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Google funded study implies that Google Trends is a valid and rigorous behavioural indicator

January 8, 2014

I find that this disclaimer at the end of this study effectively invalidates the method of the study and its results.

This project was supported by a Google.org grant from 2012, although Google.org played no role in designing or conducting this study.

The results of the study (that more people searched for health issues on Google during the recession) are trivial and – with the best will in the world – of little value except for providing a plug for Google Search and Google Trends. Of course a Google Trend means something but to imply – as this study does – that a Google Trend for selected search items  is a rigorous and valid representation of a human behavioural pattern is more than a little fanciful.

Benjamin M. Althouse et al, Population Health Concerns During the United States’ Great Recession, Am J Prev Med 2014;46(2):166–170

Press Release: 

The group examined Americans’ Google search patterns and discovered that during the recent Great Recession, people searched considerably more frequently for information about health ailments. The kinds of problems indicated by the queries weren’t life threatening, but they could keep someone in the bed a few days, like ulcers, headaches, and back pain. 

In total, the team found there were more than 200 million excess queries of this kind during the Great Recession than expected.

“While it’s impossible to uncover the motives for increased searches, they likely indicate a person being ill, and ill enough to seek out online information or remedies,” Ayers said. The same group previously published a report showing that queries for anxiety and depression also increased substantially during the Great Recession.

The authors themselves write:

google search

Without first a study on whether the usage of Google search is actually representative of any part of the population, and whether a trend in such usage permits conclusions regarding the motives for such usage, this study is little more than an advertisement for Google Search and Google Trends.

Just as with Facebook surveys and profound conclusions, I am not at all sure that this “study” can even be considered science  – let alone good science. It is published  – believe it or not – in a journal of preventive medicine,  but it has little to do with medicine and more to do with PR and  Google’s image.

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Best “Bad science” stories of 2013

January 6, 2014

Business Insider carries its top 10 “dumb”/false/bulls**t science stories of 2013.

(Turney and his Ship of Fools easily qualify for such a list but will have to wait for next year).

(in reverse order)

10. A scientist claimed vaccines make you gay

9.  A TIME Magazine cover “cured cancer”

8. PETA claimed chicken wings can shrink a baby’s penis

7. A chiropractor broke a baby’s neck

6. A scientist used math to “prove” gay marriage is wrong

5. Portland rejected water fluoridation

4. Anti-Vaxxer Jenny McCarthy joined The View

3.  Bigfoot DNA sequenced

2. The return of Cold Fusion

1. Terrible nature “documentaries”

My particular favourite is of the Nigerian “Chibuihem Amalaha, an award winning student at the University of Lagos, is claiming that he’s “disproved” gay marriage through science — and he used the power of magnets to do so. His “groundbreaking” work is backed by the university”.

050913F.scientifically-prov.jpg - 050913F.scientifically-prov.jpg

Scientifically proved that gay marriage is wrong (image thisdaylive.com)

But that’s not all. Amalaha, who says he’ll win a Nobel prize one day, has also used chemistry, biology, and mathematics to disprove gay marriage.

His mathematics of gay marriage is particularly illuminating. In an interview with This Day Live he says:

In mathematics which is another core area of science, I used what is called the principle of commutativity and idepotency. Commutativity in mathematics is simply the arrangement of numbers or arrangement of letters in which the way you arrange them don’t matter. For example, if you say A + B in mathematics you are going to have B + A. For example, if I say two plus three it will give five. If I start from three, I say three plus two it also give you five showing that two plus three and three plus two are commutative because they gave the same results. That shows that A + B will give you B + A, you see that there is a change. In A + B, A started the journey while in B + A, B started the journey. If we use A as a man and use B as a woman we are going to have B + A that is woman and man showing that there is a reaction. A + B reacted, they interchanged and gave us B + A showing that commutativity obeys that a man should not marry a man and a woman should not marry a woman. If you use idempotency, it’s a reaction in mathematics where A + A = A. Actually in abstract algebra, A + A =2A but we are less concerned with the numerical value two. We are more less concerned with the symbols A, you find out that A + A will give you A showing that the whole thing goes unchanged. It didn’t change unlike commutativity A + B give B + A there is a change. A started the journey in commutativity and A + B gave us B + A and B started the journey after the equality sign. But in the case of idempotency A + A will give you A showing that it goes unreacted. You started with A and you meet A ,the final result is A. Showing that a man meeting a man A + A will produce a man there is no reaction, it goes unreacted and in chemical engineering you have to send the material back to the reactor for the action to be carried out again showing that it goes unreacted. That is how mathematics has shown that gay marriage is wrong because commutativity proves that gay marriage is wrong. Idempotency also proves that gay marriage is wrong. So these are the principles I have used to prove gay marriage wrong in physics, chemistry, biology, mathematics and by the grace of God I am the only one that has proved this in the whole world.

