# Launch NewsARIANESPACE FLIGHT VA215 - EUTELSAT 25B/Es’hail 1 & GSAT-7, August 29, 2013

#### Notebook

News Reporter
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LANCEMENT ARIANESPACE VA215 - EUTELSAT 25B/Es’hail 1 et GSAT-7
La Revue d’Aptitude au Lancement (RAL) s’est déroulée le mardi 27 août à Kourou et a autorisé les opérations de chronologie pour le Vol Ariane 5 ECA avec EUTELSAT 25B/Es’hail 1 et GSAT-7.
Pour son quatrième lancement Ariane 5 de l’année, Arianespace mettra en orbite deux satellites de télécommunications EUTELSAT 25B/Es’hail 1 pour l’opérateur qatari Es’hailSat et l’opérateur européen Eutelsat et GSAT-7 pour l’ISRO (Indian Space Research Organisation).
Le choix d’Arianespace par de grands opérateurs et constructeurs du secteur des télécommunications spatiales illustre la reconnaissance internationale d’un service de lancement de qualité. Par sa fiabilité et sa disponibilité, Arianespace reste le système de lancement de référence mondiale.
Le lancement sera effectué depuis l'Ensemble de Lancement Ariane n° 3 (ELA 3) à Kourou en Guyane française.
Le décollage du lanceur Ariane 5 ECA est prévu le plus tôt possible dans la fenêtre de lancement suivante :

> KOUROU : de 17h30 à 18h20, le 29 août 2013

> GMT : de 20h30 à 21h20, le 29 août 2013
> PARIS : de 22h30 à 23h20, le 29 août 2013
> WASHINTON : de 16h30 à 17h20, le 29 août 2013

Pour suivre l’événement en direct sur Internet et en haut débit, connectez vous sur le site www.arianespace.com
(commentaires depuis Kourou en français et en anglais à partir de H-15 mn). Le site Arianespace dispose désormais d'une plate-forme d'hébergement mondiale. Suivez également le lancement en direct sur iPad et iPhone (l’application Arianespace est téléchargeable gratuitement sur iTune).

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ARIANESPACE FLIGHT VA215 - EUTELSAT 25B/Es’hail 1 & GSAT-7
THE LAUNCH READINESS REVIEW (RAL) took place in Kourou on Tuesday August 27, 2013 and authorized count-down operations for the EUTELSAT 25B/Es’hail 1 & GSAT-7 launch. Arianespace will orbit two telecommunications satellites on its fourth Ariane 5 launch of the year: Eutelsat 25B/Es’hail 1 for the Qatari and European operators, Es’hailSat and Eutelsat, and GSAT-7 for the Indian Space Research Organization (ISRO).
The choice of Arianespace by leading space communications operators and manufacturers is clear international recognition of the company’s excellence in launch services.
It will be launched from the Ariane launch complex N° 3 (ELA3), in Kourou, French Guiana.
THE ARIANE 5 ECA LAUNCHER LIFT-OFF for this flight is scheduled on August 29 to 30, 2013 as soon as possible within the following launch window:
> KOUROU: Between 05:30pm and 06:20pm on August 29, 2013
> TU: Between 08:30pm and 09:20pm on August 29, 2013
> PARIS: Between 10:30pm and 11:20pm on August 29, 2013
> WASHINTON: Between 04:30pm and 05:20pm on August 29, 2013Our website www.arianespace.com has upgraded to high-speed transmission and a full-screen format to make it easier for you to follow the company’s activities and to enjoy future launch webcasts. You can also watch the video transmission live on your iPad or iPhone, the Arianespace App is available on iTune and it’s free.

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#### Notebook

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##### Scientist
Coming up on T-45 minutes. Go Ariane...

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#### Galactic Penguin SST

##### Geek Penguin in GTO
News Reporter
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For the third time in less than a year satellites from Europe and India are sharing a ride to geo-stationary orbit on an Ariane 5 rocket. Tomorrow's launch will carry Eutelsat 25B, yet another big communication satellite for that European company - although with a twist, as that satellite is shared with Qatar based Es’hailSat (which also means that this is the first Qatari owned satellite). Not surprisingly, the satellite will serve TV broadcasting and regular communication services through the Middle East, Central Asia and northern Africa.
The Indian representative today is GSAT-7, the 17th Indian satellite to fly on an Ariane since 1981. Carrying UHF, C and Ku band transponders, the government and military are among the bigger users for this comsat.

