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Young, Larry

Publications and source records attributed to Young, Larry.

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2022

Mid-Air Helicopter Delivery at Mars Using a Jetpack

Mid-Air Helicopter Delivery (MAHD) is a new Entry, Descent and Landing (EDL) architecture to enable in situ mobility for Mars science at lower cost than previous rover missions. It uses a jetpack to slow down a Mars Science Helicopter (MSH) after separation from the backshell, and reach aerodynamic conditions suitable for helicopter take-off in mid air. MAHD's lander-free approach leaves enough room in the aeroshell to accommodate larger rotors. This drastically improves flight performance compared to heritage EDL approaches, notably +60\% science payload mass. MAHD also brings cost savings, a simpler architecture, improved surface access and can reach higher elevations on Mars. This paper introduces a design for the MAHD system architecture and operations. We present a mechanical configuration which fits both MSH and the jetpack within the 2.65-m Mars heritage aeroshell, and a jetpack control architecture which fully leverages the available helicopter avionics. We discuss preliminary numerical models of the flow dynamics resulting from the interaction between the jets, the rotors and the side winds. We define a force-torque sensing architecture capable of handling the wind and trimming the rotors to prepare for safe take-off. Finally, we analyze the dynamic environment and closed-loop control simulation results to demonstrate the preliminary feasibility of MAHD.

Balaram, J.↗
NASA NTRS2018

A GNSS Receiver for Small-Sats Enabling Precision POD, Radio Occultations and Reflections

A low cost, low power, and low mass GNSS receiver (called Cion) has been developed and is currently flying on the CICERO cubesats. The receiver was designed in less than a year by JPL for Tyvak and GeoOptics for use in the GeoOptics CICERO constellation and leverages 25 years of JPL GNSS reciever design experience. Cion uses a commercial off-the-shelf (COTS) computer along with existing space qualified RF down-converters, software, and firmware to produce atmospheric Radio Occultation (RO) data. By combining a FPGA with dual core ARM processor and an embedded system controller, the Xilinx Zynq processor is an enabling technology that provides a customizable digital signal processing platform integrated into the computer (System on a chip) and enables off-the-shelf hardware to become the main engine behind this software defined radio. Using Linux for the on-board computer allows for fast development times and liberal use of existing open source software libraries. The parts of the receiver that require realtime implementation are performed in the Field Programmable Gate Array (FPGA), which can also be reprogrammed in flight. While the Zynq is not rad hard, the silicon on insulator (SOI) technology is rad tolerant ‘by accident’, allowing for its use in many space-based applications. Early results show that the Cion is working as designed, has demonstrated the first known GLONASS occultations, and obtains high quality atmospheric profiles with excellent lower troposphere penetration (near Earth’s surface).

Young, Larry↗
NASA NTRS2017

Flight Dynamics of Mars Helicopter

Starting with the first attempted flybys of Mars in the 1960s, human exploration of the Red Planet has evolved through ever-more sophisticated means, with the use of orbiters, stationary landers, and more recently rovers that have traveled over distances of tens of kilometers in search of new knowledge. Yet, despite discussion since the early days of space exploration, no mission has so far attempted to unlock the aerial dimension of Mars exploration through the use of atmospheric flyers. This could be about to change, as NASA is currently considering sending a small helicopter to the Martian surface as part of a future mission, as a technology demonstration to verify the feasibility and utility of using helicopters for future Mars exploration. The use of helicopters promises to bridge a resolution gap in current Mars exploration capabilities—betweeen orbiters providing large-area imagery at low resolution, and rovers that provide detailed imagery limited by line-of-sight from the current rover location. Paired with a rover, a helicopter can act as a forward reconnaisance platform, helping to identify promising science targets or mapping the terrain ahead of the rover. Looking further ahead, helicopters may one day carry their own science payloads to areas that are inaccessible to rovers.

