Mars Orbiter Mission

              Artist's rendering of the MOM orbiting Mars

Mission type	Mars orbiter
Operator	ISRO
COSPAR ID	2013-060A
SATCAT №	39370
Website	www.isro.org/mars/home.aspx
Mission duration	6 months (planned)[1]
Spacecraft properties
Bus	I-1K[2]
Manufacturer	ISAC
Launch mass	1,337 kg (2,948 lb)[3]
Dry mass	500 kg (1,100 lb)
Payload mass	15 kg (33 lb)[4]
Dimensions	1.5-metre (4 ft 11 in) cube
Power	840 watts[2]

Start of mission
Launch date	5 November 2013, 09:08 UTC[5]
Rocket	PSLV-XL C25[6]
Launch site	Satish Dhawan FLP
Contractor	ISRO
Orbital parameters
Reference system	Areocentric
Periareon	365.3 km (227.0 mi)
Apoareon	80,000 km (50,000 mi)
Inclination	150.0° [7]
Period	76.72 hours
Epoch	Planned
The Mars Orbiter Mission (MOM), also called Mangalyaan "Mars-craft" (Sanskrit मंगल maṅgala "Mars" + यान yāna "craft"),[9][10] is a Mars orbiter launched into Earth orbit on 5 November 2013 by the Indian Space Research Organisation (ISRO).[11][12][13][14] It was successfully inserted into Mars orbit on 24 September 2014, making India the first nation to send a satellite into Mars orbit on its first attempt, and the first Asian nation to do so.[15][16][17][18] The mission is a "technology demonstrator" project aiming to develop the technologies required for design, planning, management, and operations of an interplanetary mission.[19] The Mars Orbiter Mission probe lifted-off from the First Launch Pad at Satish Dhawan Space Centre SHAR, Sriharikota, Andhra Pradesh, using a Polar Satellite Launch Vehicle (PSLV) rocket C25 at 09:08 UTC (14:38 IST) on 5 November 2013.[20] The launch window was approximately 20 days long and started on 28 October 2013.[5] The MOM probe spent about a month in Earth orbit, where it made a series of seven altitude-raising orbital manoeuvres before trans-Mars injection on 30 November 2013 (UTC).[21] It is India's first interplanetary mission and ISRO has become the fourth space agency to reach Mars, after the Soviet space program, NASA, and the European Space Agency.[22][23] The spacecraft is currently being monitored from the Spacecraft Control Centre at ISRO Telemetry, Tracking and Command Network (ISTRAC) in Bangalore with support from Indian Deep Space Network (IDSN) antennae at Byalalu.[24] The MOM mission concept began with a feasibility study in 2010, after the launch of lunar satellite Chandrayaan-1 in 2008. The government of India approved the project on 3 August 2012,[25] after the Indian Space Research Organisation completed 125 crore (US$21 million) of required studies for the orbiter.[26] The total project cost may be up to 454 crore (US$74 million).[11][27] The satellite costs 153 crore (US$25 million) and the rest of the budget has been attributed to ground stations and relay upgrades that will be used for other ISRO projects.[28] The space agency had initially planned the launch on 28 October 2013 but was postponed to 5 November 2013 following the delay in ISRO's spacecraft tracking ships to take up pre-determined positions due to poor weather in the Pacific Ocean.[5] Launch opportunities for a fuel-saving Hohmann transfer orbit occur about every 26 months, in this case, 2016 and 2018.[29] The Mars Orbiter's on-orbit mission life will be between six and ten months. Assembly of the PSLV-XL launch vehicle, designated C25, started on 5 August 2013.[30] The mounting of the five scientific instruments was completed at ISRO Satellite Centre, Bangalore, and the finished spacecraft was shipped to Sriharikota on 2 October 2013 for integration to the PSLV-XL launch vehicle.[30] The satellite's development was fast-tracked and completed in a record 15 months.[31] Despite the US federal government shutdown, NASA reaffirmed on 5 October 2013 it would provide communications and navigation support to the mission.[32] ISRO chairman stated in November 2013 that if the MOM and NASA's orbiter MAVEN were successful, they would complement each other in findings and help understand Mars better.[33] The ISRO plans to send a follow-up mission with a greater scientific payload to Mars in the 2017–2020 timeframe; it would include an orbiter and a stationary lander.[34] Objectives The primary objective of the Mars Orbiter Mission is to showcase India's rocket launch systems, spacecraft-building and operations capabilities.