12-year long Rosetta Mission comes to an end with Spacecraft diving into the Comet

Perhaps nothing can quench boundless human curiosity and enthusiasm other than the amazing feats of science that enamour inquisitive mind. The incredible power of science by bestowing wings to power of imagination and creativity of mankind ushered scientific ilk into a new world of exciting innovations and discoveries. The exhilarating, imagination defying feats of space explorations send shudders of excitement that enthral science enthusiasts and researchers as well. One such mission that marvelled the scientific community with phenomenal accomplishments was the Rosetta mission. On Sep 30^th the $1.46 billion mission successfully ended its illustrious 12-year long journey in the space by diving into the Comet 67P as planned.

The Mission

The International Rosetta Mission was approved in November 1993 by the European Space Agency (ESA)’s Science Program Committee as part of Planetary Corner Stone Mission under its long term space Science Program. The mission was originally scheduled for a rendezvous with the comet 46 P/Wiratenin but due to postponement of launch of the spacecraft twice, the new target was comet 67 P/ Churyumov-Gerasimenko. Comet was named after the discoverers Klim Churyumov and Svetlana Gerasimenko who first identified it in September 1969. The mission was aptly named after Rosetta Stone, the slab of volcanic basalt that provided the key to unravel the Egyptian hieroglyphs. Similarly, Scientists hoped that Rosetta mission would unfold mysteries of oldest building blocks of solar system, the Comets.

Comet Exploration

Comets are small icy bodies which originate either in the Oort Cloud that exist far beyond the orbit of the Pluto or from the Kuiper Belt located beyond the orbit of Neptune and releases gas or dust. When comets pass close to the sun they get heated up and begin to outgas thus displaying visible atmosphere or Coma and sometimes a tail. Usually the dust consists of ice, carbon dioxide, ammonia, methane and more. Evolutionary biologists believed that numerous comets impounded the surface of fledging Earth 4.6 billion years ago bringing with them water and other organic compounds needed for generation of life on Earth. A critical analysis of the comet mass would help understand in detail the evolution of the solar system and presence of extraterrestrial life. Comet 67 P believed to have originated from Kuiper belt belongs to Jupiter Family Comets is controlled by Jupiter’s gravity. Due to collisions or gravitational perturbations these icy bodies are ejected from the Kuiper belt and fall towards sun.

Rosetta Space Craft

Rosetta is a robotic spacecraft launched on 2^nd March 2004 by the Ariane V rocket. It has two main elements: The Rosetta Space probe orbiter with 12 scientific instruments and Philae, a robotic lander had additional 5 instruments. It was designed to both orbit and land on the comet for a detailed study of the comet. Before entering a phase of hibernation in June 2011 when the instruments on board were powered down to conserve energy, it made three flybys of Earth and one flyby of Mars in 2007. It had passed by two asteroids: 2867 Steins in 2008 and 21 Lutetia in 2010. It created a buzz in the scientific community by waking up to a pre-set alarm after 31 months of hibernation on January 20^th 2014 to begin its rendezvous in space with the comet 67P. After 10 years, five months and four days it orbited around Sun for five times traversed a distance of 6 billion kilometres. Rosetta took 10 years to reach the Comet. Moreover, it was travelling at much faster speeds which couldn’t ever be reached by spacecrafts leaving the Earth. Hence since its launch in 2004, Rosetta used the gravity of Earth and Mars as a slingshot to pick up the acceleration needed to enter the Comet’s trajectory. All the operations are controlled from the European Space Operations Centre (ESOC) Darmstadt, Germany.

Philae’s touch down with the Comet

The succeeding events post-hibernation were meticulously planned wherein the robotic lander Philae of Rosetta was all set to land on the surface of the comet. Accordingly, Rosetta slowed down to enter an orbit around the Comet in May 2014.  Landing was planned from the sunward side of the orbit to encounter less dust and reduce impact of a hard collision on Philae. On 6^th August 2014 Rosetta had rendezvous with Comet 67P and after closer study of surface properties of Comet, exact site of landing was decided. In August 2014, Rosetta became the first spacecraft to orbit around a comet. By September the distance between Comet and Rosetta was reduced by series of burns on its thrusters. As Rosetta was closing nearer to Comet another major challenge was communication. Since the radio transmission signals travelling at a speed of light took 45 minutes to reach the nearest Gold Stone radio dish in California.  It was also decided that Philae will touch down on the site Agilika, a place located on smaller lobe of Comet.

On November 12^th 2014, Rosetta accomplished scientifically challenging mission in the history of the space explorations so far. At nearly 500 million Kilometers distance from Earth, between Mars and Jupiter, 100kg Philae lander ejected from the spacecraft Rosetta and landed on the Comet surface. In common parlance, it was a process, wherein tried to transfer an object from one speeding bullet train to another. Both of them are flying at a speed of 65,000 km an hour. The task is onerous as crucial details like the densities, surface atmosphere of the Comet and other details of the landing site are not known. Moreover, the unusual double lobed shape of the Comet was not known until the rendezvous with the Comet.

