SpaceX Starship : First Flight : Starbase, TX : 20 April 2023 - DISCUSSION

[Joffan]

It is worth noting that to place the horizon at 20 nautical miles offshore you need an altitude of ~110 m. So if it is clear enough the returning booster should disappear beneath the horizon for ground level observers (although they might just be able to see splashes/fireballs) but good optics placed on top of say an at least partially stacked launch integration tower or a 400 ft condominium should be able to track it all the way down...

Normal building rules for Kauai are essentially "no taller than a palm tree" (taken as 50ft). No doubt with some (e.g. military) exemptions, but it ain't Maui.

[eriblo]

It is worth noting that to place the horizon at 20 nautical miles offshore you need an altitude of ~110 m. So if it is clear enough the returning booster should disappear beneath the horizon for ground level observers (although they might just be able to see splashes/fireballs) but good optics placed on top of say an at least partially stacked launch integration tower or a 400 ft condominium should be able to track it all the way down...

Normal building rules for Kauai are essentially "no taller than a palm tree" (taken as 50ft). No doubt with some (e.g. military) exemptions, but it ain't Maui.

I was talking about the SH booster which will be hard to see from Kauai no matter how high you are 

With regard to Starship splashdown: Ground level has a different meaning in Kauai compared to South Padre Island - From a quick look at the map it looks like Kalalau Lookout should provide excellent views to the north and at ~4000 ft be plenty high enough. Actually seeing something through 100 km of dense atmosphere is a different matter...

[tater]

It is worth noting that to place the horizon at 20 nautical miles offshore you need an altitude of ~110 m. So if it is clear enough the returning booster should disappear beneath the horizon for ground level observers (although they might just be able to see splashes/fireballs) but good optics placed on top of say an at least partially stacked launch integration tower or a 400 ft condominium should be able to track it all the way down...

Normal building rules for Kauai are essentially "no taller than a palm tree" (taken as 50ft). No doubt with some (e.g. military) exemptions, but it ain't Maui.

I was talking about the SH booster which will be hard to see from Kauai no matter how high you are 

With regard to Starship splashdown: Ground level has a different meaning in Kauai compared to South Padre Island - From a quick look at the map it looks like Kalalau Lookout should provide excellent views to the north and at ~4000 ft be plenty high enough. Actually seeing something through 100 km of dense atmosphere is a different matter...

Waialeale is also about the wettest place on Earth. Being there without clouds would be amazing luck. We drove up, and for maybe 15 seconds we could see down a canyon to the surf before it closed up again in thick clouds.

[cuddihy]

Should only be ~ 260 km from the NASA /USSF Maui optical sites on top of Haleakala. Well within range for the parts of the entry & descent where it will be in ionization signal cutout. (60-20 km altitude)

[oldAtlas_Eguy]

Should only be ~ 260 km from the NASA /USSF Maui optical sites on top of Haleakala. Well within range for the parts of the entry & descent where it will be in ionization signal cutout. (60-20 km altitude)

Ionization signal cutout occurs for communicating to transceivers on the ground to the sides or below the entering vehicle. A Starlink terminal can still link to a near overhead Starlink sat during this period. NASA actual linked to TDRSS during some reentry testing they did to gather data while in the ionization blackout period which was also in the Kauai area on the inflatable heat shield experiments.

The use of a Starlink terminal would be a seperate FCC application for this flight than the normal FCC application for TLM and CC comms during a launch attempt.

[JAFO]

Ok, dumb question: what's wrong with putting a WB-57 up near the impact/landing zone to record the reentry/landing? Would the problem be getting it out of the way if it frags on reentry and is in the debris footprint?
TIA
 

[su27k]

With regard to tracking Starship reentry over the Pacific, don't forget this unfunded Space Act Agreement with NASA announced last year:

Space Exploration Technologies Corp. (SpaceX) of Hawthorne, California

SpaceX will partner with Langley to capture imagery and thermal measurements of its Starship vehicle during orbital re-entry over the Pacific Ocean. With the data, the company plans to advance a reusable thermal protection system, which protects the vehicle from aerodynamic heating, for missions returning from low-Earth orbit, the Moon, and Mars.

[M.E.T.]

Is the Pacific splashdown spot in US territorial waters? Thinking this might be a consideration in preventing covert Raptor recovery attempts by “interested parties”.