[40] Specifically, the primary objective is to develop the technologies required for design, planning, management and operations of an interplanetary mission, comprising the following major tasks:[19] design and realisation of a Mars orbiter with a capability to perform Earth-bound maneuvres, cruise phase of 300 days, Mars orbit insertion / capture, and on-orbit phase around Mars; deep-space communication, navigation, mission planning and management; incorporate autonomous features to handle contingency situations. The secondary objective is to explore Mars' surface features, morphology, mineralogy and Martian atmosphere using indigenous scientific instruments.[40] Spacecraft Measurements The lift-off mass was 1,350 kg (2,980 lb), including 852 kg (1,878 lb) of propellant.[2] Bus The spacecraft's bus is a modified I-1 K structure and propulsion hardware configuration, similar to Chandrayaan 1, India's lunar orbiter that operated from 2008 to 2009, with specific improvements and upgrades needed for a Mars mission.[40] The satellite structure is constructed of an aluminium and composite fibre reinforced plastic (CFRP) sandwich construction. Power Electric power is generated by three solar array panels of 1.8 m × 1.4 m (5 ft 11 in × 4 ft 7 in) each (7.56 m2 (81.4 sq ft) total), for a maximum of 840 watts of power generation in Mars orbit. Electricity is stored in a 36 Ah Li-ion battery.[2] Propulsion A liquid fuel engine with a thrust of 440 newtons is used for orbit raising and insertion into Mars orbit. The orbiter also has eight 22-newton thrusters for attitude control.[41] Its propellent mass is 852 kg.[2] Communications Communications are handled by two 230-watt TWTAs and two coherent transponders. The antenna array consists of a low-gain antenna, a medium-gain antenna and a high-gain antenna. The high-gain antenna system is based on a single 2.2-metre (7 ft 3 in) reflector illuminated by a feed at S-band. It is used to transmit and receive the telemetry, tracking, commanding and data to and from the Indian Deep Space Network.[2] Payload Scientific instruments LAP Lyman-Alpha Photometer 1.97 kg MSM Methane Sensor For Mars 2.94 kg MENCA Mars Exospheric Neutral Composition Analyser 3.56 kg TIS Thermal Infrared Imaging Spectrometer 3.2 kg MCC Mars Colour Camera 1.27 kg The 15 kg (33 lb) scientific payload consists of five instruments:[4][42][43] Atmospheric studies Lyman-Alpha Photometer (LAP) – a photometer that measures the relative abundance of deuterium and hydrogen from Lyman-alpha emissions in the upper atmosphere. Measuring the deuterium/hydrogen ratio will allow an estimation of the amount of water loss to outer space. Methane Sensor For Mars (MSM) – will measure methane in the atmosphere of Mars, if any, and map its sources.[4] Particle environment studies Mars Exospheric Neutral Composition Analyser (MENCA) – is a quadrupole mass analyser capable of analysing the neutral composition of particles in the exosphere. Surface imaging studies Thermal Infrared Imaging Spectrometer (TIS) – will measure the temperature and emissivity of the Martian surface, allowing for the mapping of surface composition and mineralogy of Mars. Mars Colour Camera (MCC) – will provide images in the visual spectrum, providing context for the other instruments. Telemetry and command Further information: Telemetry and Telecommand The Indian Space Research Organisation Telemetry, Tracking and Command Network performed navigation and tracking operations for the launch with ground stations at Sriharikota, Port Blair, Brunei and Biak in Indonesia,[44] and after the spacecraft's apogee became more than 100,000 km, an 18-metre (59 ft) and an 32 m (105 ft) diameter antenna of the Indian Deep Space Network were utilised.[45] The 18-metre (59 ft) dish-antenna was used for communication with the craft until April 2014, after which the larger 32 m (105 ft) antenna was used.[46] NASA's Deep Space Network is providing position data through its three stations located in Canberra, Madrid and Goldstone on the US West Coast during the non-visible period of ISRO's network.[47] The South African National Space Agency's (SANSA) Hartebeesthoek (HBK) ground station is also providing satellite tracking, telemetry and command services.[48]