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Flawless launch of ISRO’s GSLV

January 5, 2014

ISRO is riding high.

After a flawless launch of the GSLV-D5 using an indigenous cryogenic engine for the first time, it now remains to insert the GSAT-14 satellite into its operational orbit. In three orbit raising manoeuvres, using the Liquid Apogee Motor, on board, GSAT-14 will reach the intended circular Geo-stationary orbit.

Graphic ISRO

“It is a tough job to understand and master cryogenic technology. It is ultimate and we have put in a lot of efforts and made it possible. Today, we can say and prepare with more confidence for the next mission of C-25 stage with 25 tonnes of propellant and 20 tonnes of cryogenic engine thrust for the GSLV MK-3 D-1 mission in early 2017. The high-end cryogenic engine is slated for completion and testing by 2015,” Vikram Sarabhai Space Centre director S Ramakrishnan told TOI minutes after the lift-off of GSLV-D5. 

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Heigh-ho, ISRO, it’s off to Mars we go

November 30, 2013

UPDATE!!

Trans-Mars injection has been completed successfully.

  • Trans Mars Injection (TMI) operations completed successfully. The liquid engine burn time was 1328.89 sec and the imparted incremental velocity was 647.96 m/sec.
  • Trans Mars Injection (TMI) operation began at 00:49 hrs (IST) on Sunday Dec 01, 2013.
  • Forward rotation of spacecraft, to put it into the right orientation to perform Trans Mars Injection (TMI) operation has been completed successfully at 00:30 hrs IST on Dec 1, 2013

=================

A big night for ISRO and congratulations are due! And not least for ISRO’s coverage of the event – almost live – on their Facebook page. (I have not been too enamoured of the ISRO website but somebody did a great job on the live updates).

The Indian Mars Orbiter (Mangalyaan) successfully completed its final burn in earth orbit and has been inserted into a Trans Mars Trajectory (to be confirmed). It may just be one small step in Man’s exploration of space but it is a giant leap for ISRO. After spending a month in 6-ever increasing orbits around Earth the craft now has a 300 day journey to get to Mars with the possibility of 3 mid-course corrections before the liquid engine has to be fired up again to enter into orbit around Mars.

So far, so good!

A number of “firsts” for the Indian Space Research Organisation (ISRO) and, no matter what may now happen, a great many accomplishments already in the bag. The lack of a sufficiently powerful rocket necessitated that the craft first enter earth orbit and then the month-long, laborious compared to NASA, procedures where the space craft engine had to be used  to first to increase the earth orbits and then – tonight – be fired for an extended time (23 minutes) to be inserted into a heliocentric Trans Mars Trajectory.

Mission Operations Complex ISTRAC Bangalore.

Mission Operations Complex ISTRAC Bangalore.

Photo

One hour before the final engine firing the craft was put under the control of its on-board computer which was to carry out the final burn. Forward rotation of the spacecraft to put it into the right orientation for the burn was carried out and completed about 20 minutes before firing. Engine firing started on schedule just before the craft reached perigee. The actual burn of the 440 N Liquid Engine lasted its planned 23 minute long firing entirely under local on-board computer control. The objective was to impart an incremental velocity of 648 m/s and the indications are that that was achieved. The engine firing manoeuver seems to have gone exactly to plan. The orbit determination team have now to confirm now confirmed the trajectory actually achieved.

The new heliocentric orbit is yet to be confirmed. confirmed

The ISRO chorus (with apologies to Walt Disney)

Heigh-ho, ISRO

It’s off to Mars we go

We keep on working all day long

Heigh-ho, ISRO 

Photo: Liquid Engine propels MOM into Mars Transfer Trajectory and India into interplanetary space !Trans-Mars injection has been completed successfully.