[Vanspace]

Is the Pacific splashdown spot in US territorial waters? Thinking this might be a consideration in preventing covert Raptor recovery attempts by “interested parties”.

Pacific Missile Range

This is where the US tests all its most advanced weapons. While details are obviously not available,it is presumably wired with every tracking, imaging and monitoring system that unlimited top secret funds can dream up. I suspect that if a seal farts in the area they will know.

[philw1776]

I was in the camp that SH would hop and then quickly try for orbit.
Instead, SpaceX went all Saturn V on us and is going for an all up full stack orbital attempt, albeit with likely fewer SH raptors, maybe ~16 or so.

I guess I fail to see the difference. Or were you one of the "Starship can do SSTO" crowd? They pretty much need a full(ish) stack to get it to orbit with margin to spare.

I have no idea what you're talking about. Said nothing about SS SSTO.
The SH can orbit a SS with far fewer than 28 engines. I've run the #s and so have many others here.

It was not an accusation. But there is a whole thread of people who think that Starship can do SSTO if you add enough engines to it. My confusion comes from reading your original message (see bolded)... It seems like there is only two ways for Starship to get to orbit. SSTO or full stack. So if you are not in the SSTO camp, why is a full stack surprising?

(And I know a full 28 engines is not needed, hence the "full(ish) stack")

Expected SH hop first.
Instead surprised that SpaceX going directly to full stack Saturn V style with possibly just over half the engines (speculation)

[kevinof]

Is the Pacific splashdown spot in US territorial waters? Thinking this might be a consideration in preventing covert Raptor recovery attempts by “interested parties”.

Not unless it’s within 12 miles of U.S. landmass, which it won’t. Assuming it sinks, it will be in very deep water.  My chart says 4km deep around there.

[envy887]

Admittedly, I only have a KSP-level knowledge of orbital mechanics, so please gently educate me if I'm wrong here.

Can this actually complete a full orbit? Looking at the times (SECO @ 521, Ship Splashdown @ 5420) I'm having a hard time seeing how they launch from Boca Chica, orbit all the way around past Boca Chica, and then make it another 300 degrees around to Kauai.

Assuming the answer is "No, it doesn't go all the way around"... Will this achieve orbital velocity and then do a de-orbit burn? Or will it just be a very long ballistic trajectory? (The lack of a second burn of the second stage would suggest it's the later.)

So , since it's getting real , What could be the final orbit of Starship after insertion. Will they keep it low to minimise TPS heating for the time being , also since the landing (or splashdown) is 90 minutes after liftoff , from Boca TX to Hawaii in eastward direction could mean the it will complete a single orbit before re-entering.

Also will they be testing the R-Vacs for the first time in Orbit?

I think the flight will be suborbital, but only just, like a shuttle eternal tank. Then you can target the landing zone even if the raptors fail to complete the deorbit burn.

Edit: Also starship landing occurs at T+90 minuets, so exactly like an ET

OK Orbit but one that is just barely such that it will rapidly decay to the point it will reenter around Kauji. If on the way up it is off target (this is just a few 10s of m/s) then it will either splash before or after Kuaji into the Pacific somewhere.

I can't reconcile "achieve orbit" with rapidly decaying around T+90mins.  That just doesn't compute for me.  Achieving Orbit necessarily means a full once-around.

"until performing a powered, targeted landing" suggests to me that they would achieve a meaningful orbit insertion and then perform a deorbit burn, or perhaps even a deorbit-acceleration burn to test EDL at a higher than orbital velocity.

Once you go beyond 180° around you're essentially orbital: In the sense that your semi-major axis is longer than the planet radius. This also means you have orbital velocity.

Ballistic trajectories end at 180° of the way around.

For example for such a flight an orbit like 270x30km would work well (with perigee around West coast of Mexico). But note that such an orbit has the same energy as 150x150km (I'm assuming spherical Earth for simplicity, real orbit would be a bit different).

And of course they can chose higher orbit and active deorbit.

The Verge is reporting that the maximum altitude will be 72 miles, or 120 km. I don't know if that's enough to get 20,000 miles downrange before reentering.

[OneSpeed]

The Verge is reporting that the maximum altitude will be 72 miles, or 120 km. I don't know if that's enough to get 20,000 miles downrange before reentering.