Launch location:

Kourou Launch pad ELA-3 5° 14'06.34"N, 52° 46'06.34"W

Launch dates and times:

{colsp=7}Launch times

Time Zone |
Kourou / UTC-3
|
Delhi / UTC+5.5
|
Paris /CEDT
|
Universal / UTC
|
Washington / EDT
|
Los Angeles / PDT
Launch time (Primary):
|
17:30​
|
02:00​
|
22:30​
|
20:30​
|
16:30​
|
13:30​
on:
|
Aug. 29, 2013
|
Aug. 30, 2013
|
Aug. 29, 2013
|
Aug. 29, 2013
|
Aug. 29, 2013
|
Aug. 29, 2013

{colsp=7}
[highlight][eventTimer]2013-08-29 20:30:00?before|after;%dd% Days %hh% Hours %mm% Minutes %ss% Seconds %c%[/eventTimer] Ariane flight VA-215 Launch[/highlight]​

Live Coverage Of The Launch:

Eutelsat 25B / Es'hail 1 communication satellite:

Mission Summary

Eutelsat Communications and ictQATAR (representing the State of Qatar) announced in July 2010 that Space Systems/Loral has been selected to build the high-performance satellite they will jointly own and operate at the 25.5° East location in geostationary orbit. The joint satellite will be named Eurobird 2A / Es'hail 1.

The selection of prime contractor marks the next step forward in the partnership signed in May by Eutelsat and ictQATAR to invest in and operate a high-capacity satellite at 25.5° East, one of the two longstanding and anchored neighbourhoods serving rapidly expanding markets in the Middle East, North Africa and Central Asia regions. The two organisations selected Space Systems/Loral to deliver a spacecraft with a more than 15-year design life based on the Space Systems/Loral 1300 satellite bus, which is a decades-proven, modular platform with high power capability and flexibility for a broad range of applications.

To enter into service in early 2013, this powerful satellite will provide a significantly expanded mission and superior coverage across Middle East, North Africa and Central Asia to follow on from Eutelsat's Eurobird 2 satellite, which is currently operated at 25.5° East. In addition to securing Ku-band continuity for Eutelsat and additional Ku-band resources for ictQATAR, it will initiate a Ka-band capability to open business opportunities for both parties. The spacecraft's multi-mission architecture will enable ictQATAR and Eutelsat to respond to demand for the fastest-growing applications in the Middle East and North Africa, including video broadcasting, enterprise communications and government services. The television market will in particular benefit from the installed base of more than 13 million satellite homes already equipped for Direct-to-Home reception from this neighbourhood.

In December 2011 Eutelsat announced, that their satellite assets will be renamed under a unified brand name effective from March 2012. This satellite will become Eutelsat 25B / Es'hail 1.

{colsp=2}Summary
Parameter | Value
Working Orbit:​
| GEO
Orbital Location:​
| 25.5° East
Coverage:​
| Middle East, North Africa and Central Asia
ApA at separation:​
| 35786 km
PeA at separation:​
| 249.3 km
Inc at separation:​
| 3.5°

Characteristics|
Astra 2F
Customer:​
|
• Eutelsat
/ Es’hailSat
Prime contractor:​
|
• Space Systems/Loral
Platform:​
|
• LS-1300
Mass at Separation:​
|
• 6310 kg
Dry Mass:​
|
• ?
Stabilization:​
|
• 3 axis stabilized
Dimensions (stowed):​
|
• 7.2 x 2.2 x 2.3 m
Dimensions (deployed span):​
|
• 25.5 m
On-board power:​
|
• 12kW at start of life
|
• 32 Ku-band transponders
• 14 Ka-band transponders
Life time:​
|
• 15 years
Transponders coverage:​
|

|

|

|

|

GSAT-7 communication satellite:

Mission Summary

GSAT-7 / INSAT-4F is a multi-band satellite carrying payloads in UHF, S-band, C-band and Ku-band. It is planned to be launched during 2011 onboard GSLV and positioned at 74º East. The satellite weighs 2650 kg with a payload power of 2000 W and mission life of 9 years.

