SpaceX Falcon 9 : GPS III-3 : Cape Canaveral : June 30, 2020

[gongora]

Looks like this indicates the orbital inclination is ~55.01 degrees with the apogee being ~20,183 kilometers.

Where's the perigee number located on the TLE?

Neither the apogee nor perigee is directly given in the TLE.  What you interpreted as apogee is actually a date/time field.

[gongora]

From Celestrak: (inclination) 55.01   (apogee) 20,168   (perigee) 387

[ZachS09]

Looks like this indicates the orbital inclination is ~55.01 degrees with the apogee being ~20,183 kilometers.

Where's the perigee number located on the TLE?

Neither the apogee nor perigee is directly given in the TLE.  What you interpreted as apogee is actually a date/time field.

I see. I'm not good with TLEs, so thanks for the insight.

[CorvusCorax]

Question: SpaceX used to ignite the engines a few seconds before T-0 - ramp up thrust, then release the launch clamps at T-0 if everything is OK. This was very visible for example with the Falcon Heavy Demo launch

In the last couple of launches I watched, that didn't seem to be the case anymore, it looks like SpaceX ignites engines at T-0 and lift of is a second or two later.

Of course that could be due to lag in the stream vs countdown clock. ( On-board video is a few seconds behind callouts, but even ground video might possibly be a little bit delayed ) and if SpaceX simply reduced the time used for spoolup, it might just look that way.

So - did SpaceX change that procedure / definition of T=0  - and if so, when was that? With the introduction of Block 5 ?

[smoliarm]

Looks like this indicates the orbital inclination is ~55.01 degrees with the apogee being ~20,183 kilometers.

Where's the perigee number located on the TLE?

Neither the apogee nor perigee is directly given in the TLE.  What you interpreted as apogee is actually a date/time field.

I see. I'm not good with TLEs, so thanks for the insight.

It's not that difficult to do the calculations of apogee and perigee with TLEs.
here are the formulas:
https://forum.nasaspaceflight.com/index.php?topic=35275.msg1824463#msg1824463

and the general info on TLE format:
https://en.wikipedia.org/wiki/Two-line_element_set

[ChrML]

Question: SpaceX used to ignite the engines a few seconds before T-0 - ramp up thrust, then release the launch clamps at T-0 if everything is OK. This was very visible for example with the Falcon Heavy Demo launch

In the last couple of launches I watched, that didn't seem to be the case anymore, it looks like SpaceX ignites engines at T-0 and lift of is a second or two later.

Of course that could be due to lag in the stream vs countdown clock. ( On-board video is a few seconds behind callouts, but even ground video might possibly be a little bit delayed ) and if SpaceX simply reduced the time used for spoolup, it might just look that way.

So - did SpaceX change that procedure / definition of T=0  - and if so, when was that? With the introduction of Block 5 ?

The commentary said that this applies to this launch too. Fire up engines at T-2 and release clamps at T-0.

I noticed it looked like they released at T+2 aswell. But they also called out stage separation 2 sec before the video showed it, so I think the video stream could be a little delayed overall from the overlay and mission audio.

[FutureSpaceTourist]

More launch photos by Ben Cooper (in addition to ones SpaceX have already released)

https://twitter.com/launchphoto/status/1278139805243752449

First look: Falcon 9 launches GPS III-SV03

https://twitter.com/launchphoto/status/1278142099276419073

Another as Falcon 9 launches GPS III-SV03

[Shanuson]

What are the orbital elements after SECO-1 and SECO-2?

https://spaceflightnow.com/2020/06/29/u-s-military-makes-adjustments-in-gps-launch-to-allow-for-spacex-booster-landing/

Targeted orbit is 402 by 20,197 kilometers inclined 55 degrees.

vs

From Celestrak: (inclination) 55.01   (apogee) 20,168   (perigee) 387

This makes a 29km lower apogee and 15km lower perigee. A short come of 15.79 kJ/kg satellite mass. Someone with more knowledge could tell us the deltaV of that or how much longer stage 2 would have needed to burn?

[jacqmans]

SMC and its partners successfully launch third GPS III satellite

SMC Public Affairs / Published June 30, 2020

LOS ANGELES AIR FORCE BASE – EL SEGUNDO, Calif. --
The U.S. Space Force and its mission partners successfully launched the third Global Positioning Systems (GPS) III satellite at  4:10 p.m. EDT, June 30 from Space Launch Complex - 40 at Cape Canaveral Air Force Station, Florida. The Lockheed Martin-built satellite was carried to orbit aboard a Space Exploration Technologies Corporation (SpaceX) Falcon 9 Launch Vehicle.