Rosetta pictures indicated that surface of the comet was highly undulated with wicked slopes and elevated rocks. Comet was believed to be 4 kilometers wide, orbits around Sun in 6.6years with average temperature of -70C. Philae piggybacking on Rosetta separated from its mother, from a distance of 12 kilometers from comet with unfolded legs. To escape the weak gravity of comet Philae was endowed with Harpoons to anchor the Comet’s surface. Philae was designed to land on a slope of 30 degrees and once anchored it was supposed to transmit high-resolution pictures of the comet’s surface and perform analysis of Comet’s surface. The instruments on board can dig the surface and heat them to measure their properties. Unfortunately, the harpoons failed to fire upon landing so it bounced three times before settling down under a shadow of cliff in Abydos region. As a result, solar panels failed to provide enough energy for carrying out any analysis. Though Philae managed to send few images in the next days, it went silent on 14^th November 2014. Fortunately, the lander was revived on June 13^th 2015, when the Comet moved closer to Sun. It was observed that Philae had been collecting enough samples all the while but didn’t have enough power to send signals.

During this period Rosetta was tracking the Comet and conducting analyses of gases emitted by it, studying its atmosphere and gravity. Last month Rosetta again tracked Philae. Now with Comet heading towards Jupiter and Rosetta powered by Solar Panels wouldn’t have enough energy to keep up, scientists have decided to annul the program by allowing Rosetta to gently dive into the Comet.  Since comet surface is porous, Rosetta’s fall would be rather a slow-motion collision rather than a violent crash. Controlled impact gave scientists a chance to observe the surface properties of the Comet more clearly and till to the last minute, the spacecraft was sending back lots of images. The final landing place was a smooth patch in the head region of duck-shaped comet. The speed upon impact was close to walking speed pace. The end of the mission was signaled by blank computer screens and absence radio signal chatter.

Accomplishments of Rosetta Mission

Till now, Rosetta mission had successfully carried out its objectives of global characterization of asteroids, determination of their dynamic properties, surface morphology and composition. Analysis of data relayed by Rosetta, indicated that comets are not no longer dirty snowballs. But snowy dust ball, harboring organic compounds, carbon-based molecules the building blocks of life. The northern hemisphere of Comet’s nucleus was filled with dunes and ripples similar to that on Venus, Earth and Venus. It doesn’t have robust atmosphere and high gravity but has structures resembling sand dunes.

It was found that Comet 67P was darker than Charcoal without much water and ice. Northern hemisphere is relatively warm compared to southern hemisphere indicating existence of seasons. Researchers are currently busy analyzing the huge quantities of data collected by Rosetta and are hopeful of hitting at robust clues about the origins of Earth. Comets are basically the remnants of debris existing in space after creation of Solar System. Thus, this mission is extraordinary for its miraculous adventures in space and for overwhelming exhilaration it generated.

https://www.youtube.com/watch?v=KHPPToSNdik

Earlier Cometary Explorations

Cometary explorations began in 1978 with the launch of NASA’s International Cometary Explorer. It passed the tail of Comet Giacoinni-Zinner and Comet Halley. It was followed by two Russian probes, Vega-1 and Vega-2 in 1984; Japanese twin spacecrafts Sakigake and Suisei (1985); ESA’s Giotto in 1985. NASA’s missions include- Deep Space 1(1998), Stardust (1999), Contour (2002), Deep Impact (2005) which was retired in 2010. Rosetta is the first mission that attempted to land on the nucleus of comet.

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ISRO masters Multi-Burn Technology through PSLV-C35

ISRO has mastered the multi-burn technology by successfully placing satellites into two different orbits. The advanced version of the ISRO’s workhorse PSLV-C35 during the launch on September 26^th hoisted 8 satellites into multiple orbits.

About PSLV-35

PSLV made its debut in 1993, over the years earned a formidable reputation for its consistent performance. PSLV vehicles capitalizes on the unique advantage of using a combination of solid rocket motors and liquid-fuelled engines. PSLV known to be reliable and effective launch vehicle so far had delivered payloads in straight mission and never attempted to accommodate flexible missions where payloads are deployed into different orbits. Lifting satellites to different orbits invariably requires multiple restarts. The current PSLV mission was designed accommodate this feature. Consequently, engineers reworked the design of the L-2-5 engines in the upper stage of PSLV responsible for multiple start. This was achieved by developing new propellant handling techniques so that propellant would settle prior to engine start-up so that engines would take only liquid propellants and no gas bubbles. Moreover, additional power margins are included in PS4 (Upper stage) for extended coast periods so that PSLV can conduct missions for long hours. Initial tests for restarting of the upper stage were conducted in December 2015. After its successful performance in initial tests, a second round of tests set stage for final flight were completed in June 2016. After a green signal from the Launch Authorisation Board (LAB), the flight was conducted on Monday. Multi-burn technology involves switching on and off of rocket engines endowing the launch vehicle the ability to deliver satellites to two different orbits.

