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

[Cabbage123]

Seems like a controlled ocean landing for B7, but a terminal velocity impact for S24. Is that right?

Has that always been the plan, or was there previously speculation of a controlled landing for S24 too?

Why no soft landing for S24? Would it have sufficient propellant left?

[tenkendojo]

Am I the only one who's most excited to see how would those heat tiles hold up upon reentry?

[joek]

Seems like a controlled ocean landing for B7, but a terminal velocity impact for S24. Is that right?

Has that always been the plan, or was there previously speculation of a controlled landing for S24 too?

Why no soft landing for S24? Would it have sufficient propellant left?

Yes to B7 controlled landing. As to the S24, quite a bit of discussion upthread starting around post #734.

[TomH]

Do we have any information on drone boats or airborne small drones near the two landing zones to take photos/video or record any other data?

[Zed_Noir]

Do we have any information on drone boats or airborne small drones near the two landing zones to take photos/video or record any other data?

The Starship splashdown zone is in the Pacific Missile Range Facility (aka Barking Sands) that have the most extensive optical tracking and imaging capabilities that the DoD can get theirs hands on. Also the venerable nuke sniffer aircraft (aka WB-57 Canberra) will get tracking footage of the reenty from high altitude. Of course we might never get to see all the images acquire by the DoD.

[PM3]

Is the plan still to stay slightly below orbital velocity for safety reasons? To avoid the necessity of a deorbiting burn?

Technically it's not going to be below orbital velocity,  it's just that the low point of the orbit is within the upper atmosphere .

So what does the "30 meters per second difference" refer to, that Tim Dodd mentioned in the video "Elon Musk explains updates to Starship and Starbase" (at 23:10)? Not 30 m/s below orbital velocity? Or is that information outdated?

[Edit: corrected typos in video title]

Confirmation that this will be a suborbital flight:

"The Starship upper stage will fire its engines until 9 minutes and 20 seconds after liftoff. That will place the vehicle on a “nearly orbital” trajectory, an FAA official said on background, reaching a peak altitude of about 235 kilometers before reentering."

https://spacenews.com/faa-issues-license-for-first-starship-integrated-test-flight/

[tyrred]

Is the plan still to stay slightly below orbital velocity for safety reasons? To avoid the necessity of a deorbiting burn?

Technically it's not going to be below orbital velocity,  it's just that the low point of the orbit is within the upper atmosphere .

So what does the "30 meters per second difference" refer to, that Tim Dodd mentioned in the video "Elon Musk explains updates to Starship and Starbase" (at 23:10)? Not 30 m/s below orbital velocity? Or is that information outdated?

[Edit: corrected typos in video title]

Confirmation that this will be a suborbital flight:

"The Starship upper stage will fire its engines until 9 minutes and 20 seconds after liftoff. That will place the vehicle on a “nearly orbital” trajectory, an FAA official said on background, reaching a peak altitude of about 235 kilometers before reentering."

https://spacenews.com/faa-issues-license-for-first-starship-integrated-test-flight/

What a scoop - confirmation that the Orbital Test Flight isn't actually going to orbit?

Why ever would they call it test flight, then?

We need confirmation its not actually even a test, pronto!

 

[daedalus1]

Is the plan still to stay slightly below orbital velocity for safety reasons? To avoid the necessity of a deorbiting burn?

Technically it's not going to be below orbital velocity,  it's just that the low point of the orbit is within the upper atmosphere .

So what does the "30 meters per second difference" refer to, that Tim Dodd mentioned in the video "Elon Musk explains updates to Starship and Starbase" (at 23:10)? Not 30 m/s below orbital velocity? Or is that information outdated?

[Edit: corrected typos in video title]

Confirmation that this will be a suborbital flight:

"The Starship upper stage will fire its engines until 9 minutes and 20 seconds after liftoff. That will place the vehicle on a “nearly orbital” trajectory, an FAA official said on background, reaching a peak altitude of about 235 kilometers before reentering."

https://spacenews.com/faa-issues-license-for-first-starship-integrated-test-flight/

What a scoop - confirmation that the Orbital Test Flight isn't actually going to orbit?

Why ever would they call it test flight, then?

We need confirmation its not actually even a test, pronto!

 

That's just confusion over whether th 'trajectory' skims the top of the atmosphere or not. It is orbital velocity but the low point is in the atmosphere  - as explained multiple times here and elsewhere.

