S. Ramadurai

Detection of living cells in stratospheric samples

Air samples collected aseptically over tropical India at various stratospheric altitudes ranging from 20 to 41 km using cryosampler assemblies carried on balloons flown from Hyderabad have shown evidence of living microbial cells. Unambiguous evidence of living cells came from examining micropore filters on which the samples were recovered with the use of voltage sensitive lipophilic dyes that could detect the presents of active cells. Clumps of viable cells were found at all altitudes using this technique, and this conclusion was found to be consistent with images obtained from electron microscopy. Since the 41 km sample was collected well above the local tropopause, a prima facie case for a space incidence of these microorganisms is established. Further work on culturing, PCR analysis and isotopic analysis is in progress.

A dust model for the cosmic microwave background

The cosmic microwave background may be explained on the basis of absorption and reemission of the light from galaxies by graphite whiskers of lengthsl≃0.1-1 mm. The mass density of such particles required is of the order of 10−34 g cm−3.

Production and propagation of cosmic ray H2 and He3 nuclei

The results of detailed calculations on the production of H2 and He3 nuclei by cosmic ray protons and helium nuclei in interstellar medium are presented. The flux and energy spectra of these nuclei as well as those of cosmic ray H1 and He4 nuclei in the vicinity of the Earth are calculated. For this purpose the source spectra are assumed to be in the form of a power law in total energy per nucleon with an additional velocity dependent term. This spectrum denoted as Fermi Spectrum, is about midway between the power law spectrum in rigidity and in total energy per nucleon. The fluxes are calculated taking into account: (1) energy dependent cross-sections of thirteen nuclear reactions of cosmic ray protons and helium nuclei with interstellar H1 and He4 leading to the production of H2 and He3 nuclei, (2) angular distributions and kinematics of these reactions, (3) ionization loss of the primary and secondary nuclei in interstellar medium, (4) elastic collisions of cosmic ray protons and helium nuclei, (5) distributions of cosmic ray path-lengths in in terstellar space as in gaussian and exponential forms, and (6) interplanetary modulation of cosmic rays from the numerical solution of the complete Fokker-Planck equation describing the diffusion, convection and adiabatic deceleration of cosmic ray nuclei in the solar system. On comparing the calculated values of H2/He4 and He3/(He3+He4) as a function of energy with the observed data of several investigators, it is found that agreement between the calculated values and most of the observed data is obtained on the basis of: (a) source spectrum in the form of ‘Fermi’ Spectrum, (b) distribution of path-lengths as in the gaussian form with a mean value of 4 g cm−2 of hydrogen or as in exponential form with leakage path length of 4 g cm−2.

A balloon Experiment to detect microorganisms in the outer space

The results of biological studies of a cryosampler flown with a balloon, in which air samples were collected at altitudes ranging from 20 to 41 km, well above the Tropopause over Hyderabad, are described. In the analysis carried out in Cardiff, voltage-sensitive dyes that could detect the presence of viable cells were used on these air-samples. Clumps of viable cells were found to be present in samples collected at all the altitudes. The images obtained from electron microscopy are consistent with the above finding. Reference is also made to another paper presented at this conference describing the identification of bacterial species in the sample carried out in Sheffield. Counter arguments are discussed against the criticism that the detected cells and microorganisms (in the samples collected above the local tropopause at 16 km) are due to terrestrial contamination.

Search for living cells in stratospheric samples

Air samples are to be collected at various altitude sin the stratosphere using balloons flown form Hyderabad, India. The samples will be passed through sterile micropore filters, after which the filters will be analyzed using voltage sensitive lipophilic dyes to detect the presence of either active or non-active cells. Organisms detected in this manner will be studied using static mass spectroscopy to establish isotropic ratios 13C/12C and D/H, which would distinguish between terrestrial and extraterrestrial cells.

The fermi mechanism and the source spectrum of cosmic ray nuclei

It is shown that the velocity term, occurring in the expression for the rate of energy gain by the Fermi mechanism of acceleration, is to be taken into account in case of acceleration of non-relativistic particles. A spectral form of accelerated particles is derived on this basis and is called the ‘Fermi Spectrum’. At non-relativistic energies this spectral form is significantly different from the currently used forms of power law in total energy per nucleon and in rigidity, and lies about midway between them. It is shown that using this form of source spectrum of cosmic ray nuclei, satisfactory agreement can be obtained between the calculated values and the observed ones of the ratios of H2/He4 and He3/He4, and the energy spectra of protons and helium nuclei near the Earth.

Extinction of dinosaurs: A possible novel cause

A novel cause of mass extinction of fauna close to the (K/T) Boundary is suggested. A large amount of non-protein amino acids (AIB and ISOVAL) has been observed close to this event. It is speculated that these amino acids may be toxic and are responsible for the extinction. The toxicity level is estimated for this suggestion to be true and experimentalists are encouraged to test this level of toxicity for the amino acids.

The synthesis of26Al during combined hydrogen and helium-burning reactions

We have studied the synthesis of26Al during combined hydrogen and helium-burning processes in high temperature and density conditions. The possible sites for these processes are believed to be the neutron star surfaces where the density ranges from ρ=104−107 g cm−3 and temperature range from 108−8×108 K. The screening effect which leads to an enhancement of nuclear reaction rates is taken into account whenever necessary. A detailed calculation of the abundances of26Al and27Al isotopes is presented here. Finite amounts of26Al is found to be produced atT=2×108 K and ρ=108 g cm−3 due to these combined reactions. This situation is likely to be realized during the γ-ray burst events on neutron star surface. The amount of material processed in the burst sources is very little compared to the amount of material processed in Novae or Supernovae. Thus it is suggested that rather than contributing to the overall amount of26Al, γ-ray bursts are likely to contribute more significantly to the inhomogeneity of26Al distribution in interstellar medium.

Interstellar propagation and electron capture processes of galactic cosmic ray heavy ions in space

Abstract The new information on galactic cosmic rays (GCR) derived from the Spacelab-3 cosmic ray experiment “Anuradha” shows that at 25–125 MeV/N GCR sub-iron and iron (Z = 21–28) particles consists of a mixture of partially ionized and fully ionized ions. Computation of electron capture and loss cross sections in hydrogen in 1–50 MeV/N energy range are made for Fe, Cr, Ti and Ni. From these it is concluded that: (1) these GCR particles must have captured orbital electrons at energies of about 1–5 MeV/N and (2) these particles are then reaccelerated to 300–500 MeV/N most probably in interstellar medium by collisions with SNR shock fronts. Some reacceleration may take place also in heliospheric boundary region. It is suggested that these observations of partially ionized GCR ions of about 100 MeV/N in Spacelab-3 provide a direct evidence of reacceleration of GCR.

The mystery of the cosmic boron abundance

The observed high abundance of boron in type I carbonaceous chondrites may be due to the presence in the primitive solar nebula of graphite grains which have been irradiated by high energy nucleons at some stage of their history. The boron atoms thus produced by spallation reactions are stably locked within interstellar graphite grains and could make a significant contribution to the boron abundance of C1 chondrites.