“Our team is committed to achieving excellence and reaching the “gold standard” of position, navigation, and timing. GPS III satellites will pioneer innovation and I look forward to seeing new technologies developed for the United States Space Force,” said Cordell DeLaPena, program executive officer for SMC’s Space Production Corps. “At SMC, we are proud to deliver our third GPS III satellite and will continue to operate at a high caliber.”

The first-stage booster of SpaceX’s Falcon 9 Launch Vehicle was successfully recovered approximately 20 minutes after liftoff by the company’s autonomous spaceport drone ship in the predicted landing area. This launch marks the first NSSL mission where a launch provider has attempted to recovered flight hardware.

“The successful GPS III SV03 launch and recovery serves as another step in our journey with industry partners to create innovative, flexible, and affordable services to meet NSSL mission objectives and propel U.S. dominance in space.” said Col. Robert Bongiovi, Launch Enterprise director. “I’m proud of my team’s 81st successful National Security Space Launch and look forward to our additional National Security Space missions with SpaceX.”

GPS III’s SV03 separated from its upper stage approximately 88 minutes after launch. Engineers and operators at Lockheed Martin’s Waterton facility will now begin on-orbit checkout and tests which are estimated to complete in two weeks. Operational use is expected to begin as early as August 2020.

“The GPS III program continues to build on its successes by delivering advanced capabilities for the United States Space Force, and maintaining the “gold standard” for position, navigation and timing.” said Col. Edward Byrne, Medium Earth Orbit Space Systems Division chief.

SV03 will join the current GPS constellation comprised of 31-operational spacecraft, and will be the 22nd military code-capable satellite to the fleet. GPS satellites operate in MEO at an altitude of approximately 20,200 km (12,550 miles) in six planes. Each satellite circles the earth twice per day. GPS provides positioning, navigation, and timing services for billions of users worldwide. GPS III, the newest generation of GPS satellites, brings new capabilities to users, including three times greater accuracy, and up to eight times improved anti-jamming capabilities

[jacqmans]

SpaceX photos

[CorvusCorax]

What are the orbital elements after SECO-1 and SECO-2?

https://spaceflightnow.com/2020/06/29/u-s-military-makes-adjustments-in-gps-launch-to-allow-for-spacex-booster-landing/

Targeted orbit is 402 by 20,197 kilometers inclined 55 degrees.

vs

From Celestrak: (inclination) 55.01   (apogee) 20,168   (perigee) 387

This makes a 29km lower apogee and 15km lower perigee. A short come of 15.79 kJ/kg satellite mass. Someone with more knowledge could tell us the deltaV of that or how much longer stage 2 would have needed to burn?

I was too lazy to do the calculation myself. according to this tool: https://www.satsig.net/orbit-research/delta-v-geo-injection-calculator.htm
the difference between 387 x 20168  km and 387 x 20197 km is 1.07 m/s  -- I'm not entirely sure about the gs Falcon9 S2 pulls just before end of burn, because it's likely throttled down to limit them, but assuming 3g, this would be somewhere around 30 milliseconds.

For the satellite to lift the perigee from 387 km instead of 402 to 20168 is 2.18 m/s (regardless of apogee)
and to get from 20168 circular to 20197 circular is another 2.12 m/s

so to make up for the shortcoming, the sat needs to spend 4.3 m/s of deltaV

interestingly it all comes down to the lower perigee. S2 must already have been in a slightly too low parking orbit, but it mostly made up for it. Pushing the apogee from 387 to 20168 km costs 3.33 m/s more than from 402 to 20197 km costs. So in a way S2 already made up for most of its shortcoming. Had it burnt only for the same deltaV needed to get to the 402x20197 transfer orbit at a 387km perigee it would have ended in a 387x20079  km orbit

edit: that's wrong, as it assumes a circular starting orbit. but the stage starts from either a 168x387 km or from a 168x402 km orbit. and to lift the perigee to circular in 402 is 4.22 m/s more expensive than in 387. so in fact total deltaV of getting from 168x387 to 387x20168 km is 63.40m/s + 2014.67 m/s = 2078.07 m/s  - while getting from 168x402 to 402x20197 km is  67.62 m/s + 2011.34 m/s = 2078.96 m/s - that means S2 was in a lower parking orbit than it was supposed to and then underperformed by 0.89 m/s

mind you - even calling that "underperform" is a joke - this is well within uncertainty margins. It was a "good transfer orbit"


Edit2: Just for completeness, the difference between a 168x387 km parking orbit and a 168x402 km parking orbit is around 4.28 m/s


Edit3: Another good question is the accuracy of Celestrak - what's the margin of error there?