Mission profile Timeline of operations Phase Date Event Detail Result Reference(s) Geocentric phase 5 November 2013 09:08 UTC Launch Burn time: 15:35 min in 5 stages Apogee: 23,550 km [49] 6 November 2013 19:47 UTC Orbit raising manoeuvre Burn time: 416 sec Apogee: 23,550 km to 28,825 km [50] 7 November 2013 20:48 UTC Orbit raising manoeuvre Burn time: 570.6 sec Apogee: 28,825 km to 40,186 km [51][52] 8 November 2013 20:40 UTC Orbit raising manoeuvre Burn time: 707 sec Apogee: 40,186 km to 71,636 km [51][53] 10 November 2013 20:36 UTC Orbit raising manoeuvre Incomplete burn Apogee: 71,636 km to 78,276 km [54] 11 November 2013 23:33 UTC Orbit raising manoeuvre (supplementary) Burn time: 303.8 sec Apogee: 78,276 km to 118,642 km [51] 15 November 2013 19:57 UTC Orbit raising manoeuvre Burn time: 243.5 sec Apogee: 118,642 km to 192,874 km [51][55] 30 November 2013, 19:19 UTC Trans-Mars injection Burn time: 1328.89 sec Successful heliocentric insertion [56] Heliocentric phase December 2013 – September 2014 En route to Mars – The probe was travelling a distance of 780,000,000 kilometres (480,000,000 mi) in a parabolic trajectory around the Sun[46] to reach Mars. As of 9 June 2014, the probe has travelled 460 million km in its path to Mars, and was about 100 million km away from Earth.[57] This phase plan includes up to four trajectory corrections if needed. [58][59][60][61][62] 11 December 2013 01:00 UTC 1st Trajectory correction Burn time: 40.5 sec Success [51][60][61][62] 9 April 2014 2nd Trajectory correction (planned) Not required Rescheduled for 11 June 2014 [57][59][62][63][64] 11 June 2014 11:00 UTC 2nd Trajectory correction Burn time: 16 sec Success [57][65] August 2014 3rd Trajectory correction (planned) Not required[57][66] [59][62] 22 September 2014 3rd Trajectory correction Burn time: 4 sec Success [59][62][67] Areocentric phase 24 September 2014 Mars orbit insertion Burn time: 24 min & 14 sec Success

Launch As originally conceived, ISRO would have launched MOM on its new Geosynchronous Satellite Launch Vehicle (GSLV),[69] but the GSLV has failed twice in two space missions in 2010, ISRO is still sorting out issues with its cryogenic engine,[70] and it was not advisable to wait for the new batch of rockets since that would have delayed the MOM project for at least three years.[71] ISRO had to make a choice between delaying the Mars Orbiter Mission and switching to the less-powerful PSLV. They opted for the latter. There is no way to launch on a direct-to-Mars trajectory with the PSLV as it does not have the power. Instead, ISRO launched it into Earth orbit first and slowly boosted it into an interplanetary trajectory using multiple perigee burns to maximize the Oberth effect.[69] On 19 October 2013, ISRO chairman K. Radhakrishnan announced that the launch had to be postponed by a week as a result of a delay of a crucial telemetry ship reaching Fiji Islands. The launch was rescheduled for 5 November 2013.[72] ISRO's PSLV-XL placed the satellite in Earth orbit at 09:50 UTC, on 5 November 2013,[26] with a perigee of 264.1 km, an apogee of 23,903.6 km, and inclination of 19.20 degrees,[49] with both the antenna and all three sections of the solar panel arrays deployed.[73] During the first three orbit raising operations, ISRO progressively tested the spacecraft systems.[55] The orbiter's dry mass is 500 kg (1,100 lb), and it carries 852 kg (1,878 lb) of fuel and oxidiser. Its main engine, which is a derivative of the system used on India's communications satellites, uses the bipropellant combination monomethylhydrazine and dinitrogen tetroxide to achieve the thrust necessary for escape velocity from Earth. It will also be used to slow down the probe for Mars orbit insertion and subsequently, for orbit corrections.