In its longest missions conducted so far that lasted for 2hrs 15 minutes and 33 seconds, PSLV-C35 weighing 320 tons and measuring 44.4mts lifted off from the first launch pad of the Satish Dhawan Space Centre, SHAR, Sriharikota, carrying eight satellites of total weight 675 kg. The major Indian weather satellite SCATSAT-1 weighing 371kg was deployed into a Sun Synchronous Orbit (SSO) at an inclination of 98.1 degrees over the equator.  While the two other Indian satellites PRATHAM (10 Kg) developed by IIT B students and PISAT (5.25kg) constructed by PES University, Bangalore and five other foreign satellites were placed in a 689 Km Polar Orbit at 98.21-degree inclination. PRATHAM was aimed at estimating the Total Electron Count (TEC) and PISAT Nanosatellite was constructed for remote sensing applications.

On its 37^th mission PSLV-C35, after a flight of around 17 minutes, SCATSAT-1 separated from the PSLV fourth stage. After separation solar panels were deployed automatically and ISRO’s Telemetry, Tracking and Command Network (ISTRAC) and Bangalore took over the control of the satellite. SCATSAT is a continuity to the Ocean SAT-II Scatterometer (popularly termed as Oscat) launched in September 2009 to provide wind vector data products for weather forecasting, cyclone detection and tracking services to users. This Earth observation satellite carries a ku-band Scatterometer similar to OceanSat-II and has mission life of 5 years.  OScat was the first microwave remote sensing satellite. It earned global repute for contributing the areas of wind-retreival, weather-forecasting, cyclone-tracking and prediction. It accurately predicted Cyclone Phalin that hit Odisha and avoided loss of human life. The 17 minutes’ ascent for deployment of SCATSAT involved standard patterns of flight and was relatively hassle-free. But the PSLV still had the task of placing the seven other satellites in a different orbit.

Post SCATSAT deployment

The PSLV began to coast over the South Polar region and then ascended towards the Northern Hemisphere. After a gap of one hour 22 minutes, when the PSLV is in North polar region, the two engines of the PS4 were reignited and fired for 20 seconds. As a result, it entered into an elliptical orbit which is 725km from one side of the earth and 685 km from other side. Again after 50 min, when PS4 was coasting in the South Polar region, engines were fired for another 20 seconds. This second firing propelled the rocket to enter the circular orbit of 669 km altitude with an inclination of 98.21 degree. Within the next three minutes the dual launcher adapter separated from PSLV fourth stage and the first satellite to separate was ALSAT-1N followed by NLS-19, PRATHAM, PISAT, ALSAT-1B, ALSAT-2B and PATHFINDER-1.

Foreign Satellites

Other than PRATHAM and PISAT which are of Indian origin, rest of them belonged to international customers. ALSAT series satellites are from Algeria. The 103 kg, ALSAT 1B earth observation satellite aids in environment and disaster monitoring, ALSAT-2B weighing 117 kg is a high resolution remote sensing satellite with panchromatic and multispectral imaging capability and the 7kg ALSAT-1N is a Nanosatellite built by students for technology demonstration. NLS-19 is 8kg Canadian Nanosatellite used to perform experiments for reducing the space debris and tracking commercial aircraft. Finally, the PATHFINDER-1 of Black Sky Global of Seattle, is a 44kg American microsatellite used for commercial high resolution imaging. With this PSLV-C35 launch, ISRO has so far delivered 42 Indian payloads and 79 foreign satellites. As a precedent ISRO conducts four PSLV launch missions. This launch was fifth PSLV launch, a record for this year and seems to be in line with ISRO’s long term goals for PSLV of carrying out 6 to 8 launches a year to gradually shift the vehicle’s satellite services for commercial purposes. Europe’s Vega rocket clocking seven successful launches this year emerged as stiff competitor for PSLV. Vega operators are aiming to increase their launches to 10 per a year. Similarly, Khurinchev Space Centre of Moscow and its commercial wing, International Launch Services of Reston, Virginia with the announcement of two variant Proton Launch Vehicles for small satellites is also offering tough competition to ISRO. While ISRO undoubtedly has immense cost benefit ratio over the rest, they must indeed work really hard to stay ahead in the commercial satellite launching market.

