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

[Lars-J]

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).

But if the data that suggests that those 4 are not raising their orbits is correct, the failure could have something to do with propulsion. Either guidance or the thrusters themselves.

[Lars-J]

From the updates thread:

Nice close ups of the booster:

Wow, the black areas (interstage and around the base) look basically like new, despite three flights and a very thermally intense third flight. Looks like SpaceX really nailed that material for Block 5.

[DAZ]

In another thread, someone has provided a link that they are tracking the height of all the satellites.  This link shows 57 of them climbing in orbit, 2 of them not changing their orbit, and 2 of them descending in their orbit presumably to be decommissioned.

[wannamoonbase]

Wow, the black areas (interstage and around the base) look basically like new, despite three flights and a very thermally intense third flight. Looks like SpaceX really nailed that material for Block 5.

What would the core look like if it was fully covered in that material? 

It may not have any benefit but it looks like it could fly 100 times and look factory fresh.

[Vettedrmr]

Wow, the black areas (interstage and around the base) look basically like new, despite three flights and a very thermally intense third flight. Looks like SpaceX really nailed that material for Block 5.

I realize the reentry was at night, but were the gridfins actually radiating in the visible spectrum?  I don't ever remember seeing that before, and to see the fins almost looking unused in the video you referenced is amazing to me.

Does anyone know how much margin was left over for a F9 recoverable flight?

TIA, and have a good one,
Mike

[niwax]

...

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).

One interesting speculation I've read is that the four satellites that are slower in raising their orbit are the ones that rotated most on release and had to wait for the reaction wheels to desaturate. That would mean they might be otherwise fine but they'll need to adjust their deployment procedure or accept a few days delay before raising the orbit.

[Pete]

I realize the reentry was at night, but were the gridfins actually radiating in the visible spectrum?  I don't ever remember seeing that before,...

We have seen gridfins glow visibly. Not only glow, but leave a trail of 'flame', and once on the ground that gridfin had significant erosion of it lattice (aluminum gridfin era)..

Glowing in the visible spectrum? On this flight the video cut out at the critical point, so we definitely did not see glowing gridfin. We DID see lovely glowing hypersonic plasma passing *though* the gridfin.

We have seen some very glowy bits on the gridfins themselves (titanium era) on previous launches even in daylight, but whether this comes from glowing hot metal is debateable. The glow comes at least partially and very possibly totally from the abused air slamming into the gridfin.

[ArbitraryConstant]

grid fins during reentry are visible at about 21 minutes during the Starlink launch video

I don't know if that's glowing visibly though. I've noticed the on board cameras tend to pick up near infrared which appears white. The reason is CCDs pick up infrared unless filtered, which SpaceX's obviously aren't.

[Kansan52]

IR is very likely. Most digital cameras (including phone cameras) are unfiltered (as stated above). You can see the effect with your own phone camera with an IR remote. Turn on the camera, point the front of the remote at the camera, and press the buttons on the remote. Volume and Channel buttons are the best.

This will work with digital cameras that are not in a phone.

[Barley]

We have seen gridfins glow visibly. Not only glow, but leave a trail of 'flame', and once on the ground that gridfin had significant erosion of it lattice (aluminum gridfin era)..

What alloy of aluminum retains any structural strength while it's glowing?

I'd expect glowing aluminum to be so soft that it would not so much erode as simply disappear into the slipstream.

[cscott]

We have seen gridfins glow visibly. Not only glow, but leave a trail of 'flame', and once on the ground that gridfin had significant erosion of it lattice (aluminum gridfin era)..

What alloy of aluminum retains any structural strength while it's glowing?

I'd expect glowing aluminum to be so soft that it would not so much erode as simply disappear into the slipstream.

Heating from hypersonic shockwaves is quite localized, especially at sharp points. Hence erosion as the "hot spot" moves rearward from the leading edge.

Vaporization absorbs and carries away heat very effectively, which is why ablative heat shields work.

The non-leading edges of the Al grid fins were effectively protected by the "ablative heat shield" at the leading edge.

[ArbitraryConstant]

IR is very likely. Most digital cameras (including phone cameras) are unfiltered (as stated above). You can see the effect with your own phone camera with an IR remote. Turn on the camera, point the front of the remote at the camera, and press the buttons on the remote. Volume and Channel buttons are the best.

I've noticed some recent phone cameras seem to be filtered these days.

I think it's possible that to the eye the grid fins would appear to be a very dull dim red, and the reason the cameras aren't seeing that is because it's washed out by the much brighter near infrared. I tried this with my stove a few years ago before IR filters were as common and it looked white but with a mk1 eyeball it was a dull red.

It occurred to me that for SpaceX near infrared may actually be a feature because I've noticed it picks up things like the grid fins and rocket plume at high altitude that don't show up well visually, especially at night. They get near infrared by leaving out the filter.

[kessdawg]

SpaceX:

Update on Starlink Satellites

 

The following update about the Starlink satellites can be attributed to a SpaceX spokesperson:

 

“We continue to track the progress of the Starlink satellites during early orbit operations. At this point, all 60 satellites have deployed their solar arrays successfully, generated positive power and communicated with our ground stations.