Liquid Engine propels MOM into Mars Transfer Trajectory and India into interplanetary space !Trans-Mars injection has been completed successfully. ISRO

 

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Moment of truth approaches for India’s Mars Orbiter Mission

November 28, 2013

When everything is for the first time,achievements are incremental and there are very many critical “moments of truth” to meet and overcome. But now comes a very large “moment of truth” as ISRO prepares to inject the Mars Orbiter spacecraft into its Trans Mars Trajectory.

India’s Mars Orbiter (Mangalyaan) is currently in its final orbit around the earth and is scheduled to fire its 440 Newton liquid engine at 0049 hours IST on Sunday morning ( 1919 GMT Saturday 30th November).  It entered its final Earth orbit yesterday which has an orbital period of 5575 minutes (just under 4 days) and it should be approaching apogee later tonight (early hours of Friday morning) and the next engine burn will take place at perigee. Currently apogee is about 193,000 km from earth and perigee is around 350km.

The spacecraft must first be manoeuvred into the right attitude using its thrusters for the firing of its main engine which must then be fired to impart the correct change of velocity (delta-vee). Both, an incorrect attitude and/or an incorrect delta-vee are potential sources of error. Three mid-course corrections are planned  (the first on December 11th) but the margin of error allowable is still extremely small. Too low a velocity change could leave the craft in earth orbit or put it into a heliocentric orbit which does not get close enough to Mars. Too high a delta-vee would also put the craft into a heliocentric orbit which would eventually decay into the sun. I believe there is no chance of achieving a velocity high enough to escape the sun. And even if the velocity change is correct but the direction is too far in error then just another orbital path around the sun would result.

NDTV:“The trans-Mars injection- we are planning to depart on December 1, 2013 early hours of 00:49 hours IST and we are going to burn a liquid engine for duration of roughly 23 minutes which will impart an incremental velocity of 648 metres per second consuming a fuel of 198 kgs,” ISRO Scientific Secretary V Koteswara Rao told reporters in Bangalore.

K. Radhakrishnan, ISRO Chairman. (For the) trans-Mars injection and its insertion into the Martian orbit, the firing of the liquid engine is done in a closed loop mode. Here, a precision accelerometer is used to estimate the incremental velocity added as the liquid engine burns and when the accelerometer gives a feedback that the required incremental velocity added to the spacecraft has been achieved, the burning of the liquid engine is automatically terminated. So, minor variations in the performance of the liquid engine will not matter because we are cutting off its burning based on the delta-v that is achieved. That is why we call it closed loop of firing. … The spacecraft’s propulsion system, i.e., the 440 Newton liquid engine, will complete its first phase of operations on December 1. It has to be re-started for its operation on September 24 (2014).

MOM Trans Mars Injection ISRO

MOM Trans Mars Injection ISRO

ISRO: This voyage is achieved by a combination of navigation and propulsion technologies, governed by the gravity of Sun and Mars, and assisted by the 440 N Liquid engine. Further fine tuning of the trajectory is achieved using the Attitude and Orbit Control Thrusters during the Trajectory Correction maneuvers planned en route.

… on December 11, we plan to have one small firing for mid-course correction of the spacecraft. There may be one more mid-course correction during the helio-centric phase, and subsequently, a fortnight before the spacecraft’s arrival near Mars, there will be one more mid-course correction. So there will be three mid-course corrections between December 1, 2013 and September 24, 2014. 

Mangalyaan is eventually to be placed into a Martian orbit, with a periapsis height of 365 km, apoapsis height of 80,000 km and an orbital period of about 77 hours.

So on Saturday I shall have as many of my fingers crossed as I can manage. I suspect there will be many others doing the same across India.

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Posted in Development, Engineering, India, Science, Space, Technology | 1 Comment »

A liking for alcohol is genetic

November 28, 2013

Yet another paper which purports to show that bad behaviour is due to genetic compulsions. In this case a faulty gene is supposed to cause compulsive consumption of alcohol. If all bad behaviour can be shown to be due to genetic compulsions, it follows that nobody can be held accountable for their behaviour.

The press release is from Newcastle University but the researchers come from five universities. It is a 10 year project funded by the Medical Research Council to study genetic effects on alcohol dependence. “.. we don’t understand about how and why consumption progresses into addiction, but the results of this long-running project suggest that, in some individuals, there may be a genetic component”  says Professor Hugh Perry (MRC), “…. it could help us to identify those most at risk of developing an addiction and ensure they receive the most effective treatment.”

