NEAR MSI Albedo Mosaics

Originators

Golish, D.R., Brodbeck, J.I., Webber, C., Becker, K.J., Bennett, C.A., DellaGiustina, D.N.

Publisher

USGS Astrogeology Science Center

Publication Date

2023-06-16

Abstract

This download consists of 14 Eros global albedo mosaics across 7 filters and 2 map projections (Simple Cylindrical and Sinusoidal). The data is hosted as GeoTiffs with PDS4 and ISIS3 detached labels. A full description of the data is available in the download and the ancillary PDF. New data Recently, MSI data has been archived (DOI: 10.17189/sv8w-5125) with a new deblurring method applied (Golish et al., 2023). This method uses the same mathematical foundation as the original, but develops new blur models and processes the images to avoid edge-artifacts from the Fourier transforms. The new data has improved qualitative sharpness for all filters, particularly those at extreme wavelengths. With this new data, we generate global albedo maps for Eros in each of MSI’s seven filters. To enable color analyses (e.g., color ratios, band depths), we create albedo maps which are corrected to 0 degrees phase (0 deg incidence, 0 deg emission) with per-filter photometric models, rather than 30/30/0 angles used for the existing published basemaps.
Shape model The shape model used to control and project the images for mosaicking is publicly available (Gaskell, 2020) at the Planetary Data System Small Bodies Node (PDS SBN). The shape model was created from 21,135 MSI images consisting of 1,579,014 vertices and 3,145,728 plates with an average resolution of 27 meters. The model contains 9,443,000 voxels with 75,554 coarse voxels.

• filter 1, 550 nm
• filter 2, 450 nm
• filter 3, 760 nm
• filter 4, 950 nm
• filter 5, 900 nm
• filter 6, 1000 nm
• filter 7, 1050 nm

Backgroud: The Near Earth Asteroid Rendezvous (NEAR) – Shoemaker spacecraft observed asteroid 433 Eros for approximately 1 year in 2000 and 2001. While in a series of orbits (with distances to surface varying from hundreds to tens of km), NEAR’s Multispectral Imager (MSI) acquired over 100,000 images with of the surface in all seven of its narrowband chromatic filters. The majority of these images were acquired with the 950 nm filter, but enough were acquired in all filters to image most of the asteroid surface. Creating global mosaics with these images is challenging for two reasons. First, Eros’s extremely irregular shape made imaging under consistent conditions infeasible. The surface was heterogeneously imaged with different resolutions and photometric conditions. Moreover, the irregular shape makes image registration (both image to image and image to shape model) more difficult. It is correspondingly difficult to map the shape to any common map projections. Second, a failed burn before entering orbit deposited hydrazine fuel on the outer surface of the MSI, causing significant blurring of all surface-resolved images. The MSI team, during mission operations, developed an effective deblurring technique that they applied to all images (Li et al., 2002). The technique struggled with the highest and lowest wavelengths, but worked well in the middle of the MSI bandpass. As such, most images were acquired with the central filter (950 nm) and much of the Eros surface science was done at this wavelength. Accordingly, the two existing published basemaps of the Eros surface (Bussey et al., 2002) were generated using 950 nm images.
References: Golish, D.R., DellaGiustina, D.N., Becker, K.J., Bennett, C.A., Robinson, M., Crombie, M.K., 2023. Blur remediation in NEAR MSI images. Icarus 400, 115536. https://doi.org/10.1016/j.icarus.2023.115536. Bussey, D.B.J., Robinson, M.S., Edwards, K., Thomas, P.C., Joseph, J., Murchie, S., Veverka, J., Harch, A.P., 2002. 433 Eros Global Basemap from NEAR Shoemaker MSI Images. Icarus 155, 38–50.https://doi.org/10.1006/icar.2001.6771. Gaskell, R.W., 2020. Gaskell Eros Shape Model V1.0, urn:nasa:pds:gaskell.ast-eros.shape-model::1.0 [WWW Document]. NASA Planetary Data System. URL https://doi.org/10.26033/0hpf-4e64. Li, H., Robinson, M.S., Murchie, S., 2002. Preliminary Remediation of Scattered Light in NEAR MSI Images. Icarus 155, 244–252. https://doi.org/10.1006/icar.2001.6745.

