Rolf Hastrup

Mars network for enabling low-cost missions

Abstract Mars is the first planet where significant steps are being taken to establish a “virtual presence throughout the solar system”—one of NASAs strategic goals. Preparations are under way to begin implementation of an evolving Mars Network of satellites to meet the future communications and navigation challenges of the ongoing international Mars exploration campaign. The Mars Network concept is to deploy two classes of satellites. The first class is very low-cost MicroSats, launched piggyback on Ariane 5, for deployment in 800-km circular orbits in a variety of planes for frequent global contacts. From their low orbits, the MicroSats provide highly efficient relay communication links for small, energy constrained landers, and their orbital motion provides strong navigation signatures. The second, larger class of Mars areostationary satellites (MARSats) are deployed in 17,000-km orbits with 1-sol periods, as required, to support very high bandwidth users.

Integrated network architecture for sustained human and robotic exploration

The National Aeronautics and Space Administration (NASA) Exploration Systems Mission Directorate is planning a series of human and robotic missions to the Earths Moon and to Mars. These missions will require telecommunication and navigation services. This paper sets forth presumed requirements for such services and presents strawman lunar and Mars telecommunications network architectures to satisfy the presumed requirements. The paper suggests that a modest ground network would suffice for missions to the near-side of the Moon. A constellation of three Lunar Telecommunications Orbiters connected to a modest ground network could provide continuous redundant links to a polar lunar base and its vicinity. For human and robotic missions to Mars, a pair of areostationary satellites could provide continuous redundant links between a mid-latitude Mars base and Deep Space Network antennas augmented by large arrays of 12-m antennas

Communicating with Mars during periods of solar conjunction

A reliable communications link between Mars and Earth will be required during the initial phase of the human exploration of Mars. The direct communications link can easily be realized during most of the 780-day Earth-Mars synodic period, except when this link encounters increased intervening charged particles during superior solar conjunctions. The effects of solar charged particles are expected to corrupt the data signals to varying degrees. During superior solar conjunctions of interplanetary spacecraft, flight projects routinely scale down or suspend operations by invoking command moratoriums, reducing tracking schedules, and progressively lowering data rates. The actual operations scenarios will vary between flight projects and from conjunction to conjunction. This paper presents results of a study conducted to determine to what extent and by what techniques communications may be maintained throughout Mars-Sun-Earth superior conjunction periods that could occur during early human Mars exploration missions. Using a number of techniques discussed in this paper, it should be possible to maintain some degree of communication throughout all of the superior conjunctions occurring between 2015 and 2026, except for one occurring in 2023, in which actual occultation of the signal source by the Suns disk occurs.

Deep space telecommunications, navigation, and information management: Support of the space exploration initiative

Abstract The United States Space Exploration Initiative (SEI) calls for the charting of a new and evolving manned course to the Moon, Mars, and beyond. This paper discusses key challenges in providing effective deep space telecommunications, navigation, and information management (TNIM) architectures and designs for Mars exploration support. The fundamental objectives are to provide the mission with means to monitor and control mission elements, acquire engineering, science, and navigation data, compute state vectors and navigate, and move these data efficiently and automatically between mission nodes for timely analysis and decision-making. Although these objectives do not depart, fundamentally, from those evolved over the past 30 years in supporting deep space robotic exploration, there are several new issues. This paper focuses on summarizing new requirements, identifying related issues and challenges, responding with concepts and strategies which are enabling, and, finally, describing candidate architectures, and driving technologies. The design challenges include the attainment of: 1) manageable interfaces in a large distributed system, 2) highly unattended operations for in-situ Mars telecommunications and navigation functions, 3) robust connectivity for manned and robotic links, 4) information management for efficient and reliable interchange of data between mission nodes, and 5) an adequate Mars-Earth data rate.

Mars relay satellite: Key to enabling & enhancing low cost exploration missions

Abstract Currently there is a renewed focus on Mars exploration both by NASA and the international community. This renewed interest appears to be manifesting itself in numerous low-cost missions employing small, lightweight elements. A formidable problem facing these low-cost missions is communications with Earth. Providing adequate direct-link performance has very significant impacts on spacecraft power, pointing, mass and overall complexity. Additionally, there are serious connectivity constraints, especially at higher latitudes. A Mars relay satellite can enable and enhance low-cost missions to Mars, and the multi-mission application of a Mars relay satellite is especially attractive. Key attributes of a Mars relay network architecture are presented, including: in-situ and Mars-Earth connectivity, performance and operational benefits for the mission elements and the Deep Space Network. In addition, the paper illustrates that a variety of orbits may be employed for relay support, including orbits also suitable for the multi-functional role of remote sensing.

Microwave systems applications in deep space telecommunications and navigation: Space Exploration Initiative architectures

The US Space Exploration Initiative (SEI) calls for the charting of a new and evolving manned course to the Moon, Mars, and beyond. The fundamental SEI support objectives are to provide the mission with means to monitor and control mission elements, acquire engineering, science, and navigation data, compute state vectors and navigate, and move these data efficiently and automatically between mission nodes for timely analysis and decision-making. Microwave links provide the means to communicate between system nodes, and the essential radio metrics to navigate; later, these probably will be augmented with optical links. The general mission telecommunications and navigation support requirements and resulting architectures for SEI mission support are described, and then the implications of these on the role of microwave technology in these architectures, particularly for Mars exploration support, are discussed. >

Evolving earth-based and in-situ satellite network architectures for Mars communications and navigation support

Results of on-going studies to develop navigation/telecommunications network concepts to support future robotic and human missions to Mars are presented. The performance and connectivity improvements provided by the relay network will permit use of simpler, lower performance, and less costly telecom subsystems for the in-situ mission exploration elements. Orbiting relay satellites can serve as effective navigation aids by supporting earth-based tracking as well as providing Mars-centered radiometric data for mission elements approaching, in orbit, or on the surface of Mars. The relay satellite orbits may be selected to optimize navigation aid support and communication coverage for specific mission sets.

Telecommunications And Navigation Systems Design For Manned Mars Exploration Missions

This paper discusses typical manned Mars exploration needs for telecommunications, including preliminary navigation support functions. It is a brief progress report on an ongoing study program within the current NASA Jet Propulsion Laboratory Deep Space Network (DSN) activities. In support of NASA Office of Exploration mission requirements, system performance & design options - including DSN architecture, and technology needs to support these exploration opportunities over the next 25 years are outlined. A typical Mars exploration case is defined, and support approaches comparing microwave and optical frequency performance for both local in-situ and Mars-Earth links are described. An objective of this paper is also to identify optical telecommunication and navigation technology development opportunities in a Mars exploration program. A local Mars system telecommunication relay and navigation capability for service support of all Mars missions has been proposed as part of an overall Solar System communications network. The effects of light-time delay and occultations on real-time mission decision-making is discussed; the availability of increased local mass data storage may be more important than increasing peak data rates to Earth. The long term frequency use plan will most likely include a mix of microwave, millimeterwave and optical link capabilities to meet a variety of deep space mission needs.