Genetic screening of the foetus and abortion of the alcoholicly inclined perhaps! Prevention being better than an impossible cure.

Quentin M. Anstee, Susanne Knapp, Edward P. Maguire, Alastair M. Hosie, Philip Thomas, Martin Mortensen, Rohan Bhome, Alonso Martinez, Sophie E. Walker, Claire I. Dixon, Kush Ruparelia, Sara Montagnese, Yu-Ting Kuo, Amy Herlihy, Jimmy D. Bell, Iain Robinson, Irene Guerrini, Andrew McQuillin, Elizabeth M.C. Fisher, Mark A. Ungless, Hugh M.D. Gurling, Marsha Y. Morgan, Steve D.M. Brown, David N. Stephens, Delia Belelli, Jeremy J. Lambert, Trevor G. Smart, Howard C. Thomas. Mutations in the Gabrb1 gene promote alcohol consumption through increased tonic inhibition. Nature Communications, 2013; 4 DOI:10.1038/ncomms3816

Newcastle University Press Release

Researchers have discovered a gene that regulates alcohol consumption and when faulty can cause excessive drinking. They have also identified the mechanism underlying this phenomenon.

The study showed that normal mice show no interest in alcohol and drink little or no alcohol when offered a free choice between a bottle of water and a bottle of diluted alcohol.

However, mice with a genetic mutation to the gene Gabrb1 overwhelmingly preferred drinking alcohol over water, choosing to consume almost 85% of their daily fluid as drinks containing alcohol – about the strength of wine.

The consortium of researchers from five UK universities – Newcastle University, Imperial College London,  Sussex University, University College London and University of Dundee – and the MRC Mammalian Genetics Unit at Harwell, funded by the Medical Research Council (MRC), Wellcome Trust and ERAB, publish their findings today in Nature Communications.

Dr Quentin Anstee, Consultant Hepatologist at Newcastle University, joint lead author said: “It’s amazing to think that a small change in the code for just one gene can have such profound effects on complex behaviours like alcohol consumption.

“We are continuing our work to establish whether the gene has a similar influence in humans, though we know that in people alcoholism is much more complicated as environmental factors come into play. But there is the real potential for this to guide development of better treatments for alcoholism in the future.”

…. a team led by Professor Howard Thomas from Imperial College London introduced subtle mutations into the genetic code at random throughout the genome and tested mice for alcohol preference. This led the researchers to identify the gene Gabrb1 which changes alcohol preference so strongly that mice carrying either of two single base-pair point mutations in this gene preferred drinking alcohol (10% ethanol v/v – about the strength of wine), over water.

The group showed that mice carrying this mutation were willing to work to obtain the alcohol-containing drink by pushing a lever and, unlike normal mice, continued to do so even over long periods. They would voluntarily consume sufficient alcohol in an hour to become intoxicated and even have difficulty in coordinating their movements.

So my preference for scotch rather than Newcastle Brown Ale is probably also genetic!.

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New Denisovan genome indicates inter-breeding with another, unknown, archaic human

November 19, 2013

The period some 30,000 – 50,000 years ago is getting positively crowded with different branches of humans. The direct ancestors of modern humans lived and interbred not only with Neanderthals and Denisovans but also apparently with still another, as yet unknown, branch of humans.

Nature: New genome sequences from two extinct human relatives suggest that these ‘archaic’ groups bred with humans and with each other more extensively than was previously known.

The ancient genomes, one from a Neanderthal and one from a different archaic human group, the Denisovans, were presented on 18 November at a meeting at the Royal Society in London. They suggest that interbreeding went on between the members of several ancient human-like groups living in Europe and Asia more than 30,000 years ago, including an as-yet unknown human ancestor from Asia. ..

… All humans whose ancestry originates outside of Africa owe about 2% of their genome to Neanderthals; and certain populations living in Oceania, such as Papua New Guineans and Australian Aboriginals, got about 4% of their DNA from interbreeding between their ancestors and Denisovans, who are named after the cave in Siberia’s Altai Mountains where they were discovered. The cave contains remains deposited there between 30,000 and 50,000 years ago. 

