Posts Tagged ‘Polar Satellite Launch Vehicle’

MOM turns its camera on Earth while preparing for critical insertion into Mars trajectory

November 21, 2013

While the MOM spacecraft “Mangalyaan” is in orbit around Earth, its systems and scientific instruments are being tested to prepare for the critical burn at 0036 IST on 1st December (1906 GMT 30th November) to inject it into a Mars trajectory. The colour camera has been turned on Earth during testing and ISRO has released this photograph.

This image was taken yesterday at around 1350 hrs (IST) from a height of almost 70,000 km above earth and has a spatial resolution of 3.5 km.

Earth from MOM 20131120 image ISRO

Earth from MOM 20131120 image ISRO

The spacecraft’s engine has so far been fired as follows:

  • first orbit-raising manoeuvre 416 seconds
  • second orbit raising manoeuvre 570.6 seconds
  • third orbit raising manoeuvre 707 seconds
  • fourth orbit-raising manoeuvre (time not specified, firing curtailed inadvertently)
  • fourth supplementary orbit raising manoeuvre 303.8 seconds
  • fifth orbit raising manoeuvre 243.5 seconds

The next critical burn (the seventh) has to to use the 440 Newton liquid engine again to impart a delta-v of nearly 648 m/s and the engine will have its longest burn time of 1,351 seconds. Three mid course corrections on the spacecraft’s journey to Mars are planned for and the fuel carried has to also cater for finally braking to enter into Mars orbit.

The Hindu carries a long, fascinating interview with  K. Radhakrishnan, ISRO Chairman. The article is a little unusual in its length and technical detail which most Indian newspapers would fight shy of! Some selected extracts below but the entire interview is worth reading:

After the Polar Satellite Launch Vehicle (PSLV-C25) put India’s Mars Orbiter into a perfect earth-bound orbit on November 5, it has been a smooth journey so far for the spacecraft. The Indian Space Research Organisation (ISRO) boosted the Mars Orbiter’s apogee in six complex manoeuvres executed between November 7 and 16. ISRO did this by giving commands from the ground to the spacecraft’s propulsion system, called 440 Newton engine, to fire. A crucial event of the trans-Mars injection of the spacecraft will take place on December 1 by a prolonged firing of the 440 Newton engine.

…. Till now, we have completed six manoeuvres including a supplementary one. Currently, the spacecraft’s apogee is 1,92,915 km. 

In the early hours of December 1, around 00.36 hours, we have the trans-Mars injection of our Mars spacecraft. On that day, we are going to use the 440 Newton liquid engine again to impart a delta-v, that is, an incremental velocity of nearly 648 metres a second to the spacecraft and the engine will burn for 1,351 seconds. It is crucial in the sense that we need to give the exact velocity required to take the spacecraft from the earth-orbit, passing through the sphere of influence of the earth which extends up to 9.25 lakh km from the earth, cruise through the long helio-centric phase, then get into the sphere of influence of Mars, and on its arrival near Mars on September 24, 2014, it has to be put into 376 km plus or minus 50 km above Mars at that point of time. On the same day, the next crucial operation of the spacecraft’s Mars orbit insertion has to take place. When this running of the 440 Newton liquid engine takes place on December 1, we also have eight numbers of 22 Newton control thrusters firing. 

There are two tasks for them. One is the spacecraft’s attitude control. Secondly, if it is required, they will aid the 440 Newton thrusters to augment its thrust-level. Both the functions will be performed and the Mars spacecraft will then be moving towards the helio-centric orbit. Then 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. 

With the velocity imparted to the spacecraft on December 1, 2013, we will have an estimate of its expected position on September 24, 2014. We will be continuously tracking the spacecraft and if there are deviations vis-à-vis the end goal, we will make the corrections. So December 1 will be a crucial operation. 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. There is thus a long gap. 

How confident are you that you can re-start the 440 Newton engine after it has hibernated in deep space for about 300 days during the spacecraft’s voyage? 

We have been using the 440 Newton engine for our Geo-synchronous Satellite – GSAT- missions where the spacecraft’s orbit has to be raised about a week after its launch. In the case of Chandrayaan-1, we had to restart the operation after a fortnight. For that, we had qualified the liquid engine in 2008 to restart after one month. 

During the last two years, considering the specific requirements of our Mars Orbiter Mission for re-starting the spacecraft’s 440 Newton engine after it has idled for about 300 days, we had done these two actions. One is we have provided a set of parallel circuits for the propellants’ flow-lines and also provided redundancy in the form of a latch-valve. So what essentially happens is that one portion of the fluid circuit will be closed after December 1. The parallel path will be energised for the operation in September 2014. 

……. In the spacecraft’s orbit-raising manoeuvres, during its 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. …… 

Up to (925,000) km from the Earth, the spacecraft will be in the sphere of influence of the Earth. Subsequently, it will be moving into the helio-centric phase of its flight. It is a long one, where you have to look at the influence of other planets and the Moon and then the solar radiation pressure acting on the spacecraft. That pressure varies with respect to time because the geometry of the sun and the spacecraft matters here. This is something we have not done so far and this helio-centric phase of the flight is new to us. 

In Chandrayaan-1, we had travelled up to (400,000) km, which was well within the sphere of influence of the Earth. But here for the first time, we are moving out of the sphere of influence of the earth. So how the spacecraft will behave during the helio-centric flight of 680 million km along the arc is new to us. Then the spacecraft gets into the sphere of influence of Mars which is nearly six lakh km from Mars. 