San Martin, Miguel↗
NASA NTRS2017

Flight Dynamics of Mars Helicopter

Helicopters have the potential to transform Mars exploration by providing a highly mobile platform for forward reconnaissance as an aid for ground-based systems. Helicopter flight on Mars is challenging due to the extremely thin atmosphere, which is only partially offset by a reduction in gravity. NASA is considering the possibility of sending a small helicopter to the Martian surface as part of a future mission. In this paper we focus on flight dynamics and controllability issues for the proposed Mars Helicopter, in particular the areas in which the dynamics departs from typical behavior on Earth. We discuss insights gained from modeling and simulation, as well as system identification performed with a test vehicle in the relevant atmospheric condition, culminating in the first demonstration of controlled helicopter flight in Martian atmospheric conditions in May 2016.

San Martin, Miguel↗
NASA NTRS2008

Rotorcraft Technology for HALE Aeroelastic Analysis

Much of technology needed for analysis of HALE nonlinear aeroelastic problems is available from rotorcraft methodologies. Consequence of similarities in operating environment and aerodynamic surface configuration. Technology available - theory developed, validated by comparison with test data, incorporated into rotorcraft codes. High subsonic to transonic rotor speed, low to moderate Reynolds number. Structural and aerodynamic models for high aspect-ratio wings and propeller blades. Dynamic and aerodynamic interaction of wing/airframe and propellers. Large deflections, arbitrary planform. Steady state flight, maneuvers and response to turbulence. Linearized state space models. This technology has not been extensively applied to HALE configurations. Correlation with measured HALE performance and behavior required before can rely on tools.

Young, Larry↗
NASA NTRS2005

A Multi-Sensor Approach To Estimation of Tropospheric Delays

We will discuss techniques for optima1 integration of atmospheric measurements from collocated GPS receiver, pointed WVR, and a barometer, capitalizing on the unique strength of each sensor, and minimizing the impact of the sensor's weaknesses. The goal is to improve our ability to estimate line of sight (LOS) total atmospheric delay, which is required in support of certain high precision applications, such as radio science, and deep space navigation. The benefits from improved atmospheric sensing extend to many other applications such as geodesy and time transfer.

optical integration↗
NASA NTRS2004

NASA's global differential GPS system and the TDRSS augmentation service for satellites

NASA is planning to launch a new service for Earth satellites providing them with precise GPS differential corrections and other ancillary information enabling decimeter level orbit determination accuracy, and nanosecond time-transfer accuracy, onboard, in real-time. The TDRSS Augmentation Service for Satellites (TASS) will broadcast its message on the S-band multiple access channel of NASA's Tracking and Data Relay Satellite System (TDRSS). The satellite's phase array antenna has been configured to provide a wide beam, extending coverage up to 1000 km altitude over the poles. Global coverage will be ensured with broadcast from three or more TDRSS satellites. The GPS differential corrections are provided by the NASA Global Differential GPS (GDGPS) System, developed and operated by NASA's Jet Propulsion Laboratory. The GDGPS System employs a global ground network of more than 70 GPS receivers to monitor the GPS constellation in real time. The system provides real-time estimates of the GPS satellite states, as well as many other real-time products such as differential corrections, global ionospheric maps, and integrity monitoring. The unique multiply redundant architecture of the GDGPS System ensures very high reliability, with 99.999% demonstrated since the inception of the system in Early 2000. The estimated real time GPS orbit and clock states provided by the GDGPS system are accurate to better than 20 cm 3D RMS, and have been demonstrated to support sub-decimeter real time positioning and orbit determination for a variety of terrestrial, airborne, and spaceborne applications. In addition to the GPS differential corrections, TASS will provide real-time Earth orientation and solar flux information that enable precise onboard knowledge of the Earth-fixed position of the spacecraft, and precise orbit prediction and planning capabilities. TASS will also provide 5 seconds alarms for GPS integrity failures based on the unique GPS integrity monitoring service of the GDGPS System.

Global Postitioning Satellite (GPS)↗
NASA NTRS2004

From BlackJack to GOX: the transfer, test, and validation of the ROCSat-3 GPS occultation receiver

ROCSat-3's primary instrument is the GPS Occultation Receiver (GOX) and is based on the Jet Propulsion Laboratory's (JPL) proven BlackJack GPS Receiver. The COSMIC GOX receivers will demonstrate an important new operational data type for near-real-time assimilation into weather models by providing over 2500 atmospheric profiles per day with a global distribution.

GPS Occultation Receiver↗