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Splendid Success of GSLV operational launch

With the successful operational launch of GSLV F-05 rocket that hoisted the meteorological satellite INSAT-3DR into the geostationary transfer orbit (GTO), ISRO has entered into a new phase of self-reliance. Till now, PSLV (Polar Satellite Launch Vehicles), the trusted workhorse adorned the prestigious crown of ISRO with over consecutive 30 successful launches. PSLV could hoist satellites weighing few kilograms to less than 1400kg limiting ISRO’s capability of launching heavy satellites. PSLV are capable of carrying remote sensing satellites which are lighter and are placed in polar orbits. These satellites weigh from few hundred kilograms to about a tonne. Polar orbits are orbits in which satellites don’t move in tandem with the rotation of the earth and hence they are not suitable for communication. The cost efficiency and the reliability of PSLV has been established in the segment of the smaller satellites. India already boasts of 30 to 35% cheaper launches than other countries. Whereas Communication satellites are heavier, weigh 2 to 5 tons and need big boosters. GSLV series of vehicles are designed to hoist heavy satellites into the geosynchronous orbits 36,000km above the equator, where the satellite moves in tandem to earth’s rotation and hence service of satellite is available to the user all the time. GSLV (Geosynchronous Launch Vehicle) can carry satellites weighing over 1.5 tonnes to 4 tonnes. For heavier satellites of over 4 tonnes India employs Ariane-6 rocket of European Space Agency. Satellite launching services of foreign providers are very high. ISRO with three consecutive successful launches can now induct GSLVs for launch of heavy commercial satellites. Previous successful launches with the indigenous cryogenic engines were GSLV-D5 of January 2014 and GSLV-D6 August 2015 that launched GSAT-14 and GSAT-6 satellites into the designated orbits.

About the Launch & Satellite

The 49 meter- long, GSLV MkII, weighing 450 tons, powered by an indigenous cryogenic engine CE-7.5, lifted off from the second launch pad of Satish Dhawan Space Centre, Sriharikota delivered the satellite with remarkable precision. Launch was delayed by 40 minutes due to gas leak in a ground circuit. INSAT-3DR weighed 2211 kg of which 1225 kg is propellant. The propellant helps in satellite to fire up from the GTO to geostationary orbit and to maintain the satellite in the orbit slot during its life time. It is an advanced satellite with an imaging system, an atmospheric Sounder, Data-Relay Transponder & Satellite-aided search and Rescue Transponder. Imaging system with infrared and color camera can provide better night time pictures, images storms. Camera will take images every 26 minutes and its life span is 10 years.  Sounder would collect data on humidity, temperature and ozone data from different layers of atmosphere. The satellite has solar arrays, generating power. This satellite will track storms and tropical cyclones, will relay data from remote weather stations and ocean buoys to weather forecast centers, precisely indicate distress signals from ships and planes, aiding in search and rescue operations. INSAT-3DR will supplement the services of INSAT-3D launched in 2013.  INSAT-3DR now joins the conglomerate of meteorological satellites operated by ISRO- KALPANA, INSAT-3A and INSAT-3D.

Teething Problems with GSLV                                                     

India’s tryst with GSLV which began in 1986 was beset with many obstacles. When India announced its decision to start the project, several countries stepped forward to help and train personnel. Indeed, US and French companies had put forth their proposals. But India declined them because of high costs. Eventually India clinched an agreement with Russian company Glavkosmos by 1990 for supply of seven cryogenic engines of 7.5 tons thrust along with the transfer of cryogenic technology. But in 1993 irked by the Indo-Russian deal, US severely objected Russia selling cryogenic technology to India as this would be a violation under the Missile Technology Control regime (MTCR).  As per MTCR guidelines, members established a “no undercut” policy means if a member denies sale of technology to another country, then the policy has to be strictly adhered by all other members. Further developed countries felt that their business interests would be severely threatened by India’s entry into the heavy satellite-launch business. Under pressure Russian company backed off from transferring technology, but supplied cryogenic engines and an additional mock-up engine. As a result, ISRO had to single-handedly sweat out to the technology which was zealously protected by all nations. Indigenous engines were eventually built at Liquid Propulsion Systems Centre, Thiruvananthapuram.

GSLV Variants

GSLV is a three stage launcher and ISRO has three variants- MkI, MkII, MkIII. All these variants have the solid-fuel first stage and a liquid fuel second stage powered by Vikas engine. The third stage of MkI uses the Russian cryogenic engines while the third stage CUS (Cryogenic Upper Stage) of MkII and MkIII have the indigenously developed engines CE-7.5 and CE-2- respectively. MkIII developmental flight is scheduled for launch by December 2016 is capable of carrying much heavier payloads. It will piggy-back GSAT-19 communication satellite. Once MkIII also establishes its reliability India will be become self-sufficient in terms of launching capacities. GSLV F-05 is an MkII variant capable of carrying payloads of around 2.5 tons. MkII has assured ISRO of its reliability during its two developmental flights. Unlike in developmental flight, during operational flight (the current launch) flight parameters (like altitude, relative velocity, time etc) or flight routes will not be tested.

