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Wednesday, February 8, 2017

ISRO to launch a record 104 Satellites on Feb15th@0932 IST aboard PSLV C37

Updates are added on top ..  Earlier posts are pushed down. 

( Upadte 22Feb/10 AM IST )

Here is what I feel is the orientation changes of Launch Capsule during release of satellites based on the real-time video.

Below, On left is reproduced an image posted earlier showing the photograph of Launch Capsule ( 4th stage ) captured from the PSLV C37 assembly video.
It is superimposed with the symbol that we will use in this post.
Little Red square is the location of camera that shows the release of Cartosat 2D and INS 1A and INS 1B.
Blue and Yellow represent P+ and P- cameras respectively.

 The symbol is superimposed on the launch geometry posted earlier showing the orientation of Launch Assembly in 3 orientations along the PSLV C37 launch path.

 Only the Launch Capsule is shown on Right.

Vehicle started from SHAR and brought the capsule in the position shown on top .. the Orange cylinder is the 4th stage engine pointed backwards. Within about 40 seconds after the PS4 shutdown the capsule is rotated so that the satellites which are attached to this assembly are facing backwards. alsothe capsule is rolled 1/4 th turn so that the Red square camera is now on 'left' of the path.

Cartosat and INS satellites are released in this position but in the video it appears that the satellites are released while the camera is on the 'TOP' surface of satellite. It is not so. The arc of Earth in the background is actually the Eastern edge illuminated with morning Sunlight.

( Upadte 17Feb/10 AM IST ) 
Here are some graphics showing the Geographical location where the satellites were released.

 Here the light blue running North-South shows the intended orbit in which the satellites were to be released, An earlier post ( 10 Feb ) shows how the PSLV C37 rises from SHAR ( Sriharikota ) to this orbit.
Figure on left shows various Receiving and Control stations involved during this launch. They are : SHAR, Thiruvananthpuram ( TVM ), Port Blair, Mauritius and a Norwegian station at South Pole ( TROLL ).
 Every station has a limit of its visibility. It can,t communicate beyond this boundary due to the curvature of Earth's sphere which is shown by the circles around each station witha radius of about 2700 Kms.
Notice that from launch to the point marked as C37, The rocket is visible to at least one station. But at that point the orbit goes beyond the visibility of MAU station and is not visible to any station till it reaches near South pole.
If you had seen the live coverage you may remember that for about 6 minutes all the people in control room were just sitting anxiously but doing nothing.  Actually the real satellite launch activity was going on at that time ( almost 80 satellites were released in that period ) but there was no communication from the vehicle that all satellites were released correctly because there was no communication between the vehicle and control room.
Only after the vehicle entered visibility of TROLL did they know that 'all is well' and we could see their gloomy faces turning into satisfactory grin.

The region where these satellites were released is shown in the figure on Right.

( Upadte 15Feb/8PM IST ) 

Early today morning ( 0358 UT/ 0928 IST ) PSLV C37  rocket was ignited and it faultlessly entered the intended orbit of 505Kms/97.5deg inclination after 16 minutes of powered flight.

After a minute it released 3 Indian Satellites viz Cartosat 2D, INS 1A  and INS 1B.

After another minute it started hurling out the 101 NanoSats for next 10 minutes.

In between for 6 minutes there was a silence period because the launcher was not visible to any receive station on Earth. ( It went out of visibility range of Mauritius station and came into visibility of Antarctic Station  of India 6 minutes later ). However the satellite launch was continuing during this period also. Confirmation of these launches was received only after Antarctica station received the telemetry.   ( A HOLD YOUR BREATH period of anxiety).

ISRO also had mounted several good cameras ( unlike in the earlier mission ) onbord and it released the footage later.

Here is the grab form that video:

New stars appear in the sky!!!

These are just a part of the flock of satellites being released by PSLV C37 which released 104 satellites in one go forming a starry appearance in the dark sky near the Satellite Housing .
Image is a grab from ONBOARD camera video footage released by ISRO.

