SpaceX Falcon 9 : Formosat-5 : SLC-4E Vandenberg : Aug 24, 2017 : DISCUSSION

[vanoord]

From SpaceX on Facebook:

Falcon 9 and FORMOSAT-5 are vertical on Space Launch Complex 4 East (SLC-4E) at Vandenberg Air Force Base in California. Weather is 90% favorable for today’s 42-minute launch window which opens at 11:51 a.m. PDT, or 18:51 UTC.

Following stage separation, Falcon 9’s first stage will attempt a landing on the “Just Read the Instructions” droneship stationed in the Pacific Ocean. Launch webcast will go live about 15 minutes before liftoff → spacex.com/webcast

The window seems to open a minute later than previously advertised.

[whitelancer64]

Apologies since I know this has been addressed before and elsewhere, but I'm not recalling why there isn't yet an on-shore landing zone that's available at Vandenburg instead of needing the drone ship?

There is. SpaceX has built a landing pad right next to SLC-4E, at the former SLC-4W.

It is not yet approved for use, IIRC it is currently under environmental review.

[king1999]

This article implied that they are trying to recover the fairing for this mission:

https://www.wired.com/story/spacex-will-lose-millions-on-its-taiwanese-satellite-launch/

The loss-leading mission puts all the more pressure on SpaceX’s strategy of reusability. SpaceX indicated it will also attempt to recover the rocket’s payload fairing––that encapsulates the satellite––during takeoff, which is worth around $6 million. Elon Musk says that a factory fresh Falcon 9 booster accounts for 70 percent of the $37 million in direct launch costs which totals to around $26 million. If SpaceX can reuse that booster enough times to pay for itself, the long-term loss from Formosat-5 will not be as significant.

[schaban]

I think boost back is missing so JRTI and it support ships will be close to fairing and perhaps even participate in recovery effort?

[ZachF]

What times do the launch window open and close?  The opening time is usually in the update thread title, but appears to be currently missing.

It launches about an hour from now.

[Skylab]

I think boost back is missing so JRTI and it support ships will be close to fairing and perhaps even participate in recovery effort?

There is no boost back if you don't intend to land near/at your launch site.

[Lars-J]

I think boost back is missing so JRTI and it support ships will be close to fairing and perhaps even participate in recovery effort?

There is no boost back if you don't intend to land near/at your launch site.

Sometimes they do a burn to target the ship, if the ship is not roughly where a ballistic trajectory will take the stage. Think of the boost back burn as a landing spot targeting burn, it isn't always back to the launch site.

[Skylab]

I think boost back is missing so JRTI and it support ships will be close to fairing and perhaps even participate in recovery effort?

There is no boost back if you don't intend to land near/at your launch site.

Sometimes they do a burn to target the ship, if the ship is not roughly where a ballistic trajectory will take the stage. Think of the boost back burn as a landing spot targeting burn, it isn't always back to the launch site.

I don't want to get into semantics, but isn't that variant included in the entry burn? Boostback to me always seemed like the literal meaning.

[envy887]

I think boost back is missing so JRTI and it support ships will be close to fairing and perhaps even participate in recovery effort?

There is no boost back if you don't intend to land near/at your launch site.

Sometimes they do a burn to target the ship, if the ship is not roughly where a ballistic trajectory will take the stage. Think of the boost back burn as a landing spot targeting burn, it isn't always back to the launch site.

I don't want to get into semantics, but isn't that variant included in the entry burn? Boostback to me always seemed like the literal meaning.

No. Iridium Flight 2 had bad weather near the original landing zone, so they moved the ship significantly away. The booster had to do a boostback burn to target the new landing location.

[Skylab]

No. Iridium Flight 2 had bad weather near the original landing zone, so they moved the ship significantly away. The booster had to do a boostback burn to target the new landing location.

Right, I remember the new position, just never realised that was a boostback. Thanks!

[Lars-J]

Sometimes they do a burn to target the ship, if the ship is not roughly where a ballistic trajectory will take the stage. Think of the boost back burn as a landing spot targeting burn, it isn't always back to the launch site.

I don't want to get into semantics, but isn't that variant included in the entry burn? Boostback to me always seemed like the literal meaning.

The "boost-back" and landing burns help to narrow the landing point, but the "boost-back" burn (if done) does the vast majority of aiming. The entry burn is just there to reduce velocity to avoid breaking up in the thicker atmosphere. And as envy887 states, the boost-back burn could be a sideways burn - or even forward, it all depends where the landing barge is placed.

[Skylab]

Sometimes they do a burn to target the ship, if the ship is not roughly where a ballistic trajectory will take the stage. Think of the boost back burn as a landing spot targeting burn, it isn't always back to the launch site.

I don't want to get into semantics, but isn't that variant included in the entry burn? Boostback to me always seemed like the literal meaning.

The "boost-back" and landing burns help to narrow the landing point, but the "boost-back" burn (if done) does the vast majority of aiming. The entry burn is just there to reduce velocity to avoid breaking up in the thicker atmosphere. And as envy887 states, the boost-back burn could be a sideways burn - or even forward, it all depends where the landing barge is placed.

Understood. Bit of a misnomer then, but I understand you can hardly describe every situation with a few labels. Right, will stay quiet hoping for a good launch in about half an hour!

[ChrisC]

Watching the countdown to coverage start on SpaceX's video feed, I'm wondering ... For most launches in the past, their coverage started at precisely T-20 minutes.  Last time with CRS-12, though, it start later in the count, at T-13.  Let's see when this one starts.

EDIT: slate / music started at around T-20

EDIT: coverage started at around T-12; cheated down even more

[mrhuggy]

Nice lunch time rocket launch but it sounds like its been done from the cafeteria.

[sanman]

The "boost-back" and landing burns help to narrow the landing point, but the "boost-back" burn (if done) does the vast majority of aiming. The entry burn is just there to reduce velocity to avoid breaking up in the thicker atmosphere. And as envy887 states, the boost-back burn could be a sideways burn - or even forward, it all depends where the landing barge is placed.

Don't the waffleIrons/gridFins/X-wings do some aiming too, during atmospheric descent?

[Lars-J]

Wow, this is a lofted trajectory, more than I was expected... 435km up and counting, and only now is it starting to burn horizontally.

EDIT: And now above 600km, burning downwards to circularize.

[sghill]

Does that landing leg look right to you guys?

[whitelancer64]

Does that landing leg look right to you guys?

I don't see anything wrong with it?

[Lars-J]

Does that landing leg look right to you guys?

It looks fine to me... Perhaps you can tell us what you see?

[chrisking0997]

Does that landing leg look right to you guys?

I don't see anything wrong with it?

I dont either, but I am starting to think they should repaint the droneship names in the opposite direction