Monday, January 13, 2014

Some interesting tidbits!

Although this a comparatively old presentation (around 2009), it provides a load of valuable information. Some information is dated and no longer applies. Many things in this presentation will already be known to people who are following the Indian Space Program closely over the last few years.

Well, the basic Mk II configuration seems to have changed a bit with the GS2 already containing 40 tons of propellant in both of its flights (D3 and D5). The MkIIA configuration will have payload fairing which will be 4m in diameter. The CUS with 15 tons of propellant is said generate 90kN of thrust against 75kN of the current engine (although it can be already throttled above 75kN but not to 90kN).

Thursday, May 2, 2013

Martians! Here we come!

The Mars mission, India's first ever to a distant planet was announced by our Prime Minister Dr. Manmohan Singh during India's 66th Independence Day celebrations. This was to be a considerable challenge to our burgeoning space program considering the fact that even countries with established space programs such as the Russia Federation have found it difficult to achieve much success when it comes to the red planet.

But ISRO on the other hand has things going right for them on the deep space exploration side of the things. Buoyed by the success of Chandrayaan 1 and the impeding launch of Chandrayaan 2 missions to our moon, the scientists at ISRO are confident of achieving yet another feat with Mars mission.

The mission itself has always been short of details except for the occasional new reports saying that the orbiter is on schedule for a 2014 launch. Every piece of information that can be found on this mission is indeed valuable. There are certain titbits from mission that we would like to share.

  • The Mars orbiter will be placed in an elliptical orbit of around 500 X 80,000 km around the red planet. It is much more difficult to put an orbiter into a circular orbit. A circular orbit requirement would require a significant increase in the fuel carried by the orbiter and hence its weight. It would also make the procedure of achieving the required orbit much more complex. The orbiter would first be inserted into an elliptical orbit. Then through a series of burns the apoapsis would need to be reduced to achieve a circular orbit. An elliptical orbit on the other hand reduces the complexity but doesn't make it any more easier to achieve.

  • The orbiter will be launch by the PSLV-XL, the same version which launched the Chandrayaan 1. ISRO understandably wants to go with the proven workhorse as opposed to the GSLV even if it means much stringent weight limitations of the orbiter. This might also be one of the reasons for choosing an elliptical orbit as a circular orbit means more fuel which in turn means more weight. The PSLV should be capable of sending a orbiter with ~200 kg of space for instruments  to the Martian orbit.     

  • The orbiter would need around 300 days to reach Mars and is supposed be launched during October-November 2013. The launch window is very important since missions to Mars can be launched when Earth and Mars are relatively close to each other. This window occurs only once every 26 months. So, miss this window and the mission will have to wait for another 2 years.

  • The orbiter is supposed to carry very few instruments, considering the weight limitations and all the instruments are planned to be Indian. The goal of the mission to establish the capability to send orbiters to Mars, so if this mission is successful much bigger missions may follow.
There are a lot of challenges in this mission. Some more intimidating than others but all of which have to be overcome for success. Some of the significant challenges as mentioned by ISRO are

  • The spacecraft needs shielding from the radiation in the Van Allen belt and also the deep space radiation. The spacecraft will have a significant and prolonged exposure to radiation so it needs augmented radiation shielding.  

  • There is a communication delay of ~20 mins between Earth and Mars. This is due to enormous distance that varies between 55-385 million kms between the two bodies. Compare this with the 2 second communication delay between the Earth and the Moon which are separated by 384,000 kms.

  • The propulsion system of the spacecraft needs to be robust and reliable. The spacecraft propulsion system will remain dormant for almost 300 days when the spacecraft is travelling from Earth to Mars. Then once it is close to Mars, the propulsion system has to work exactly as it should to insert the spacecraft into orbit around Mars.