Watch the video (…/15-feb-2017/pslv-c37-lift-and-onboard-…) and enjoy the floating and spinning of so many birds in space at a height of 500+ kms above ground.

It is breathtaking!!!!! ....some being released from top side and some appearing from bottom side seen over Earth surface. Notice the Edge of Earth on right side of next image. 

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( Update : 14Feb/ 9 PM IST )

A grab from Integration video showing the assembly of Satellite Bay

Satellite identification is my interpretation ..  not official version 

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( Update : 10Feb/ 11AM IST )

Based on the warning to air-traffic at Chennai airport, a graphic showing the path of the rocket is drawn on Right.

Left part shows the path as seen from top while the right hand part shows the altitude aspect

Notice how the rocket avoids Srilanka by going around it to avoid the falling debris to cause harm to land based area.

This turning around is popularly known as " Dog Leg Maneuver" .

16.5 minutes after ignition the rocket attains its intended orbit of 510 Kms and  The 1st satellite to be released  17.5 minutes after the rocket ignition is  Cartosat 2D, followed immediately by the remaining 2 Indian satellites INS 1A and INS 1B.

A minute later the release of other satellites starts and all of those are released in next 10 minutes thus achieving the record launch of 104 satellites in a single flight.

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First post:

Just like Indian Cricket team, ISRO is set to make a record of attaining a century this month.

In fact it is set to launch 104 -  yes, you read it right 1 0 4  -  satellites during a single flight on Feb 15th using a PSLV  rocket in its C37 flight.

Interestingly there are only 3 Indian satellites on this flight :

 - Cartosat-2D
 - INS-1A
 - INS-1B.
( The 3 weigh   639kg + 13KG + 13Kg )

 Rest 101 are very small satellites ( Generally called Nano Satellites due to their miniature size and light weight. ) from US ( 96 Sats ), Israel ( 2 Sats ), Kazakistan, UAE and Netherlands ( 1 Sat each ).
These 101 satellites  weigh about 500 Kgs.

A Typical DOVE satellite

 - 88 satellites are DOVE satellites of PLANET, a US based company involved in Earth Imaging Services. ( They already have 12 DOVEs in operation ..  now with 88 new sats they will have 100!!!! ).  All mind boggling numbers!!

Most of the non-ISRO satellites are being co-ordinated by a Netherlands entity,  ISIS – Innovative Solutions In Space  - which has pioneered as a nano-satellite developer and mission operator.

They have developed a four satellite container called QuadPack which holds the 4 satellites till the QuadPack is launched by the rocket  and releases them later independently.

We can speculate that there may be 25 QuadPacks aboard PSLV C37 arranged around the 3 large Indian Satellites. ( A Crowdy environment ..  isn't it ?? ).

BTW, ISRO is expected to recover about half of Launch Cost from these satellite operators for launching these satellites.

While we await the official document about the launch from ISRO an interesting question has been raised in one of the discussion forum:

What if one of those 88 sats are programmed to explode thus causing the loss of Cartosat & crush PSLV image in the market?

We know that any launch vehicle operator will test the satellite thoroughly before being integrated with the rocket, the possibility can't be denied totally.

What re your views? Please tell in the comments section ..  I am sure it is an interesting question and we could have some lively discussion here !!

Friday, September 23, 2016

PSLV C35 flight on 26th Sept 2016

  PSLV-C35 will launch the Indian SCATSAT-1 for ocean and weather related studies and seven co-passenger satellites into polar  Orbit. It is scheduled to be launched on Monday morning at 9:12 hrs (IST) on September 26, 2016

The outstanding feature of this flight is that this is the first mission of PSLV in which it will be launching its payloads into two different orbits.

 The other satellites are from Algeria, Canada and USA as well as two satellites from Indian Universities/ Academic Institute.