INSAT-4 series is planned to have seven satellites, INSAT-4A through INSAT-4G with INSAT-4D as a spare. The transponder capacity of this series has been worked out after evaluating the requirement projected by different uses/user departments. It is planned that, by 2007, INSAT system will have about 250 transponders in various bands catering to a demand of up to 11 Giga Bits Per Second (GBPS) capacity.

{colsp=2}Summary
Parameter | Value
Working Orbit:​
| GEO
Orbital Location:​
| 74° East
Coverage:​
| India land mass
ApA at separation:​
| 35786 km
PeA at separation:​
| 249.3 km
Inc at separation:​
| 3.5°

Characteristics|
GSAT-10
Customer:​
|
• Indian Space Research Organisation
Prime contractor:​
|
• Indian Space Research Organisation
Platform:​
|
• I-2K bus
Mass at Separation:​
|
• 2650 kg
Dry Mass:​
|
• ?
Stabilization:​
|
• 3-axis stabilized
Dimensions (stowed):​
|
• 3.1 m x 1.7 m x 2.0 m
On-board power:​
|
• 3 kW at end of life
|
• ? C-band transponders
• ? Ku-band transponders
• UHF-band transponders
Life time:​
|
• 7 years
Transponder coverage:​
|
• ?

|

Launch Vehicle:

{colsp=2}Characteristics

|
{colsp=2}
Ariane 5 ECA
Prime contractor:​
|
Height:​
| 50.5 m with upper stage and payload fairing

Diameter:​
| max 11.56 m

Liftoff mass:​
| 780 metric tonnes

| ~10 tonnes at GTO (1500 m/s to GEO)

SOLID ROCKET BOOSTER (EAP):​
|
• 2 X P241 motor
• Empty 38 tonnes
• Propellants 240 tonnes (HTPB)
• Thrust in vacuum 700 tonnes of force
• Thrust at sea level 509.9 tonnes of force
CRYOGENIC MAIN CORE STAGE (EPC):​
|
• 1 X Vulcain-2 engine
• Empty 14.7 tonnes
• Propellants 170 tonnes (LOX + LH2)
• Thrust in vacuum 139 tonnes of force
• Thrust at sea level 96 tonnes of force
CRYOGENIC UPPER STAGE (ESC-A):​
|
• 1 X HM7B engine
• Empty 4.54 tonnes
• Propellants 14.9 tonnes (LOX + LH2)
• Thrust in vacuum 6.7 tonnes of force
|
• Diameter 5.4 m
• Length 17 m
• Mass 2675 kg

The vehicle's reliability statistics according to http://www.spacelaunchreport.com/log2013.html#rate:

Code:
================================================================
Vehicle     Successes/Tries Realzd Pred  Consc. Last     Dates
Rate  Rate* Succes Fail
================================================================
Ariane 5-ECA     40    41    .98  .95     40    12/11/02 2002-

Ariane VA215 Ascent Profile

The launcher’s attitude and trajectory are totally controlled by the two onboard computers, located in the Ariane 5 vehicle equipment bay (VEB).
7.05 seconds after ignition of the main stage cryogenic engine at T-0, the two solid-propellant boosters are ignited, enabling liftoff. The launcher first climbs vertically for 6 seconds, then rotates towards the East. It maintains an attitude that ensures the axis of the launcher remains parallel to its velocity vector, in order to minimize aerodynamic loads throughout the entire atmospheric phase, until the solid boosters are jettisoned.
Once this first part of the flight is completed, the onboard computers optimize the trajectory in real time, minimizing propellant consumption to bring the launcher first to the intermediate orbit targeted at the end of
the main stage propulsion phase, and then the final orbit at the end of the flight of the cryogenic upper stage.
The main stage falls back off the coast of Africa in the Atlantic Ocean (in the Gulf of Guinea).
On orbital injection, the launcher will have attained a velocity of approximately 9,374meters/second, and will be at an altitude of about 627.9 kilometers.
The fairing protecting the EUTELSAT 25B/Es’hail 1 and GSAT-7 spacecraft is jettisoned shortly after the boosters are jettisoned at about T+193 seconds.