From our understanding of the Mars gravity model, the influence of the atmosphere of Mars, the influence of the two satellites of Mars and the solar radiation pressure there on the spacecraft are very important. This is also a new thing that we are attempting. 

So the navigation of the Mars spacecraft from the orbit of the Earth to the orbit of Mars, passing through all these three phases, is a new knowledge that we are acquiring and validating during the next 300 and odd days.

Read the whole article.

Frugal engineering for India’s Mars mission

November 6, 2013

India has been struggling to bridge the gap to more developed nations without necessarily having to follow exactly the same path as that followed by other nations. Especially to achieve the development objectives in less time than it has taken those who did it first. Doing more with less is the name of the game and “Frugal engineering” (or “frugal innovation”) is defining a new paradigm for development.

There may perhaps not be any better example of the dictum that necessity is the mother of invention than can be found in India. Whether it is a refrigerator, ECG device or an automobile, Indian engineers have brought innovative products to market by designing them outside-in. …….

It may seem a contradiction, but some infrastructure gaps in India have positively affected Indian innovation: they have forced entrepreneurs and companies to adopt technologies that make relying on existing infrastructure (creaking and unreliable as it is in many ways) simply irrelevant. Indian engineers have invented a battery-powered, ultra-low-cost refrigerator resistant to power cuts; an automatic teller machine for rural areas; and even a flour mill powered by a scooter. People in the West, with its constant access to electricity, have little motivation to pursue such innovations. The Indian mobile phone industry is the poster child for leapfrogging over infrastructural constraints. A limited fixed-line infrastructure created an opportunity for mobile phones to reach many more people. Mobile telephony is also relatively cheap, sharable, and easily repaired. And thus, a new frontier of global innovation opened in India. …… 

The Indian mission to Mars which launched yesterday is another example of frugal engineering at work.

Hindustan Times:

India’s successful Mangalyaan launch is as much a financial accomplishment as a technical milestone. The entire Mars mission has cost the Indian Space Research Organisation a mere around Rs. 450 crore ($75 million) and took 15 months to put together. Much of the Martian price tag is for ground stations and relay upgrades that will be used for other Isro projects. The actual satellite costs a mere $25 million ( Rs. 153 crore), says Pallav Bagla of Science magazine. Comparison: Nasa’s similar MAVEN Mars project will cost 10 times more and will take three times longer.

Isro is widely cited as an example of “frugal engineering” …..  A US state department scientific adviser once said that Isro had reduced satellite assembly costs to a tenth of Nasa’s.

Isro’s accomplishments are remarkable given its tiny budget: $700 million ( Rs. 4,270 crore) in 2012-13. Despite a space programme whose financial base is the ninth largest, India is generally rated the world’s number six space power.

Of this, only 7% is allotted for planetary exploration. Isro’s prime directive has and continues to be the finding of technical means to support socio-economic goals such as education, medicine, water and disaster management.

Isro also defrays government support through a commercial arm, Antrix. Through the sale of satellite imagery, satellite launches and so on, Antrix earned a pre-tax Rs. 2 billion in 2010 alone. …..

India’s 100th space mission puts two satellites into orbit

September 10, 2012

The Indian space programme started 50 years ago and the Indian Space Research Organisation (ISRO) has now achieved its 100th mission. Of course there is a debate on whether this is money is well spent considering the many needs in the country. My own view is that it is. The long term development of technology, I think, takes precedence over some short term benefits if the money was spent elsewhere.

Daily Mail:The Indian space programme reached yet another milestone with the successful launch of the Polar Satellite Launch Vehicle (PSLV) carrying two foreign satellites from the Satish Dhawan spaceport, Sriharikota, in Andhra Pradesh on Sunday morning. 

This is the Indian Space Research Organisation’s (ISRO) 100th mission, which began with an experimental satellite called Aryabhata launched by a Russian rocket in April 1975. 

Incidentally, 2012 also marks 50 years of the start of the programme beginning with sounding rockets launched from Thumba in Kerala. …… 

The launch was delayed by two minutes – from 9.51 am to 9.53 am – after a safety analysis of data relating to space debris and asteroids. 

ISRO officials said this was a normal precaution taken to ensure safe journey for satellites to avoid any collision with space objects. 

Both satellites have been placed into their orbits precisely.

The count of 100 space missions includes 63 Indian satellites, 36 launch vehicle missions and one reusable space recovery mission.

The Hindu: 

Prime Minister Manmohan Singh on Sunday congratulated scientists of the Indian Space Research Organisation (ISRO) for the successful launch of the Polar Satellite Launch Vehicle C-21 from Sriharikota.

Expressing happiness at witnessing the launch, Dr. Singh complimented the Department of Space and the ISRO fraternity on this “spectacular success.”

“As ISRO’s 100th space mission, today’s [Sunday’s] launch is a milestone in our nation’s space capabilities,” he told a gathering of scientists that included the former ISRO chiefs.

Dr. Singh also congratulated EADS Astrium of France and the Osaka Institute of Technology of Japan on the successful launch of their satellites. This achievement was a testimony to the commercial competitiveness of the Indian space industry and a tribute to Indian innovation and ingenuity.

He noted that the year also marked the 50th anniversary of the commencement of India’s space programme and acknowledged the presence of many stalwarts of the earlier space programmes, including Project Directors of space missions. “Given the string of successes since then, we often forget how challenging space technology is and what a relatively new field it continues to be.” …..

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