New Satellite Launch

Aquos76

Courtesy of boards member "Zaphod"

There is a thread about this already in the Foreign Satellite forum, but seen as its about to launch and can be view live on line from here

I thought I would post a link here also.

Mods feel free to delete this post once the Launch is finished.

Aquos76

Launch has been cancelled until tomorrow night due to bad weather

byte

Let's hope there's no delays tonight, as the mindless ramblings of the presenters in the background got quite annoying!

watty

11.10pm Irish time...

Aquos76

yeah, he went on a bit alright.

Aquos76

Looks like we are all set for the Launch tonight, in less than 10 mins.

Aquos76

Launch went according to plan tonight.

byte

Yup, all went to plan. Still watching the progress.

watty

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Another Ariane 5 success, with a new record performance to geostationary transfer orbit.

Ariane 5 delivered a record performance during Arianespace's second heavy-lift flight of 2007, deploying two large telecommunications satellites into geostationary transfer orbit today.

Launched from the ELA-3 complex at Europe's Spaceport, the Ariane 5 orbited ASTRA 1L for SES ASTRA and Galaxy 17 for Intelsat � marking the 18th consecutive success for Arianespace's workhorse launch vehicle.

"This comes less than two months after our previous success, which demonstrates our consistent launch tempo," said Arianespace Chairman & CEO Jean-Yves Le Gall. "We have launched six Ariane 5s and two Soyuz in less than twelve months, establishing Arianespace as the world reference for the launch services industry."

The customers for today's mission are key international satellite communications companies, and both are long-time users of Arianespace launch services.

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So Astra 1L will in about 2 months take over from Astra 2C which will then move from 19.2E to 28.2E to add extra capacity for Ireland & UK.

http://www.ses-astra.com/corpSite/site_en/04_ASTRAFleet/03_satellite_list/astra2c/index.php

I think it has 16 Transponders in use out of a total of 28 at the minute.

That is 100 to 200 MPEG2 SD channels, 200 to 400 MPEG4 SD channels or about 40 to 80 HD channels, depending DVB-S or DVB-S2 usage and quality.

28 Transponders
Total: 56 channels
10.70 - 11.20 GHz: 32 channels (Band C / Band D) • 11.70 - 12.20 GHz: 24 channels (Band E / Band F)

From http://www.ses-astra.com/corpSite/documentsShared/satellite_factsheets/0_2C_Footprint_FactSheet.pdf

I've no idea if they can change the footprint size. It will be different shape due to the different angle of the beam on the ground from 28.2 instead of current 19.2

Johnny Storm

watty wrote:

So Astra 1L will in about 2 months take over from Astra 2C which will then move from 19.2E to 28.2E to add extra capacity for Ireland & UK.....

For my info, how much fuel do these yokes have onboard to move themselves? I could imagine they would have to have some fuel for "station-keeping" as they say on Star Trek but surely to move orbits would take a LOT of fuel?

dingoxh

The commentator last night said it was using 1.5 tonnes per second during the lauch......

watty

Not a lot to change position. A small burn one way to start moving, do nothing for weeks, then a small burn opposite to slow down to geosyncronous again. The slower you change position the less fuel it takes. This is part of why it will be nearly two months till change over of 1L. Also they have tests to do.

The 1.5tonnes a second is the launch craft engines. The satellites have very small engines and small amount of fuel.

This is also why older "birds" are in a more inclined orbit. The Earth is inclined to the Solar plane (one reason for seasons) so a perfect equatorial orbit needs occasional burns as you are "cutting" the Solar plane. The minimum fuel orbit is close to the solar plane, which would be so inclined that a fixed dish would only "see" the satellite maybe an hour or less twice a day.

They actually have the satellites very slightly inclined (a regular size dish won't notice) to save fuel, which is why for many regular satellites a 4m dish would need a elevation actuator to track the inclination or it would lose the signal twice a day.

Some newer satellites have Ion Drive as well as traditional gas propulsion. The ion drive uses very much less fuel but requires daytime solar panel power.

Zaphod

Johnny Storm wrote:

For my info, how much fuel do these yokes have onboard to move themselves? I could imagine they would have to have some fuel for "station-keeping" as they say on Star Trek but surely to move orbits would take a LOT of fuel?

Once on station, the spacecraft must frequently perform a variety of stationkeeping maneuvers over its mission life to compensate for orbital perturbations. The principal perturbation is the combined gravitational attractions of the sun and moon, which causes the orbital inclination to increase by nearly one degree per year. This perturbation is compensated by a north-south stationkeeping maneuver approximately once every two weeks so as to keep the satellite within 0.05° of the equatorial plane. The average annual velocity increment is about 50 m/s, which represents 95 percent of the total stationkeeping fuel budget. Also, the slightly elliptical shape of the earth's equator causes a longitudinal drift, which is compensated by east-west stationkeeping maneuvers about once a week, with an annual velocity increment of less than
2 m/s, to keep the satellite within 0.05° of its assigned longitude.


Satellites launched in the late 1980s and 1990s typically have an integrated propulsion system that use a bipropellant combination of monomethyl hydrazine as fuel and nitrogen tetroxide as oxidizer. The specific impulse is about 300 seconds and fuel margin not used for the apogee maneuver can be applied to stationkeeping. Also, since the apogee engine is restartable, it can be used for perigee velocity augmentation and supersynchronous transfer orbit scenarios that optimize the combined propulsion capabilities of the launch vehicle and the spacecraft.

For example, the INTELSAT VII satellite, built by Space Systems/Loral, has a Marquardt 490 N apogee thruster and an array of twelve 22 N stationkeeping thrusters manufactured by Atlantic Research Corporation with a 150:1 columbium nozzle expansion ratio and a specific impulse of 235 seconds. For an Ariane launch the separated mass in GTO is 3610 kg, the mass at BOL is 2100 kg, and the mass at EOL is 1450 kg. The mission life is approximately 17 years.

GTO - geostationary transfer orbit
BOL - beginning of life; EOL - end of life.

From "Rocket Thrust Equations and Launch Vehicles : The fundamental principles of propulsion and launch vehicle physics"

Johnny Storm

Thanks!

Zaphod

https://www.youtube.com/watch?v=W4PE8LK2Ga0

Zaphod

https://www.youtube.com/watch?v=eYUh-hMaNiM

Zaphod

Pretty neat onboard cam during rocket launch from Vandenburg airforce base. Action starts at 2min30s and the payload is finally exposed in the last 20 secs.

https://www.youtube.com/watch?v=IvB-8CWw9eU

watty

Some newer statellites have Ion drive as well as traditional propulsion. Ion drive uses the Solar power panel electricity to increase the thrust meaning less weight of propellent need be carried, or same weight and longer life.

Tony

Thanks that was very cool

Zaphod wrote: »

Pretty neat onboard cam during rocket launch from Vandenburg airforce base. Action starts at 2min30s and the payload is finally exposed in the last 20 secs.

https://www.youtube.com/watch?v=IvB-8CWw9eU