Author Topic: OneWeb constellation (+900 sats) to be built by Airbus  (Read 29524 times)

Offline denis

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Re: OneWeb constellation (+900 sats) to be built by Airbus
« Reply #40 on: 06/01/2016 06:15 PM »
From https://twitter.com/pbdes, some news on suppliers selection:

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OneWeb/Airbus names MDA (antennas, Canada), Sodern (star trackers, France) & Teledyne Defence (repeaters, UK) as contractors for 900 sats.

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Sodern, to produce 1,800 OneWeb star trackers (2 per sat), says new model is 1/10th mass/volume of predecessor, 1/50-1/100 cost, 5 yr life.

Offline Sam Ho

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Re: OneWeb constellation (+900 sats) to be built by Airbus
« Reply #41 on: 06/27/2016 02:27 PM »
The OneWeb FCC filing is here:
http://licensing.fcc.gov/myibfs/forwardtopublictabaction.do?file_number=SATLOI2016042800041

OneWeb is based in the UK, but they need FCC approval for the US segment.

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The OneWeb System will consist of approximately 720 satellites, plus in-orbit spares, with the capability to increase the number of satellites. The satellites will operate in LEO at an altitude of approximately 1200 km, using 18 orbital planes, each consisting initially of up to 40 satellites, with an 87.9 degree inclination of the orbital plane.

Offline Comga

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Re: OneWeb constellation (+900 sats) to be built by Airbus
« Reply #42 on: 06/27/2016 03:49 PM »
Notice that the image and the original video, is "airbrushed" near both poles.  Despite this you can still see what look like collapsing rings of satellites near the north pole.  If they didn't blur the images, we would see an exaggerated version (Each satellite illustration is scaled up to one or two hundred kilometers to be visible) of what's really happening: Satellites are crossing orbits about six times per second.  Every one of these potential collisions must be controlled, even when a satellite dies, as they inevitably will. 

To my mind this is the biggest challenge for OneWeb, and every other big constellation, bigger than building a thousand satellites or launching them.

What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline Nilof

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Re: OneWeb constellation (+900 sats) to be built by Airbus
« Reply #43 on: 07/05/2016 04:59 PM »
At 1200 km altitude, there should be lots of room to vary the altitudes of satellites in different orbital planes so that the orbits don't intersect.

For example, you could have plane 1 at 1200 km altitude over the pole, plane 2 is at 1205 km altitude... ect until plane 18 at 1290 km altitude.

Since orbital period is proportional to the semi major axis, you can ensure that all orbits have the same period by having apoapsis and periapsis over the poles and flipping the order of the altitudes at the north and south poles, so that all orbits have the same major axis.
« Last Edit: 07/05/2016 04:59 PM by Nilof »
For a variable Isp spacecraft running at constant power and constant acceleration, the mass ratio is linear in delta-v.   Δv = ve0(MR-1). Or equivalently: Δv = vef PMF. Also, this is energy-optimal for a fixed delta-v and mass ratio.

Online jongoff

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Re: OneWeb constellation (+900 sats) to be built by Airbus
« Reply #44 on: 07/05/2016 06:19 PM »
At 1200 km altitude, there should be lots of room to vary the altitudes of satellites in different orbital planes so that the orbits don't intersect.

For example, you could have plane 1 at 1200 km altitude over the pole, plane 2 is at 1205 km altitude... ect until plane 18 at 1290 km altitude.

Since orbital period is proportional to the semi major axis, you can ensure that all orbits have the same period by having apoapsis and periapsis over the poles and flipping the order of the altitudes at the north and south poles, so that all orbits have the same major axis.

One possible fly in the ointment for this approach is that at different altitudes, you're going to get different nodal regression rates. Not wildly different, but different enough that you're going to have to constantly be performing stationkeeping maneuvers to keep your planes spaced evenly. There may be some clever way of keeping the periods the same, and the nodal regressions the same while not having them all in the same altitude band, but that's beyond my level of orbital dynamics fu.

~Jon

Offline savuporo

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Re: OneWeb constellation (+900 sats) to be built by Airbus
« Reply #45 on: 12/19/2016 04:14 PM »
http://www.parabolicarc.com/2016/12/19/oneweb-raises-12-billion-global-satellite-internet/

OneWeb Raises $1.2 Billion for Global Satellite Internet

Small but very important step in getting something made.
« Last Edit: 12/19/2016 04:15 PM by savuporo »
Orion - the first and only manned not-too-deep-space craft

Offline savuporo

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Orion - the first and only manned not-too-deep-space craft

Offline Katana

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Re: OneWeb constellation (+900 sats) to be built by Airbus
« Reply #47 on: 01/18/2017 07:24 AM »
At 1200 km altitude, there should be lots of room to vary the altitudes of satellites in different orbital planes so that the orbits don't intersect.

For example, you could have plane 1 at 1200 km altitude over the pole, plane 2 is at 1205 km altitude... ect until plane 18 at 1290 km altitude.

Since orbital period is proportional to the semi major axis, you can ensure that all orbits have the same period by having apoapsis and periapsis over the poles and flipping the order of the altitudes at the north and south poles, so that all orbits have the same major axis.
Kilometers of clearance maybe safe for normal operation, but if one collision happens, the debris cloud could flood into orbits of other satellites and cause avalanche collision of thousands satellites.

