SpaceX F9 : Starlink v0.9 : May 23, 2019 - DISCUSSION

[Kabloona]

...
Elon had said he does not believe in asteroid mining
...

Do you recall when and where?

Here:

https://www.quora.com/Why-doesnt-Elon-Musk-mine-asteroids-for-profit

[Comga]

Well lets hope this is the moment Elon Musk gets into the astronomy business and do his usual disruption. Perhaps one could guilt-shame SpaceX into launching a couple of really cheap space based telescopes each year.

Edit:
Corrected for somewhat better spelling.

There is no money to be earned in Astronomy. From the government point of view, Astronomy is a jobs program to train and keep educated people. From the science point of view its an absolute necessity to learn more about the universe. The first can be attributed to money, the second cannot. Elons disruption of Astronomy would be enormous with SH and SS alone. (edit: Full disclosure: I work in astronomic instrumentation)

What about asteroid charting for planetary defense and commercial expolitation? Elon had said he does not believe in asteroid mining, but once a few StarScopes are up, it would take very little to start assembling a database, just in case. And in the unlikely case in which asteroid mining companies start to make money, this database would be very valuable.

There is no established commercial market in planetary defense or asteroid mining.
It is hard to imagine either in the foreseeable future.

[AUricle]

Interesting observation regarding the Starlink "train", from start to finish.

https://imgur.com/gallery/3T9LWXn

[spacenut]

All one has to do is take a drive out into the countryside where electric lighting is minimal.  Ask a farmer or rancher if you can set up a telescope on their property.  Most likely they will say it will be ok.  My stepson lives in the country 45 minutes away, and we can see far more stars than in the city. 

[Lars-J]

Interesting observation regarding the Starlink "train", from start to finish.

https://imgur.com/gallery/3T9LWXn

This is expected, and caused by our planet rotating under the 'fixed' plane of the Starlink satellites. As the satellites spread out more and more, it will look less like a they are on a line.

[Arb]

...
Elon had said he does not believe in asteroid mining
...

Do you recall when and where?

Here:

https://www.quora.com/Why-doesnt-Elon-Musk-mine-asteroids-for-profit

Thanks.

I was in the audience then...

The relevant bit from Quora:

Elon Musk at a conference at the Royal Aeronautical Society:

"I'm not convinced there's a case for taking something, say, platinum, that is found in an asteroid and bringing it back to Earth."

Emphasis mine. Says nothing about in-space use.

[Robotbeat]

...
Elon had said he does not believe in asteroid mining
...

Do you recall when and where?

Here:

https://www.quora.com/Why-doesnt-Elon-Musk-mine-asteroids-for-profit

Thanks.

I was in the audience then...

The relevant bit from Quora:

Elon Musk at a conference at the Royal Aeronautical Society:

"I'm not convinced there's a case for taking something, say, platinum, that is found in an asteroid and bringing it back to Earth."

Emphasis mine. Says nothing about in-space use.

That's a derivative market, not a fundamental one. Thus, it's smaller and not a source for intrinsic funding the way customers on Earth is.

...I'm sure Musk thinks we'll be using Martian materials for building Martian buildings. But that's not really a viable market you can get investment for. ~8 billion consumers is a heck of a lot bigger market.

[tyrred]

...
Elon had said he does not believe in asteroid mining
...

Do you recall when and where?

Here:

https://www.quora.com/Why-doesnt-Elon-Musk-mine-asteroids-for-profit

Thanks.

I was in the audience then...

The relevant bit from Quora:

Elon Musk at a conference at the Royal Aeronautical Society:

"I'm not convinced there's a case for taking something, say, platinum, that is found in an asteroid and bringing it back to Earth."

Emphasis mine. Says nothing about in-space use.

That's a derivative market, not a fundamental one. Thus, it's smaller and not a source for intrinsic funding the way customers on Earth is.

...I'm sure Musk thinks we'll be using Martian materials for building Martian buildings. But that's not really a viable market you can get investment for. ~8 billion consumers is a heck of a lot bigger market.

Yes. Martian markets will become a different thing entirely.

[intelati]

https://twitter.com/spacexfleet/status/1133786062772424704

SpaceX are not attempting to retract the landing legs on B1049.3.

Recovery technicians are currently removing them from the booster.

I'm wondering if SpaceX recently made a design change on the landing legs, and that's why the legs on B1056.1 (CRS-17) were retracted upon arrival at Port Canaveral, and the legs on B1049.3 are not retractable?

That is our belief. We don't (think....) have any confirmation of the change, but it is certainly suggestive.

Also, you posed in the updates thread.

[Pete]

One Starlink item from Gwynne's talk:  56 of the payloads are working well.  4 of them are misbehaving in some way but are nevertheless in communication.

Honest question:
What is the industry "normal" trouble rate for the first launch of minisatellites?

Is the above 6.7% "misbehaving" rate better, worse or similar to the norm?

And what are likely causes for problems? I understood (assumed) that the 60 Starlink satellites were identical clones of each other. Could this be a result of deployment damage? Possibly variant manufacturing techniques resulting from development during construction? Possibly actual different designs being field-tested?

[cscott]

And what are likely causes for problems? I understood (assumed) that the 60 Starlink satellites were identical clones of each other.