Cryogenic Technology

Cryotechnology is incredibly difficult. In general, three types of rocket fuels are used- Solid, Liquid and gaseous. Solid fuels despite releasing more amount of energy than liquids are not preferred because of their high density. Liquid fuels flow and release more energy than gaseous fuels. It is established that when hydrogen gas burns in presence of oxygen, the combustion reaction generates 30% more thrust than other rocket fuels. In cryogenic technology, both hydrogen and oxygen are cooled to such a low temperature that they become liquids, occupy less space and start flowing. Hydrogen and Oxygen are liquefied under very low temperatures. Hydrogen is cooled to -253°C and Oxygen to -183°C and stored in pressurized chambers with extreme care as they are brittle, explosive in nature and can evaporate quickly. These propellants can’t be pumped into combustion chambers using normal pumps, special turbo pumps are to be employed. All operations must be condensation free. Presence of moisture can be disastrous for a launch. The magnitude of the extreme complexity is truly onerous.

So far ISRO conducted 10 launches with GSLV starting with GSLV-D1 (Mk1) in April 2001. Of which four launches have failed, one was a partial success and with the latest meticulous launch India seems to have tamed the “naughty boy” (GSLV fondly recalled by Indian scientists) GSLV. With this success, ISRO is now geared to launch second robotic mission to Moon Chandrayaan-2 in 2018 with a GSLV MkII variant. Moreover, with Space X’s Falcon 9 exploding ahead of its scheduled flight, global markets are experiencing the crunch of reliable launch vehicles for heavy satellites. GSLV F-05 successful launch boosted and substantially improved ISRO’s chances of making a mark in satellite launching services as a reliable player. ISRO’s reliability with MkIII would further establish its stature as trusted player facilitating its entry into the $300 billion global satellite-launching industry.

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NASA’s JUNO mission scripted a new history

America couldn’t have asked for more on its birthday. NASA has yet again scripted a momentous success through insertion of Juno Spacecraft into Jupiter’s orbit on a very special day. NASA has accomplished such astounding feats earlier on the historically important July 4^th, the independence day of America. Previous successes include-landing of Sojourner of Mars Pathfinder Mission on Martian surface in 1997 and the collision of  Deep Impact with Comet Tempel 1 in 2005. Juno mission assumes extraordinary significance since, it aims to unravel the origins of our Solar System by understanding the origin and evolution of Jupiter.

Around four and half million years ago, a giant cloud of gas and dust, called nebula collapsed to form our solar system. Sun formed first, and later on the swirling cloud condensed to form various planets, asteroids and comets. The first planet formed from the Hydrogen and Helium left after the birth of Sun was Jupiter. It is the largest, oldest planet of our Solar System. Unlike earth, it retained the remnants of original nebula, making it an ideal planet to trace the origins of Solar System. Juno Mission was commissioned to understand the unique atmosphere composition of Jupiter, determine the amount of water in its atmosphere, global structure and composition, map magnetic rings, gravity fields, explore and study its magnetosphere, northern and southern lights at its poles i. e., auroras. The mission is aptly named as Juno, because as per the Roman Mythology, Jupiter, the King of Gods camouflaged with clouds to hide his mischief. Jupiter’s wife Goddess Juno could penetrate the clouds and decipher the mystery. Juno spacecraft is now assigned the task of unfolding the mysteries of this largest terrestrial planet. While it is known that Jupiter largely contains Hydrogen and Helium, the search is now on to know the composition of other heavy elements present in the planet. Besides, the enchanting characteristic features like swirling clouds, bands, storms, the great red spot had enthused scientists to explore the planet.

The crushing weight of Jupiter resulted in generation of extreme temperature and pressures deep inside. Consequently the gaseous hydrogen is squeezed into electrically conducting liquid metallic hydrogen causing the production of extremely strong magnetic field similar to solar magnetic field. As a result any charged particle flying through the space gets pulled into Jupiter’s magnetic field. The material so caught is channeled towards poles creating an intense light showers or aurorae or the Northern and Southern light (similar to polar auroras on earth). Evading the pull of powerful magnetosphere of Jupiter became a formidable task for the Space scientists contemplating Jupiter missions. Juno spacecraft was scientifically designed to carry powerful instruments on board to observe and capture the aurora lights in ultraviolet radiation that can enhance our understanding of Jupiter’s magnetic field.

