The Vikram Sarabhai Space Centre is a major space research centre of the Indian Space Research Organisation , focusing on rocket and space vehicles for India's satellite programme. It is located in Thiruvananthapuram, in the Indian state of Kerala.The centre had its beginnings as the Thumba Equatorial Rocket Launching Station in 1962. It was renamed in honour of Dr. Vikram Sarabhai, the father of the Indian space program.The Vikram Sarabhai Space Centre is one of the main Research & Development establishments within ISRO. VSSC is an entirely indigenous facility working on the development of sounding rockets; Rohini and Menaka launchers; ASLV, PSLV GSLV and the GSLV Mk III.VSSC's current director is S. Ramakrishnan. He took over from P.S. Veeraraghavan on December 31, 2012. Wikipedia.
News Article | April 23, 2016
Indian scientists have claimed that they have developed the world's lightest material ever made by man, called Silica Aerogel, also referred to as "frozen smoke" or "blue air." This synthetic material can be incorporated both on Earth as well as in space, and comes with outstanding thermal resistance. It can be smartly used as a filler in soldiers' uniforms to keep them warm when subjected to freezing cold climatic conditions, explained by scientists at the Vikram Sarabhai Space Center (VSCC), Thiruvananthapuram, India. Indian soldiers posted in regions such as the Siachen Glacier where the weather conditions are extremely cold and harsh, can really benefit from this heat-inducing material. It could prove to be a real life saver to these military personnel. The uniform worn by these soldiers is quite heavy and weighs around 3 kilograms (6.6 pounds). "Using this material, the jackets' weight can be brought down to around 200 to 300 grams (0.44 to 0.66 pound) and shoes to around 800 grams (1.77 pounds)," said K Sivan, Ph.D. director of VSCC. It is interesting to note that owing to its extreme weightlessness it can even be gently placed atop a delicate flower! Incredible, isn't it? "It is the world's lightest synthetic material made by man. It is a highly guarded technology. We have indigenously made it in India. It is used for insulating the rocket's surface." said Sivan. Scientists are hoping that this material can be incorporated diligently into rocket engines. However, the uses of this lightweight material can go far and beyond insulation. Sivan added that the material can have applications for other items, such as thermal jackets, foot insoles, as well as window glazing. He particularly points out that it can prove to be extremely useful for people working in very frigid environments, in a very strategic way. Thermal jackets and foot insoles? Looks like lightweight thermal clothing made from silica aerogel might make way for a new trend in the near future, promptly replacing the current array of heavy furry winter clothing. Further, in freezing cold regions such as Antarctica, if the windows are painted with this silica aerogel material, it can aptly work as an insulator and provide ample protection from the icy cold winds. Aerogel predominantly contains air - a whopping 99 percent! Hence, it is being slated for use in the space center's next mission to the moon namely Chandryaan-2. The upsides are plenty, but the downside to this material is that it is extremely delicate and fragile. Scientists are trying to address this issue by testing and trying various ways to toughen the material and make it more resilient. Aerogel actually came into existence a couple of decades ago. In the 1930s, aerogel was invented at the NASA's Glenn Research Center in Cleveland, and has since been used in space related applications. © 2016 Tech Times, All rights reserved. Do not reproduce without permission.
Karmalkar S.,Indian Institute of Technology Madras |
Saleem H.,Vikram Sarabhai Space Center
Solar Energy Materials and Solar Cells | Year: 2011
We have earlier introduced the power law equation, j=1-(1-γ)v- γvm, where j=J/Jsc and v=V/V∝, to simplify determination of the JV curve, fill-factor and peak power point of an illuminated solar cell from a few measurements as well as physical parameters. However, the validity of the various formulae and parameter extraction procedure was established for a limited class of cells, having moderately convex JV curves with fill-factors of 0.560.77 and obeying single exponential theory with bias independent photocurrent. This paper presents a thorough validation of the model proposed earlier. New formulae and parameter extraction procedure are presented to extend the applicability of the power law equation to a much wider variety of cells. The JV curves considered in this paper range from concave (fill-factor<0.25) to highly convex (fill-factor>0.85), and their theoretical expressions contain bias dependent photocurrent and double exponential terms. It is shown that the power law equation also simplifies the calculation of the cell bias point for an arbitrary load. © 2010 Elsevier B.V. All rights reserved.