Most are already using their onboard propulsion system to reach their operational altitude and have made initial contact using broadband phased array antennas.

SpaceX continues to monitor the constellation for any satellites that may need to be safely deorbited. All the satellites have maneuvering capability and are programmed to avoid each other and other objects in orbit by a wide margin.

...

Sounds like they aren't intentionally de-orbiting any of these initial batch of satellites?

[Danderman]

SpaceX:

Update on Starlink Satellites

 

The following update about the Starlink satellites can be attributed to a SpaceX spokesperson:

 

“We continue to track the progress of the Starlink satellites during early orbit operations. At this point, all 60 satellites have deployed their solar arrays successfully, generated positive power and communicated with our ground stations.

Most are already using their onboard propulsion system to reach their operational altitude and have made initial contact using broadband phased array antennas.

SpaceX continues to monitor the constellation for any satellites that may need to be safely deorbited. All the satellites have maneuvering capability and are programmed to avoid each other and other objects in orbit by a wide margin.

...

Sounds like they aren't intentionally de-orbiting any of these initial batch of satellites?

Sounds like the opposite: when a satellite is at end of life, it will be intentionally de-orbited.

[Barrie]

SpaceX:

Update on Starlink Satellites

 

The following update about the Starlink satellites can be attributed to a SpaceX spokesperson:

 

“We continue to track the progress of the Starlink satellites during early orbit operations. At this point, all 60 satellites have deployed their solar arrays successfully, generated positive power and communicated with our ground stations.

Most are already using their onboard propulsion system to reach their operational altitude and have made initial contact using broadband phased array antennas.

SpaceX continues to monitor the constellation for any satellites that may need to be safely deorbited. All the satellites have maneuvering capability and are programmed to avoid each other and other objects in orbit by a wide margin.

...

Sounds like they aren't intentionally de-orbiting any of these initial batch of satellites?

Sounds like the opposite: when a satellite is at end of life, it will be intentionally de-orbited.

In particular it sounds like they might de-orbit the 4 which are "misbehaving"

[spacenut]

The grid fins on the first stage are not made of aluminum anymore.  In Block 5 versions they are made of titanium so they can be reused. 

[Jcc]

SpaceX:

Update on Starlink Satellites

 

The following update about the Starlink satellites can be attributed to a SpaceX spokesperson:

 

“We continue to track the progress of the Starlink satellites during early orbit operations. At this point, all 60 satellites have deployed their solar arrays successfully, generated positive power and communicated with our ground stations.

Most are already using their onboard propulsion system to reach their operational altitude and have made initial contact using broadband phased array antennas.

SpaceX continues to monitor the constellation for any satellites that may need to be safely deorbited. All the satellites have maneuvering capability and are programmed to avoid each other and other objects in orbit by a wide margin.

...

Sounds like they aren't intentionally de-orbiting any of these initial batch of satellites?

Sounds like the opposite: when a satellite is at end of life, it will be intentionally de-orbited.

In particular it sounds like they might de-orbit the 4 which are "misbehaving"

Amazing how many different understandings can come from the same cryptic update. The important bits of information: all 60 satellites have deployed their arrays and have thrust and control. They are in the process of verifying full functionality, some sats have been cleared to proceed to operational orbit, other are still being validated, none have been determined to be faulty yet.

[Barrie]

Amazing how many different understandings can come from the same cryptic update. The important bits of information: all 60 satellites have deployed their arrays and have thrust and control. They are in the process of verifying full functionality, some sats have been cleared to proceed to operational orbit, other are still being validated, none have been determined to be faulty yet.

Yes, quite. They will work the issues as far as they can, and will only dispose of any satellite which can't provide service.

It might actually be quite a positive thing to be seen to be disposing of a dud.  Ill wind, silver lining, etc

[StuffOfInterest]

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).

But if the data that suggests that those 4 are not raising their orbits is correct, the failure could have something to do with propulsion. Either guidance or the thrusters themselves.

If the four have issues that will make them unusable for the test program, why raise their orbit only to have to bring it back down again for deorbiting?  Makes sense to keep them in the lower orbit until a determination is made.  Maybe that will be SOP in the future, perform all checkout in the lower orbit and then only raise when all issues are resolved.

[kessdawg]

SpaceX:

Update on Starlink Satellites

 

The following update about the Starlink satellites can be attributed to a SpaceX spokesperson:

 

“We continue to track the progress of the Starlink satellites during early orbit operations. At this point, all 60 satellites have deployed their solar arrays successfully, generated positive power and communicated with our ground stations.

Most are already using their onboard propulsion system to reach their operational altitude and have made initial contact using broadband phased array antennas.

SpaceX continues to monitor the constellation for any satellites that may need to be safely deorbited. All the satellites have maneuvering capability and are programmed to avoid each other and other objects in orbit by a wide margin.

...

Sounds like they aren't intentionally de-orbiting any of these initial batch of satellites?

Sounds like the opposite: when a satellite is at end of life, it will be intentionally de-orbited.

Sorry, let me rephrase.  Prior to launch it was speculated that some satellites would be intentionally de-orbited immediately to test that feature.  This statement seems to indicate that wasn't SpaceX's plan.