 Juno spacecraft, designed under the New Frontiers Program was hoisted into space by the expendable launch vehicle Atlas 551 rocket on August 5^th 2011 from Cape Canaveral, Florida. Equipped with nine instruments-microwave radiometer for atmospheric sounding and composition (MWR), vector magnetometer (MAG), plasma and energetic particle detector (JADE and JEDI), Ultra violet imager/spectrometer (UVS), infrared imager/spectrometer (JIRAM), radio/plasma wave experiment (waves), gravity/radio science system (Gravity science) and Junocam the spacecraft will orbit around Jupiter 37 times and pass over the planet within 3100miles range to make all crucial observations. Strength of gravity will aid in calculating mass and a measure of magnetic radiation helps in knowing composition. Powered by three extended solar panels of 20mts jutting out from a hexagonal body Juno spins at 2 revolutions per minute to remain stable. To protect the spacecraft from the high energy radiations emanated by Jupiter (20,000 times as intense as earth’s magnetic field), it was armored with 180kg of titanium shields.

After travelling for two years, in October 2013, Juno made earth’s flyby (was within 350 miles of Earth’s reach). Earth’s gravity propelled Juno towards Jupiter. Atlas rocket provided half of the energy needed for Juno to reach Jupiter and the other half was provided by earth’s flyby. When Juno arrived near Jupiter, it was moving faster than any human-made object ever fired, moving at a speed of hundred and sixty-five thousand miles an hour. To enter the Jupiter’s orbit it had to slow down. It was precisely at this moment on July 4^th, 9pm, Pacific Standard Time, engines were fired for 35 minutes. Juno’s rotation rate increased to 5rpm and altitude is changed to enter the Jupiter’s orbit or capture orbit. Even the speed was reduced to 1212 miles per hour to facilitate insertion into Jupiter’s orbit. Accurate firing of the engine made the $1.1 billion worth mission a tremendous success.  Any discrepancy at this stage would have doomed it. In 1995 NASA’s previous mission to Jupiter, Galileo arrived at the planet in 1995 but its instruments including antenna were irreparably damaged by radiation. Galileo indeed captured breathtaking images of the ammoniac clouds swirling around the planet.  

Juno is now almost five hundred forty million miles from earth, electronic signals would take 48 min to travel.  Juno’s orbital insertion was tracked by Jet Propulsion Laboratory (JPL), Pasadena, California and Lockheed Martin Juno Operations Centre, Colorado.  Juno entered the capture orbit where the probe will stay for 107 days. Scientist preferred this long route rather than direct insertion, 14-day orbit, as this requires more fuel. Capture orbit on the other hand, needs less fuel and scientists would get a chance to recheck the functioning of all the instruments on the board and can make some initial observations. On November 2^nd, Juno’s first science orbit would begin when engine is burned again to increase its speed.  In order to minimize the effect of radiations, Juno will fly along a long elliptical orbit with a closet range of 3100 miles at the south of the orbit and extends to 1.2 million miles from Jupiter (flying beyond the orbit of Jupiter’s moon Castillo). Extended elliptical orbits would keep the solar panels in sunlight.

Data collection from the instruments would begin from October 2016. Juno’s mission life is 2 years. Engines will be fired for the final time in February 2018 when it will crash into Jupiter’s atmosphere as planned. While the spacecraft would trigger its own annihilation, instruments on board will capture data.

 

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The Looming Threat of Zika Virus

Brazil grappling with money laundering scams, drinking water crisis and political unrest is now racing towards a health epidemic of dangerous proportions, the Zika Virus. The South American country all set to unveil Rio Summer Olympics, biggest sporting fiesta on the planet in over six months is now grappling with health emergency, Zika virus. Brazil emerged as epicenter of Zika virus (ZIKV), a mosquito-borne disease transmitted by Aedes sp. Zika virus, a member of flavi viridae family and is related to yellow fever, west Nile and dengue fever virus. Zika is not contagious. The vital modes of transmission modes are blood transfusions and mother-to-child transmission. While the virus was believed to migrate through sexual contact, there is no conclusive research evidence as yet.

The virus was first identified and isolated from a caged Rhesus monkey in Zika forest of Uganda in 1947. In 1952 researchers isolated Zika Virus from the serum of an affected human being in Uganda and Tanzania. Only 20% of the people infected by Zika virus will develop symptoms. The symptoms are similar to those exhibited by other arbo virus like dengue and common symptoms include fever, skin rashes, conjunctivitis, muscle and joint pains, malaise and headache. Symptoms are mild and last for 2-7 days and hence no specified treatment is recommended. Medicines used to treat common cold and fever are usually prescribed. In absence of causalities dedicated research to develop vaccines weren’t initiated on large scale. But now with recent outbreak of the epidemic in Brazil, pharmaceutical majors are now focusing attention towards vaccine development. Researchers believe that it would take at least 5 years to develop vaccine for Zika virus. Thus far, the only preventive measure against Zika virus is effective control of vector (mosquito) population.