Hegde P.,Hokkaido University |
Hegde P.,Vikram Sarabhai Space Center |
Kawamura K.,Hokkaido University
Atmospheric Chemistry and Physics | Year: 2012
Aerosol samples were collected from a high elevation mountain site (Nainital, India; 1958 m a.s.l.) in the central Himalayas, a location that provides an isolated platform above the planetary boundary layer to better understand the composition of the remote continental troposphere. The samples were analyzed for water-soluble dicarboxylic acids (C2-C 12) and related compounds (ketocarboxylic acids and α-dicarbonyls), as well as organic carbon, elemental carbon and water soluble organic carbon. The contributions of total dicarboxylic acids to total aerosol carbon during wintertime were 1.7% and 1.8%, for day and night, respectively whereas they were significantly smaller during summer. Molecular distributions of diacids revealed that oxalic (C2) acid was the most abundant species followed by succinic (C4) and malonic (C 3) acids. The average concentrations of total diacids (433±108 ng m-3), ketoacids (48±23 ng m-3), and α-dicarbonyls (9±4 ng m-3) were similar to those from large Asian cities such as Tokyo, Beijing and Hong Kong. During summer most of the organic species were several times more abundant than in winter. Phthalic acid, which originates from oxidation of polycyclic aromatic hydrocarbons such as naphthalene, was found to be 7 times higher in summer than winter. This feature has not been reported before in atmospheric aerosols. Based on molecular distributions and air mass backward trajectories, we conclude that dicarboxylic acids and related compounds in Himalayan aerosols are derived from anthropogenic activities in the highly populated Indo-Gangetic plain areas. © 2012 Author(s). CC Attribution 3.0 License.
Comparison between crosslink densities derived fromstress-strain data and theoretically data evaluatedthrough the α-model approach for a polyuretha nenetwork system based on hydroxyl terminatedpolybutadiene and isophorone-diisocyanate
Sekkar V.,Vikram Sarabhai Space Center
Journal of Applied Polymer Science | Year: 2010
The crosslink density (CLD) for polyurethane elastomeric networks based on hydroxyl terminated polybutadiene and isophorone-diisocyanate was theoretically calculated with α-model equations the employing the functionality distribution and extent of reaction as input parameters. The theoretical crosslink density (vt) was compared with the CLD values computed from stress-strain data evaluated at various strain rates. The methods for the calculation of the CLD from stress- strain data were based on the Mooney-Rivlin and Young's modulus approaches. Theoretical stress-strain curves were generated on the basis of vt conforming to both phantom and affine model calculations. The experimental stress- strain plots aligned more closely to the affine model line. The deviation of the experimentally derived stress-strain curves from the theoretical affine curve was probably due to the presence of temporarily trapped physical entanglements. From the stress-strain data, the concentrations of true chemical crosslinks and physical entanglements were estimated individually. © 2010 Wiley Periodicals, Inc.
