Melissa Soriano

Direct-to-Earth communications with Mars Science Laboratory during Entry, Descent, and Landing

Mars Science Laboratory (MSL) undergoes extreme heating and acceleration during Entry, Descent, and Landing (EDL) on Mars. Unknown dynamics lead to large Doppler shifts, making communication challenging. During EDL, a special form of Multiple Frequency Shift Keying (MFSK) communication is used for Direct-To-Earth (DTE) communication. The X-band signal is received by the Deep Space Network (DSN) at the Canberra Deep Space Communication complex, then down-converted, digitized, and recorded by open-loop Radio Science Receivers (RSR), and decoded in real-time by the EDL Data Analysis (EDA) System. The EDA uses lock states with configurable Fast Fourier Transforms to acquire and track the signal. RSR configuration and channel allocation is shown. Testing prior to EDL is discussed including software simulations, test bed runs with MSL flight hardware, and the in-flight end-to-end test. EDA configuration parameters and signal dynamics during pre-entry, entry, and parachute deployment are analyzed. RSR and EDA performance during MSL EDL is evaluated, including performance using a single 70-meter DSN antenna and an array of two 34-meter DSN antennas as a back up to the 70-meter antenna.

Spacecraft-to-earth communications for Juno and Mars Science Laboratory critical events

This paper describes the Entry, Descent, and Landing (EDL) Data Analysis system (EDA). The EDA software supports the real-time interpretation of Multiple Frequency-Shift Keying (MFSK) tones provided by the spacecraft. The objective of this software is to provide communication of status between the spacecraft and the mission personnel on Earth during critical events when low rate telemetry is not possible due to high dynamics and low signal-to-noise ratio (SNR). Although these communications cannot be used to affect the landing due to the length of time required at these distances, this information is important in the case of a mission failure. Mars Science Laboratory will utilize the EDA software during EDL. Juno usage will include Jupiter orbital insertion (JOI), with predicted SNR of 12-15 dB-Hz. Results are presented from the Juno tones test. Simulated signals were also generated for Juno at JOI and Mars Science Laboratory (MSL) EDL and these results are analyzed.

Implementation of a Digital Signal Processing subsystem for a Long Wavelength Array station

This paper describes the implementation of a Digital Signal Processing (DP) subsystem for a single Long Wavelength Array (LWA) station.12 The LWA is a radio telescope that will consist of many phased array stations. Each LWA station consists of 256 pairs of dipole-like antennas operating over the 10–88 MHz frequency range. The Digital Signal Processing subsystem digitizes up to 260 dual-polarization signals at 196 MHz from the LWA Analog Receiver, adjusts the delay and amplitude of each signal, and forms four independent beams. Coarse delay is implemented using a first-in-first-out buffer and fine delay is implemented using a finite impulse response filter. Amplitude adjustment and polarization corrections are implemented using a 2×2 matrix multiplication.

Cold atom laboratory mission system design

Cold Atom Laboratory (CAL) is a multi-user facility that will provide the ability to study ultra-cold quantum gases in a microgravity environment. The laboratory is an internal payload that will operate on the International Space Station (ISS) in 2016. Principal Investigators from various universities will trade off in designing experiment sequences that vary different parameters, such as magnetic field strength or timing. The primary science data consists of two images of the cold atoms captured successively at the end of each experiment.

Improved spacecraft tracking and navigation using a Portable Radio Science Receiver

The Portable Radio Science Receiver (PRSR) is a suitcase-sized open-loop digital receiver designed to be small and easy to transport so that it can be deployed quickly and easily anywhere in the world. The PRSR digitizes, down-converts, and filters using custom hardware, firmware, and software. Up to 16 channels can be independently configured and recorded with a total data rate of up to 256 Mbps. The design and implementation of the systems hardware, firmware, and software is described. To minimize costs and time to deployment, our design leveraged elements of the hardware, firmware, and software designs from the existing full-sized operational (non-portable) Radio Science Receivers (RSR) and Wideband VLBI Science Receivers (WVSR), which have successfully supported flagship NASA deep space missions at all Deep Space Network (DSN) sites. We discuss a demonstration of the PRSR using VLBI, with one part per billion angular resolution: 1 nano-radian / 200 μas. This is the highest resolution astronomical instrument ever operated solely from the Southern Hemisphere. Preliminary results from two sites are presented, including the European Space Agency (ESA) sites at Cebreros, Spain and Malargüe, Argentina. Malargües South American location is of special interest because it greatly improves the geometric coverage for spacecraft navigation in the Southern Hemisphere and will for the first time provide coverage to the 1/4 of the range of declination that has been excluded from reference frame work at Ka-band.

Development of the science data system for the international space station Cold Atom Lab

Cold Atom Laboratory (CAL) is a facility that will enable scientists to study ultra-cold quantum gases in a microgravity environment on the International Space Station (ISS) beginning in 2016. The primary science data for each experiment consists of two images taken in quick succession. The first image is of the trapped cold atoms and the second image is of the background. The two images are subtracted to obtain optical density. These raw Level 0 atom and background images are processed into the Level 1 optical density data product, and then into the Level 2 data products: atom number, Magneto-Optical Trap (MOT) lifetime, magnetic chip-trap atom lifetime, and condensate fraction. These products can also be used as diagnostics of the instrument health. With experiments being conducted for 8 hours every day, the amount of data being generated poses many technical challenges, such as downlinking and managing the required data volume. A parallel processing design is described, implemented, and benchmarked. In addition to optimizing the data pipeline, accuracy and speed in producing the Level 1 and 2 data products is key. Algorithms for feature recognition are explored, facilitating image cropping and accurate atom number calculations.

Design and implementation of a Deep Space Communications Complex downlink array

This paper describes the design and implementation of an array system that includes a frequency domain beamformer that will coherently combine the downlinked signals from up to eight inputs at each of NASAs three Deep Space Communications Complexes (DSCC). The array signal processor digitizes inputs with an intermediate frequency (IF) bandwidth of 100 to 600 MHz, coherently combines the inputs digitally, and transforms the combined waveform back to analog. Real-time correlation measurements are used for delay and phase calibration, allowing the system to adjust for atmospheric variations. A Downlink Array system is operational at each DSCC. Initial results from passes with the New Horizons spacecraft are presented and system performance is analyzed.