Eutelsat OneWeb: Constellation - General Thread

[MikeAtkinson]

There are good reasons why current navigation satellites are MEO (10-15 hour orbits):
1. only about 30 satellites required (including spares).
2. global coverage from one orbital inclination.
3. out of the way of orbital junk
4. more benign environment for the atomic clocks
5. it makes inter-satellite links easier, which helps control and atomic clock calibration, and importantly for a military system allows continued operation even when ground stations have been taken out.

The OneWeb constellation is LEO and LEO global navigation satellite services (GNSS) satellites have a number of deficiencies to overcome:
1: far more satellites are needed to have at least 4 above 20 degrees above the horizon at any one time.
2. in order to cover the poles and equator efficiently several orbital inclinations are needed.
3. avoidance maneuvers for orbital junk mean that the satellite will not be available for navigation, until its new orbit is determined.
4. OneWeb does not currently have inter-satellite links.


I don't believe that the OneWeb bus is large enough for both a navigation and comms payload on the same satellite. So probably separate comms and nav satellites.

All of these deficiencies can be overcome, but it won't be cheap or easy. In my opinion probably better to start with a completely new satellite bus, optimised for GNSS.

The large number of LEO satellites needed for a GNSS constellation makes affordability very difficult to achieve, payload, bus, launch and operational costs will have to be very low.

[Rondaz]

Consortium including @GOVUK emerges as favorite to acquire bankrupt @OneWeb broadband satellite network: https://geekwire.com/2020/british-led-consortium-emerges-favorite-acquire-oneweb-broadband-satellite-network/ H/T
@pbdes
@FT
@Megaconstellati
@TMFAssociates
@cashel

https://twitter.com/b0yle/status/1276614931501027328

[Rocket Rancher]

With all due respect to all the stories written so far, how do they know the UK bid is the favorite? Have we seen/heard about any other bids yet? If so, please share with us. This is the first inning of the speculation game, there will be so much more to come in the next several days. So just strap in and enjoy the commentary here on NSF. 

[ChrisWilson68]

twitter.com/space_mog/status/1276506132127907842

This makes no sense for many other reasons too. They don’t actually have spectrum priority, they have shared spectrum & nothing about this company is UK, except post office box. Money would be better spent on actual UK satellite industry!

I think this is disingenuous on Elon's part. Isn't SpaceX also participating in DARPA Blackjack? If so, he'd know that one of their focuses is on the idea of making variants of telecom megaconstellation satellites that allows them to host military payloads, including PNT ones...

Please don't attribute malice to someone just because you disagree with that person's assessment.

Of course Elon knows about the idea of taking advantage of large constellations for additional purposes.  So do I and so do a lot of other posters on here who have expressed similar sentiments about this bid by the UK being folly.  You don't have to believe that it's never a good idea to reuse a satellite bus for another purpose or have one satellite with two payloads to believe this particular deal is not the most cost-effective way for the UK to meet its goals.

It's like buying the bankrupt Delorean auto company in the Chapter 11 auction because you want to put a time machine in a car.  Just buy a car from someone else for your time machine.

[gongora]

twitter.com/space_mog/status/1276506132127907842

This makes no sense for many other reasons too. They don’t actually have spectrum priority, they have shared spectrum & nothing about this company is UK, except post office box. Money would be better spent on actual UK satellite industry!

I think this is disingenuous on Elon's part. Isn't SpaceX also participating in DARPA Blackjack? If so, he'd know that one of their focuses is on the idea of making variants of telecom megaconstellation satellites that allows them to host military payloads, including PNT ones...

Please don't attribute malice to someone just because you disagree with that person's assessment.

Of course Elon knows about the idea of taking advantage of large constellations for additional purposes.  So do I and so do a lot of other posters on here who have expressed similar sentiments about this bid by the UK being folly.  You don't have to believe that it's never a good idea to reuse a satellite bus for another purpose or have one satellite with two payloads to believe this particular deal is not the most cost-effective way for the UK to meet its goals.

It's like buying the bankrupt Delorean auto company in the Chapter 11 auction because you want to put a time machine in a car.  Just buy a car from someone else for your time machine.

Elon's tweet is disingenuous for other perfectly valid reasons.  OneWeb's HQ/control center is in London.  OneWeb does have spectrum priority in parts of the world that don't have their own system for assigning priority and just go by the ITU dates.

[Robotbeat]

I disagree with Elon, but when I defended this idea, I got excoriated on Twitter LOL.

One possibility for a GNSS payload is to do what the Japanese did (experimentally) on their local GNSS satellites: instead of having an on-board atomic clock, simply re-broadcast from an atomic clock at the ground station. This drastically reduces the cost, weight, etc of a GNSS payload, perhaps enough to use the OneWeb bus.