SCATSAT-1 will be placed into a 730 km Polar Orbit. Others  will be placed into a 689 km polar orbit.
Dual Launch Adapter

PSLV is a 4 stage rocket and all the satellites are placed in the front noselike structure.
 This cone protects the satellites while the rocket is cruising through atmosphere. As the launch progresses the stages are ignited and after their function is over are discarded. While the 2nd stage is burning the rocket has attained 100+ kms and the atmosphere is almost nil. So at 115 Kms the nose covering the satellites  ( called Fairing in technical jargon ) is discarded exposing the Dual Launch Adapter ( DLA ) which contains all the satellites to be launched. This is called as DUAL because it has two chambers ..  front one has the main satellite SCATSAT and the rear part contains the remaining satellites.

 Next Figure shows the path that the PSLV will take from SHAR. The Blue line is the intended orbit of SCATSAT.
After lifting off the rocket rises and while rising it turns towards sea and in SE direction, In order to avoid flying over SriLankan landmass it turns around  it ( This  is called as Dog Leg  maneuver because of the typical shape ).
Then it turns further while rising in such a way that it rises to 730 Kms over equator with a speed of 7.5 kms.The SCATSAT is released at this stage into its intended orbit.

After launching SCATSAT  at 730 kms altitude and inclination of 98.1 deg,  the Launcher moves towards South pole. After about moving for half an orbit from backside of Globe appears over North Pole when the second ignition takes place ( using a station ranging and command station located at Svalbard ?? ). This is to reduce the altitude to  689 Kms in preparation for the release of other satellites. .Then when the DLA is near South pole remaining satellites are released.

 A detailed launch sequence for this launch is shown here:

In all viewes the s/c is moving from North to South in front of viewer.

Then after another half an orbit, when the launcher is over South pole at 689 kms altitude one more ignition is used ( to fine tune launch conditions ?? ).  After shutdown of this ignition the Dual Launch adapter is released.
After half a minute delaythe remaining satellites are released with an inclination of 98.21 deg ( Alsat-1N, NLS 19, Pratham, PiSAT, Alsat-1B, Alsat-2B and Pathfinder-1 .. in that order ) in about 2.5 minutes while the launcher is moving South to North behind the globe in graphic.

Notice that the Earth is rotating continuously from left to right.

SCATSAT-1 is a continuity mission for Oceansat-2 Scatterometer to provide wind vector data products for weather forecasting, cyclone detection and tracking services to the users. The satellite carries Ku-band scatterometer similar to the one flown onboard Oceansat-2. The spacecraft is built around standard IMS-2 Bus and the mass of the spacecraft is 377 kg. The spacecraft will be put in SSP orbit of 720 km altitude with an inclination of 98.1 deg by PSLV-C35. The mission life of the satellite is 5 years.

 PISat is a 5.7 kg Student satellite from PESIT, Bengaluru.

Pratham is a 10 kg satellite from IIT-Bombay's Dept of Aerospace Engg.

Other satellites are from International customers.


Update  27Sept 2016/1300 IST

Following graphic shows the position of launched satellites after one day  ( today ):

First figure shows the location where SCATSAT was inserted in the Red coloured orbit. Then it released other 7 satellites after two burns of 4th stage.

After about a day we can see all those satellites spread out in two orbits.

Officially the satellites have yet to be alloted with their respective names. Currebtly these have been identified alphabetically as objects A to K. Wait!  ..  How many are A to K?    ( There is no I to avoid confusion with 1 ) ..  TEN.

But we know that in all 8 satellites were launched then how come there are 10?

The extra two are .. 1. Dual Launch Adapter ( DLA ) which was ejected after first re-burn of 4th stage ..  and 2. the 4th stage itself .

Although the satellites are yet to be officially identified their positions imply to identifying at least a few :

Object H is clearly a lonely SCATSAT-1.

Objects J and A are clearly different from the other lot.  One is a DLA which was independently ejected and the other one is 4th stage.

Keep tuned in we will let you know as soon as it is officially declared

Monday, September 5, 2016

GSLV F05 Flight .. scheduled for 8th Sept.

