Courtney Duncan

Real-Time Navigation for Mars Missions Using the Mars Network

A NASA Mars technology program task is developing a prototype, embedded, real-time navigation system for Mars final approach and entry, descent, and landing using the Mars Network’s Electra ultrahigh frequency transceiver. The Mars Network is ideally situated to provide spacecraft-to-spacecraft navigation via the Electra ultrahigh frequency transceiver, which is a versatile telecommunications payload that is capable of providing autonomous on-orbit, real-time trajectory determination using two-way Doppler measurements between a Mars approach vehicle and a Mars Network orbiter. A set of analyses based on the 2010 encounter at Mars between the MarsScienceLaboratory and theMarsReconnaissanceOrbiter demonstrate that the navigation system is capable of achieving a 300m or better atmosphere entry knowledge error and that the resulting technology is a key component to enabling pinpoint landing. The development approach, software design, and test results from an engineering development unit are presented.

Expected EDL navigation performance with spacecraft to spacecraft radiometric data

Pinpoint landing (defined for the purpose of this discussion as landing within 1km of a preselected target) is a key Advanced Entry, Descent and Landing (EDL) technology for future Mars landers. Key scientific goals for Mars exploration, such as the search for water and characterization of aqueous processes on Mars, the study of mineralogy and weathering of the Martian surface and the search for preserved biosignatures in Martian rocks, require placing landers at pre-defined locations of greatest scientific interest. The capability to land within 1 km of a pre-defined landing site will improve safety and enable landing within roving range of sites of scientific interest while avoiding hazardous areas. A critical component of the closed-loop guidance, navigation and control (GN&C) system required for pinpoint landing is position and velocity estimation in real time. Spacecraftto-spacecraft navigation will take advantage of the UHF link between two spacecraft (i.e. to an orbiter from an approaching lander for EDL telemetry relay) to build radiometric data, specifically the total count carrier phase of the Doppler shifted 2-Way coherent UHF signal, that are processed to determine position and velocity in real time. The improved onboard state knowledge provided by spacecraft-to-spacecraft navigation will reduce the landed position error and improve the performance of entry guidance. Results from the first of two years planned for this effort are documented here, including selection and documentation of prototype algorithms that will go forward into flight code along with analysis results used to define the algorithm set.

Real-Time EDL Navigation Performance Using Spacecraft to Spacecraft Radiometric Data

A two-year task sponsored by NASAs Mars Technology Programs Advanced Entry, Descent and Landing (EDL) work area includes investigation of improvements to EDL navigation by processing spacecraft-to-spacecraft radiometric data. Spacecraft-to-spacecraft navigation will take advantage of the UHF link between two spacecraft (i.e. to an orbiter from an approaching lander for EDL telemetry relay) to build radiometric data, specifically the velocity between the two spacecraft along the radio beam, that are processed to determine position and velocity in real time. The improved onboard state knowledge provided by spacecraft-to-spacecraft navigation will improve the performance of entry guidance by providing a more accurate state estimate and ultimately reduce the landed position error. A previous paper documented the progress of the first year of this task, including the spacecraft definitions, selection and documentation of the required algorithms and analysis results used to define the algorithm set. The final year of this task is reported here. Topics include modifications to the previously selected algorithm set for implementation, and performance of the implemented algorithms in a stand-alone filter, on an emulator of the target processor and finally on a breadboard processing unit.

Expected Performance of the Electra Transceiver for Mars Missions

The Electra UHF Transceiver, developed at NASA’s Jet Propulsion Laboratory, will provide accurate trajectory determination for future Mars missions. Autonomous on-orbit navigation and guidance will enable maneuvers such as aerocapture and surface landings within 1 km. In order for the Electra to perform its function, it must be able to acquire and track a 2-way signal under a wide range of vehicle dynamics and signal strengths as a vehicle approaches Mars. In anticipation of the testing of two Engineering Development Units of the Electra, a standard approach trajectory is deflned using Mars Science Laboratory as an example. This trajectory demonstrates the dynamic operating environment that the tracking loops will encounter during a planetary approach. A detailed link analysis is presented for a variety of receiver design and system model parameters. It is determined that the current hardware design should be able to establish a measurement link at a range of 100,000 km from an orbiting vehicle. This initial acquisition range may be extended with future algorithm enhancements.

Real Time Mars Approach Navigation aided by the Mars Network

A NASA Mars technology project is described that is building a prototype embedded real time Mars approach navigation capability which can be hosted on the Mars Network’s Electra transceiver. The paper motivates the reason for doing real time Mars approach navigation via a set of analyses demonstrating its utility for enabling Mars pin-point landing (< 1-km landing error). The development approach, software design, and test results are discussed. Finally, the way forward towards a flight demonstration on the Mars Science Laboratory is presented

LMRST-Sat: A small, high value-to-cost mission

The Communications, Tracking, and Radar Division at NASAs Jet Propulsion Laboratory (JPL) and the Space and Systems Development Lab (SSDL) at Stanford University are collaborating to fly a nanosat-class mission for costs usually associated with small technology development tasks, a few

Mars Helicopter Technology Demonstrator

100K. The mission hosts a JPL-developed Low Mass Radio Science Transponder (LMRST) on a university-class CubeSat bus as a satellite that occupies a total volume of two liters plus deployable antennas. In low earth orbit, the LMRST payload will provide a far-field source for calibration of Deep Space Network X-Band equipment in the form of an integer turnaround X-Band transponder with support for ranging modulation. The CubeSat bus provided by SSDL supplies power, structural support, and command and telemetry while on orbit. CubeSat development and operations are conducted as a student project.

Metrology, attitude, and orbit determination for spaceborne interferometric synthetic aperture radar

Nomenclature ADC Analog-to-Digital Converter BIB Battery Interface Board COTS Commerical Off-the-shelf CPU Central Processor Unit dof degrees-of-freedom ECM Electronics Core Module EDM Engineering Design Model FC Flight Controller FFB FPGA/Flight-Controller Board FPGA Field-Programmable Gate Array GPIO General Purpose Input/Ouput GPS Global Positioning System IC Integrated Circuit IMU Inertial Measurement Unit MCU Microcontroller Unit MEMS Microelectromechanical System NAV Navigation NSB Navigation/Servo Controller Board ROI Region of Interest RTE Return-to-Earth SEL Single-Event Latch-up SOM System On a Module SPI Serial Peripheral Interface TCB Telecommunications Board UART Universal Asynchronous Receiver/Transmitter