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SpaceX General Section / Re: Starlink : General Discussion - Thread 3
« Last post by su27k on Today at 01:45 am »
So starlinks are getting brighter again. They will also start getting even brighter with the larger sized ones.

This "dimmer than original" covers up the elephant in the room that is always ignored. They are only at the smaller magnitude when they reach final orbit. However, there are always hundreds of satellites on their way up to orbit (which takes several months. Starship is gonna change this to possibly thousands). In a couple years, there will also start to be many hundreds (or thousands) constantly on their way DOWN from orbit to be removed as they hit their 5yr lifespan or whatever and are replaced. So while some starlink satellites are at their minimum magnitude, there will always be a large number of satellites that are much brighter. The constellation will never be finished, there will always be many hundreds on their way up or down.

No and No.

They won't get even brighter with the larger sized ones since the larger sized ones will use better mirror material, it's all laid out in their brightness mitigation document. I would also expect later builds of Gen1 to reduce brightness again due to the use of this new material.

And satellites in transit is not "elephant in the room", SpaceX talks about them in every brightness related documents, there's no effort to try to ignore them. Also their impact should be minimal, i.e. not an "elephant" since:
1. SpaceX expects to use Starship to inject Gen2 satellites directly to their plane, this avoids the drifting to nearby orbital plane and speed up orbital raising from a few months to a few weeks.
2. Since Gen2 is 30,000 satellites, this means replacing 6,000 satellites every years assuming 5 year life span. Assuming orbital raising/deorbit takes 4 weeks, this means at any time there're only 461 x 2 = 922 satellites in transit, a very small number comparing to the entire constellation and inconsequential to astronomy (multiple astronomers have said the initial constellation does not have big impact to astronomy, 900 satellites is much smaller the Gen1)
3. The satellites in transit would be grouped together in a few satellite trains (probably less than 10), this means they're easier to avoid for astronomers
4. When the satellites are in lower orbit, they appear more briefly during twilight, thus further reduce their impact
5. In addition, SpaceX is also refining the attitude control and solar array pointing during these two phases to reduce brightness, they can do this because when raising orbit or deborit, satellite doesn't need to provide service thus doesn't need to keep a fixed orientation wrt ground, and can live with less power.
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Zoom/crop from new RGV Aerial Photography post. Looks like San Martin is getting extended some.
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I suppose one point of comparison between Firefly/Northrop Grumman and Blue Origin/ULA is whether the latter deal was a factor in Blue Origin transitioning into an Old Space company (or just "behaving exactly like an Old Space company," if you subscribe to the belief that any space company founded in the 21st century is by definition a New Space company and always retains that label). Because if Firefly does work more closely with Northrop Grumman (up to and including acquisition), will they retain their nimbleness?

Perhaps a bit off-topic for this thread, but I'm sure Northrop Grumman has looked closely at the ULA deal and how to not recapitulate it, if they want to get Antares 330 (and subsequently MLV) launching on time.

I do not wish to argue whether or not Blue Origin is "acting like an old space company", that is for another thread, but they certainly wound up with a lot on their plate with undertaking the BE-4 contract with ULA. BE-4 was clearly to be a somewhat less ambitious engine which would have been far easier and likely quicker to do. The downstream impact for this on New Glenn, was huge. It transformed that rocket into something clearly far larger than it was intended to be, and it already was an ambitious project to begin with.

Northrup Grumman and Firefly Aerospace's deal may or may not be structured the way that it is because both companies looked at the problems that Blue Origin and ULA had, but they really did not need to since Antares in any form has not been offered for military or NRO launches, thus both companies are freed from those restrictions, unless Northrup Grumman sees an opportunity and they decided to completely alter the second stage so that it can meet NSSL requirements. Nor have I seen any indication that, other than what the stage will need to operate using the existing LP-0A infrastructure at Wallops.

Theoretically, Firefly could get around some of these changes by simply changing their Beta rocket first stage ground support infrastructure to be more like that at LP-0A, it's certainly early enough for them to do so. They do have the problem that they will likely need to separate production lines since the interstages will not be the same by any stretch.
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Updated the Starlink stats page. Now 3451 Starlinks launched; 3179 in orbit..  10/5/2022

https://twitter.com/planet4589/status/1577829316246884352
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If you love the rocket rumble play it all the way through! Car alarms going off at the end.  Crew-5 today..

https://twitter.com/GregDieselPhoto/status/1577800953889177604

Weirdly this tweet was flagged as having potentially sensitive content...
Some auto-moderation bot has probably been trained to associate multiple car alarms with some kind of traumatic event or possible catastrophe.
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https://twitter.com/thejackbeyer/status/1577807251942780928

Quote
STARlink. A SpaceX Falcon 9 transits our star while lofting the Starlink 4-29 group into orbit from Vandenberg Space Force Base this afternoon. @NASASpaceflight

This, but as a Metal Print in the Shop? :D
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Other US Launchers / Re: US Launch Schedule
« Last post by Salo on Today at 12:58 am »
https://twitter.com/cbs_spacenews/status/1577798475076583424
Quote
William Harwood @cbs_spacenews
F9/Starlink 4-29: LIFTOFF! At 7:10:30pm EDT (2310 UTC)
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A quick visual aid for the scale of the sat variants.

Interesting that the brightness mitigation document they posted at the end of July kind of suggests that gen2 satellites will have L shape similar to gen1 satellites. I can imagine how two solar arrays you pictured might work but I would expect the description of "terminator tracking" and the illustration to be more specific about how each array rotates.

Quote

To scatter sunlight hitting the front side of the solar arrays, the second-generation satellites will
point the solar arrays away from the Sun when crossing the terminator (the line on Earth's
surface separating night and day) in a maneuver called "terminator tracking." This maneuver
will point the knife edge of the solar array at the earth limb, which minimizes brightness when
viewed from the ground, as shown in the image below.
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Phew, Space Coast Live is gonna give me a lot of work spotting boosters if they keep launching like this. Just a few minutes ago another Falcon 9 booster passed by the VAB at KSC, likely to be B1069-3 for Hotbird 13F launch next week from SLC-40.

B1073 - Lower right picture..

https://twitter.com/Alexphysics13/status/1577810330662707200
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