OSIRIS-REx Laser Altimeter (OLA)

OSIRIS-REx Laser Altimeter (OLA)
Name	OSIRIS-REx Laser Altimeter (OLA)
Mission	OSIRIS-REx
Operator	Canadian Space Agency; NASA
Manufacturer	MacDonald, Dettwiler and Associates; Canadian Space Agency
Type	Laser altimeter
Launch	2016
Target	101955 Bennu
Status	Deployed on OSIRIS-REx; data archived

OSIRIS-REx Laser Altimeter (OLA) The OSIRIS-REx Laser Altimeter (OLA) is a scanning lidar instrument flown on the OSIRIS-REx asteroid sample-return mission, designed and delivered by the Canadian Space Agency with industrial contribution from MacDonald, Dettwiler and Associates. It produced high-resolution three-dimensional topography of the near-Earth asteroid 101955 Bennu to support sampling site selection, navigation, and geophysical studies. OLA complemented imaging from the OSIRIS-REx Camera Suite and spectral measurements from instruments such as OSIRIS-REx Visible and Infrared Spectrometer.

Overview

OLA was part of the payload manifest for OSIRIS-REx, a mission led by NASA's Goddard Space Flight Center in partnership with the Canadian Space Agency and executed by the University of Arizona. The instrument applied time-of-flight ranging using pulsed laser illumination to record dense point clouds across Bennu's surface, enabling comparisons with previous planetary lidar instruments like Mars Orbiter Laser Altimeter and Lunar Orbiter Laser Altimeter. OLA's role intersected with navigation teams at NASA Goddard and sampling engineers from the OSIRIS-REx Team during critical phases such as Reconnaissance and TAG (Touch-And-Go).

Instrument Design and Specifications

OLA consisted of a scanning transmitter/receiver assembly, a precision timing subsystem, and flight electronics integrated into the spacecraft bus built by Lockheed Martin Space Systems. The laser head used pulsed near-infrared lasers with a repetition rate and pulse energy tailored for the small-body environment, while the receiver employed avalanche photodiodes and photon-counting electronics similar to those used on instruments developed at Canadian Space Agency laboratories. The instrument provided range measurements with single-shot precision on the order of centimeters and angular scanning accomplished by a two-axis gimbaled mirror, producing swaths comparable in density to lidar surveys by ICESat and airborne systems used by Natural Resources Canada. Mass, power, field-of-view, and telemetry design conformed to constraints imposed by the Atlas V (401) launch vehicle and the OSIRIS-REx spacecraft's thermal control and data handling architecture.

Science Objectives and Measurements

OLA's primary science objectives included high-resolution topographic mapping, determination of surface roughness and slope distributions, and support for geophysical modeling of 101955 Bennu's shape, mass distribution, and rotation state. The instrument produced three-dimensional digital terrain models that, when integrated with imagery from the PolyCam and spectral maps from OVIRS, enabled lithologic and regolith analyses. Measurements from OLA informed studies related to Yarkovsky and YORP effect modeling, crater counting calibration for planetary chronology, and assessments of boulder distribution relevant to sampleability and surface processes driven by solar radiation pressure and microgravity regolith dynamics.

Data Processing and Products

Raw OLA measurements were processed into calibrated range points, corrected for instrument timing biases, spacecraft attitude from the Inertial Measurement Unit (IMU), and range walk effects using algorithms developed by teams at the Canadian Space Agency and the University of Winnipeg. Point clouds were registered to spacecraft trajectory solutions provided by NASA Deep Space Network tracking and optical navigation from the OSIRIS-REx optical navigation team. Final products included precision digital terrain models (DTMs), 3-D point-cloud tiles, local slope and roughness maps, and cross-referenced products aligned with images from the MapCam instrument; these products were archived with metadata compatible with planetary data system standards employed by NASA Planetary Data System.

Mission Operations and Usage on OSIRIS-REx

During mission phases—Approach, Preliminary Survey, Detailed Survey, Reconnaissance, and TAG rehearsal—OLA provided continuous altimetric coverage to refine the Bennu shape model used by flight dynamics teams at NASA Goddard and maneuver planners at Lockheed Martin. OLA data contributed to hazard mapping and to the selection of primary and secondary sample sites overseen by the OSIRIS-REx science team chaired by investigators from the University of Arizona and partners including NASA Johnson Space Center. The instrument operated under operational constraints coordinated with mission timelines, downlink budgets via the Deep Space Network, and spacecraft pointing requirements managed by the OSIRIS-REx mission operations center.

Results and Scientific Contributions

OLA delivered unprecedented centimeter- to meter-scale topography of a primitive near-Earth asteroid, revealing detailed boulder populations, crater morphologies, and surface textures that constrained Bennu's geologic history and regolith processes. Combined with compositional mapping from instruments such as OVIRS and OTES, OLA-enabled DTMs informed interpretations of carbonaceous material distribution and heterogeneity that bear on early Solar System evolution theories involving protoplanetary disk processes and asteroid-meteorite connections. The altimetric record improved knowledge of Bennu's rotational dynamics, mass distribution, and YORP-driven evolution, aiding subsequent modeling by researchers at institutions including NASA Jet Propulsion Laboratory and the Southwest Research Institute. OLA's legacy includes high-resolution public data products used by the planetary science community, follow-on mission planning for sample-return missions like Hayabusa2, and methodological advances in small-body lidar operations that inform future instruments proposed to European Space Agency and international missions.

Category:Spacecraft instruments Category:Canadian Space Agency instruments Category:OSIRIS-REx