SpaceX Falcon 9 : Iridium NEXT Flight 2 (June 25, 2017) : Discussion

[tvg98]

Stcks pointed out on Reddit that JTRI will be about 70 km closer to the pad than for the for the previous mission. Does this imply a lower velocity at MECO, or could they use a more lofted trajectory this time round?

[stcks]

Why the Hail Mary ASDS trajectory?

300 km from the launch site isn't a Hail Mary. The GTO missions do more than twice that.

[SweetWater]

Why the Hail Mary ASDS trajectory? Is it because of the up mass of the 10 satellites? I figured they would move the ASDS JTRI parallel with VAFB, just offshore to test RTLS on the west cost.
Any thoughts?

Maybe SpaceX wants to test something - guidance, software governing the retro and/or re-entry burns etc. - on what is, essentially, a "free" booster? They're developing quite the stable of recovered Block 3 first stages, and they want to move to Block 5 (human-rated and supporting easier reuse) sometime around the end of the year - someone please correct me if I'm wrong.

AFAIK, we don't know whether or to what degree the Block 3 boosters can be upgraded to Block 4 or Block 5. Maybe SpaceX wants to do a live test of an extreme recovery. If they get the first stage back, great; if not, they get valuable data, and the stage was paid for in any case.

[stcks]

Maybe SpaceX wants to do a live test of an extreme recovery. If they get the first stage back, great; if not, they get valuable data, and the stage was paid for in any case.

Again, this isn't extreme. Its less punishing than the first Iridium mission and basically the same distance as CRS-8.

[Steve D]

Maybe SpaceX wants to do a live test of an extreme recovery. If they get the first stage back, great; if not, they get valuable data, and the stage was paid for in any case.

Again, this isn't extreme. Its less punishing than the first Iridium mission and basically the same distance as CRS-8.

I have noticed on the last few launches that the first stage flip and burn seem to be alot quicker then before. Maybe that helps minimize the distance down range.

[Pete]

I have noticed on the last few launches that the first stage flip and burn seem to be alot quicker then before. Maybe that helps minimize the distance down range.

The rapid flip is only needed when a boostback burn is needed, i.e. for a return to launch site or for a drone ship closer to shore than the normal trajectory distance.

After MECO, each second of delay before start of boostback burn costs you:
1 less second of flight time, *and*
2.5 kilometers more horizontal distance to cover back to your landing pad.
.
This means every second of wasted time costs you something like 50 m/s of delta-v needed on the boostback burn in addition to the minimum. (and some more on the re-entry burn, because you will be arriving faster)

[input~2]

EASTERN NORTH PACIFIC.
1. HAZARDOUS OPERATIONS 1949Z TO 2106Z DAILY
25 AND 26 JUN:
A. IN AREA BETWEEN
32-23N 31-35N AND 120-39W 120-24W.
B. IN AREA BOUND BY
31-35N 121-11W, 31-35N 119-49W,
28-48N 119-46W, 28-48N 121-06W.
2. CANCEL THIS MSG 262206Z JUN 17.//

Authority: WESTERN RANGE 070031Z JUN 17.

SOUTH PACIFIC.
DNC 06, DNC 29.
1. HAZARDOUS OPERATIONS 2211Z TO 2243Z DAILY
25 AND 26 JUN IN AREA BETWEEN
27-56S 72-46S AND 146-53W 140-10W.
2. CANCEL THIS MSG 262343Z JUN 17.//

Authority: WESTERN RANGE 070031Z JUN 17.

[VulpesJack]

EASTERN NORTH PACIFIC.
1. HAZARDOUS OPERATIONS 1949Z TO 2106Z DAILY
25 AND 26 JUN:
A. IN AREA BETWEEN
32-23N 31-35N AND 120-39W 120-24W.
B. IN AREA BOUND BY
31-35N 121-11W, 31-35N 119-49W,
28-48N 119-46W, 28-48N 121-06W.
2. CANCEL THIS MSG 262206Z JUN 17.//

Authority: WESTERN RANGE 070031Z JUN 17.