I don't think this is correct. If you look back through the NSF threads, folks identified a number of different mechanical variations among the stack of sixty in the pre-launch photos.  A more plausible assumption would be that the stack are *not* identical, and that in addition to the visible mechanical variants there are probably a number of less obvious electronic or procedural variants being tested as well.  This maximizes the amount of testing you can perform with a single launch.

[Robotbeat]

SpaceX is still iterating on this stuff. Elon warned before launch there was a particularly high chance of this launch having glitches since it was the first try.

Very little of this stuff has been in space before. A lot has changed since Tintin A and B, so this stuff has almost no space heritage. I'd actually say they're doing better than you might expect.

[smoliarm]

...

Honest question:
What is the industry "normal" trouble rate for the first launch of minisatellites?
...

- I'm afraid there is no comparable trouble rate here, just because nobody tried to mass-produce minisats so far.
NORMAL production approach in the satellite industry: each satellite is hand-made and hand-tested - in a very thorough way.
From what I heard, SpaceX uses quite different approach - much like automobile production or even home appliances. I.e., they try to automate production as much as possible, and they try to simplify testing as well.
Nobody tried to make satellites this way before, they are the first.

Is the above 6.7% "misbehaving" rate better, worse or similar to the norm?

For the reason above there is no *norm*.
So, I'd suggest to reformulate this way:
**Is 6.7% of "misbehaving" satellites - acceptable for the first mass-production run?**
- IMHO, yes.

[ArbitraryConstant]

So, I'd suggest to reformulate this way:
**Is 6.7% of "misbehaving" satellites - acceptable for the first mass-production run?**
- IMHO, yes.

Agreed. Not only that but the fact they're still in contact with the remainder very likely means they have a good idea of what's wrong with them and will be able to improve the success rate with subsequent launches.

[ArbitraryConstant]

Here's a question: https://twitter.com/elonmusk/status/1132078782217539584

Krypton thrusters operative, satellites initiating orbit raise every 90 mins

What does this mean? Are they operating the hall effect thrusters in some kind of pulsed mode? I was under the impression electric thrust would have to be more continuous. This sounds more like they're gradually raising apogee with a pulse every perigee.

If they're charging batteries and then doing a thruster pulse periodically, they wouldn't have to keep the thrusters pointed in the same direction all the time. They'd be able to point the spacecraft with reaction wheels in addition to the single axis tracking of the solar panel to do 2-axis tracking. The antennas are phased array so they can probably compensate for sun tracking when the network is active.

[matthewkantar]

The orbital period is around 90 minutes, each satellites is using thrusters at the sweet spot in the orbit to effect raising or plane changes.

[ArbitraryConstant]

The orbital period is around 90 minutes, each satellites is using thrusters at the sweet spot in the orbit to effect raising or plane changes.

That's the impression I get, I just didn't realize electric propulsion could be pulsed like that. I understood it to be more of a "leave it on for weeks or months" type situation.

Is the Starlink krypton thruster also best in class for thrust to weight just like Merlin? 

[niwax]

The orbital period is around 90 minutes, each satellites is using thrusters at the sweet spot in the orbit to effect raising or plane changes.

That's the impression I get, I just didn't realize electric propulsion could be pulsed like that. I understood it to be more of a "leave it on for weeks or months" type situation.

Is the Starlink krypton thruster also best in class for thrust to weight just like Merlin? 

It's also a question of battery capacity. If they can't cycle the batteries by 4-5 kWh every hour, they have to wait for the sun to come around again.

[Llian Rhydderch]

For the reason above there is no *norm*.
So, I'd suggest to reformulate this way:
**Is 6.7% of "misbehaving" satellites - acceptable for the first mass-production run?**
- IMHO, yes.

Agree that there "is no norm."

Moreover, the data we do have on potential sat misbehaving is sketchy, and preliminary.

Based on this post in the update thread with analysis posted just a few hours ago, it would appear that it is quite premature to say some sats are definitely and clearly "misbhaving"

None of the objects classified as payloads matched positions predicted by the CSpOC/@18SPCS orbital elements (then 1.4 days old), where as the four objects classified as debris did. This suggests that all 60 #Starlink satellites are operational and adjusting their orbits.

So, perhaps SpaceX has achieved 60/60 with some capability to adjust their orbits.

Time will tell.  But the signs from all sources are not all negative (that some ~7% are failed).  This data indicates the opposite.

[Slarty1080]

For the reason above there is no *norm*.
So, I'd suggest to reformulate this way:
**Is 6.7% of "misbehaving" satellites - acceptable for the first mass-production run?**
- IMHO, yes.

Agree that there "is no norm."

Moreover, the data we do have on potential sat misbehaving is sketchy, and preliminary.

Based on this post in the update thread with analysis posted just a few hours ago, it would appear that it is quite premature to say some sats are definitely and clearly "misbhaving"

None of the objects classified as payloads matched positions predicted by the CSpOC/@18SPCS orbital elements (then 1.4 days old), where as the four objects classified as debris did. This suggests that all 60 #Starlink satellites are operational and adjusting their orbits.

So, perhaps SpaceX has achieved 60/60 with some capability to adjust their orbits.

Time will tell.  But the signs from all sources are not all negative (that some ~7% are failed).  This data indicates the opposite.

It could be that any failures are nothing to do with the thrusters and positioning system but with communications or other aspects (the sats might succeed in getting to the right orbits but not be of any use when they get there).