Orbit raising manoeuvres Orbit trajectory diagram (not to scale). Several orbit raising operations were conducted from the Spacecraft Control Centre (SCC) at ISRO Telemetry, Tracking and Command Network (ISTRAC) at Peenya, Bangalore on 6, 7, 8, 10, 12 and 16 November by using the spacecraft's on-board propulsion system and a series of perigee burns. The aim was to gradually build up the necessary escape velocity (11.2 km/s) to break free from Earth's gravitational pull while minimising propellant use. The first three of the five planned orbit raising manoeuvres were completed with nominal results, while the fourth was only partially successful. However, a subsequent supplementary manoeuvre raised the orbit to the intended altitude aimed for in the original fourth manoeuvre. A total of six burns were completed while the spacecraft remained in Earth orbit, with a seventh burn conducted on 30 November to insert MOM into a heliocentric orbit for its transit to Mars. The first orbit-raising manoeuvre was performed on 6 November 2013 at 19:47 UTC when the 440 newtons (99 lbf) liquid engine of the spacecraft was fired for 416 seconds. With this engine firing, the spacecraft's apogee was raised to 28,825 km, with a perigee of 252 km.[50] The second orbit raising manoeuvre was performed on 7 November 2013 at 20:48 UTC, with a burn time of 570.6 seconds resulting in an apogee of 40,186 km.[51][52] The third orbit raising manoeuvre was performed on 8 November 2013 at 20:40 UTC, with a burn time of 707 seconds resulting in an apogee of 71,636 km.[51][53] The fourth orbit raising manoeuvre, starting at 20:36 UTC on 10 November 2013, imparted an incremental velocity of 35 m/s to the spacecraft instead of the planned 135 m/s as a result of underburn by the motor.[54][74] Because of this, the apogee was boosted to 78,276 km instead of the planned 100,000 km.[54] When testing the redundancies built-in for the propulsion system, the flow to the liquid engine stopped, with consequent reduction in incremental velocity. During the fourth orbit burn, the primary and redundant coils of the solenoid flow control valve of 440 newton liquid engine and logic for thrust augmentation by the attitude control thrusters were being tested. When both primary and redundant coils were energised together during the planned modes, the flow to the liquid engine stopped. Operating both the coils simultaneously is not possible for future operations, however they could be operated independently of each other, in sequence.[55] As a result of the fourth planned burn coming up short, an additional unscheduled burn was performed on 12 November 2013 that increased the apogee to 118,642 km,[51][55] a slightly higher altitude than originally intended in the fourth manoeuvre.[51][75] The apogee was raised to 192,874 km on 15 November 2013, 19:57 UTC in the final orbit raising manoeuvre.[51][75] Trans-Mars injection Simulated view of Mars Orbiter Mission along with Mars, Sun, Mercury and Earth on 3rd October 2014 at 17ː00 UTC. The Mars Orbiter Mission satellite is at an altitude of about 1300 miles from Mars at the time Further information: Trans-Mars Injection On 30 November 2013 at 19:19 UTC, a 23-minute engine firing initiated the transfer of MOM away from Earth orbit and on heliocentric trajectory toward Mars.[76] The probe was travelling a distance of 780,000,000 kilometres (480,000,000 mi) to reach Mars.[77] Trajectory correction manoeuvres Four trajectory corrections were originally planned, but only three were carried out.[59] The first trajectory correction manoeuvre (TCM) was carried out on 11 December 2013, 01:00 UTC, by firing the 22 newtons (4.9 lbf) thrusters for a duration of 40.5 seconds.[51] As observed in April 2014, MOM is following the designed trajectory so closely that the trajectory correction manoeuvre planned in April 2014 was not required. The second trajectory correction manoeuvre was performed on 11 June 2014, at 16:30 hrs IST by firing the spacecraft's 22 newton thrusters for a duration of 16 seconds.[78] The third planned trajectory correction manoeuvre was postponed, due to the orbiter's trajectory closely matching the planned trajectory.[79] The third trajectory correction was also a deceleration test 3.9 seconds long on 22 September 2014.[67] Mars orbit insertion The plan was for insertion into Mars orbit on 24 September 2014,[8][68] approximately 2 days after the arrival of NASA's MAVEN orbiter.[80] The 440N liquid apogee motor was successfully test fired at 09:00 UTC (14:30 IST) on 22 September for 3.968 seconds, about 41 hours before actual orbit insertion.[81][82][83] On 24 September 2014, at IST 04:17:32 satellite communication changed over to the medium gain antenna. At IST 06:56:32 forward rotation started and locked the position to fire, at IST 07:14:32 an attitude control manoeuvre took place with the help of thrusters after eclipse started at IST 07:12:19 and LAM (Liquid Apogee Motor) starts burning at IST 07:17:32 and ends at IST 07:41:46. After that reverse manoeuvre took place, the spacecraft successfully enters Martian orbit.[67][84][85] Status MOM will be set on a highly elliptical orbit around Mars, with a period of 3.2 days and a planned periapsis of 423 km (263 mi) and apoapsis of 80,000 km (50,000 mi).[82] Commissioning and checkout operations are planned over the coming weeks to prepare MOM's instruments for science operations.[1]
Team Some of the leading scientists working on the Mars Orbiter Mission project are:[35][36] K. Radhakrishnan – Chairman, ISRO M.Y.S. Prasad – Director, Satish Dhawan Space Center Sriharikota[37] A. S. Kiran Kumar – Director, SAC[38] V. Adimurthy – Mission Concept Designer, MOM[39] Mylswamy Annadurai – Programme Director, MOM B. S. Chandrashekar – Director, ISTRAC P. Robert – Operations Director, MOM Subbiah Arunan – Project Director, MOM V. Kesavaraju – Post-Launch Mission Director, MOM P. Ekambaram – Operations Director, MOM P. Kunhikrishnan – Launch Mission Director, PSLV-XL Jitendra Nath Goswami – Director, Physical Research Laboratory ISRO S. K. Shivkumar – Orbiting payload Director, ISAC B. Jayakumar – Launch Vehicle Director, PSLV