  • The most challenging phase is certainly inserting the spacecraft into orbit around Mars. The room for error in this phase is minimal and could result in the spacecraft being lost in the depths of space. This critical event will ensure whether the mission is a success.
 ISRO has a daunting task ahead of it to ensure that this mission goes as planned given such a large number of variables involved. There are scientists who are working day and night to ensure just that. So, wishing success for ISRO with this challenging mission that is set to boost India's image in the world to new heights.

SuperNova is back

SuperNova is pleased to inform everyone that we are back after a long hiatus. The blog would like to thank all its readers for the numerous positive feedbacks and the constant encouragement. That's the thing that keeps us up and running.

SuperNova hopes to keeps its readers constantly updated with the happenings within the Indian Space scene and much more. A report on the upcoming Mars mission will be the first step in that direction and the post should be up shortly.



Saturday, December 3, 2011

US interest in Indian Human Spaceflight Program

This release from PIB caught attention, for it mentions:

The United states has also expressed interest to collaborate with India on Human Space Flight as stated in the joint statement of Indian Prime Minister and US President during November 2010.
We had previously heard from the media about Boeing offering to help with the Indian Human Spaceflight Program. That could have possibly involved India co-developing (or buying in harsher terms) a variant of the CST-100 that Boeing has been developing for the CCDev Program. But, there hasn't much news on willingness of NASA, the official government space entity, to support India in it's Human Spaceflight ambitions. This old bit news points to NASA's "interest" in assisting India although whether such an assistance would be in India's interest is a different question altogether.



Friday, July 22, 2011

Updates on Chandrayaan-2 and GSLV

In a recent interview to LiveMint, the chairman of ISRO, Dr. K. Radhakrishnan was asked some question regarding the GSLV and the effects of it's two successive failures on the launch of Chandrayaan-2, planned for 2013.

Does it mean all major missions till Chandrayaan-2 will only use indigenous engines? Since the Russian engine has to be examined, will Chandrayaan-2 be delayed?
Yes, it has to be tested on indigenous cryogenic engines, and we’ll only use our engines for future launches, but that is not why there will be a delay. Historically, the Chandrayaan missions are a joint Indo-Soviet mission. The agreement was that the lander [that will descend on the moon] and the (lunar) rover (a robot vehicle) would be provided by the Russians. We wanted to put a smaller rover; it’s something new that we are developing. However, in Russia there was a rethink. They decided they’ll only develop the lander and some instruments related to it. That means India would have to make a bigger rover, a decision taken almost a year ago. There are also preliminary design reviews to be undertaken this year to select which instruments are to be carried onboard the mission. So it’s not only GSLV (engines); there are other reasons for the delay.

On the GSLV,
Next week you’re launching a satellite on the Polar Satellite Launch Vehicle (PSLV). When can we next expect a launch aboard a Geosynchronous Satellite Launch Vehicle (GSLV) with our own cryogenic engine, given that previous attempts have resulted in failure?