[HVM]

Does SpX have a checkbox for "silent crowd" it the order form? Or what?
Both GPS launches were quite quiet, is it a military thing or Rona.

[Vettedrmr]

Well, the first one was expendable, and SpaceX typically haven't provided much in the way of on-board cameras on those flights.  But this one was recoverable, and I noticed the lack of coverage as well.  IDK why; they showed normal S2 coverage, and normal coverage from the entry burn down.

In any case, a good launch and payload insertion, that's the important stuff!

Have a good one,
Mike

[CorvusCorax]

Does SpX have a checkbox for "silent crowd" it the order form? Or what?
Both GPS launches were quite quiet, is it a military thing or Rona.

The launch was in memoriam a dead colonel. Maybe they kept the noise down in order to press F.

[Herb Schaltegger]

Edit3: Another good question is the accuracy of Celestrak - what's the margin of error there?

Years ago, I used to do a lot of amateur satellite spotting and tracking. At least as of that time, and likely still today, Celestrak gets their data straight from US government sources - used to be NORAD, then US SPACECOM. I dunno what the name of the organization is today but it’s almost certainly the same folks.

In fact, all the amateur sites (n2yo, Heavens Above, etc) get their data from the same place, or did when I was actively sat-tracking for fun.

Having said that, the question then devolves to: “What is the margin of error in SPACECOM’s - or whomever’s - data?”

That depends on whether the satellite is being actively tracked by radar or optically from the ground, and how often; whether the satellite vehicle itself is active and providing an internal state vector and/or other form of self-navigation and reporting that back to ground stations, and if so, is the satellite operator providing that data to SPACECOM? Has the satellite actively maneuvered since the data was publicized and if so, by how much? Etc.

Lots of variable and many thousands of objects to track. Accuracy will no doubt be better for large, easily-tracked objects like the ISS or for craft way out at GSO that maneuver only rarely and by relatively small amounts.

[FutureSpaceTourist]

https://twitter.com/spacexfleet/status/1278319962717851649

Tracking suggests that Just Read the Instructions droneship is now underway from the LZ, bound for Port Canaveral.

Why did it take so long? I'd guess that they didn't finish securing the booster before it got dark and had to wait until this morning.

[edkyle99]

If I'm counting right, this was the 54th Falcon 9 launch from SLC-40 (not including the AMOS 6 campaign).  That is one less than the 55 launches that I believe Titan 3C/34D/CT/4 performed from this pad over the years, so the next launch will match that bit of history.

 - Ed Kyle

[ugordan]

If I'm counting right, this was the 54th Falcon 9 launch from SLC-40 (not including the AMOS 6 campaign).  That is one less than the 55 launches that I believe Titan 3C/34D/CT/4 performed from this pad over the years, so the next launch will match that bit of history.

Your previous post had me hunting and counting for that 1 discrepancy and just as I was about to reply, you retracted it. 

Anyway, I guess soon we should be thinking of SLC-40 as being most famous for launching F9. Nonetheless, the Cassini spacecraft launch by a Titan IV-B is still one of the highlights of this pad for me, personally.

[FutureSpaceTourist]

https://twitter.com/considercosmos/status/1278398913624657927

Wait for it...  New super slowmo of #GPSIIISV03 catenary umbilical release. The special gray thermal conductivity band enters the frame a few seconds later. 

Congrats @SpaceX @SpaceForceDoD and @elonmusk, liftoff was beautiful 🎥🚀🌌 #CosmicPerspective

[OnWithTheShow]

Target Orbit from upthread: 402 (perigee) by 20,197 (apogee) inclined 55 degrees
Initial TLE From Celestrak: 387 (perigee) by 20,168 (apogee) 20,168 inclined 55.01

A difference of

3.7% of perigee
.001% of apogee
.0002% of inclination

I didnt see a target orbit for the Atlas V (held up as a model of launch accuracy) launch of USSF-7 but if you use Tory Bruno's bullseye chart it looks like (using ruler tools in photoshop) if was off by about:

11% of perigee
0% of apogee
.06% of inclination

All seems within the margin of error considering the differences in delta v can be measured in milliseconds of thrust