Offline Ronsmytheiii

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Re: OneWeb constellation (+900 sats) to be built by Airbus
« Reply #48 on: 02/24/2017 02:12 PM »
Oneweb considering adding roughly 2,000 more satellites to initial 600 satellite constellation

http://spacenews.com/oneweb-weighing-2000-more-satellites/
"Every vision is a joke until the first man accomplishes it; once realized, it becomes commonplace." - Robert Goddard

Offline meberbs

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Re: OneWeb constellation (+900 sats) to be built by Airbus
« Reply #49 on: 02/24/2017 02:35 PM »
At 1200 km altitude, there should be lots of room to vary the altitudes of satellites in different orbital planes so that the orbits don't intersect.

For example, you could have plane 1 at 1200 km altitude over the pole, plane 2 is at 1205 km altitude... ect until plane 18 at 1290 km altitude.

Since orbital period is proportional to the semi major axis, you can ensure that all orbits have the same period by having apoapsis and periapsis over the poles and flipping the order of the altitudes at the north and south poles, so that all orbits have the same major axis.
Kilometers of clearance maybe safe for normal operation, but if one collision happens, the debris cloud could flood into orbits of other satellites and cause avalanche collision of thousands satellites.
I am curious how this is currently handled by Iridium, since that is the most similar existing constellation and should have the same problem, just on a smaller scale.

Online jongoff

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Re: OneWeb constellation (+900 sats) to be built by Airbus
« Reply #50 on: 02/25/2017 03:19 AM »
I am curious how this is currently handled by Iridium, since that is the most similar existing constellation and should have the same problem, just on a smaller scale.

Iridium is so much smaller than most of the proposed megaconstellations (66 vs ~650-2600 for OneWeb, and 3000-4000 each for SpaceX, Boeing, and Samsung) that I'm not sure how relevant their situation is. More to the point the research Dr Lewis from the University of Southhampton on the impact of megaconstellations on the debris environment suggests that end of life disposal reliability is much more critical for big constellations.

http://eprints.soton.ac.uk/391464/ is a good example of some of the recent research.

~Jon

Offline CyndyC

There was a hugely relevant panel discussion on "Space Traffic Management" at AIAA SciTech 2017, and the video is archived on Livestream:

https://livestream.com/AIAAvideo/SciTech2017/videos/146497817?origin=digest&mixpanel_id=136b121d63432e-06c456027-316f6852-13c680-136b121d635aad&acc_id=9915092


Also, below is a brief video which corresponds directly to meberbs reference to Iridium:

« Last Edit: 02/25/2017 03:10 PM by CyndyC »
"Once a Blue, always a Blue." -- USN/USMC Flight Demonstration Squadron

Offline meberbs

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Re: OneWeb constellation (+900 sats) to be built by Airbus
« Reply #52 on: 02/25/2017 03:24 PM »
I understand that Iridium doesn't have nearly the same criticality on disposal as the mega constellations will. my question is what technique do they use to both keep the constellation in formation, and avoid collisions near the poles between operational satellites. I attached a relevant screenshot from the video.

It appears that the planes have slightly different inclinations, or the intersection would look a bit more regular. The slightly different inclinations might match with small altitude differences so they still have the same precession rate. It looks like they have 3 passing through the intersection at a time (in the screenshot 3 are incoming, and 3 are outgoing. If I have time, I might take a closer look at the TLEs, and maybe pull them into STK to see how close they really get to each other.

Offline envy887

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Re: OneWeb constellation (+900 sats) to be built by Airbus
« Reply #53 on: 02/25/2017 05:02 PM »
There is a good visualization at http://stuffin.space/?search=iridium

Because the satellites are not inclined at 90 degrees, they never cross more than one other orbital plane at a time. So they do not typically get very close to each other.

Offline CyndyC

A single frame from the Space Traffic Management video, not including the 2000 satellites One Web might be adding:
"Once a Blue, always a Blue." -- USN/USMC Flight Demonstration Squadron

Offline CameronD

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Re: OneWeb constellation (+900 sats) to be built by Airbus
« Reply #55 on: 02/27/2017 12:16 AM »
A single frame from the Space Traffic Management video, not including the 2000 satellites One Web might be adding:

Does SpaceX really have 4,425 satellites in orbit??  More than Boeing and OneWeb combined?  I must have missed something... 
« Last Edit: 02/27/2017 12:54 AM by CameronD »
With sufficient thrust, pigs fly just fine - however, this is not necessarily a good idea. It is hard to be sure where they are
going to land, and it could be dangerous sitting under them as they fly overhead.

Online nacnud

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Re: OneWeb constellation (+900 sats) to be built by Airbus
« Reply #56 on: 02/27/2017 01:21 AM »
They plan to have that many, they have none currently.

Edit, well OK they have a Dragon up there but no comsats.
« Last Edit: 02/27/2017 01:22 AM by nacnud »

Online gongora

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Re: OneWeb constellation (+900 sats) to be built by Airbus
« Reply #57 on: 02/28/2017 03:03 PM »
Tweet from Peter B. de Selding
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#OneWeb's Wyler: After 1st launch in March 2018, we test for 5 months, then start launches on @Arianespace Soyuz rockets every 21 days.

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Re: OneWeb constellation (+900 sats) to be built by Airbus
« Reply #58 on: 02/28/2017 03:08 PM »
Tweet from Caleb Henry
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OneWeb's Wyler: First 10 sats in 2018, service in 2019, global coverage by 2021.

Offline eeergo

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Re: OneWeb constellation (+900 sats) to be built by Airbus
« Reply #59 on: 02/28/2017 03:41 PM »
Cross-posting from the conditional merger thread: http://forum.nasaspaceflight.com/index.php?topic=42428.msg1648367#new
-DaviD-

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