Ariane VA215 Ascent Timeline

Event|Time rel lift-off|Time UTC|Comment (altitude, velocity)
Start of synchronized sequence|-00:07:00|20:23:00|
Ignition of the cryogenic main stage engine (EPC)|00:00:00|20:30:00|
Liftoff (Ignition of solid boosters)|00:00:07.3|20:30:07.3|0 km 0 m/s
End of vertical climb and beginning of pitch rotation (10 seconds duration)|00:00:12.6|20:30:12.6|0.1 km 37.5 m/s
Beginning of roll manoeuvre|00:00:17|20:30:17|0.3 km 74.1 m/s
Jettisoning of solid boosters|00:02:23|20:32:23|67.7 km 2014 m/s
Payload Fairing Separation|00:03:13|20:33:13|106.9 km 2284 m/s
Shut-down of main cryogenic stage|00:08:46|20:38:46|161.2 km 6929 m/s
Separation of main cryogenic stage|00:08:52|20:38:52|161 km 6956 m/s
Ignition of upper cryogenic stage (ESC-A)|00:08:54|20:38:54|161 km 6958 m/s
Injection|00:24:53|20:54:53|627.9 km 9374 m/s
Separation of Eutelsat 25B satellite|00:27:45|20:57:45|1060.2 km 9035 m/s
Separation of Sylda 5|00:29:10|20:59:10|1319.7 km 8844 m/s
Separation of GSAT-7 satellite|00:34:26|21:04:26|2459.1 km 8099 m/s

Weather forecast for Kourou, French Guiana on August 29, 2013 (4 p.m.)
Partly cloudy with a chance of a thunderstorm and rain. Fog overnight. Low of 23C. Winds from the ESE at 10 to 15 km/h.

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##### Scientist
T-10 mins now ... video presentation now running on Arianespace.tv

---------- Post added at 08:31 PM ---------- Previous post was at 08:20 PM ----------

Launch ! ! !

---------- Post added at 08:32 PM ---------- Previous post was at 08:31 PM ----------

SRB seps at 70km

---------- Post added at 08:33 PM ---------- Previous post was at 08:32 PM ----------

2.23km/sec at 100km alt

---------- Post added at 08:35 PM ---------- Previous post was at 08:33 PM ----------

2.98km/s at 150.0 km alt

---------- Post added at 08:38 PM ---------- Previous post was at 08:35 PM ----------

interesting ... they flattened off at 165km and then accelerated to orbital velocity

#### C3PO

Donator
interesting ... they flattened off at 165km and then accelerated to orbital velocity

That's the most efficient way when the last stage has relatively low acceleration. The altitude drops to 140 km before orbital mechanics makes the altitude rise again.
The STS used a similar profile.

#### Galactic Penguin SST

##### Geek Penguin in GTO
News Reporter
Donator
Both satellites have separated from the upper stage. :thumbup:

Yesterday we saw the successful flight of the largest performance rocket available today (counting GTO performance ), but Ariane 5 makes up for being the 2nd largest one in the world - and flying successfully for the 4th time this year! Arianespace should be proud of flying the only EELV-heavy class launcher that can hold on a 5-7 times per year flight rate in the world - and perfectly for 50+ times. Kudos to the Ariane team!

#### N_Molson

Donator
That's the most efficient way when the last stage has relatively low acceleration.

Yes, typical of launchers that have powerful SRBs for ascent, in Ariane's case generating 90% of the thrust. Was about the same for the Shuttle.

##### Scientist
That's the most efficient way when the last stage has relatively low acceleration. The altitude drops to 140 km before orbital mechanics makes the altitude rise again.
The STS used a similar profile.

Watching again - it got to 167.1 km at 4.42 km/s, then down the hill to 140.9km at 7.80 km/s, before arcing upwards.

I find it interesting that this profile is more efficient than a continual increase in altitude, or at most a leveling off, versus actually descending. Is there a limit to the efficiency of this profile (e.g. ad absurdiam, you would fly straight up to 167km, then angle prograde + say 10 degrees to accelerate to orbital velocity, but that would be crazy, right?!)

#### N_Molson

Donator
As said above, the altitude(time) function is mostly dependant of the acceleration that the vehicle engines can provide at a given instant. So it is completely vehicle-specific, and they use this ascent profile because they have calculated it is the most optimal for Ariane 5.