India's GSLV-F05 carrying the Insat 3DR comsat is on the Second launch pad awaiting its Sep. 8 launch.  Second Launch Pad with a assembly tower of 82 M hight ( equivalent to about 25 storey building ) can be used to launch both PSLV and GSLV rockets of ISRO. These images show a comparison of GSLV and PSLV both graphically and in images.


NOTE: The rocket is also called as Motor or Engine. We may use these terms interchangeably in the following write up.
 ========== =============== ============== ============= ======== ========
Come Sept 8th, 2016, ISRO will launch INSAT-3DR satellite which  is for Meteorological Imaging applications using a GSLV rocket. This flight is named as GSLV F05 flight.

We will try to give here some facts which may make your viewing of Launch Video  an interesting affair rather than just a clap clap affair. 

INSAT-3DR  is a Meteorological applications satellite,  Imaging in Middle Infrared band and  in two Thermal Infrared bands. It also carries a Data Relay Transponder as well as a Search and Rescue Transponder.
It has a lift-off mass of 2211 kg, ( including 1255 kg of propellant).  The  solar array can generate 1700 Watts of power. 

To give an idea of its weight and size here is a fact sheet comparing it with a popular car:

                The Car                                            INSAT-3DR

  Weight :   1350 Kgs                                       2200 Kgs   ( So it weighs about 1.5 times car )
   Size   :  1.5M x  1.7M  X  3.6M                   1.6M  X 1.5M  X  2.4M

GSLV Rocket :

The GSLV F05 is a 3 stage rocket  with a  Cryogenic Liquid Upper stage.

The 1st stage is made up of a central core and 4 strap-on motors.  The central core is a massive 2.8 M diameter. It contains 138 Tons of solid fuel which can produce a thrust of 4700 kN.  

Each of  4  strap-on rockets ( called L40 )  is  2.1 meters in diameter,  contains 42 Tons of propellant and can produce a thrust of 680 kN.   Thus altogether the 1st stage ( Central core + 4 add-ons ) creates a force of  about 7400 kN to lift the rocket off the pad.
BTW how much fuel do these giants consume? Hold your breath: Altogether the 1st stage consumes more than 2400 Kgs per second. But there is a silver lining to this consumption - every second the rocket is loosing 2400 kgs of dead weight so it aids in  accelerating the rocket in addition to the brute force acceleration generated by the engines! So by the time the 2nd stage ignites, the rocket is lighter by 360,000 kgs. And when the 2nd stage separates the dead-weight of 1st stage also reduces the load  further. 
                                                             The graph here shows the events during launch.    The X Axis is Time in seconds from liftoff. Red line is the height that the rocket reaches and Blue line is the speed of rocket multiplied by 40.    Actual speed is less than 10 Km/s but it appears just as the green line near X axis so it was multiplied by 40 to show the variations as seen in Blue line.
Incidentally, the 1st stage is ignited a bit differently than the PSLV wherein add-on motors are switched on 2 first, and then the remaining 2. In case of GSLV, 4.8 seconds before the actual liftoff time ( referred as To ) , the four L40 boosters  are ignited simultaneously. Notice that the central main core is not yet ignited so the thrust is not sufficient to lift the rocket. After ensuring that these 4 engines are working properly the central core is ignited at To and these five motors together lift the rocket vertically up to clear the height of launch facilities. Then it starts turning ( Technically called Pitching and Rolling maneuvers ) seawards.

After burning the 1st stage for about 2.5 minutes the the second stage is ignited ..  yes, the 1st stage is still attached and is still burning at this time! This method is called Hot-Staging and it helps in pushing off the 1st stage by the exhaust of 2nd stage. The 2nd stage is 2.8 meters in diameter,  contains 45 Tons of propellant and can produce a thrust of 800 kN. 
By this time the rocket would have risen to an altitude of 72 Kms and attained a speed of 2.4 Kms/sec. 
( A bit off topic : remember that the scramjet test of ISRO a few days ago was carried out at 6 Mach speed which is nearly this speed and so it is possible to use the scramjet  engine in place of the current upper stages if required in future. )
While all this is happening the rocket also does maneuvers to turn east and a bit to south so that ultimately  it is possible to release the satellite on equator.