It's funny how simply proposing another possibility as reason why you can't dismiss something out of hand (without better knowledge) gets attacked so vociferously...

[alexterrell]

There are good reasons why current navigation satellites are MEO (10-15 hour orbits):
1. only about 30 satellites required (including spares).
2. global coverage from one orbital inclination.
3. out of the way of orbital junk
4. more benign environment for the atomic clocks
5. it makes inter-satellite links easier, which helps control and atomic clock calibration, and importantly for a military system allows continued operation even when ground stations have been taken out.

The OneWeb constellation is LEO and LEO global navigation satellite services (GNSS) satellites have a number of deficiencies to overcome:
1: far more satellites are needed to have at least 4 above 20 degrees above the horizon at any one time.
2. in order to cover the poles and equator efficiently several orbital inclinations are needed.
3. avoidance maneuvers for orbital junk mean that the satellite will not be available for navigation, until its new orbit is determined.
4. OneWeb does not currently have inter-satellite links.


I don't believe that the OneWeb bus is large enough for both a navigation and comms payload on the same satellite. So probably separate comms and nav satellites.

All of these deficiencies can be overcome, but it won't be cheap or easy. In my opinion probably better to start with a completely new satellite bus, optimised for GNSS.

The large number of LEO satellites needed for a GNSS constellation makes affordability very difficult to achieve, payload, bus, launch and operational costs will have to be very low.

Probably worth adding that
- Accurate atomic clocks that will work in space for a few decades are not cheap. Perhaps too expensive to put on several low Earth orbit satellites?
- A lower orbit may be subject to orbital perturbations that can change the actual orbit from the calculated orbit by meters.
- The GNSS chip sets on the ground will need to constantly acquire satellites and drop satellites as come into and exit from view. That is going to be more processor (and battery) intensive. Plus no GNSS chip set maker will bother to add One Web.

Some commentators have suggested that OneWeb could be used as an integrity check on GPS/Galileo, to warn against spoofing. This is probably correct. However, there is a much cheaper and more robust technology that would serve this purpose: Loran C.

(Loran C was developed way back in the last Century and uses massive high powered (MW scale) long wave transmissions. It was almost scrapped due to poor accuracy, but after the terrorist attacks Governments felt they needed it as a backup. However, it has too few transmissions to be effected. A transmission tower would cost $10 million at least and maybe $1m per year to operate - small change compared to OneWeb. And of course, Loranc C is very unsexy 1960s technology - all be it with modern overlays).

[alexterrell]

My previous comment pointing out the political nature of this was deleted. But this is a political purchase (if it goes ahead) and these always work out badly.

And it is uncontroversial to note that the politicians pushing this decision do not have an understanding of the technology.

(In that respect, is the description of SLS as "Senate Launch System" allowed?)

The Daily Telegraph has also reported that a few Chinese companies, including auto maker Geely have submitted bids. That is going to make the whole thing a lot more political.

[Kaputnik]

So who wants to take a stab at what would need to be done to turn OneWeb into a positioning system?
As Robotbeat says, have the atomic clock external to the satellites, for starters. What could be achieved with the birds already on orbit?

[Welsh Dragon]

So who wants to take a stab at what would need to be done to turn OneWeb into a positioning system?
As Robotbeat says, have the atomic clock external to the satellites, for starters. What could be achieved with the birds already on orbit?

You may be able to do something, but I'm sure it would be a whole lot easier to just buy back into Galileo, which was definitely on the table until the UK decided it wasn't.

[niwax]

So who wants to take a stab at what would need to be done to turn OneWeb into a positioning system?
As Robotbeat says, have the atomic clock external to the satellites, for starters. What could be achieved with the birds already on orbit?

I have a hard time figuring out what parts they even have that could be used as a baseline to work from. OneWeb doesn't actually own the bus and manufacturing, all of that was part of a 50-50 joint venture with Airbus. Considering Airbus is also a creditor in the bankruptcy, so gets a part of OneWebs share in the joint venture, using the bus amounts to buying it off Airbus just like any other. The bus itself can't easily be reconfigured to do anything else because it doesn't actually contain a communication payload in the traditional sense, they are designed as dumb analog repeaters. You can't go and add your own messages because there is no communcations logic - just a pipe from input to output. As far as user terminals, the latest we heard was that they were outsourced to someone else. The topic of launches has also been discussed to death - any cheap market rate they could get, pretty much, but nothing amazing either.

And I don't see why we should expect anything else. The history of OneWeb shows that they had to take every inflexible compromise they could get to arrive at a fragile but potentially workable solution. If they had succeded it would have been because they had sacrificed every part of their system that didnt lead to the quickest functioning product for the sake of cost. But any way forward, even staying in the communication industry, would have been very hard work.