My sims so far suggest that 120km could be the apogee for the Super Heavy booster. Orbital insertion usually happens around 167km or higher. I agree with sebk, 273 x 55 is my current estimate for Starship's (single) orbit.

[envy887]

The Verge is reporting that the maximum altitude will be 72 miles, or 120 km. I don't know if that's enough to get 20,000 miles downrange before reentering.

My sims so far suggest that 120km could be the apogee for the Super Heavy booster. Orbital insertion usually happens around 167km or higher. I agree with sebk, 273 x 55 is my current estimate for Starship's (single) orbit.

That would make more sense. I don't think 3/4 of an orbit would even be possible below 120 km, since drag is still quite significant at that altitude.

[Gridfire]

I have come late to this thread but would like to pitch a few ideas for consideration.

Firstly landing / touchdown observation. For SS and BN if entering the water, SX could simply obtain 3 floating objects. Scrap pleasure craft hulls, foam filled water tanks etc. Fit each with 3 mooring winches for anchors (3 for position keeping), tow them out and and anchor them in a triangular array for coverage lets say 500m from the anticipated touch down location then load each with gyro stabilised camera mounts. Gyro selfie sticks are dirt cheap now then hope they don't get splattered or burnt up. Video transmitters on each could help.

Secondly if they are intact, they may not sink. I would expect the last command on touchdown would be to shut all valves. You then have a couple of large almost empty tanks full of gas. Great buoyancy. Then they only need safeing and towing to an appropriate location for lifting out of the water.

If they do sink, before flight you fit a buoyancy block to the outside with a lifting line attached long enough for the water depth and with a hydrostatic release. The item sinks, the buoyancy floats up both marking the location and allowing easier retrieval. I can see a problem with the strength of the line required and proofing for re-entry but this could be worked around.

Finally I have many years of experience on oil rigs. Most semi-submersible rigs like Phobos and Deimos can moor and use Dynamic positioning in fact DP mooring only is relatively new -the older generation are only moored using 8-12 winches shared around the corners. I have been on a DP rig that was moored and using DP. Perhaps the power generation and mooring winches have been left intact. All that is needed is a flat deck (not easy in the time but who knows). They are then towed to the landing location and moored on anchors using widely available vessels and techniques used in the oil industry for many years. Both these rigs had 4 powerful mooring winches. In a previous life they may have been moored with this on the drilling location and used their DP for fine positioning. Finally it may be necessary to have GPS telemetry from the rig for last second landing point correction but only within a few meters.
 

[DistantTemple]

I have come late to this thread but would like to pitch a few ideas for consideration.

Firstly landing / touchdown observation. For SS and BN if entering the water, SX could simply obtain 3 floating objects. Scrap pleasure craft hulls, foam filled water tanks etc. Fit each with 3 mooring winches for anchors (3 for position keeping), tow them out and and anchor them in a triangular array for coverage lets say 500m from the anticipated touch down location then load each with gyro stabilised camera mounts. Gyro selfie sticks are dirt cheap now then hope they don't get splattered or burnt up. Video transmitters on each could help.

Secondly if they are intact, they may not sink. I would expect the last command on touchdown would be to shut all valves. You then have a couple of large almost empty tanks full of gas. Great buoyancy. Then they only need safeing and towing to an appropriate location for lifting out of the water.

If they do sink, before flight you fit a buoyancy block to the outside with a lifting line attached long enough for the water depth and with a hydrostatic release. The item sinks, the buoyancy floats up both marking the location and allowing easier retrieval. I can see a problem with the strength of the line required and proofing for re-entry but this could be worked around.

Finally I have many years of experience on oil rigs. Most semi-submersible rigs like Phobos and Deimos can moor and use Dynamic positioning in fact DP mooring only is relatively new -the older generation are only moored using 8-12 winches shared around the corners. I have been on a DP rig that was moored and using DP. Perhaps the power generation and mooring winches have been left intact. All that is needed is a flat deck (not easy in the time but who knows). They are then towed to the landing location and moored on anchors using widely available vessels and techniques used in the oil industry for many years. Both these rigs had 4 powerful mooring winches. In a previous life they may have been moored with this on the drilling location and used their DP for fine positioning. Finally it may be necessary to have GPS telemetry from the rig for last second landing point correction but only within a few meters.

