Autonomous Spacecraft Navigation With Pulsars

An external reference system suitable for deep space navigation can be defined by fast spinning and strongly magnetized neutron stars, called pulsars. Their beamed periodic signals have timing stabilities comparable to atomic clocks and provide characteristic temporal signatures that can be used as natural navigation beacons, quite similar to the use of GPS satellites for navigation on Earth. By comparing pulse arrival times measured on-board a spacecraft with predicted pulse arrivals at a reference location, the spacecraft position can be determined autonomously and with high accuracy everywhere in the solar system and beyond. The unique properties of pulsars make clear already today that such a navigation system will have its application in future astronautics. In this paper we describe the basic principle of spacecraft navigation using pulsars and report on the current development status of this novel technology.Comment: 22 pages, 12 figures, 2 tables, to be published in the proceedings of the workshop "Relativistic Positioning Systems and their Scientific Applications", held on 19-21 Sept. 2012, Brdo near Kranj, Sloveni

Comparison of giant radio pulses in young pulsars and millisecond pulsars

Pulse-to-pulse intensity variations are a common property of pulsar radio emission. For some of the objects single pulses are often 10-times stronger than their average pulse. The most dramatic events are so-called giant radio pulses (GRPs). They can be thousand times stronger than the regular single pulses from the pulsar. Giant pulses are a rare phenomenon, occurring in very few pulsars which split into two groups. The first group contains very young and energetic pulsars like the Crab pulsar, and its twin (PSR B0540-69) in the Large Magellanic Cloud (LMC), while the second group is represented by old, recycled millisecond pulsars like PSR B1937+21, PSR B1821-24, PSR B1957+20 and PSR J0218+4232 (the only millisecond pulsar detected in gamma-rays). We compare the characteristics of GRPs for these two pulsar groups. Moreover, our latest findings of new features in the Crab GRPs are presented. Analysis of our Effelsberg data at 8.35 GHz shows that GRPs do occur in all phases of its ordinary radio emission, including the phases of the two high frequency components (HFCs) visible only between 5 and 9 GHz.Comment: Proceedings of the 363. WE-Heraeus Seminar on: Neutron Stars and Pulsars (Posters and contributed talks) Physikzentrum Bad Honnef, Germany, May.14-19, 2006, eds. W.Becker, H.H.Huang, MPE Report 291, pp.64-6

Polarization characteristics of the Crab pulsar's giant radio pulses at HFCs phases

We discuss our recent discovery of the giant radio emission from the Crab pulsar at its high frequency components (HFCs) phases and show the polarization characteristic of these pulses. This leads us to a suggestion that there is no difference in the emission mechanism of the main pulse (MP), interpulse (IP) and HFCs. We briefly review the size distributions of the Crab giant radio pulses (GRPs) and discuss general characteristics of the GRP phenomenon in the Crab and other pulsars.Comment: AIP Conference Proceedings "Astrophysical Sources of High Energy Particles and Radiation", eds. T. Bulik et al. (NY:AIP), Volume 801, 2005, pp. 324-32

An Experimental Investigation of the Dead Time of Geiger-Mueller Counters

As ever more sensitive and precise experiments are being performed with Geiger Counters, especially in cosmic ray research, the resolving power of these instruments assumes an ever increasing importance. With the present perfection of electronic circuitry, this resolving time has become largely a function of the dead time of the Geiger counter tube itself. It was therefore proposed to investigate methods of reducing this dead time. Only self-quenching counter tubes had to be considered in this connection since the dead time of all other types of Geiger counters is inherently longer