Science and Technology - Part II

An in-depth knowledge of Latest Technologies plus a thorough understanding of basic sciences is necessary to score high in Science and Technology questions of Paper 1 (General Studies). Links are provided to buy the important Science and Technology books available in the market in a prelims perspective.

ASTROSAT
ASTROSAT is India’s first dedicated multi wavelength space observatory. This scientific satellite mission endeavours for a more detailed understanding of our universe. One of the unique features of ASTROSAT mission is that it enables the simultaneous multi-wavelength observations of various astronomical objects with a single satellite.

ASTROSAT will observe universe in the optical, Ultraviolet, low and high energy X-ray regions of the electromagnetic spectrum, whereas most other scientific satellites are capable of observing a narrow range of wavelength band.

Multi-wavelength observations of ASTROSAT can be further extended with co-ordinated observations using other spacecraft and ground based observations. All major astronomy Institutions and some Universities in India will participate in these observations.

ASTROSAT has a lift-off mass of about 1513 kg. It will be launched into a 650 km orbit inclined at an angle of 6 deg to the equator by PSLV-C30.

Applications:
The high porosity and very large surface area of silica aerogels can also be utilized for applications as gas filters, absorbing media for desiccation and waste containment, encapsulation media, and hydrogen fuel storage.

Aerogel can be used in drug delivery systems due to their biocompatibility. The first residential use of aerogels is as an insulator in the Georgia Institute of Technology's Solar Decathlon House, where it is used as an insulator in the semitransparent roof.

Aerogels are a more efficient, low-density form of insulation than the polyurethane foam currently used to insulate refrigerators, refrigerated vehicles, and containers.

Foams are blown into refrigerator walls by chlorofluorocarbon (CFC) propellants, the chemical that is the chief cause of the depletion of the earth's stratospheric ozone layer. Replacing chlorofluorocarbon-propelled refrigerant foams with aerogels could help eliminate this problem.

Another type of aerogels is organic, which is made of carbon and hydrogen atoms. Mount Everest climbers have used Aerogel insoles, as well as sleeping bags lined with the material.

NASA used aerogels to trap space dust particles aboard the Stardust spacecraft. The particles vaporize on impact with solids and pass through gases, but can be trapped in aerogels. NASA also used aerogel for thermal insulation of the Mars Rover and space suits. ISRO is going to use this material on moon rover in Chandryaan-2 mission of India.

Graphene
Graphene: the world's first 2D material. Since graphene’s isolation in 2004, it has captured the attention of scientists, researchers and industry worldwide.

It is ultra-light yet immensely tough.
It is 200 times stronger than steel, but it is incredibly flexible.
It is the thinnest material possible as well as being transparent.
It is a superb conductor and can act as a perfect barrier - not even helium can pass through it.

Applications:
Clean drinking water for millions. Graphene membranes could see huge progress in water purification technology in developing countries and provide more efficient desalination plants.
Electronics and energy storage could also be revolutionised by graphene. Flexible, durable, semi-transparent mobile phones. Wearable technology, clothing that communicates. Electric sports cars. Lightweight planes. These are the future technologies which are becoming realistic in our present.

What does graphene look like?
Graphene is made up of a hexagonal lattice of carbon atoms in a honeycomb like structure.
It is just one-atom thick but absorbs 2.3% of light so it can be seen with the naked eye.
It can potentially be used to create semi-transparent electronics.

GAGAN
Indian Space Research Organization (ISRO) and Airports Authority of India (AAI) have implemented the GPS Aided Geo Augmented Navigation-GAGAN project as a Satellite Based Augmentation System (SBAS) for the Indian Airspace. The objective of GAGAN to establish, deploy and certify satellite based augmentation system for safety-of-life civil aviation applications in India has been successfully completed.

The system is inter-operable with other international SBAS systems like US-WAAS, European EGNOS, and Japanese MSAS etc. GAGAN GEO footprint extends from Africa to Australia and has expansion capability for seamless navigation services across the region. GAGAN provides the additional accuracy, availability, and integrity necessary for all phases of flight, from enroute through approach for all qualified airports within the GAGAN service volume.

GAGAN though primarily meant for aviation, will provide benefits beyond aviation to many other user segments such as intelligent transportation, maritime, highways, railways, surveying, geodesy, security agencies, telecom industry, personal users of position location applications etc.

Some of its benefits are improved efficiency, direct routes, increased fuel savings, approach with vertical guidance at runways, significant cost savings because of the withdrawal of ground aids and reduced workload of flight crew and air traffic controllers.
The system would be available for the member states of the South Asian Association for Regional Cooperation (SAARC).

IRNSS
IRNSS is an independent regional navigation satellite system consisting of 7 satellites launched by India. It is designed to provide accurate position information service to users in India as well as the region extending up to 1500 km from its boundary, which is its primary service area.

An Extended Service Area lies between primary service area and area enclosed by the rectangle from Latitude 30 deg South to 50 deg North, Longitude 30 deg East to 130 deg East.

IRNSS will provide two types of services, namely, Standard Positioning Service (SPS) which is provided to all the users and Restricted Service (RS), which is an encrypted service provided only to the authorised users.

The IRNSS System is expected to provide a position accuracy of better than 20 m in the primary service area.

Some of the applications of IRNSS are:

Terrestrial, Aerial and Marine Navigation
Disaster Management
Vehicle tracking and fleet management
Integration with mobile phones
Precise Timing
Mapping and Geodetic data capture
Terrestrial navigation aid for hikers and travellers
Visual and voice navigation for drivers
It will be called NAVIC (Navigation with Indian Constellation)

The system will be similar to the Global Positioning System (GPS) operated by the United States with 24 satellites and the Glonass, Galileo and BeiDou systems of Russia, Europe and China respectively.

Silica aerogels have drawn a lot of interest both in science and technology because of their low bulk density (up to 95% of their volume is air), hydrophobicity, low thermal conductivity, high surface area, and optical transparency. Aerogels are synthesized from molecular precursors by sol-gel processing.

Special drying techniques must be applied to replace the pore liquid with air while maintaining the solid network. Supercritical drying is most common; however, recently developed methods allow removal of the liquid at atmospheric pressure after chemical modification of the inner surface of the gels, leaving only a porous silica network filled with air.

Scientists from Indian Space Research Organisation (ISRO) have indigenously developed world’s lightest synthetic material called ‘silica aerogel’ or ‘blue air’. It was developed by the team of scientist from ISRO’s e Vikram Sarabhai Space Centre, Thiruvananthapuram. Silica Aerogel is the lightest synthetic material ever made by man.

By:Balalatha Mallavarapu