WHO is predicting an outbreak and major countries have issued travel advisory asking pregnant women from traveling to affected countries. Zika is speculated to spread to both Americas except Canada and Chile. Since May 2015 the viral infection has spread to 21 countries. Lack of immunity among the population and prevalence of Aedes mosquito, the carrier of the disease led to surge in infection levels. Unfortunately controlling spread of disease in highly interconnected world has now become an arduous task. Mosquitoes are now considered the worst enemies of mankind for being vectors of several devastating diseases like Malaria, dengue fever killing hundreds and thousands of people.

Environmentalists said that urbanization and deforestation created ideal conditions for the multiplication of disease causing vectors. Following explosive spread of Zika virus, Brazilians are under intense international pressure to curtail the vector population. They have adopted a judicious mix of old and new mosquito controlling strategies to contain the viral transmission. Genetically engineered mosquitoes harboring a lethal gene are released in the outskirts of cities. GM mosquitoes breed with native population and the gene when passed onto the offspring dies before reaching adulthood. Consequently, the vector population is now precisely kept under check. Biotech companies have now devised genetic overdrive methods like spreading sterility trait in Aedes to rapidly control virus carrying vectors. Another approach is infecting mosquitoes with Wolbachia bacterium, which prevents mosquito from carrying the virus. Bacterium is passed onto the subsequent generations through infected eggs thus the lethal effects of mosquito bites are overcome.

First well documented case of Zika virus was described in 1968 when no potential fatalities were reported. Three potent lineages of Virus were identified- two from African and one from Asian. From 1951 to 1981 human infections were reported in African countries and in parts of India, Indonesia, Malaysia, Thailand, Philippines and Vietnam. The viral strains now found in Americas bear close similarities with the French Polynesian strains. The virus for several decades remained benign since its first. The first major outbreak of Zika occurred in Yap island of Federated States of Micronesia. By 2013 it spread to French Polynesia where the infected persons were diagnosed with severe neurological problems including the occurrence of rare disorder Guillain Barre Syndrome. It is an auto-immune disease that occurs when the immune system attacks the peripheral nerves causing muscle weakness, tingling, loss of sensation and eventually total paralysis. Within span of three months of viral infection, 40 such cases were reported in Yap island. Incidentally the virus caught the attention of researchers as it spread to Australia, France, Japan, Norway and Easter Island.

In 2014, the viral genome was decoded. The single stranded positive RNA virus with the help of host cell machinery replicates and churns out smaller proteins-which includes the capsid, membrane, envelope and seven non-structural proteins. The virus infects the host cell, invades the immune system and takes over dendritic cells. Researchers believed that the three lineages of the virus might have evolved from Uganda in 1920 and through series of recombination events, it has become more adaptive. In May 2015, the virus made its first appearance in South America in Brazil. Perhaps it was imported into the region during the FIFA cup of 2014 and was spread through the bite of Aedes sp mosquitoes. Health experts estimated that by around 2015 around million people might have been infected. Since the outbreak of disease in 2015 there has been whopping increase in the birth of babies with microcephaly in Brazil. While Zika virus was suspected to have caused the birth defect, definite links are not yet established.  But viral traces are found in the amniotic fluid, placental tissues, miscarried babies and in the brains of the babies died of microcephaly immediately after birth. While strong links suggests that Zika virus had caused the genetic-defects in the newborn babies, the immune responses of Zika virus are hard to detect. Zika virus is becoming hard to detect because of its similar immune responses as of dengue virus and most of the Brazilian population are exposed to dengue virus too. Researchers opine that the relatively mild Zika virus due to continued genetic changes is now predisposed to acquire disease-sparking capabilities.

With disproportionate increase in number of microcephalic infants in Brazil researchers are more worried about the resurgence of a viral outbreak. Microcephaly is characterized by four malformations-loss of large degree of brain tissue, unusually smooth and wrinkleless brains, numerous calcium deposits and smaller cerebellums. Unfortunately microcephalic condition of the fetus in most cases, cann’t be detected with ultrasound scans during the first 20 weeks in expectant mothers. It is towards the end of second trimester usually genetic defects can be detected with ultrasound. By 24 weeks aborting a foetus is risky and not legally approved.  Sometimes microcephalic condition remains undetected and appears when babies are born. The affected children display varied mental disabilities- intellectual abilities are stunted, communication is hindered. They may be profoundly disabled and might be confined to wheel chairs for the rest of their lives. In wake of the severity of the disease, Centre for Disease Control and WHO advised women to delay pregnancy and asked to avoid travelling to the affected regions. With Zika virus gradually transcending the boundaries of Latin American countries, US is now highly worried at the propensity of Zika becoming a pandemic in Americas. Health experts as of now, squashed such worries and believed that Zika by and large might cause localized infections in few clusters in US if any. The robust health and sanitation system is geared up to avert any major health threat to US. On the contrary, Indian health experts expressed severe concerns about a possible Zika outbreak as the country regularly encounters outbreak of dengue and chikungunya caused by the bite of Aedes aegypti mosquito, carrier of Zika virus. Traces of Zika were detected in India in 1952-53 but there was no reported outbreak. With 26 million children born every year India is at high risk.

