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Thread: Satellite T16 Discussion

  1. #81
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    Quote Originally Posted by Doctor j View Post
    Finally, Probably been there a couple of days.
    STA request said IOT ~ 3 weeks then drift to 100.85 degrees west

    Doctor j

    It said the drift would require 7 weeks. I'm guessing that lengthy timeline is probably due to its electric propulsion making maneuvering slower...

  2. #82
    Edgecutter bakers12's Avatar
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    So with electric propulsion, has the word "burn" been replaced with something else that means "engine operation?" Not kidding, I really don't know anything about this type of engine. I assume it's different than the xenon motors on previous DirecTV spacecraft.
    Dear God, Please send clothes for all those poor ladies in Daddy's computer. Amen.

  3. #83
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    Quote Originally Posted by bakers12 View Post
    So with electric propulsion, has the word "burn" been replaced with something else that means "engine operation?" Not kidding, I really don't know anything about this type of engine. I assume it's different than the xenon motors on previous DirecTV spacecraft.
    Rather than burning fuel they use a type of ion propulsion or Hall thruster that uses electrical power an as input along with a propellant such as xenon. The amount of thrust they can produce is a lot less, but they use much less propellant. So they'll either have a longer useful fuel life or carry less fuel which means reduced launch mass. They have more than adequate thrust for station keeping, but bigger movements take longer than chemical propulsion.

    The other satellite launched in T16's mission had a fully electric propulsion so unlike T16 it is using it for orbit raising. So it isn't expected to reach GSO until Q4 this year. So they saved even more launch mass by not using chemical propulsion for orbit raising, but they have to wait a while for it to reach its proper orbit (and then presumably another 2-3 months for IOT and reaching its final destination)

  4. #84
    Super Moderator Doctor j's Avatar
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    Quote Originally Posted by slice1900 View Post
    Rather than burning fuel they use a type of ion propulsion or Hall thruster that uses electrical power an as input along with a propellant such as xenon. The amount of thrust they can produce is a lot less, but they use much less propellant. So they'll either have a longer useful fuel life or carry less fuel which means reduced launch mass. They have more than adequate thrust for station keeping, but bigger movements take longer than chemical propulsion.

    The other satellite launched in T16's mission had a fully electric propulsion so unlike T16 it is using it for orbit raising. So it isn't expected to reach GSO until Q4 this year. So they saved even more launch mass by not using chemical propulsion for orbit raising, but they have to wait a while for it to reach its proper orbit (and then presumably another 2-3 months for IOT and reaching its final destination)
    Latest Eutelsat 7C data shows painfully slow transfer to GSO:
    EUTELSAT 7C_13
    Lon 104.1979° W
    Lat 1.8032° S
    Alt (km) 29 423.620
    Azm 296.3°
    Elv -29.4°
    RA 02h 17m 49s
    Decl -9° 15' 41"
    Range (km) 38 506.849
    RRt (km/s) 1.617
    Vel (km/s) 2.590
    Direction Ascending
    Eclipse No
    MA (phase) 92.3° (65)
    TA 155.1°
    Orbit # 32

    Name EUTELSAT 7C_13
    NORAD # 44334
    COSPAR designator 2019-034-B
    Epoch (UTC) 2019-07-03 19:12:00
    Orbit # at Epoch 28
    Inclination 6.003
    RA of A. Node 57.095
    Eccentricity 0.6960926
    Argument of Perigee 186.491
    Revs per day 2.11682695
    Period 11h 20m 15s (680.25 min)
    Semi-major axis 25 622 km
    Perigee x Apogee 1 409 x 37 079 km
    BStar (drag term) 0.000000000 1/ER
    Mean anomaly 151.613
    Propagation model SDP4

    Perigee only1409 KM after 2 weeks!!

    Doctor j

  5. #85
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    Quote Originally Posted by slice1900 View Post
    It said the drift would require 7 weeks. I'm guessing that lengthy timeline is probably due to its electric propulsion making maneuvering slower...
    The 0.7 degree/day drift is normal for non emergency movements.

  6. #86
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    Quote Originally Posted by Spear61 View Post
    The 0.7 degree/day drift is normal for non emergency movements.
    Thanks I didn't realize it was always that slow. I guess I didn't remember it taking that long previously.

  7. #87
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    The three week IOT should be complete about now, so TLEs should begin to show T16 moving toward 101 in the next few days, and arrive on station around Labor Day. At some point we'll see a filing for T15 to move back to 103, presumably scheduled for sometime in September, and then 103ca tpns 1-8 should appear.

  8. #88
    Super Moderator Doctor j's Avatar
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    TLE today, AT&T T16 still at 134.75

    For those keeping up with "all electric" Eutelsat 7C 3 and 1/2 weeks post launch
    Orbit is 3116 x 39405 , painfully slow rise to Geostationary

    Doctor j

  9. #89
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    Quote Originally Posted by slice1900 View Post
    The three week IOT should be complete about now, so TLEs should begin to show T16 moving toward 101 in the next few days, and arrive on station around Labor Day. At some point we'll see a filing for T15 to move back to 103, presumably scheduled for sometime in September, and then 103ca tpns 1-8 should appear.
    It was 83 km below geo early morning on June 30 and on station mid morning on July 3.

  10. #90
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    Humph ...

    I guess you could say this is related to T16's eventual arrival at 101W. But I see included in the narrative posted here for an STA to move T9S over from 101.1°W to 101.2°W. It mentions that T4S is reaching EOL and after all traffic is transferred to T9S, will then be "deorbited" (i.e., moved to a graveyard orbit of course) sometime later this year.

    So I guess station-keeping fuel levels for more years notwithstanding, the "old geezer" T4S will be decommissioned this year ....

    Interesting ....

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