Observing the Perseids

This is the most famous of all meteor showers. It never fails to provide an impressive display and, due to its summertime appearance, it tends to provide the majority of meteors seen by non-astronomy enthusiasts.

This meteor shower gets the name "Perseids" because it appears to radiate from the constellation Perseus. An observer in the Northern Hemisphere can start seeing Perseid meteors as early as July 23, when one meteor every hour or so could be visible. During the next three weeks, there is a slow build-up. It is possible to spot five Perseids per hour at the beginning of August and perhaps 15 per hour by August 10. The Perseids rapidly increase to a peak of 50-80 meteors per hour by the night of August 12/13 and then rapidly decline to about 10 per hour by August 15. The last night meteors are likely to be seen from this meteor shower is August 22, when an observer might see a Perseid every hour or so.

For observers in the Southern Hemisphere, the Perseid radiant never climbs above the horizon, which will considerably reduce the number of Perseid meteors you are likely to see. Nevertheless, on the night of maximum, it is possible to see 10-15 meteors per hour coming up from the northern horizon.

There are other, weaker meteor showers going on around the same time as the Perseids, but the Perseids will generally appear to move much faster across the sky than meteors from the other showers. In fact, the Perseids are among the fastest moving meteors we see every year. Another way to know if the meteor you saw was a Perseid is to mentally trace the meteor backwards. If you end up at Perseus then you have probably seen a Perseid meteor! If you are not sure where Perseus is in the sky, the following charts will help you find it from both the Northern Hemisphere and Southern Hemisphere:

                            Location of the Perseids
                    For Northern Hemisphere Observers

                 

This represents the view from mid-northern latitudes at about 2:00 a.m. local time around August 12 and 13. The graphic does not represent the view at the time of maximum, but is simply meant to help prospective observers to find the radiant location. The red line across the bottom of the image represents the horizon. (Image produced by the Author using SkyChart III and Adobe Photoshop.)