[PM3]

That's just confusion over whether th 'trajectory' skims the top of the atmosphere or not. It is orbital velocity but the low point is in the atmosphere  - as explained multiple times here and elsewhere.

Nope. The perigee of a "nearly orbital trajectory" is not in the atmosphere but below sea level.

The confusion was caused by SpaceX calling it an "Orbital Flight Test". But they have stopped doing so - it now is just the "Starship Flight Test" on the SpaceX website and on the mission patch.

[FutureSpaceTourist]

[steveleach]

That's just confusion over whether th 'trajectory' skims the top of the atmosphere or not. It is orbital velocity but the low point is in the atmosphere  - as explained multiple times here and elsewhere.

Nope. The perigee of a "nearly orbital trajectory" is not in the atmosphere but below sea level.

The confusion was caused by SpaceX calling it an "Orbital Flight Test". But they have stopped doing so - it now is just the "Starship Flight Test" on the SpaceX website and on the mission patch.

Sorry, are you saying that the documents show that S24 will have a perigee below sea level, or that the definition of a "nearly orbital trajectory" is that the perigee is below sea level?

[FutureSpaceTourist]

Doesn’t sound or look great:

[envy887]

That's just confusion over whether th 'trajectory' skims the top of the atmosphere or not. It is orbital velocity but the low point is in the atmosphere  - as explained multiple times here and elsewhere.

Nope. The perigee of a "nearly orbital trajectory" is not in the atmosphere but below sea level.

The confusion was caused by SpaceX calling it an "Orbital Flight Test". But they have stopped doing so - it now is just the "Starship Flight Test" on the SpaceX website and on the mission patch.

The confusion is because we don't have a good word to describe trajectories that have orbital speed and energy but also have a velocity vector direction that will result in entering the atmosphere before a complete revolution.

Such trajectories are much better described as "orbital" than "suborbital", but neither is completely accurate.

You're not helping resolve the confusion by using the less accurate term.

[meekGee]

That's just confusion over whether th 'trajectory' skims the top of the atmosphere or not. It is orbital velocity but the low point is in the atmosphere  - as explained multiple times here and elsewhere.

Nope. The perigee of a "nearly orbital trajectory" is not in the atmosphere but below sea level.

The confusion was caused by SpaceX calling it an "Orbital Flight Test". But they have stopped doing so - it now is just the "Starship Flight Test" on the SpaceX website and on the mission patch.

The confusion is because we don't have a good word to describe trajectories that have orbital speed and energy but also have a velocity vector direction that will result in entering the atmosphere before a complete revolution.

Such trajectories are much better described as "orbital" than "suborbital", but neither is completely accurate.

Only because they're near circular.  If you fly straight up half way towards the moon, with almost escape speed...  Still suborbital?

The "sub" denotes that orbital velocity was not achieved, like an intercontinental trajectory.

[Legios]

Is the plan still to stay slightly below orbital velocity for safety reasons? To avoid the necessity of a deorbiting burn?

Technically it's not going to be below orbital velocity,  it's just that the low point of the orbit is within the upper atmosphere .

So what does the "30 meters per second difference" refer to, that Tim Dodd mentioned in the video "Elon Musk explains updates to Starship and Starbase" (at 23:10)? Not 30 m/s below orbital velocity? Or is that information outdated?

[Edit: corrected typos in video title]

Confirmation that this will be a suborbital flight:

"The Starship upper stage will fire its engines until 9 minutes and 20 seconds after liftoff. That will place the vehicle on a “nearly orbital” trajectory, an FAA official said on background, reaching a peak altitude of about 235 kilometers before reentering."

https://spacenews.com/faa-issues-license-for-first-starship-integrated-test-flight/

What a scoop - confirmation that the Orbital Test Flight isn't actually going to orbit?

Why ever would they call it test flight, then?

We need confirmation its not actually even a test, pronto!

 

That's just confusion over whether th 'trajectory' skims the top of the atmosphere or not. It is orbital velocity but the low point is in the atmosphere  - as explained multiple times here and elsewhere.

Wouldn't that just be a ballistic trajectory ala an ICBM.

SpaceX is just not performing a circularization burn.  But just because it has the energy for orbit, if it doesn't circularize, it's not orbital

[sebk]

Is the plan still to stay slightly below orbital velocity for safety reasons? To avoid the necessity of a deorbiting burn?

