# K-band Ranging Instrument (KBR)
*sensor . products*

Microwave inter-satellite ranging instrument used by the GRACE and GRACE-FO twin-satellite gravity missions.

## Specifications
- **manufacturer**: nasa-jpl
- **product status**: operational
- **deployment context**: orbital
- **sensor**: {"instrument_family":"gravimeter","gravimeter_principle":"sst-ll","intersatellite_distance_km":220,"temporal_sampling_days":30,"notes":"K/Ka-band microwave ranging between paired spacecraft; used with GPS orbit data and accelerometer observations in GRACE and GRACE-FO gravity-field processing."}
- **entity type**: sensor
- **last verified date**: 2026-06-08
- **verified by**: agency-doc
- **claim status**: agency-sourced
- **provider**: nasa-jpl
- **attributes**: {"kind":"sensor","manufacturer":"nasa-jpl","product_status":"operational","deployment_context":"orbital","description":"Microwave inter-satellite ranging instrument used by the GRACE and GRACE-FO twin-satellite gravity missions.","sensor":"{\"instrument_family\":\"gravimeter\",\"gravimeter_principle\":\"sst-ll\",\"intersatellite_distance_km\":220,\"temporal_sampling_days\":30,\"notes\":\"K/Ka-band microwave ranging between paired spacecraft; used with GPS orbit data and accelerometer observations in GRACE and GRACE-FO gravity-field processing.\"}"}
- **relevance**: in-scope

## Editorial
K-band Ranging Instrument (KBR) is the microwave inter-satellite ranging payload used by the GRACE and GRACE-FO twin-satellite gravity missions. The instrument measures changes in separation between paired spacecraft, nominally about 220 km apart, so orbit dynamics can be inverted into monthly gravity-field change [^podaac-grace][^gracefo-spacecraft]. GRACE-FO retained K/Ka-band microwave ranging as its science ranging system and added the Laser Ranging Interferometer as a technology demonstration [^gracefo-spacecraft]. On GRACE, K-band range-rate measurements were combined with GPS orbit data and accelerometer measurements to produce Level-1B inputs for gravity-field processing [^podaac-grace].

## Compositional position
- grace (missions) --[mission_payloads]--> K-band Ranging Instrument (KBR)
- grace-fo (missions) --[mission_payloads]--> K-band Ranging Instrument (KBR)

## Sources
- [podaac-grace] | Gravity Recovery and Climate Experiment, PO.DAAC | https://podaac.jpl.nasa.gov/GRACE | tier=agency-doc | accessed=2026-06-08
- [gracefo-spacecraft] | GRACE-FO spacecraft and instruments, NASA JPL | https://www.jpl.nasa.gov/news/press_kits/grace-fo/mission/spacecraft/ | tier=agency-doc | accessed=2026-06-08

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Source: https://eo-atlas.org/products/sensor/kbr
Maintainer: SpectraWorks B.V. (CC-BY 4.0)