Location of the Perseids
For Southern Hemisphere Observers

This represents the view from mid-southern latitudes at about 6:00 a.m. local time around August 12 and 13. The graphic does not represent the view at the time of maximum, but is simply meant to help prospective observers to find the radiant location. The red line across the bottom of the image represents the horizon. Although the actual radiant is below the horizon, the stars just above the horizon are those of the constellation Perseus. (Image produced by the Author using SkyChart III and Adobe Photoshop.)

History

The earliest record of Perseid activity comes from the Chinese annals, where it is said that in 36 AD "more than 100 meteors flew thither in the morning." Numerous references appear in Chinese, Japanese and Korean records throughout the 8th, 9th, 10th and 11th centuries, but only sporadic references are found between the 12th and 19th centuries, inclusive. Nevertheless, August has long had a reputation for an abundance of meteors. The Perseids have been referred to as the "tears of St. Lawrence", since meteors seemed to be in abundance during the festival of that saint in Italy on August 10th; however, credit for the discovery of the shower's annual appearance is given to Adolphe Quételet (Brussels, Belgium), who, in 1835, reported that there was a shower occurring in August that emanated from the constellation Perseus.

The first observer to provide an hourly count for this shower was E. Heis (Münster), who found a maximum rate of 160 meteors per hour in 1839. Observations by Heis and other observers around the world continued almost annually thereafter, with maximum rates typically falling between 37 and 88 per hour through 1858. Interestingly, the rates jumped to between 78 and 102 in 1861, according to estimates by four different observers, and, in 1863, three observers reported rates of 109 to 215 per hour. Although rates were still somewhat high in 1864, generally "normal" rates persisted throughout the remainder of the 19th-century.

Computations of the orbit of the Perseids between 1864 and 1866 by G. V. Schiaparelli (Italy) revealed a very strong resemblance to periodic comet 109P/Swift-Tuttle, which had been discovered in 1862. This was the first time a meteor shower had been positively identified with a comet and it seems safe to speculate that the high Perseid rates of 1861-1863 were directly due to the appearance of 109P/Swift-Tuttle, which has a period of about 135 years. Multiple returns of the comet would be responsible for the distribution of the meteors throughout the orbit, but meteors should be denser in the region closest to the comet, so that meteor activity should increase when the comet is near perihelion.

During 1973, the astronomer Brian G. Marsden examined the orbit of periodic comet 109P/Swift-Tuttle to determine when it was likely to return. The observations from the 1862 return were not the best and the uncertainty in the orbital period amounted to several years. His best bet was to try and identify a previous return. He found two good options: a comet in 1737 and one in 1750. Marsden chose the 1750 comet as the best candidate for a previous appearance of comet 109P/Swift-Tuttle and predicted the comet would return in 1981. This immediately generated excitement among meteor observers as the potential for enhanced activity unfolded. This excitement seems to have been fully justified, as the average rate of 65 per hour during 1966-1975 suddenly jumped to over 90 per hour during 1976-1983---with the high being 187 in the latter year. Although meteor observers seemed content with their observations of the enhanced activity from 109P/Swift-Tuttle, comet observers were less enthusiastic as the comet was not recovered. Following the 1983 peak, hourly rates for the Perseids declined. With a full moon occurring just a day before maximum in 1984, the Dutch Meteor Society still reported unexpectedly high rates of 60 meteors per hour. In 1985, reported rates generally fell between 40 and 60 meteors per hour in dark skies, and results were generally the same in 1986.

As the 1990s dawned, Marsden published a new prediction. If comet 109P/Swift-Tuttle was actually seen in 1737, then the comet might pass perihelion during December 1992. The comet was recovered late in the summer of 1992. Although not one of the most spectacular apparitions, the comet was well observed. But meteor observers were more interested in the Perseid display of 1993. Predictions indicated Europe was the place to be during August of 1993. Observers from around the world flocked into central Europe and were met with hourly rates of 200 to 500! High rates were still present during 1994, this time with the peak occurring over the United States.