Technically it's not going to be below orbital velocity,  it's just that the low point of the orbit is within the upper atmosphere .

So what does the "30 meters per second difference" refer to, that Tim Dodd mentioned in the video "Elon Musk explains updates to Starship and Starbase" (at 23:10)? Not 30 m/s below orbital velocity? Or is that information outdated?

[Edit: corrected typos in video title]

Confirmation that this will be a suborbital flight:

"The Starship upper stage will fire its engines until 9 minutes and 20 seconds after liftoff. That will place the vehicle on a “nearly orbital” trajectory, an FAA official said on background, reaching a peak altitude of about 235 kilometers before reentering."

https://spacenews.com/faa-issues-license-for-first-starship-integrated-test-flight/

What a scoop - confirmation that the Orbital Test Flight isn't actually going to orbit?

Why ever would they call it test flight, then?

We need confirmation its not actually even a test, pronto!

 

That's just confusion over whether th 'trajectory' skims the top of the atmosphere or not. It is orbital velocity but the low point is in the atmosphere  - as explained multiple times here and elsewhere.

Wouldn't that just be a ballistic trajectory ala an ICBM.

SpaceX is just not performing a circularization burn.  But just because it has the energy for orbit, if it doesn't circularize, it's not orbital

Nope, it's not an ICBM like trajectory at all. ICBMs dont fly more than half around the globe.

The orbit here is about 50x235km it's perigee is above surface level, but within the atmosphere. And energetically it's equivalent to 142x142km circular orbit which for a vehicle the size and mass of Starship would decay in significantly more than once around (less streamlined and with lower ballistic coefficient SkyLab started it's last full circle at ~135km)

[sebk]

That's just confusion over whether th 'trajectory' skims the top of the atmosphere or not. It is orbital velocity but the low point is in the atmosphere  - as explained multiple times here and elsewhere.

Nope. The perigee of a "nearly orbital trajectory" is not in the atmosphere but below sea level.

The confusion was caused by SpaceX calling it an "Orbital Flight Test". But they have stopped doing so - it now is just the "Starship Flight Test" on the SpaceX website and on the mission patch.

You're contradicting oneself.

The problem is Starship Integrated Test Flight will have its perigee significantly above the sea level.

There's simply no way to have single burn launch to 235km apogee and do 3/4 of the whole circle with perigee below the sea level. Perigee must be around 50km up.

So this is a murky territory with perigee in the atmosphere and the actual energy high enough for a full circle: it's 142x142km circular orbit equivalent which would take noticeably more than a full circle to decay.

[PM3]

The orbit here is about 50x235km it's perigee is above surface level, but within the atmosphere. And energetically it's equivalent to 142x142km circular orbit which for a vehicle the size and mass of Starship would decay in significantly more than once around (less streamlined and with lower ballistic coefficient SkyLab started it's last full circle at ~135km)

The whole flight is within the atmosphere, which reaches much higher than 235 km. Therefore the notion of Starship "entering atmosphere" at some  point on this flight does not make sense.

And orbital velocity is only horizontal velocity. A hyperbolic suborbital flight that has the same kinetic energy like some circular orbital flight is still a suborbital flight.

Can you please quote the source for the 50 km perigee?

There's simply no way to have single burn launch to 235km apogee and do 3/4 of the whole circle with perigee below the sea level. Perigee must be around 50km up.

This is totally wrong.

[Orbiter]

There's simply no way to have single burn launch to 235km apogee and do 3/4 of the whole circle with perigee below the sea level. Perigee must be around 50km up.

Not true. You can have perigee points below sea level and achieve a very high apogee.

[Herb Schaltegger]

The orbit here is about 50x235km it's perigee is above surface level, but within the atmosphere. And energetically it's equivalent to 142x142km circular orbit which for a vehicle the size and mass of Starship would decay in significantly more than once around (less streamlined and with lower ballistic coefficient SkyLab started it's last full circle at ~135km)

The whole flight is within the atmosphere, which reaches much higher than 235 km. Therefore the notion of Starship "entering atmosphere" at some  point on this flight does not make sense.

Only the most tenuous bits of the atmosphere reach so high, and if you’re going to play that game, there’s plenty of scattered gas and dust molecules along with stray solar protons streaming throughout the inner solar system too … but 253 km is still a vacuum for all intents and purposes.