Next year this time, we will be conducting flight stage tests (a preliminary to the launch). Flight stage readiness is one thing, but before it is inducted into a launch, we have to ensure that all the ground tests are okay. Also, when we launched the satellite in December, we used a very costly satellite (GSAT-5P)— almost Rs. 150 crore—with lots of features. This time we’ll go for a cheaper satellite (GSAT-14), something that doesn’t require much effort. At best, we’ll be able to put in some transponders in the C-band. If the vehicle underperforms, it won’t be much of a loss. If this one goes well, we will launch the GSAT-6, the “famous” one (that was embroiled in the Isro-Devas row). This, too, will go only on an indigenously developed cryogenic engine. After that it will be Chandrayaan-2 (scheduled for around 2013). There are also changes in the whole GSLV vehicle per se. From 1.5-tonne payloads, we’ve now reached about 2.2-tonne payloads. The biggest change effected is the size of the heat shield [a protective sheath that also determines the size of communication satellites to be put into orbit] and the materials we use for it. We’ve gone from 3.5m heat shields to 4m, and use composites [such as plastic fibre] instead of metal. For GSLV Mark-3, we may have to use 5m shields. 
Why is developing a GSLV so difficult?
We’ve bought seven cryogenic engines from Russia, of which we’ve used six. The results coming out of GSLV have been mixed. Sometimes unforeseen obstacles don’t emerge until it’s actually launched. For instance, when we tried to launch last April using (an) indigenous cryogenic engine, all the preliminary stages were fine and our cryogenic engine ignited—and ignition in vacuum is a difficult thing. But after a few seconds, it stopped. For it to keep going, another device called a two-steering engine (or turbo pumps, which keep the launcher steady) ought to ignite, too. This will ignite only if hydrogen and oxygen are present in exact amounts. When we looked into it, there are several possible explanations as to why the turbo pumps stopped: There are three bearings for these turbo pumps; the bearings must rotate without being (distorted) out of shape by the liquid hydrogen fuel it is submerged into. It could also be that the turbo pumps were blown out of shape. There are several things that can go wrong, and each time we have to test from scratch and develop new solutions. While all these have been looked into, we have to undertake a full ground test, before we can be sure that this will work in flight. Hopefully, this flight stage should be ready for testing in March 2012.
So what about the seventh cryogenic engine from Russia? There were reports that both Isro and Russia disagreed on technical reasons for the failure of the most recent GSLV mission in December.
The last two engines (the sixth and seventh) have greater thrust than previous engines. They was supplied in 2004 and 2005, and stored in specified conditions. So the reason for the failure (in December) was the inadvertent snapping of the connectors, well before time [connectors are critical for controlling the vehicle]. This happened because the shroud gave away (the shroud is a casing that separates the liquid and solid stages of the launch cover). It’s a cover that sits on (the) bottom of the cryogenic stage. Now, why did the shroud go? Was it the 4m heat shield? We then realized that it was the inherent vulnerability of the shroud. The shroud was at the bottom of the cryogenic stage. There were 10 connectors in two stages, and both gave way. Initially, the Russians said it was our 4m shield that was responsible. We put both our analyses, and finally the Russians also came around. We then decided that the seventh engine has to be inspected, too. We did it and found that they weren’t made in the dimensions specified to in the document. There are lots of shortcomings, and the Russians admitted it. Now, the point is that this has to be corrected before it can be used for launch and would require a detailed inspection by them.
The delay in the launch of Chandrayaan-2, at the time thought to be because of the GSLV failures, was well documented  during the weeks and months following the failure of the F06 flight. But, the additional task of having to develop the rover all by themselves is seemingly a bigger challenge for ISRO. For the record, ISRO does not have any prior experience in building rovers of any sort and different aspects like design, testing are going to take a lot of time (and assistance from the Russians). The rover design will supposedly be finalized this year. The mission itself could possibly be delayed upto 2015 and beyond while ISRO is optimistic about launching it in 2014.

Regarding the GSLV, Dr. Radhakrishnan clears the fact that all future flights of GSLV will use the indigenous upper stage (then the final Russian upper-stage will indeed go unused). The additional time and resources that will have to go into overcoming the short-comings of the Russian stage just for a single mission should have deterred ISRO from using it on any future flights.    

The next launch of the GSLV will use a comparatively inexpensive satellite in the GSAT-14. ISRO wants to ensure that if this launch were to fail, then the loss wouldn't be as great as in the case of the previous launch (GSAT-5P). In case of a successful flight (one which we pray for), the GSLV will then launch the GSAT-6 and the GSAT-7.


Sunday, July 17, 2011

PSLV notches up another success

The launch of PSLV-C17 Credit:ISRO

The PSLV has added another success in it's list after than the successful launch of the GSAT-12A on-board the PSLV-C17. This was the PSLV's 19th flight and it's 15th consecutive successful launch. The satellite was launched into a sub geostationary transfer orbit.

The 53 hour countdown started at 11:48 hours (IST) on July 13, 2011. ISRO has been generous enough to provide us with videos of launch vehicle integration which happened during the months and weeks leading upto the launch.