Those conclusions however were based on low-quality genome sequences, riddled with errors and full of gaps, David Reich, an evolutionary geneticist at Harvard Medical School in Boston, Massachusetts said at the meeting. His team, in collaboration with Svante Pääbo at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, have now produced much more complete versions of the Denisovan and Neanderthal genomes — matching the quality of contemporary human genomes. The high-quality Denisovan genome data and new Neanderthal genome both come from bones recovered from Denisova Cave.

The new Denisovan genome indicates that this enigmatic population got around: Reich said at the meeting that they interbred with Neanderthals and with the ancestors of human populations that now live in China and other parts of East Asia, in addition to Oceanic populations, as his team previously reported. Most surprisingly, Reich said, the new genomes indicate that Denisovans interbred with another extinct population of archaic humans that lived in Asia more than 30,000 years ago, which is neither human nor Neanderthal.

It would seem that when the world was still in the grip of an ice age 30,000 – 50,000 years ago, the reality of human history was not so far away from Tolkien’s Middle Earth.  Ancient history but it was only 1,500 – 2,500 generations ago. Middle Earth was where men could breed with elves and hobbits were an off-shoot of men. The Druedain were also off-shoots of men and some – if not all – orcs were deliberately bred from elves while all trolls and dragons were artificially bred.

From the J.R.R. Tolkien Encyclopedia: Scholarship and Critical Assessment

from The biology of Middle eart - Tolkien Encyclopedia

from The biology of Middle Earth – JRR Tolkien Encyclopedia

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Smooth MAVEN launch followed by flawless insertion into Mars trajectory

November 18, 2013

A very smooth launch by NASA and lift-off exactly as planned.

And with the power of the Atlas V, just 52 minutes 42 seconds after launch MAVEN had separated from the launch vehicle and had been inserted into a Hohmann Transfer Orbit and on trajectory to reach Mars on 22nd September 2014.

NASA:

At 1:28 p.m. EST, NASA’s Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft began its 10-month journey to Mars orbit, launching aboard a United Launch Alliance Atlas V rocket from Cape Canaveral Air Force Station in Florida. MAVEN will take critical measurements of the Martian upper atmosphere to help scientists understand climate change over the Red Planet’s history.

The Centaur’s single RL-10A-4-2 engine ended its second burn on time. The next major milestone is the release of NASA’s MAVEN spacecraft.

Separation! Maven is now on its own.

Very smooth and absolutely flawless.

In the meantime the Indian Mars Orbiter Mission’s Mangalyaan has another 13 days in Earth orbit in its current orbit (193,000 km apogee) before one more burn of its motors puts it also into a Hohmann Transfer Orbit which should get it to Mars orbit on 24th September 2014. Spacecraft systems – most being operated for the first (or second) time – will be tested while in earth orbit.

The “poor man’s route” to Mars!

And India and ISRO have some 49 years of US NASA Mars missions to catch up to.

And while NASA is showing live feed of the launch, ISRO’s web-site is down – presumably because it could not handle the traffic. The FB page seems fine.

isro down 20131118

isro down 20131118

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Alternate paths to Mars: NASA’s MAVEN compared to India’s MOM

November 16, 2013

Update! 18th November 2013. The launch of MAVEN – in about 1 hour from now – can be seen live on NASA TV.

The Indian Mars Orbiter Mission is primarily a test of technology and capability and self-confidence and self-belief.

With a very limited budget.

The scientific investigations of the planet and the Martian atmosphere are only a secondary or even a tertiary objective. For the Indian mission everything is virtually for the first time. For NASA and the US, the MAVEN mission which is due to launch on Monday 18th November is the 15th Mission to Mars. The first mission (Mariner 3) failed and the second mission, Mariner 4, launched in November 1964 was the first to reach Mars. In the 49 years since there have been a few failures (Mariner 8 in 1971, Mars Observer 1992, Mars Climate Orbiter in 1998 and the Mars Polar lander/Deep Space2 in 1999) and some spectacular successes for NASA with the Mars Global Surveyor in 1996 , the Phoenix Mars Lander in 2007 and the Mars Rover in 2011.

Many Mars missions have failed. Between 1960 and 1971 the Russians (USSR) failed in 11 attempts to send a spacecraft to the vicinity of Mars. The 12th attempt with M-71 in 1971 succeeded in orbiting Mars. Of eight further attempts by Russia, 4 failed to reach Mars. The Japanese Nozomi failed while cruising. Two European missions led to one orbiter (but a failed landing) and one flyby.

