SpaceX F9 : Iridium NEXT 6 with GRACE-FO : NET May 22, 2018 - DISCUSSION

[niwax]

Just read over the newly-released press kit; how is the second stage going to reach a circular orbit of 625 kilometers, using one restart, from the initial orbit of 490 kilometers?

I thought three burns would be necessary.

It's possible to change periapsis and apoapsis at the same time. The rough analogy is a right triangle, where you can achieve the same two-step X and Y axis movement by taking the hypotenuse. Just more complicated

According to the press kit the burn is just 8s. So possibly just a transfer orbit? The dv to circularize from an 490-625km elliptical orbit is minimal an they are looking to deploy multiple satellites, so they definitely have some maneuvering capability.

[Comga]

Just read over the newly-released press kit; how is the second stage going to reach a circular orbit of 625 kilometers, using one restart, from the initial orbit of 490 kilometers?

I thought three burns would be necessary.

Of the 164 kg of hydrazine onboard each Iridium NEXT satellite, 38 kg is budgeted for "Insertion - Mission Orbit".
With an Isp of 220 seconds and a spacecraft mass of 840 kg, according to Gunter's it is left to the reader to verify that this is adequate to raise the apogee from the 490 km by 625 km transfer orbit, assuming the Falcon 9 second stage takes care of the plane change.

[envy887]

Just read over the newly-released press kit; how is the second stage going to reach a circular orbit of 625 kilometers, using one restart, from the initial orbit of 490 kilometers?

I thought three burns would be necessary.

Of the 164 kg of hydrazine onboard each Iridium NEXT satellite, 38 kg is budgeted for "Insertion - Mission Orbit".
With an Isp of 220 seconds and a spacecraft mass of 840 kg, according to Gunter's it is left to the reader to verify that this is adequate to raise the apogee from the 490 km by 625 km transfer orbit, assuming the Falcon 9 second stage takes care of the plane change.

I get 99.9 m/s available, and only 36.8 m/s required to circularize. Seems like that would work.

[edkyle99]

Just a note that the first stage will burn for about 166 seconds according to the press kit, which is about 23 seconds longer than during previous Block 4 Iridium launches that used downrange recovery.  The initial second stage burn will be about 436 seconds long, much longer than previous 383 sec-ish first burns for Iridium missions that went to lower (180 x 625 km) transfer orbits.

This despite the fact that total payload mass is significantly less than during those previous Iridium missions (~5.5 tonnes versus 8.6 tonnes).  The higher, circular initial orbit and subsequent plane change apparently suck up the performance difference and still require the using up of some or all of the former first stage recovery boost capability.

I wonder if these five Iridiums might actually weigh more at launch than the others, loaded with more propellant to handle the extra delta-v orbit-raising requirement.
 
 - Ed Kyle

[IntoTheVoid]

Three additional patches
Source: http://spacexpatchlist.space/

Wow! Did someone really forget the 'X' in SpaceX? I hope that's not an official patch.

Edit: The patch with the die, under the 5 pips.

[gongora]

I'm pretty sure Matt Desch mentioned at some point that these 5 satellites aren't getting dropped off in the normal Iridium deployment orbit (they will use more fuel to get to their final orbit), but I can't remember where the reference is.  Does anyone else recall that?

[Comga]

Three additional patches
Source: http://spacexpatchlist.space/

Wow! Did someone really forget the 'X' in SpaceX? I hope that's not an official patch.

What missing "X"?  It's there on the rocket. The long, curved part of it is grey, not blue, like several official versions.
Its a limitation of the low resolution that comes with stitching.

[Comga]

Three additional patches
Source: http://spacexpatchlist.space/

Wow! Did someone really forget the 'X' in SpaceX? I hope that's not an official patch.

What missing "X"?  It's there on the rocket. The long, curved part of it is grey, not blue, like several official versions.
Its a limitation of the low resolution that comes with stitching.

The patch with the die, under the 5 pips.

You are correct.
That's pretty funny.
In addition to dice being a rather questionable graphic for something as dicy as a rocket launch....

[LouScheffer]

Just a note that the first stage will burn for about 166 seconds according to the press kit, which is about 23 seconds longer than during previous Block 4 Iridium launches that used downrange recovery.  The initial second stage burn will be about 436 seconds long, much longer than previous 383 sec-ish first burns for Iridium missions that went to lower (180 x 625 km) transfer orbits.

Maybe the G-force limits for Grace are lower than that of Iridium, so they have to throttle back and hence burn longer?

[gongora]

In the Iridium NEXT overview post (https://forum.nasaspaceflight.com/index.php?topic=35112.msg1222679#msg1222679) I seem to have a mistake somewhere in my destinations for the satellites of each launch.  Matt Desch said recently that Planes 2, 3, 6 will each have 2 spares (13 sats), which would make me think Planes 1, 4, 5 each have 1 spare (12 sats).  When I total up the launches I get 11 in Plane 1 and 14 in Plane 2.  Can anyone spot where I'm going wrong?

[Norm38]

Is that  a new Block 5 interstage?  Or is it just really really sooty?

[ZachS09]

Is that  a new Block 5 interstage?  Or is it just really really sooty?

It's a sooty interstage because the F9 and American flag can be seen on the side.

The Block 5 interstage is completely black and those logos are moved to the first stage fuel tank.

[Joffan]

Three additional patches
Source: http://spacexpatchlist.space/

Wow! Did someone really forget the 'X' in SpaceX? I hope that's not an official patch.

Edit: The patch with the die, under the 5 pips.

You have to join the dots to find the X :-)

[HarryM]

Fog here in Paso Robles finally burning through! Hope to get a good view, though sun-glare at the time of day and direction (due south) could be an issue.

[gongora]

In the Iridium NEXT overview post (https://forum.nasaspaceflight.com/index.php?topic=35112.msg1222679#msg1222679) I seem to have a mistake somewhere in my destinations for the satellites of each launch.  Matt Desch said recently that Planes 2, 3, 6 will each have 2 spares (13 sats), which would make me think Planes 1, 4, 5 each have 1 spare (12 sats).  When I total up the launches I get 11 in Plane 1 and 14 in Plane 2.  Can anyone spot where I'm going wrong?

Many thanks to the person who pointed me to an old post:

Tweet from Matt Desch:

Changed our plan recently. L3 goes to Plane 4 now: all 10 will go in service. L4 to Plane 2: 8 slated for operation, 2 to drift to P1.

Iridium's press release for flight 4 still gave the old information of only drifting one satellite.

[intrepidpursuit]

They commented that there was something disappointing happening on another camera that didn't relate to the second stage or the primary mission. Failed recovery experiment with the faring?

[dglow]

That was my first guess.

[Doesitfloat]

Loss of video from 1st stage

[Prettz]

The second stage camera looked worse than ever. What's the deal with that?

[Semmel]

Grace was actually visible for 1 or 2 frames at the upper border of the image next to the iridium sat just before the stream got cut.