The 2nd stage burns for 140 seconds lifting the altitude from 72 Kms to 132 Kms. The speed also increases from 2.4 Kms/sec to 4.9 Kms/sec.

 In between, at 115 Kms altitude ( 228 seconds from To ) , the cover which protects the satellite from atmospheric drag etc ( Payload fairing ) gets ejected since the rocket has climbed above the atmosphere at this height making the protective cover redundant.

At 132 Kms ( 293 seconds from To) the 2nd stage is shut off and ejected and 3rd Cyogenic Liquid Engine stage is ignited. 
It is fuelled with Liquid Hydrogen and Liquid Oxygen. This stage is also 2.8 meters in diameter.  This Cryo stage has the advantage that its output power can be controlled between 70 kN and 95kN.  

Cryo Stage burns for a long duration ; 293 seconds to 1012 seconds and it increases speed from 4.9 km/s to 9.7 Km/s while the altitude increases from 133 to 220 Kms.

At this time  (  1012 seconds from To ) the cryo is shut off because the the roket is now in the required orbit moving around Earth due to gravitational force on its own.

The satellite is separated a little later from the upper stage 1024.7 seconds from   To  at an altitude of 230 Kms.

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

Update : 7sept/2230 IST

In order to avoid the clash with air crafts flying in vicinity of SHAR  the aviation authorities publish Note To Airmen  ( NOTAM ) about the zone to be avoided.

Based on that NOTAM here is a likely path that the rocket will take?

Wednesday, June 22, 2016

PSLV C34 launched 20 satellites and the 4th stage was re-ignited twice afterwards

PSLV C34 carried a record 20 satellites in a single flight on 22nd June 2016.

All were ejected successfully over 10 minutes period ( about 16.5 minutes to 26.5 minutes ) from takeoff.  This graphic shows the ejection sequence w.r.t. Time and Height at which the Satellite was ejected. Table on right lists the satellites and when they were released. Green triangle indicates 4th stage cutoff. 3 Blue triangles show 6 satellites which were released in the bunches of 2.

Before we proceed further a small explanation about the process of release of satellites:

1. The sat is  NOT 'thrown' in the required orbit.

The launcher carrying satellite is brought to the required orbit and engine is shut off .. it is now in the orbit around body moving under gravity of main body just like the satellite would be. Then the satellite is released and launcher is moved out of its collision path.
So  under normal launch the last PSLV component also would be with the sat bunch  even after 1  or 2 days.

Naturally the PSLV component also would be with the sat bunch after 12 hours.
But in this particular launch  ( PSLV C34 ) the launcher is far away and in a different orbit ( slightly lower .. about 460 kms ) as compared to about 520 kms as shown in the figure here.
( Overall view is in Left and zoomed views ( From top and side )  are on right.  )


Recall that in this case the 4th stage was re-ignited twice ( 50 minutes and 100 minutes after release of last satellite ) so its orbit has to be different than the flock of satellites released earlier. 
We do not know how the re-ignition was carried out. But the effect is available for public to see.
We can see that the orbit is about 460 kms ..  so it has to move faster than the satellites which are at about 520 kms. That is the reason that PSLV component is ahead  of the satellites that it released.

Now coming to the question: Why did ISRO tried this experiment?

The 4th stage was burning for 8+ minutes before it ejected the satellites so  it would heat the nozzels . After its shuoff the surrounding chill would cool the engine. This heating and cooling cycle could cause some changes in the characteristics of engine which ISRO may be interested to know before they  take up a real multi orbit injection of satellites.

.Good wishes to you ISRO.

Tuesday, December 15, 2015

PSLV C29 flight to carry SIX satellites of Singapore on 16th Dec.