On the surface they may both seem to be similar in that both are attempting to get a spacecraft into orbit around Mars. But the missions are, in reality, quite different. MOM is essentially a first-time test of technology and capability whereas MAVEN is primarily a scientific mission utilising the deployment of now well proven US technology. Technology development on the one hand and a scientific investigation on the other.

1. NASA’s Mars Atmosphere and Volatile EvolutioN (MAVEN) is a space probe designed to study the Martian atmosphere while orbiting Mars. India’s Mars Orbiter Mission (MOM – “Mangalyaan”) is a space probe designed to explore Mars’ surface features, morphology, mineralogy and Martian atmosphere using indigenous scientific instruments while orbiting Mars.

2. MAVEN is expected to have a budget of about $672 million. MOM has a budget of about $70 million.

3. The Atlas 5 rocket to be used to launch MAVEN has the capability to lift about 7,000 kg directly into a Geostationary transfer orbit (GTO). This allows MAVEN (2500 kg) to be injected directly into a Trans-Mars trajectory from launch.

The PSLV to be used for MOM can lift about 1300 kg into a GTO. With the MOM having a mass of 1337 kg, it becomes necessary for a  launch first into earth orbit and then a multi-step transition  through ever increasing earth orbits and finally into a Trans-Mars trajectory.

4. MAVEN is due to launch on an Atlas 5 rocket at 1:28 p.m. EST (1828 GMT) on Monday (Nov. 18) from Florida’s Cape Canaveral Air Force Station. Within one hour of launch MAVEN will be in a Hohmann Transfer Orbit with periapsis at Earth’s orbit and apoapsis at the distance of the orbit of Mars. MAVEN should reach Mars orbit on 22nd September 2014.

MAVEN trajectory - NASA-LASP-JPL

MAVEN trajectory – NASA-LASP-JPL

Because of the relatively low payload capability of the PSLV for an interplanetary mission MOM will spend more than four weeks in earth orbit and has to be equipped with radiation shielding to endure the numerous passages through earth’s radiation Belts. MOM has fired its Liquid Motor six times – always when passing perigee to gradually increase the apogee of the orbit to work its way up to departing Earth orbit in a fuel-efficient manner. The sixth (including one correction) firing yesterday placed the spacecraft in a 600 by approx 193,000 kilometer orbit around Earth and sets up the proper perigee passage for the final engine burn that puts the vehicle onto its Trans-Martian Trajectory using s standard Hohmann Transfer Orbit on 30th November/ 1st December. MOM should reach Mars orbit on 24th September 2014 (2 days after MAVEN).

mangalyaan trajectory

mangalyaan trajectory

5. MAVEN’s body has a cubical shape of about 2.3 m x 2.3 m x 2 m high, spans a total of 11.4 m with its solar panels deployed and has a lift-off mass of  2,454 kg (including fuel) and has a dry payload of 903 kg.

Mangalyaan’s body is a cuboid measuring about 1.5 m per side, a span of 4.2 m with solar panels deployed and an initial mass of 1337 kg of which 852 kg is fuel.

MAVEN - MOM (NASA- ISRO)

MAVEN – MOM (NASA- ISRO)

6. MAVEN is carrying 8 main, highly sophisticated instruments. Neutral Gas and Ion Mass Spectrometer, Imaging Ultraviolet Spectrograph, Magnetometer, Solar Wind Electron Analyzer, SupraThermal And Thermal Ion Composition, Langmuir Probe and Waves antenna, Solar Energetic Particles, Solar Wind Ion Analyzer

Mangalyaan is carrying a camera, two spectrometers, a radiometer and a photometer. Together, they have a weight of about 15 kg.

7. MAVEN is targeting a science orbit of 150 by 6,200 Kilometers at an inclination of 75 degrees. It will perform measurements from a highly elliptical orbit around Mars over a period of one Earth year, with five “deep dips” at 150 km minimum altitude to sample the upper atmosphere.

Mangalyaan will be much further out and targets an operational orbit of 365 by 80,000 Kilometers with an inclination of 150 degrees and a duration of 76.72 hours from where it will perform its science mission. The MOM mission in Mars orbit is open-ended and is expected to last about 160 days.

8. MAVEN’s science phase features regular communication sessions. The spacecraft points its High Gain Antenna at Earth for high data rate communications twice per week with the exact timing depending on Deep Space Network visibility. Those comm sessions take place on Tuesday and Friday and have a duration of eight hours during which at least five hours of Earth pointing are required to downlink all science data and housekeeping telemetry. 