The boosters need to send the rocket just high enough so that the main engine and the second stage will be able to give the vehicle enough speed (which requires time) to overcome the fall towards Earth. Not high enough would result in a "crash" in the atmosphere. Too high would result in a loss of efficiency. To say things in a simple way, extra altitude boost = extra time given to reach orbital velocity.

##### Scientist
Yep - agreed. Put it high enough so that the smaller upper stage has enough time to accelerate to compensate for the altitude loss.

BUT...

Assuming it's all just PE or KE, my question is why use the primary boost to get to a higher alt (higher PE), versus rolling it over more and trading some PE for KE earlier?

I've no doubt it's because it's more efficient, but I am just curious about the theory behind choosing more PE vs KE.

#### tl8

Tutorial Publisher
Yep - agreed. Put it high enough so that the smaller upper stage has enough time to accelerate to compensate for the altitude loss.

BUT...

Assuming it's all just PE or KE, my question is why use the primary boost to get to a higher alt (higher PE), versus rolling it over more and trading some PE for KE earlier?

I've no doubt it's because it's more efficient, but I am just curious about the theory behind choosing more PE vs KE.

Because the more efficient engines work better in vacuums but they also have less force.

Look at KSP, the small engines have less force but more ISP in a vacuum. By being in space, there is time for the engine to burn and get better efficiency.

#### C3PO

Donator
Watching again - it got to 167.1 km at 4.42 km/s, then down the hill to 140.9km at 7.80 km/s, before arcing upwards.

I find it interesting that this profile is more efficient than a continual increase in altitude, or at most a leveling off, versus actually descending. Is there a limit to the efficiency of this profile (e.g. ad absurdiam, you would fly straight up to 167km, then angle prograde + say 10 degrees to accelerate to orbital velocity, but that would be crazy, right?!)

The ascent profile is always a compromise because you need to gain altitude as well as gaining tangential velocity. To avoid plunging down again you have to point slightly outwards to counteract gravity.

The problem is that if you point the thrust vector away from the velocity vector, you are using a portion of the available acceleration to change direction which reduces the tangential acceleration. You can't point straight at the Vel vector all the time because you need to control your ascent profile.

The solution is to use the first stage(s) to gain quite a bit of vertical velocity. Once the last stage is lit, you can follow the velocity vector with (relatively) low alpha angle. Until you reach orbital speed, gravity will bend the Vel vector downwards, so if you "follow" the vector down you can trade some altitude for tangential velocity. Hence the name "Gravity Turn"
As long as you don't get too much negative radial velocity and descend into thicker atmosphere, this is the most efficient ascent profile.

#### Urwumpe

##### Not funny anymore
Donator
Also, this profile mostly makes sense for rockets, which have a very low acceleration after the boosters separated. It also was used by the Space Shuttle.

It makes the first stage phase slightly more inefficient by loading more gravity losses on them, but then compensates this by having almost zero gravity losses on the later stages.

Of course, it results in a rather poor stage ratio and requires the first stage to deliver more DV as optimal... but it results in a good compromise if you have only some types of rocket engine available for the design.

#### Pipcard

##### mikusingularity
Donator
"requires the first stage to deliver more DV as optimal"

Which is why this is used by launchers with high-ISP, low thrust, hydrolox first stages that have SRBs providing most of the lift-off thrust.

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#### N_Molson

Donator
Which is why this is used by launchers with high-ISP, low thrust, hydrolox first stages that have SRBs providing most of the lift-off thrust.

Because those launchers "first stages" burn for a long time. If I remember well, Ariane's first stage burns for more than 7 minutes. And BTW the SSME of the Shuttle were lit (at varying levels) all the way up, which makes something like 10 minutes.

Ariane 5 & STS actually shared a common philosophy. Ariane 5's upper stage has a mass of 15 tons only, and a thrust of only 65 kN. It's more the profile of a third stage than a second stage (if you compare with very classical "in-line" designs - no boosters - like the Saturn-V, Proton, Falcon 9... the R-7 is quite a special case as the second stage is ignited at liftoff and the LRBs are technically the first stage). With a payload of 5-6 tons, you could put it on LEO (like 150x150 km) without starting the engine. Which would have little point but...

Atlas & Delta also fit in that category, as they are (usually) using SRMs and are able or almost able to send their second stage to orbit without ignition. But they are "better balanced", still, and don't require such a "jump then dive" ascent profile.

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