Explanation :

Context: Recently, Stardust 1.0 has been launched from USA, which became the first commercial space launch powered by biofuel.

Explanation:

Biofuels

• Any hydrocarbon fuel that is produced from an organic matter (living or once living material) in a short period of time is considered a biofuel.
• Biofuels may be solid, liquid or gaseous in nature.

First Generation Biofuels

• Fuels produced from sugar, starch, vegetable oil, or animal fats utilizing conventional technology.
• Examples: Bioalcohols, Biodiesel, Vegetable Oil, Bioethers, Biogas.

Second Generation Biofuels

• Fuels made from non-food crops such as cellulosic biofuels and waste biomass i.e. stalks of wheat and corn, and wood).
• Example: cellulose ethanol

Third Generation Biofuels

• Fuels made from micro-organisms such as algae.
• It doesn’t require cultivable/arable land for production.
• Example: Butanol

Fourth Generation Biofuels

• In the production of these fuels, crops that are genetically engineered to take in high amounts of carbon are grown and harvested as biomass.
• The crops are then converted into fuel using second generation techniques.
• Like the third generation, fourth-generation biofuels are made using non-arable land. However, unlike the third, they do not need the destruction of biomass.
• Examples: electrofuels and photo-biological solar fuels

Explanation :

• China has completed its BeiDou Navigation Satellite System constellation, coming up with a product that can potentially rival the US Global Positioning System (GPS).
• China initiated BeiDou in 1994 with aims to integrate its application in different sectors, including fishery, agriculture, special care, mass-market applications, forestry and public security.
• The name BeiDou comes from Chinese word for the Big Dipper or Plough constellation.
• It consists of 27 satellites in medium Earth orbit, five in geostationary orbit and three more in inclined geosynchronous orbits.
• The navigation satellite system was completed in three steps: BDS-1 which provided services to China, BDS- 2 to provide services to the Asia-Pacific region and BDS-3 which provides services worldwide.
• China’s navigation system uses a network of satellites and can provide positional accuracies of under ten meters (GPS provides positioning accuracies of under 2.2 meters).
• BeiDou offers services including accurate positioning, navigation and timing as well as short message communication.

Other Countries’ Navigation Systems

• The GPS is owned by the US government and operated by the US Air Force.
• Apart from this, Russia has its navigation system called GLONASS, the European Union (EU) has Galileo, while India’s is called Navigation with Indian Constellation (NavIC).

Explanation :

• Scientists in the United States have named the millimetre-wide robots Xenobots (world’s first living machines) — after the species of aquatic frog found across sub-Saharan Africa from Nigeria and Sudan to South Africa,Xenopus laevis.
• Scientists have repurposed living cells scraped from frog embryos and assembled them into entirely new life-forms.

Application

• The xenobots can move toward a target, perhaps pick up a payload (like a medicine that needs to be carried to a specific place inside a patient) — and heal themselves after being cut.

Explanation :

• Microdot Technology involves spraying thousands of the small dots laser etched with a PIN (Personal Identification Number) number, linked to the Vehicle Number, throughout the vehicle. As the polymer dots are 1mm by 1mm it is impossible to locate them.
• These can be read physically with a microscope and identified with an ultraviolet light source.
• The microdots and adhesive fix permanently and cannot be removed without damaging the vehicle itself.

Advantages

• A vehicle, which has microdots sprayed on its body, if stolen, can be easily identified with the help of this technology.
• Similarly, the use of fake spare parts can also be prevented as counterfeit ones can be singled out easily.

Explanation :

• Natural uranium is composed of various isotopes, or different types of uranium. It contains approximately 99.3% of the isotope uranium-238, and has only very small concentrations, about 7%, of the fissile isotope uranium-235. An isotope is considered fissile if it can be split by a slow moving neutron.
• Uranium-235 is the most significant fissile isotope of uranium for reactor fuel and nuclear weapons.
• Uranium needs to be in a gaseous form for enrichment due to the varying chemical and physical properties the different isotopes (U-235 and U-238) have.
• Commercially, the U235 isotope is enriched to 3 to 5% (from the natural state of 0.7%) and is then further processed to create nuclear fuel.
• At the conversion plant, uranium oxide is converted to the chemical form of uranium hexafluoride (UF6) to be usable in an enrichment facility.

Stages of Enrichment

• Uranium enriched to concentrations above 0.7% but less than 20% uranium-235 is defined as low enriched uranium (LEU). Most nuclear reactors use LEU that is about 3-5% uranium-235.
• Uranium enriched to more than 20% uranium-235 is defined as highly enriched uranium (HEU). All HEU is weapons-usable, but the lower the enrichment level the greater the amount of material required to achieve a critical mass - the amount of material required to build a bomb.
• States with nuclear weapons typically use so-called weapons-grade HEU, which is typically defined as 90% HEU or above, to minimize weapons’ size.

Explanation :

• Gravitational lensing occurs when a huge amount of matter - a galaxy cluster, for example - creates a gravitational field that magnifies light from objects behind it.
• The Milky Way today forms the equivalent of one Sun every year, but in the past, that rate was up to 100 times greater. NASA now plans to look billions of years into the past in order to understand how our Sun formed.
• The NASA program aimed at using gravitational lensing via its James Webb telescope(scheduled to launch in 2021) is called Targeting Extremely Magnified Panchromatic Lensed Arcs and Their Extended Star Formation (TEMPLATES). So, both the given statements are correct.

Source:Civil Services Chronicle Online

Explanation :

It is a form of digital cash that uses encryption technology to make it secure. Cryptocurrencies exist not as physical bills or coins but rather as lines of digitally signed computer code. Records are typically kept on ledgers known as blockchain. People can store their cryptocurrency stashes in virtual wallets that resemble online bank accounts. Cryptocurrency is supposed to be secure and anonymous.

Explanation :

Globular clusters are collections of thousands to millions of stars, moving as one unit.

Source: CSC May 2019

Explanation :

• Statement 1 is correct: The Sun’s magnetic field, from which sunspots gets generated, wraps around the sun in the east-west direction.
• Statement 2 is incorrect: At the end of a solar cycle, this magnetic dam can break, releasing huge amounts of plasma cascading like a tsunami towards the poles. Statement 3 is incorrect These tsunami waves travel at high speeds of about 1,000 km per hour carrying excess plasma to the mid-latitudes.

Explanation :

• Statement 1 is correct because dark matter emits no light and is not visible directly, so it cannot be stars or planets.
• Statement 2 is incorrect.
• Statement 3 is incorrect as Antimatter annihilates matter on contact, producing gamma rays. Astronomers do not detect them. Statement 4 is correct because Dark matter is not black hole.

Source: CSC May 2019