The integration of Solid rocket boosters with first stage.

Integration of the third and fourth stages.

Integration of the satellite and heat shield.

The GSAT-12A itself is a communications satellite of the INSAT-family, a replacement for the INSAT-3B. It was launched to address the ever-growing demand for transponders. This particular satellite carries 12 C-band transponders.

The launch window for this flight opened at 16:48 hours for 20 minutes. The weather was gloomy but there was no rain leading-up to the launch. The mission director gave the go-ahead for the launch at the scheduled launch time (16:48 hours IST). During the last 15 minutes, the onboard mission computer takes over the launch control. It is also important to mention that this particular flight was the first PSLV flight with the indigenous flight computer Vikram (which was previously used on the GSLV-D3 flight).

Due to this being a launch to sub-GTO orbit, the normal flight profile of the PSLV was altered slightly to obtain the large apogee. The configuration used here was the PSLV-XL
with 13.5 meter long strap on solid boosters that each carried nearly 12 tonnes of propellant instead of the standard version were they are 11.3 meters long and carry 9 tonnes of propellant. At liftoff the vehicle stood 44 meters tall and weighed about 320 tonnes.

The altered fight profile meant that
the fourth stage coasted for 2 minutes 25 seconds before ignition and fired for about 9 minutes. After about 20 minutes of the flight, the satellite was inserted into a sub-Geosynchronous Transfer Orbit (sub-GTO) with a perigee of 284 km and an apogee of 21,020 km with an orbital inclination of 17.9 deg. This was almost equal to the planned 284 km perigee and 21,000 km apogee orbit.

The satellite will be placed into Geostationary orbit by firing of it's onboard thrusters during the coming weeks.

Flight Brochure: Link
Image Gallery: Link

Wednesday, April 20, 2011

Shroud design to blame for GSLV failure ?

A picture showing the cryogenic stage shroud (of the ICUS)

First of all, congratulations to ISRO and the scientific community on the successful launch of PSLV-C16 carrying Resourcesat-2. ISRO has really put a lot of work into reviewing every aspect of the launch vehicles after the GSLV-F-06 failure. And the PSLV has again stood up to it's name as the the workhorse of ISRO.

Coming to GSLV-F06 flight. The failure analysis team had previously identified the cause of the snapping of connectors. Deformation in the cryogenic stage shroud was to blame. So as to what caused the deformation of the shroud, there was a difference of opinion between the Russians, who built the stage and the shroud, and ISRO.

The Russian side put the blame on the bigger payload fairing, which caused addition aerodynamic forces that led to excessive stress the shroud causing it to give way.

According to ISRO, the cause for deformation was not the bigger payload fairing but a design flaw in shroud (blaming Khrunichev, the manufacturer of stage).

This disagreement was causing the delay in the submission of the Failure Report. But, today's TOI has an article saying that the issue has been resolved. ISRO seems to have gone through with it's assessment on the cause for shroud deformation.

Link to article: Design flaw behind GSLV crash

"There is a need for correction in the design of the shroud. The shroud at the bottom of the cryogenic stage did not fulfill all service conditions during the flight, as a result of which the connectors linked to the shroud snapped. The connectors were linked to the shroud."

"The shroud was influenced by the pressure distribution that built up in the flight at around 46 seconds and was distorted. It is the distortion of the shroud that led to pulling out of the connectors, which shouldn't have happened before the separation of the stage. But since it did, the vehicle (GSLV) lost altitude and control as a signal to the strap-ons from the computer did not come, owing to the snapping of the connectors," Nair explained.

The space scientist said two key recommendations have been made for future course of action — either make the shroud stronger/tougher or do away with it altogether. "The second is a possibility which we need to work out. If that is possible, all other parameters of the GSLV are fine. A successful flight of the GSLV is not an impossibility."

The Failure report has been submitted to the Department of Space and we can expect the full report to be out in a week's time.