Pulsar studies with GRO-COMPTEL

Pulsar measurements performed by the experiment COMPTEL, aboard the Compton Gamma Ray Observatory, are described. The main results refer to the Crab and Vela pulsars whose pulse shape characteristics are given in some detail and light curves are compared with those above 50 MeV, as observed by the COS-B satellite. No other gamma-ray pulsars have been detected to date by COMPTEL, the upper limit on the pulsed signal from Geminga being compatible with indications by other experiments.     

The structural features of the germanium-silicon solid solution crystals obtained under microgravity

Structural features of germanium-silicon solid solution crystals have been investigated and silicon distribution in the crystals has been studied. All the crystals obtained under microgravity had, in spite of good external shape and facetting, a poorer internal structure than those obtained on Earth. The distribution of silicon have been shown to be non-uniform. High dislocation densities were observed.     

Fourier spectroscopy in planetary research

The application of Fourier Transform Spectroscopy (FTS) to planetary research is reviewed. The survey includes FTS observations of the Sun, all the planets except Uranus and Pluto, the Galilean satellites and Saturn's rings. Instrumentation and scientific results are considered. The prospects and limitations of FTS for planetary research in the forthcoming years are discussed.     

Incremental planning to control time-constrained blackboard-basedproblem solver [vehicle monitoring]

A planner that improves the control decisions made by a blackboard-based problem solver is described. This planner interleaves planning and execution. It sketches out major plan steps but incrementally details actions for only the next step since earlier actions influence how (and whether) to pursue a plan. The planner also reasons about time constraints, revising plans to meet problem-solving deadlines and deciding when it has done enough work on a problem. Implementation of these mechanisms is outlined, and experiments are discussed showing how they reduce overall computation and improve problem solving     

On a non-primordial origin of the cosmic background radiation and pregalactic density fluctuations

Dusty pregalactic Population III objects may provide a mechanism for an effective thermalization of the star radiation. They may generate the observed microwave background and so the high cosmic photon entropy. Assuming a tepid universe a smaller primordial entropy contribution results in reasonable mass scales and amplification factors of pregalactic density fluctuations.     

Beam-plasma discharge in near rocket region

The model of beam-plasma discharge near the rocket following electron beam injection into the ionosphere is presented. The dependence of discharge plasma density on neutral atmosphere concentration and beam parameters is found. Radioemission and luminiscence intensities from discharge are estimated. The model is consistent with the data of ARAKS and “Zarnitsa-2” experiments.     

Wave measurements in active experiments on plasma beam injection

The paper presents the results and discussion of VLF wave measurements carried out in the course of two rocket experiments on injection of a dense cesium ion beam into the ionosphere at the heights of 165–240 km. The injection was accompanied by enhancement of the broad-band noise by several orders of magnitude. The wave measurements in the frequency range of 1–11 kHz revealed two pronounced frequencies somewhat exceeding that of the lower-hybrid resonance oscillations in the background plasma and the cesium beam. The oscillations were modulated by frequencies close to the ion-cyclotron frequencies of the background plasma.     

Measurements of LET spectra and comparison to models.

We present measurements of LET spectra for near earth orbits with various inclinations and altitudes. A comparison with calculated LET spectra shows that the contribution from direct ionizing galactic cosmic rays is well described by the models. An additional contribution to the spectra originates from stopping protons and from nuclear interactions of particles with material. In the case of an interaction a large amount of energy is deposited in a small volume by target recoils or target fragments. These events will be called short range (SR) events. For a low inclination orbit radiation belt protons are the main source of these events while galactic protons become more important when increasing the inclination to near polar orbits. We show that the contribution of SR events for orbits with low altitude (324 km) and 57 degrees inclination is comparable to that for an orbit with 28 degrees inclination at a high altitude (510 km).     

The electrolytical processes in dirty ices: implications for origin and chemistry of minor bodies and related objects.

Many moonlike bodies (M approximately or = 1 Moon) beyond the Martian orbit contain large amounts of dirty ice (approximately 50%) forming thick mantle with the solid phase thermal convection. When a body moves through the inter- or nearplanetary magnetized plasma, electric current is generated in the body and its environment. The current passing through a dirty ice containing up to 10% of organic admixtures produces a lot of electrochemical effects which have a profound impact on its composition. At this stage one can hardly say something definite concerning changes experienced by organics. The changes must occur inevitably and can be of a rather unexpected and far-reaching nature, so deserving a close study. Another obvious effect is a volumetric electrolysis of ice containing alien inclusions. The electrolysis products accumulate in ice in the form of a solid solution which is capable of detonation at 15-20 wt.% of 2H2 + O2. If M > or = 1 Moon (Galilean satellites, Titan), the body loses in explosion a part of its mass in the form of vapor and ice fragments (=short-period comet nuclei), whereas if M < or = 0.2 Moon, the body breaks up totally (the Main Belt asteroids origin approximately 3.9 Byr ago). 2H2 + O2 containing cometary nuclei are capable of burning or suffer new explosions when receiving an additional energy. The combustion in the sublimation products containing also light organics and 2H2 + O2 explains unexpected energetics and nearnuclear chemistry of Comet P/Halley (e.g. great abundances of negative and positive ions, atomic carbon, CO over CO2, origin of CHON particles etc) and its distant outbursts correlated, possibly, with the Solar activity. Thus the electrochemical processes in the dirty ice with organics, along with its subsequent thermal, radiative etc. processing, open up new potentials for explanation and prediction of quite unexpected discoveries.