Purpose

Build global maps of Eros in the 7 available filters taken by MSI.

Contact and Distribution

Format

Global Mosaic, Image, Raster Data, Remote-sensing Data

Access Constraints

None

Access Scope

PDS

Use Constraints

Please cite authors

Supplemental Information

https://astrogeology.usgs.gov/search/map/Eros/MSI/NEAR_MSI_Deblurred_Images, https://doi.org/10.17189/sv8w-5125, https://doi.org/10.1016/j.icarus.2023.115536

Native Data Set Environment

ISIS v3

Astrogeology Theme

Asteroids, Cartography, Geophysical, Image Processing, Photogrammetry, Remote Sensing

Mission Names

NEAR

Online Package Link

https://astrogeology.usgs.gov/search/map/near_msi_albedo_mosaics

External File Size

(Archive 2.5 GB)

Online File Link

https://asc-pds-individual-investigations.s3.us-west-2.amazonaws.com/eros_global-albedo-maps_golish_2023/eros_global-albedo-maps_golish_2023.zip

Contact Address

2255 N. Gemini Drive

Contact City

Flagstaff

Contact State

AZ

Contact Postal Code

86001

Contact Email

astroweb@usgs.gov

Data Status and Quality

Time Period of Content (start)

2000-01-12

Time Period of Content (stop)

2001-02-06

Currentness Reference

Ground condition

Progress

Complete

Update Frequency

None planned

Logical Consistency

We used published photogrammetric control networks to register the images to each other and to the Eros shape model (Gaskell, 2020). The shape model itself is generated from the same control network. The control network includes all images for all filters used in the mosaics. We analyzed the quality of the published control networks to determine the resulting accuracy of the mosaics. The analysis used simulated images (generated with the published shape model and control networks) with MSI images. Control points were identified and compared in both sets of images to determine the offset between the two. All control points were merged into a large dataframe producing 789, 634 ground control points. Aggregate data for each image was generated for the plots provided below. The vast majority of the data were registered to within 2-3 pixels. The mosaics were generated at 10 m/pixel, therefore the average surface misregistration is between 10 and 30 meters.

Completeness Report

The MSI dataset at Eros is large and heterogeneous. While the vast majority of images were acquired with filter 4, each filter has at least a few hundred to a few thousand images. We used a Postgres SQL database to filter the images and extract lists according to a variety of metrics.

Process Description

also see Golish, D.R., DellaGiustina, D.N., Becker, K.J., Bennett, C.A., Robinson, M., Crombie, M.K., 2023. Blur remediation in NEAR MSI images. Icarus 400, 115536. https://doi.org/10.1016/j.icarus.2023.115536

Source Title

Near Earth Asteroid Rendezvous (NEAR) Data Archive

Source Online Linkage

https://pds-smallbodies.astro.umd.edu/data_sb/missions/near/index.shtml

PDS Status

PDS 4 Like

Geospatial Information

Target

Eros

System

Small Bodies

Minimum Latitude

-90

Maximum Latitude

90

Minimum Longitude

0

Maximum Longitude

360

Direct Spatial Reference Method

Raster

Object Type

Grid Cell

Raster Row Count (lines)

5341

Raster Column Count (samples)

10682

Bit Type (8, 16, 32)

32

Quad Name

Radius A

17000

Radius C

17000

Bands

1

Pixel Resolution (meters/pixel)

10

Scale (pixels/degree)

29.67

Map Projection Name

Simple Cylindrical

Latitude Type

Planetocentric

Longitude Direction

Positive East

Longitude Domain

0 to 360