Bhardwaj A.,Vikram Sarabhai Space Center |
Raghuram S.,Vikram Sarabhai Space Center
Astrophysical Journal | Year: 2012
The green (5577 Å) and red-doublet (6300, 6364 Å) lines are prompt emissions of metastable oxygen atoms in the 1 S and 1 D states, respectively, that have been observed in several comets. The value of the intensity ratio of green to red-doublet (G/R ratio) of 0.1 has been used as a benchmark to identify the parent molecule of oxygen lines as H2O. A coupled chemistry-emission model is developed to study the production and loss mechanisms of the O(1 S) and O(1 D) atoms and the generation of red and green lines in the coma of C/1996 B2 Hyakutake. The G/R ratio depends not only on photochemistry, but also on the projected area observed for cometary coma, which is a function of the dimension of the slit used and the geocentric distance of the comet. Calculations show that the contribution of photodissociation of H2O to the green (red) line emission is 30%-70% (60%-90%), while CO2 and CO are the next potential sources contributing 25%-50% (<5%). The ratio of the photoproduction rate of O(1 S) to O(1 D) would be around 0.03 (0.01) if H2O is the main source of oxygen lines, whereas it is 0.6 if the parent is CO2. Our calculations suggest that the yield of O(1 S) production in the photodissociation of H2O cannot be larger than 1%. The model-calculated radial brightness profiles of the red and green lines and G/R ratios are in good agreement with the observations made on the comet Hyakutake in 1996 March. © 2012 The American Astronomical Society. All rights reserved.
Bhardwaj A.,Vikram Sarabhai Space Center |
Jain S.K.,Vikram Sarabhai Space Center
Icarus | Year: 2012
A model for N 2 triplet states band emissions in the venusian dayglow has been developed for low and high solar activity conditions. Steady state photoelectron fluxes and volume excitation rates for N 2 triplet states have been calculated using the Analytical Yield Spectra (AYS) technique. Model calculated photoelectron flux is in good agreement with Pioneer Venus Orbiter-observed electron flux. Since inter-state cascading is important for the triplet states of N 2, populations of different levels of N 2 triplet states are calculated under statistical equilibrium considering direct electron impact excitation, and cascading and quenching effects. Densities of all vibrational levels of each triplet state are calculated in the model. Height-integrated overhead intensities of N 2 triplet band emissions are calculated, the values for Vegard-Kaplan (A3Σu+-X1Σg+), First Positive (B3Πg-A3Σu+), Second Positive (C 3Π u-B 3Π g), and Wu-Benesch (W 3Δ u-B 3Π g) bands of N 2, are 1.9 (3.2), 3 (6), 0.4 (0.8), and 0.5 (1.1)kR, respectively, for solar minimum (maximum) conditions. The intensities of the three strong Vegard-Kaplan bands (0,5), (0,6), and (0,7) are 94 (160), 120 (204), and 114 (194) R, respectively, for solar minimum (maximum) conditions. Limb profiles are calculated for VK(0,4),(0,5),(0,6) and (0,7) bands. The calculated intensities on Venus are about a factor 10 higher than those on Mars. The present study provides a motivation for a search of N 2 triplet band emissions in the dayglow of Venus. © 2011 Elsevier Inc.
Sijikumar S.,Vikram Sarabhai Space Center |
Rajeev K.,Vikram Sarabhai Space Center
Journal of Climate | Year: 2012
Regional distribution of precipitation during the onset phase of the Indian summer monsoon (15 May-15 June) shows distinct patterns in the years 2009 and 2010, with the latter having considerably more precipitation over the southeast Arabian Sea (AS) and the west coast of peninsular India. During these years, the location and regional extent of the warm pool in the AS are also distinct. In 2009, the warm pool core is located in the equatorial region, whereas in 2010 it spreads to a wide region of the AS. Sensitivity experiments with different SST forcings have been carried out using the Weather Research and Forecasting (WRF) model to understand the influence of the AS warm pool on the monsoon onset precipitation characteristics. Simulations with actual SSTs in the AS and climatological SSTs elsewhere are able to reproduce the distinct behavior of the monsoon onset precipitation observed during 2009 and 2010. These simulations show suppressed convection over the central and northern AS in 2009, while warmer SSTs in the AS favor enhanced convection during 2010 combined with a sharp contrast in the moisture transport. The strong intrusion of drier air from the north AS effectively confines the moist air mass fromthe south, causing a net transport ofmoisture toward the southwest coast of peninsular India and leads to positive anomalies in precipitation over the region in 2010. However, during 2009, the drier air from the north mixes rather easily over the AS, which suppress the convection. © 2012 American Meteorological Society.