[Kaputnik]

Don't get me wrong, I think the idea of using OneWeb as a positioning system is ridiculous, and as a UK taxpayer it makes me furious.
But from a technical standpoint, I'm curious about what you could actually achieve if you 'work the problem'.

[ncb1397]

So who wants to take a stab at what would need to be done to turn OneWeb into a positioning system?
As Robotbeat says, have the atomic clock external to the satellites, for starters. What could be achieved with the birds already on orbit?

DSAC masses 17.5 kg and is way more accurate than anything on GPS. One Web Satellites being a U.S. entity, licensing the technology from NASA/JPL should be doable.

[jak Kennedy]

With all due respect to all the stories written so far, how do they know the UK bid is the favorite? Have we seen/heard about any other bids yet? If so, please share with us. This is the first inning of the speculation game, there will be so much more to come in the next several days. So just strap in and enjoy the commentary here on NSF. 

Backed by government money? They will be able to go back many times to milk that cow.

Edit: It would be interesting to know if having the atomic clocks on the ground is feasible. One disadvantage would be that system accuracy could be swiftly degraded by taking out a few ground stations. Then again if a situation has got that serious perhaps during an attack, I doubt many things will be operable for long.

[daedalus1]

So who wants to take a stab at what would need to be done to turn OneWeb into a positioning system?
As Robotbeat says, have the atomic clock external to the satellites, for starters. What could be achieved with the birds already on orbit?

You may be able to do something, but I'm sure it would be a whole lot easier to just buy back into Galileo, which was definitely on the table until the UK decided it wasn't.

I recall that we declined because they wouldn't allow acess to 100% of the system.

[Robotbeat]

...
- The GNSS chip sets on the ground will need to constantly acquire satellites and drop satellites as come into and exit from view. That is going to be more processor (and battery) intensive.

GPS, Galileo, Glonass, and BeiDou ALREADY REQUIRE THIS. GNSS satellites are not in GSO.

Plus no GNSS chip set maker will bother to add One Web.
...

This doesn't make any sense since there are already chipset makers supporting Galileo or Glonass or BeiDou, too.

[Kaputnik]

So who wants to take a stab at what would need to be done to turn OneWeb into a positioning system?
As Robotbeat says, have the atomic clock external to the satellites, for starters. What could be achieved with the birds already on orbit?

DSAC masses 17.5 kg and is way more accurate than anything on GPS. One Web Satellites being a U.S. entity, licensing the technology from NASA/JPL should be doable.

DSAC?

Also- I presume this requires new birds, not working with the ones that are already up there?

[ncb1397]

So who wants to take a stab at what would need to be done to turn OneWeb into a positioning system?
As Robotbeat says, have the atomic clock external to the satellites, for starters. What could be achieved with the birds already on orbit?

DSAC masses 17.5 kg and is way more accurate than anything on GPS. One Web Satellites being a U.S. entity, licensing the technology from NASA/JPL should be doable.

DSAC?

Also- I presume this requires new birds, not working with the ones that are already up there?

In less than a year of operations, the mission has passed its primary goal to become one of the most stable clocks to ever fly in space; it is now at least 10 times more stable than atomic clocks flown on GPS satellites. In order to keep testing the system, NASA has extended the mission through August 2021. The team will use the additional mission time to continue to improve the clock's stability, with a goal of becoming 50 times more stable than GPS atomic clocks.

Launched in June 2019 and managed by NASA's Jet Propulsion Laboratory in Southern California, the toaster-size Deep Space Atomic Clock is a payload on a commercial satellite. As a technology demonstration, its goal is to advance in-space capabilities by developing instruments, hardware, software or the like that doesn't currently exist. These demonstration missions must also show that new technologies can reliably operate in space. The goal is to eventually see such technologies incorporated into full-scale missions.

https://www.jpl.nasa.gov/news/news.php?feature=7687

[meekGee]

I don't get it...

The current satellites and the current satellite design doesn't support this functionality.

If you want to engineer a new satellite that does it - what's the value of calling it oneWeb?

You'll be making yet another navsat system, but one that also does comms in a oneWeb backward-compatible manner.  That doesn't sound like a winner to me.

[tonya]

I don't get it...

The current satellites and the current satellite design doesn't support this functionality.

If you want to engineer a new satellite that does it - what's the value of calling it oneWeb?

You'll be making yet another navsat system, but one that also does comms in a oneWeb backward-compatible manner.  That doesn't sound like a winner to me.

The value for the UK Government is the 80% cost contribution to the bid from the other private partners in the consortium, who presumably are interested in the communication platform first.