 

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Extreme Weather Events in India

Indian Astronomy Satellite-ASTROSTAT

On September 28th Indian Space Research Organization (ISRO) has scripted yet another milestone by successfully launching Astrostat satellite dedicated exclusively for astronomical studies. Indian astronomers are immensely excited at the prospect of state-of art capabilities offered by this satellite. Designed for effective life span of five years, the satellite will endow Indian astronomers to study “radiation bands that carry information about the exotic neutron stars, newly born or exploding stars” and observe the dense effusion of hot gases around black holes.  Indian ground based telescopes- Giant Meter wave Radio Telescope at Pune and the Indian Astronomical Observatory at Ladakh enable scientists to detect radio waves and infrared radiations that penetrate earth’s atmosphere but don’t have scientific instruments to study astronomical phenomena occurring in the Ultraviolet rays, X-rays and gamma-rays. Till now they used to depend on the NASA’s Nuclear Spectroscopic Array (NuSTAR) and ESA (European Space Agency) to study various radiation bands.

 Astrostat has five instruments on board to detect multi-wavelength radiations ranging from visible light to Ultraviolet and from low-energy through high energy X-ray radiations.  The instruments include- Ultraviolet Imaging Telescope, Soft X-ray imaging telescope, Large Area X-ray proportional Counters, Cadmium Zinc telluride Imagers, Scanning Sky Monitor, and charged particle monitor. The charged particle monitor (CPM) designed to detect charged particles and sensitive to protons above 1 MeV (Mega electron Volt). Astrostat is a collaborative effort of many institutes- Tata Institute of Fundamental Research (TIFR), Mumbai, Indian Institute of Astrophysics Bangalore, Raman Research Institute Bangalore, InterUniversity Centre for Astronomy and Astrophysics Pune, Bhabha Atomic Research centre Mumbai, S.N Bose National Centre for Basic Sciences Kolkata, Canadian Space Agency, University of Leichester. The unique range of observatory capabilities will entail it to have a wide coverage unattained by any of the international space observatories till now.

The first Indian space observatory having payload of 1513  kg was launched into the Low Earth Orbit (LEO) of 650km from the surface of the earth by ISRO’s work horse PSLV-C30 at an inclination of 6 degrees from the equator. Satellites in the low earth orbits have to pass through the dense radiation belts of South Atlantic Anamoly (SAA) region that has high fluxes of protons and electrons. Great care has to be exerted when satellite passes through these regions as the high density of the energetic particles can often cause glitches in the data and can permanently damage sensitive instruments onboard.

The idea of having a space observatory was first conceived by astrophysicist Lyman Spitzer in 1946 as the electromagnetic radiations entering earth’s atmosphere are filtered and thus obstruct the view of the celestial bodies. This objective was realized with the launch of the Hubble Space Telescope named after Edwin Hubble in 1990 by NASA. Till date it is the largest and the most versatile telescope providing extremely high-resolution space images. It was uniquely designed to be serviced by astronauts and eventually it was serviced in 1993 for the first time when its main mirror was grounded inaccurately. Last servicing was done in 2009 and it is expected to last till 2030-40. Its successor James Webb Space telescope (JWST) is scheduled for launch in 2018.

India’s tryst with space observatory began in 1996 when ISRO carried out satellite-bound Indian X-Ray Astronomy Experiment in 1996.  ISRO has approved Astrostat in 2004 but its launch was inadvertently delayed. Along with the Astrostat satellite, the enhanced rocket launcher PSLV in XL configuration on its successful thirtieth launch mission piggy backed six satellites- 76kg LAPAN-A2 of Indonesia, 14kg NLS of Canada and four identical LEMUR satellites of US each weighing 28kg. In all the 320 tonne, 45m tall PSLV-C30 carried seven satellites of payload 1613kg.

The primary objectives of Astrostat are to study binary star systems containing neutron stars and black holes, study and estimate the magnetic fields of neutron stars, study star birth-regions and high energy processes occurring beyond our galaxy. While it is no parallel to the Hubble Space telescope it can be lauded as the Indian Hubble Space Telescope for Astrostat is not as powerful, as precise, as the illustrious NASA observatory. It is culmination of humble efforts of the ISRO and one of its kind bestowed with multi—wavelength capabilities. With this launch India has joined the scientific elite countries- the US, Russia, European Space Agency and Japan that own a space observatory.

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