatial resolution and measurement sensitivity is comparable with current state-of-the-art observing platforms. Two dedicated launches (two spacecraft per launch) for the TROPICS constellation mission on Rocket Lab Electron vehicles occurred in 2023 (May 8 and May 26) to place the spacecraft in 32.75-degree inclined orbits at 550 km altitude. Data will be downlinked to the ground via the KSAT-Lite ground network. NASA's Earth System Science Pathfinder (ESSP) Program Office approved the separate TROPICS Pathfinder mission, which launched on June 30, 2021, in advance of the TROPICS constellation mission as a technology demonstration and risk reduction effort. The TROPICS Pathfinder mission has provided an opportunity to checkout and optimize all mission elements prior to the primary constellation mission and is still operating nominally.

  PublisherOA PDFDOI

• CLICK-A: Optical Communication Experiments From a CubeSat Downlink Terminal

  Digital Commons - USU (Utah State University) · 2025-08-04

  otherOpen access

  The CubeSat Laser Infrared CrosslinK (CLICK) mission is a technology demonstration of low size, weight, and power (SWaP) CubeSat optical communication terminals for downlink and crosslinks. The mission is broken into two phases: CLICK-A, which consists of a downlink terminal hosted in a 3U CubeSat, and CLICK-B/C, which consists of a pair of crosslink terminals each hosted in their own 3U CubeSat. This work focuses on the CLICK-A 1.2U downlink terminal, whose goal was to establish a 10 Mbps link to a low-cost portable 28 cm optical ground station called PorTeL. The terminal communicates with M-ary pulse position modulation (PPM) at 1550 nm using a 200 mW Erbium-doped fiber amplifier (EDFA) with a 1.3 mrad FWHM beam divergence. CLICK-A ultimately serves as a risk reduction phase for the CLICK-B/C terminals, with many components first being demonstrated on CLICK-A. CLICK-A was launched to the International Space Station on July 15th, 2022 and was deployed by Nanoracks on September 6th, 2022 into a 51.6° 414 km orbit. We present the results of experiments performed by the mission with the optical ground station located at MIT Wallace Astrophysical Observatory in Westford, MA. Successful acquisition of an Earth to space 5 mrad FWHM (5 Watts at 976 nm) pointing beacon was demonstrated by the terminal on the second experiment on November 2nd, 2022. First light on the optical ground station tracking camera was established on the third experiment on November 10th, 2022. The optical ground station showed sufficient open, coarse, and fine tracking performance to support links with the terminal with a closed-loop RMS tracking error of 0.053 mrad. Results of three optical downlink experiments that produced beacon tracking results are discussed. These experiments demonstrated that the internal microelectromechanical system (MEMS) fine steering mirror (FSM) corrected for an average blind spacecraft pointing error of 8.494 mrad and maintained an average RMS pointing error of 0.175 mrad after initial blind pointing error correction. With these results, the terminal demonstrated the ability to achieve sufficient fine pointing of the 1.3 mrad FWHM optical communication beam without pointing feedback from the terminal to improve the nominal spacecraft pointing. Spacecraft drag reduction maneuvers were used to extend mission life and inform the mission operations of the CLICK-B/C phase of the mission. Results from the spacecraft drag maneuvers are also presented.

  PublisherOA PDFDOI

• First demonstration of four-mirror piezoelectric compact delay line for space interferometry

  2025-09-17

  article
  PublisherDOI

Recent grants

• Collaborative Research: Design of a Nanosat Constellation for Measuring Internal Gravity Wave Fluxes in the Earth's Stratosphere

  NSF · $343k · 2019–2022

Frequent coauthors

• Ewan S. Douglas

  University of Arizona

  86 shared

• Paula do Vale Pereira

  Florida Institute of Technology

  46 shared

• Christian Haughwout

  Massachusetts Institute of Technology

  45 shared

• Rachel Morgan

  44 shared

• Leonid Pogorelyuk

  43 shared

• Olivier Guyon

  National Astronomical Observatory of Japan

  42 shared

• Nicholas Belsten

  42 shared

• Anne Marinan

  Jet Propulsion Laboratory

  39 shared

Labs

• STAR LabPI

Education

• Ph.D., Astronomy

  Massachusetts Institute of Technology

  2003

• M.S., Astronomy

  Massachusetts Institute of Technology

  1999

• B.S., Physics

  University of California, Berkeley

  1996

Awards & honors

• Committed to Caring, MIT (2020)
• Associate Fellow, American Institute of Aeronautics and Astr…
• Outstanding UROP Mentor, MIT (2013)
• Co-Op Mentor of the Year, Cornell University (2008)
• Research Characterization of laser thermal loading on microe…