John S.R.,Vikram Sarabhai Space Center |
Kumar K.K.,Vikram Sarabhai Space Center
Climate Dynamics | Year: 2012
The present study for the first time reports the global gravity wave activity in terms of their potential energy derived from TIMED/SABER observations right from the stratosphere to the mesosphere lower thermosphere (MLT) region. The potential energy profiles obtained from SABER temperature are validated by comparing them with ground based LIDAR observations over a low latitude site, Gadanki (13. 5° N, 79. 2° E). The stratospheric and mesospheric global maps of gravity wave energy showed pronounced maxima over high and polar latitudes of the winter hemisphere. The interannual variability of the stratospheric gravity wave activity exhibited prominent annual oscillation over mid-latitudes. The equatorial gravity wave activity exhibited quasi-biennial oscillation in the lower stratosphere and semi-annual oscillation in the upper stratosphere. The MLT region maps revealed summer hemispheric maxima over polar latitudes and secondary maxima over the equatorial region. The results are discussed in the light of present understanding of global gravity wave observations. The significance of the present study lies in emphasizing the importance of satellite measurements in elucidating gravity waves, which is envisaged to have profound impact on parameterizing these waves. © 2012 Springer-Verlag.
David L.M.,Vikram Sarabhai Space Center |
Nair P.R.,Vikram Sarabhai Space Center
Atmospheric Environment | Year: 2013
Monthly mean tropospheric column O3 and NO2 retrieved from Ozone Monitoring Instrument on board Aura for the period December 2007 to November 2008 have been analysed to study the spatial and seasonal variations at selected locations over the Indian landmass and surrounding oceanic region. The annual change in tropospheric O3 and NO2 over the study region was ∼15-20 DU and ∼0.03-0.1 DU, respectively. Latitudinal gradient of -0.84 DU/° and 0.005 DU/°, respectively has been estimated for O3 and NO2 over this region. High levels of O3 were measured over parts of Arabian Sea and Bay of Bengal owing to transport from adjacent landmass. The dependence of O3 on NO2, solar radiation, cloud cover, rainfall, fire count, outgoing longwave radiation and boundary layer height (BLH) were investigated in detail along with the airflow pattern and airmass back trajectory analysis. There were regional variations in O3 seasonal patterns associated with differences in NO2, availability of solar radiation and prevailing airmass. BLH plays a role in the seasonal variation of tropospheric O3. The long-term trend in tropospheric O3 over a period of ten years has been examined for the different regions and both positive and negative trends were observed. © 2012 Elsevier Ltd.
John S.R.,Vikram Sarabhai Space Center |
Kumar K.K.,Vikram Sarabhai Space Center
Geophysical Research Letters | Year: 2013
The disparities in satellite-based observations of global gravity wave activity are discussed in terms of methods used to extract the gravity wave perturbations from background and the sensitivity of the given satellite to the gravity wave spectrum. The temperature measurements from TIMED/SABER are used to obtain the global gravity wave maps in terms of their potential energies by employing two widely used methods to extract the gravity wave perturbations viz. (1) removal of 0-6 zonal wavenumber large-scale waves and (2) high pass filter with cut-off vertical wavelength at 10 km. The present study for the first time employed these two different methods on the same satellite observations to investigate the sensitivity of global gravity wave patterns and their magnitudes to the methods used to extract them. The results showed significant differences in the gravity wave potential energy magnitudes estimated by employing these two methods. Further, employing the first method on COSMIC-measured temperature profiles, the global gravity wave pattern is estimated and the same is compared with that obtained using SABER observations. This comparison substantiated the assertion that using the same method to extract the gravity wave perturbations from different satellite observations yields the similar global gravity wave pattern. The present study thus provided very useful insights into the observed discrepancies among current global gravity wave patterns and it is envisaged that this is a step forward in unifying the existing methods to extract gravity wave parameters using space-based observations. © 2013 American Geophysical Union. All Rights Reserved.