SOUTH PACIFIC.
DNC 06, DNC 29.
1. HAZARDOUS OPERATIONS 2211Z TO 2243Z DAILY
25 AND 26 JUN IN AREA BETWEEN
27-56S 72-46S AND 146-53W 140-10W.
2. CANCEL THIS MSG 262343Z JUN 17.//

Authority: WESTERN RANGE 070031Z JUN 17.

What's the South Pacific hazard area for? S2 re-entry?

[Jarnis]

EASTERN NORTH PACIFIC.
1. HAZARDOUS OPERATIONS 1949Z TO 2106Z DAILY
25 AND 26 JUN:
A. IN AREA BETWEEN
32-23N 31-35N AND 120-39W 120-24W.
B. IN AREA BOUND BY
31-35N 121-11W, 31-35N 119-49W,
28-48N 119-46W, 28-48N 121-06W.
2. CANCEL THIS MSG 262206Z JUN 17.//

Authority: WESTERN RANGE 070031Z JUN 17.

SOUTH PACIFIC.
DNC 06, DNC 29.
1. HAZARDOUS OPERATIONS 2211Z TO 2243Z DAILY
25 AND 26 JUN IN AREA BETWEEN
27-56S 72-46S AND 146-53W 140-10W.
2. CANCEL THIS MSG 262343Z JUN 17.//

Authority: WESTERN RANGE 070031Z JUN 17.

What's the South Pacific hazard area for? S2 re-entry?

Yes.

And the larger area past the ASDS is for fairings.

[spacenut]

Is this flight going to be webcast?  If so what time will SpaceX post it?  Seems they are getting later and later posting their upcoming webcasts.

[guckyfan]

the BulgariaSat host said they will be back on sunday, so yes there will be a webcast.

[gongora]

Is this flight going to be webcast?  If so what time will SpaceX post it?  Seems they are getting later and later posting their upcoming webcasts.

About 20 minutes before a launch I go to youtube.com/spacex and click on the top entry.  Works fine (at least for those of us in the U.S.).

[Star One]

Is this flight going to be webcast?  If so what time will SpaceX post it?  Seems they are getting later and later posting their upcoming webcasts.

About 20 minutes before a launch I go to youtube.com/spacex and click on the top entry.  Works fine (at least for those of us in the U.S.).

I am in the U.K. & as I subscribe to their channel it always gets pushed to the top of my recommended list when a webcast is imminent.

[VulpesJack]

SpaceX patch from the press kit.

That's a really nice patch

[gongora]

SpaceX patch from the press kit.

That's a really nice patch

For some reason my brain wanted to interpret the darker color as land and it just wasn't working.

[guckyfan]

The grid fins are dark. So no more protective coating. Must really be the new ones.

[Star One]

The grid fins are dark. So no more protective coating. Must really be the new ones.

Seems unlike as I thought these were part of block 5 upgrades.

[Nomadd]

The grid fins are dark. So no more protective coating. Must really be the new ones.

Seems unlike as I thought these were part of block 5 upgrades.

They're not going to just fly a rocket with 50 new things someday. A lot of block 5 stuff will probably be rolled into earlier models. Things like the new grid fins will need some software tweaking and maybe a few mods and they might want the official first block 5 to have all that in it's final form.

[Star One]

The grid fins are dark. So no more protective coating. Must really be the new ones.

Seems unlike as I thought these were part of block 5 upgrades.

They're not going to just fly a rocket with 50 new things someday. A lot of block 5 stuff will probably be rolled into earlier models. Things like the new grid fins will need some software tweaking and maybe a few mods and they might want the official first block 5 to have all that in it's final form.

But it seems unlikely they would put them on this as I thought this was a block 3. Surely if you wanted to phase stuff in you'd start with the block 4.

[old_sellsword]

The grid fins are dark. So no more protective coating. Must really be the new ones.

Seems unlike as I thought these were part of block 5 upgrades.

They're not going to just fly a rocket with 50 new things someday. A lot of block 5 stuff will probably be rolled into earlier models. Things like the new grid fins will need some software tweaking and maybe a few mods and they might want the official first block 5 to have all that in it's final form.

But it seems unlikely they would put them on this as I thought this was a block 3. Surely if you wanted to phase stuff in you'd start with the block 4.

This first stage is both Block 3 and debuting the new grid fins.