Engineering topics
Cesarone, Robert J.
Publications and source records attributed to Cesarone, Robert J..
Emergency Communications for NASA's Deep Space Missions
The ability to communicate with spacecraft during emergencies is a vital service that NASA's Deep Space Network (DSN) provides to all deep space missions. Emergency communications is characterized by low data rates(typically is approximately10 bps) with the spacecraft using either a low-gain antenna (LGA, including omnidirectional antennas) or,in some cases, a medium-gain antenna (MGA). Because of the use of LGAs/MGAs for emergency communications, the transmitted power requirements both on the spacecraft andon the ground are substantially greater than those required for normal operations on the high-gain antenna (HGA) despite the lower data rates. In this paper, we look at currentand future emergency communications capabilities available to NASA's deep-space missions and discuss their limitations in the context of emergency mode operations requirements.These discussions include the use of the DSN 70-m diameter antennas, the use of the 34-m diameter antennas either alone or arrayed both for the uplink (Earth-to-spacecraft) and the downlink (spacecraft-to-Earth), upgrades to the ground transmitters, and spacecraft power requirements both with unitygain (0 dB) LGAs and with antennas with directivity (>0 dB gain, either LGA or MGA, depending on the gain). Also discussed are the requirements for forward-error-correctingcodes for both the uplink and the downlink. In additional, we introduce a methodology for proper selection of a directionalLGA/MGA for emergency communications.
The Next 25 Years of Deep Space Navigation
This slide presentation reviews the missions that will be flown into deep space in the next 25 years, the navigational challenges for these missions, and the strategies that will be used to overcome these challenges. The challenges include: (1) an incresed need for autonomous navigation, (2) an increased use of in-situ and optical navigation, (3) an increased use of low-thrust propulsion, (4) an increased need for higher accuracy in guidance, navigation, and control, and an increased need for integration between flight path and attitude control. The enabling strategies that are planned for use are: (1) Advance Radio-Metric Tracking Capabilities, (2) Expand the Use of Optical Navigation, (3) Develop General-Purpose Autonomous Navigation Capabilities, (4) Improve Frequency and Timing Systems, and (5) Develop In-situ Tracking Infrastructure. Future trends that are being developed are Optical and Autonomous Navigation
The Next 25 Years of Deep Space Navigation
This paper reviews the most probable set of NASA deep space missions that will be launched in the next twenty-five years, discusses the navigational challenges that will confront them, and outlines the most probable solutions to these challenges.
DSN Antenna Array Architectures Based on Future NASA Mission Needs
A flexible method of parametric, full life-cycle cost analysis has been combined with data on NASA's future communication needs to estimate the required number and operational dates of new antennas for the Deep Space Network (DSN). The requirements were derived from a subset of missions in the Integrated Mission Set database of NASA's Space Communications Architecture Working Group. Assuming that no new antennas are 'constructed', the simulation shows that the DSN is unlikely to meet more than 20% of mission requirements by 2030. Minimum full life-cycle costs result when antennas in the diameter range, 18m-34m, are constructed. Architectures using a mixture of antenna diameters produce a slightly lower full life-cycle cost.
The JPL roadmap for Deep Space navigation
This paper reviews the tentative set of deep space missions that will be supported by NASA's Deep Space Mission System in the next twenty-five years, and extracts the driving set of navigation capabilities that these missions will require. There will be many challenges including the support of new mission navigation approaches such as formation flying and rendezvous in deep space, low-energy and low-thrust orbit transfers, precise landing and ascent vehicles, and autonomous navigation. Innovative strategies and approaches will be needed to develop and field advanced navigation capabilities.
Architectural prospects for lunar mission support
A top-level architectural approach facilitates the provision of communications and navigation support services to the anticipated lunar mission set. Following the time-honored principles of systems architecting, i.e., form follows function, the first step is to define the functions or services to be provided, both in terms of character and degree. These will include communication as well as trackin and navigation services.
Transforming the Deep Space Network into the Interplanetary Network
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Transforming the Deep Space Network into the Interplanetary Network
Space exploration missions are undergoing a significant transformation as are the expectations of their scientific investigators and the public who participate in these great voyages of exploration.
A Study of Phased Array Antennas for NASA's Deep Space Network
In this paper we briefly discuss various options but focus on the feasibility of the phased arrays as a viable option for this application. Of particular concern and consideration will be the cost, reliability, and performance compared to the present 70-meter antenna system, particularly the gain/noise temperature levels in the receive mode. Many alternative phased arrays including planar horizontal arrays, hybrid mechanically/electronically steered arrays, phased array of mechanically steered reflectors, multi-faceted planar arrays, phased array-fed lens antennas, and planar reflect-arrays are compared and their viability is assessed. Although they have many advantages including higher reliability, near-instantaneous beam switching or steering capability, the cost of such arrays is presently prohibitive and it is concluded that the only viable array options at the present are the arrays of a few or many small reflectors. The active planar phased arrays, however, may become feasible options in the next decade and can be considered for deployment in smaller configurations as supplementary options.
(abstract) Telecommunications for Mars Rovers and Robotic Missions
Telecommunications plays a key role in all rover and robotic missions to Mars both as a conduit for command information to the mission and for scientific data from the mission. Telecommunications to the Earth may be accomplished using direct-to-Earth links via the Deep Space Network (DSN) or by relay links supported by other missions at Mars. This paper reviews current plans for missions to Mars through the 2005 launch opportunity and their capabilities in support of rover and robotic telecommunications.
(abstract) Space Communications Technologies for Interstellar Missions
This paper will examine candidate communications architectures for potential interstellar missions in an effort to determine feasibility for such links and to identify likely technology advances that will be needed to support such endeavors. Examination of this challenging and futuristic communications problem may serve to guide the direction and advancement of space telecommunications technologies useful for other nearer-term applications.