The OSIRIS-REx Laser Altimeter (OLA) is a scanning and lidar (Light Detection and Ranging uses laser pulses) instrument that will provide high resolution topographical information throughout the entire mission. The information received by OLA will create global topographic maps of Bennu, local maps of candidate sample sites, ranging in support of other instruments, and support navigation and gravity analyses.
More Information: Detailed Specifications and Instrument Operations
OLA will scan the surface of Bennu at specific intervals in the mission to rapidly map out the entire surface of the asteroid to achieve its primary objective of producing local and global topographic maps. What OLA brings back about Bennu will also be used to develop a control network relative to the center of mass of the asteroid and enhance and refine gravitational studies of Bennu.
OLA has a single common receiver and two complementary transmitter assemblies which enhance the resolution of the information brought back. OLA’s high-energy laser transmitter is used for ranging and mapping from 1 to 7.5 km. The low-energy transmitter is used for ranging and imaging at smaller distances (500 m to 1 km). The repetition rate of these transmitters sets the data acquisition rate of OLA. Laser pulses from both the low and high energy transmitters are directed onto a movable scanning mirror, which is co-aligned with the field of view of the receiver telescope limiting the effects of background solar radiation. Each pulse provides target range, azimuth, elevation, received intensity and a time-tag.
OLA has 4 operational modes. These are:
(1) Initialization - Optical head is off, communications and data transfer enabled;
(2) Standby- Transmitter temperatures are controlled to operational temperatures, communications and data transfer enabled;
(3) High Energy – For mission phases when the range is =1 km, OLA uses the high-energy transmitter, data collection is enabled; and
(4) Low Energy - For mission phases when the range is <1 km, OLA uses the low-energy transmitter, data collection is enabled.
A simple parameterized raster scanning pattern is applicable and adequate for all mission phases. OLA exceeds the mission requirements in all phases. In addition to its enhanced precision, after Orbital Phase B, OLA exceeds the coverage and data quality of all previous missions, surpassing the Hayabusa mission coverage of Itokawa by a factor of 20, and the NEAR laser rangefinder results at 433 Eros by a factor of 2 after correcting for the significant difference in size between Eros and Bennu. The OLA data will therefore provide fundamental and unprecedented asteroid science on asteroid shape and topography, providing invaluable insights on the surface processes controlling the evolution of Bennu, and on the source materials of the sample collected by the OSIRIS-REx spacecraft. OLA will also enhance performance of the other remote sensing instruments (images and spectra) by setting precise range, scale and surface slope information.
OLA is expected to be highly tolerant of contamination, but possesses no dust protection requirements, as it will not be used after the first TAG sampling.
The OLA science team is an integrated Canada/US team consisting of Alan Hildebrand (Can. PI, University of Calgary), Michael Daly (Can. Deputy PI and IS, York University), Olivier Barnouin (US IS, Johns Hopkins University/APL), Beau Bierhaus (US DIS, LM), with support from heritage instrument developers MDA and Optech.