Mangalyaan is equipped with a 2.2-meter diameter High Gain Antenna which is a parabolic X-Band reflector antenna that is used for data downlink and command uplink. Science data and spacecraft telemetry is stored in two 16Gb Solid State Recorders aboard the vehicle for downlink during regular communications sessions. Low and Medium Gain Antennas are used for low-bandwidth communications such as command uplink and systems telemetry downlink.

As missions go, MAVEN represents a Mercedes “S” class to the Volkswagen that is MOM.

Mangalyaan - MOM (ISRO)

Mangalyaan – MOM (ISRO)

Sources: 

http://www.spaceflight101.com/

http://www.spaceflight101.com/mars-orbiter-mission.html

http://www.spaceflight101.com/maven-mission-profile.html

http://www.nasa.gov/missions/index.html#.UodLu8SkoYE

http://www.space.com/

http://www.isro.org/mars/home.aspx

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Posted in Engineering, India, Science, Space, US | 10 Comments »

UPDATE! Indian Mars orbiter supplementary firing successful

November 12, 2013

The supplementary burn made this morning to correct for the incompleteness of the 4th burn yesterday appears to have been successful. The objective was to reach an orbit (apogee) of 100,000 km and this seems to have been achieved with some margin to spare. The observed change is to an orbit with an apogee of 118,462 km. The next step on 18th November is to raise the apogee to just under 200,000 km and then insert the craft into the Trans-Mars trajectory on 1st December.

So far, so good and the success of the correction by the supplementary burn is both impressive and encouraging.

ISRO: 

  • Fourth supplementary orbit raising manoeuvre of Mars Orbiter Spacecraft, starting at 05:03:50 hrs(IST) on Nov 12, 2013, with a burn Time of 303.8 seconds has been successfully completed.The observed change in Apogee is from 78276km to 118642km.

The launch and subsequent orbit manoeuvre burns so far are summarised here:

  1. The Mars Orbiter Spacecraft, India’s first interplanetary spacecraft, was launched into an elliptical earth orbit with a perigee of 248.4 km and an apogee of 23,550 km, inclined at an angle of 19.27 deg to the equator by India’s Polar Satellite Launch Vehicle in its twenty fifth flight (PSLV-C25). The achieved orbit was very close to the intended one. The launch was conducted from Satish Dhawan Space Centre (SDSC) SHAR, Sriharikota on November 05, 2013. The launch of Mars Orbiter Spacecraft occurred as scheduled from the First Launch Pad at 2:38 pm IST after a fifty six and a half hour count down. 
  2. The first orbit-raising manoeuvre of India’s Mars Orbiter Spacecraft was performed at 01:17 hrs Indian Standard Time (IST) early this morning (November 07, 2013) when the 440 Newton Liquid Engine of the spacecraft was fired for 416 seconds by commanding it from Spacecraft Control Centre (SCC) at ISRO Telemetry, Tracking and Command Network (ISTRAC) at Peenya, Bangalore. With this engine firing, the spacecraft’s apogee (farthest point to Earth) has been raised to 28,825 km, while its perigee (nearest point to Earth) is at 252 km. 
  3. The second orbit raising manoeuvre of Mars Orbiter Spacecraft, starting at 02:18:51 hrs(IST) on Nov 08, 2013, with a burn time of 570.6 seconds has been successfully completed.The observed change in Apogee is from 28814 km to 40186 km.
  4. The third orbit raising manoeuvre of Mars Orbiter Spacecraft, starting at 02:10:43 hrs(IST) on Nov 09, 2013, with a burn time of 707 seconds has been successfully completed.The observed change in Apogee is from 40186km to 71636km.
  5. In the fourth orbit-raising operation conducted on Nov 11, 2013, the apogee (farthest point to Earth) of Mars Orbiter Spacecraft was raised from 71,623 km to 78,276 km by imparting an incremental velocity of 35 metres/second (as against 130 metres/second originally planned to raise apogee to about 100,000 [1 lakh] km). The spacecraft is in normal health. A supplementary orbit-raising operation is planned for November 12, 2013, at 0500 hrs IST to raise the apogee to nearly 1 lakh km. 
mangalyaan trajectory

mangalyaan trajectory: image ISRO

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