Where the SS is planned to land is too deep for anchoring, so your cheap hulls need to be autonomous... or maybe a sea anchor if some drift can just be factored in (my bold):

Is the Pacific splashdown spot in US territorial waters? Thinking this might be a consideration in preventing covert Raptor recovery attempts by “interested parties”.

Not unless it’s within 12 miles of U.S. landmass, which it won’t. Assuming it sinks, it will be in very deep water.  My chart says 4km deep around there.

Some hints the SH will land on something and not splash.

[Gridfire]

Where the SS is planned to land is too deep for anchoring, so your cheap hulls need to be autonomous... or maybe a sea anchor if some drift can just be factored in (my bold):



Following this comment I see this is correct. Rigs can only be moored to roughly 5000ft depth which is way less than the landing location so yes, full DP would be required. This may be hard on the rigs they are converting with the bridge removed. My experience is mainly North Sea where its shallow enough to only moor with some deeper work in the GoM.

[VaBlue]

Is the Pacific splashdown spot in US territorial waters? Thinking this might be a consideration in preventing covert Raptor recovery attempts by “interested parties”.

Pacific Missile Range

This is where the US tests all its most advanced weapons. While details are obviously not available,it is presumably wired with every tracking, imaging and monitoring system that unlimited top secret funds can dream up. I suspect that if a seal farts in the area they will know.

A nice thought, but it doesn't really work that way.  I'm sure there are some additional sensors dropped down on the bottom, but that's ~20,000' deep - so it's nice if you're sniffing submarines.  Being a missile range, it'll be saturated with missile sensors (radar, telemetry, IR), but no cameras.  It's in the middle of the Pacific Ocean - there's no place to mount a camera!  Satellite?  Nope...  Not good for open ocean or missiles (unless its IR, but that's a special case). 

But it is protected ocean - meaning that its a safe place to land, free of shipping and fishing lanes.  There can be ships in the area, but they're operating in a restricted zone so they are liable for any damage - not SpaceX (or whoever is using the range).  Water depth, should SS sink (probably), will preclude any recovery attempts because the mothership would have to loiter in one sot for too long.  Long enough for someone to intervene...

[Robotbeat]

Is the Pacific splashdown spot in US territorial waters? Thinking this might be a consideration in preventing covert Raptor recovery attempts by “interested parties”.

Pacific Missile Range

This is where the US tests all its most advanced weapons. While details are obviously not available,it is presumably wired with every tracking, imaging and monitoring system that unlimited top secret funds can dream up. I suspect that if a seal farts in the area they will know.

A nice thought, but it doesn't really work that way.  I'm sure there are some additional sensors dropped down on the bottom, but that's ~20,000' deep - so it's nice if you're sniffing submarines.  Being a missile range, it'll be saturated with missile sensors (radar, telemetry, IR), but no cameras.  It's in the middle of the Pacific Ocean - there's no place to mount a camera!  Satellite?  Nope...  Not good for open ocean or missiles (unless its IR, but that's a special case). 

But it is protected ocean - meaning that its a safe place to land, free of shipping and fishing lanes.  There can be ships in the area, but they're operating in a restricted zone so they are liable for any damage - not SpaceX (or whoever is using the range).  Water depth, should SS sink (probably), will preclude any recovery attempts because the mothership would have to loiter in one sot for too long.  Long enough for someone to intervene...

Territorial waters only extend 12 nautical miles. But the Exclusive Economic Zone (EEZ) extends 200 nautical miles, so Starship's 100km-off-the-coast-of-Kauai flight is within the EEZ of the US. So that's additional protection.

[Tomness]

SpaceX has asked Airforce to use a gun ship on a F9 that landed in the water and floated. So if it survives, Free target practice or have interceptor practice on it. Fun opportunities for DOD coming up since SpaceX hired a private company for GovSat-1/SES-16 soft landing in the Ocean after intially talking to the Airforce.

SpaceX Hired Company to Destroy Floating GovSat Booster, Not USAF
http://www.americaspace.com/2018/02/09/spacex-hired-company-to-destroy-floating-govsat-booster-not-usaf/

AmericaSpace has since learned that the Air Force was, instead, initially considered to take care of the job, but a commercial company of demolition specialists was eventually hired to safely destroy the hazardous booster.

Again, not the USAF; no strike by the U.S. military was carried out on the Falcon 9.