Come 16th December 2015, India's workhorse rocket PSLV will carry 6 satellites to space.

Launch will be from First Launch Pad ( FLP ) of Sriharikota and the rocket is Core Alone (  PSLV-CA ) type.

All these satellites are from Singapore and they will be launched in a near equatorial Earth orbit of 550 Kms with an inclination of 6 deg.

 Primary payload is a 400 Kg TeLEOS-1 Satellite. This the 1st Commercial Earth Observatory of Singapore.

Other 5 co-passengers on this flight riding piggyback  are

Velox CI ..  123 Kg ..  Tropical Environment monitoring
Velox II ..  13 Kgs ..  Experimental Communications/GPS
Athenoxat I .. Experimental Remote Sensing Microsatellite
Kent Ridge I ..  78 Kgs ..  VNIR and SWIR Medium resolution Earth obeservation payload
Galassia .. 3.4 Kgs ..  used for Photon Quantum Correlation data acquisition.

Tentative Launch time is 1800 Hrs IST.


A unique feature of this flight is that 46 minutes after all the satellites are launched the 4th stage will Re-start and will remain ignited for 4 seconds.

This may appear to be an insignificant thing but there are technological achievements for ISRO if this happens.

This will provide a capability towards launching satellites in diverse orbits in a single flight.

The critical technological factor is that the engine has to be cooled before the 2nd burn.

Sunday, September 20, 2015

ASTROSAT: India's Space Observatory ... set for launch end Sept, 2015.

Come 28th September 2015, India's workhorse rocket PSLV will carry 7 satellites to space.

 PSLV (XL) C30 to be launched from 2nd Launchpad at Sriharikota will carry:
- AstroSat-1,
- LAPAN-A2 (Indonesia)
- NLS (Canada)   and
- Lemur (UK) - 4 sats.

The orbits of these satellites are very diverse: Inclinations of Lemur,Lapan and NLC are between 97 and 98 degrees while ASTROSAT has an inclination of 6 degrees.

So this is an interesting launch to watch  specially how the vehicle will be maneuvered to release these satellites.

Added 27Sep/1715 IST

So the PSLV C30  launch will be Equatorial...  as can be deducted from the NOTAM issued to Navy

We have plotted the path based on NOTAM issued by Indian Navy.

PSLV C30 path drawn using the Indian Navy's NOTAM

Added 29 Sep 2015

The PSLV C30 launched ALL the satellites in near equatorial orbits of about 6 deg inclination.

Top figure shows the satellites as they are launched on 28th. Note how all are together in one bunch.

Next part shows the position of the satellites a day after launch and the same view is zoomed in the lowest portion of image showing how the satellites have started spreading ..  but still in the launch orbit .

In a few days individual sat operators will start maneuvers to push the satellites in their final designated polar orbits with 97 deg inclination

Watch this place for further updates/commentary  regarding how the orbits will be changed..

Current parameters for objects a to h are as follows:

Object Period ( min ) Inclination Apogee Perigee
Sat A                97.55               5.99     650                633     
Sat B                97.54               6.00     650                632     
Sat C                97.52              6.01      650                630     
Sat D                97.51             6.00       650                630     
Sat E                97.56              6.01      650                 634     
Sat F                97.57              6.00       650                635     
Sat G                97.58             6.00       650                635  
Sat Housing 97.28               5.96      649                608     

Exact satellites have still to be identified officially.

Thursday, August 20, 2015

SITE... the First experiment in community TV

40 years back, starting 1st August 1975, For the first time in the world an experiment to transmit signals directly from the satellite to a community TV was conducted using a US satellite ATS-6 and Direct Reception sets ( DRS )  in over 2000 TV sets in India.

Called SITE ( Satellite Instructional Television Experiment ), this experiment provided data base for studies in Community TV.

One of the managers of this experiment compiles the facts here.

The B/W picture on left shows one of the first large antennas in India, a starting point of career in satcom for many youngsters then ( including yours truly ).