The Perseid radiant turns out to be complex. The main radiant is situated near the star Eta Persei, but other radiants appear to be active at the same time. As long ago as 1879, W. F. Denning (England) pointed out that he had "detected the existence of two other simultaneous showers from Chi and Gamma Persei." This latter shower is one of the most active of the secondary radiants and seems to have been frequently observed during the twentieth century---especially with telescopic aid. One of the most recent examples of the complexity of the Perseid meteor shower was revealed in three studies of the radiant conducted during 1969 to 1971, by observers in the Crimea. In addition to the main radiant near Eta Persei, they confirmed the existence of the major radiants near Chi and Gamma Persei, as well as minor radiants near Alpha and Beta Persei. These meteor showers are generally short-lived and exhibit radiants that move nearly parallel to the main radiant.

There is an uneven size distribution within the stream. One very interesting characteristic of the Perseids is that there are times when larger, brighter meteors are much more plentiful than smaller, fainter meteors. In 1953, A. Hruska (Czechoslovakia) found that Perseids were brighter during August 8-12, slightly fainter on August 12/13, and notably fainter by August 14/15. In 1956, Z. Cephecha (Czechoslovakia) found the meteors were brightest on the night of Augsut 6/7 and faintest on the night of August 13/14. A similar pattern has been noted by more recent studies during the 1980s and 1990s. All of the magnitude studies have one thing in common---they point to an irregular mass distribution within the Perseid stream. Some of this is most likely due to the Earth encountering filaments of material representing different that comet Swift-Tuttle has moved in during the last 2000 years.

There is an odd variation from year to year in the number of Perseids exhibiting persistent trains. One of the first astronomers to study this was M. Plavec (Czechoslovakia), who examined 8028 Perseids seen during the period spanning 1933 to 1947. He noted the 45% of Perseids exhibited persistent trains in 1933, while this was value changed to 60% in 1936, 35% in 1945, and 53.3% in 1947. Plavec noted that he could not correlate the variations to sunspot numbers. It could be that this is also tied in to Earth encountering different orbital filaments perviously shed by comet Swift-Tuttle.

PSLV-C23

Extremely glad to have witnessed the successful launch of PSLV-C23. I congratulate our scientists who have worked tirelessly for the launch. Our space programme has overcome many hurdles. At the same time it is one of the most cost effective programmes. This should make us proud.

We have achieved a lot & we have to go a long way. Continued progress in space must remain

our national mission! 

అఆఇఈ

అఆఇఈ                                  

            (అమ్మ ఆనందం ఇల్లు ఈతరం)

      

                    అఆఇఈ లేవు నా రాతలో

               కాని నా జీవితంలో అవి నా ఓనామలు

                  అనుక్షణం నాకు ప్రేమ అందిస్తుంది

               ప్రతి పని యందు నాకు అండగా ఉంటూ

                          ‘అమ్మ’ గా ఆదరిస్తుంది...

                        విజయమైన పరాజయమైన

              అవిశ్రాంతం నాకు ‘ఆనందం’ అందిస్తుంది...

            అన్ని విషయాలలోను 'ఇల్లె' నా ప్రపంచంగా

                      ఉంటు అన్నింట నిలిచింది...

                  ప్రతి కథనం నాతో సాగే ఓ పాదంలా

                'ఈతరం' తో పాటు నన్ను నడిపిస్తుంది

                                                       ఇట్లు

                                                       ప్రేమతో,

                                                    మీ... అఆఇఈ...

                      

                     జయ  హింద్...(PVGS)...      

MY NOTE-2

MY NOTE-2 

If any one say that i am irresponsible at my life. I am saying to them it is wrong. 

In everybody life enjoyment is a part but it is not in my life.

I am different from now days youth. 

I have my own ability to take over my life. 

Please make sure of it because my goal is to give a brand name as PVGS this name should be poplar.

 To say that i am only responsible of my life.

 So please make were of my life to succeeded my goal.

                PVGS

        IT IS NOT NAME

             IT IS A BRAND OF ALL THING