Author Topic: SpaceX Falcon 9 : TESS : April 18, 2018 : Discussion  (Read 147084 times)

Offline Elthiryel

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Re: SpaceX Falcon 9 : TESS : April 18, 2018 : Discussion
« Reply #340 on: 04/20/2018 03:35 PM »
If you mean getting to final science orbit without a lunar flyby, Falcon 9 could not do it. It would require firing at the apogee and F9 second stage doesn't have the capability to coast for such a long time (at least tens of hours if I'm not wrong) and start the engine.
« Last Edit: 04/20/2018 03:36 PM by Elthiryel »
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Offline envy887

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Re: SpaceX Falcon 9 : TESS : April 18, 2018 : Discussion
« Reply #341 on: 04/20/2018 05:17 PM »
If you mean getting to final science orbit without a lunar flyby, Falcon 9 could not do it. It would require firing at the apogee and F9 second stage doesn't have the capability to coast for such a long time (at least tens of hours if I'm not wrong) and start the engine.

TESS's science orbit is not circular so the final burn would not be at the final apogee. But it is much higher (both apogee and perigee) than GEO, so F9 probably could not put it there directly.

Offline chipguy

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Re: SpaceX Falcon 9 : TESS : April 18, 2018 : Discussion
« Reply #342 on: 04/20/2018 06:19 PM »
Actual TESS orbit before first apogee burn according to Space-track.

NORAD   SATNAME   INTLDES      PERIOD      INCL   APOGEE   PERIGEE
43435   TESS         2018-038A   10244.32   29.54   299450   296

Did they overperform? I remember apogee target of 270k km.

Keep in mind that the apogee of such an eccentric orbit is very sensitive to final velocity
error of a low height burn. That also means very little delta V by TESS to change it.

Offline Ben the Space Brit

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Re: SpaceX Falcon 9 : TESS : April 18, 2018 : Discussion
« Reply #343 on: 04/20/2018 09:51 PM »
Didn't F9 have sufficient capability to deliver TESS directly to its final orbit, or nearly so, and saved the maneuvering? 

They didn't want to leave the upper stage on the same trajectory as TESS (a potential collision hazard), so they left some propellent in the Falcon-9 to push the U/S into a heliocentric disposal orbit.
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Offline TorenAltair

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Re: SpaceX Falcon 9 : TESS : April 18, 2018 : Discussion
« Reply #344 on: 04/20/2018 10:03 PM »
It seems they gave TESS a little more as reserve. Inclination is listed as 29.54 degrees, planned were 28.5 though it might be possible that TESS already tested its own engine.

Offline deruch

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Re: SpaceX Falcon 9 : TESS : April 18, 2018 : Discussion
« Reply #345 on: 04/21/2018 01:16 AM »
Actual TESS orbit before first apogee burn according to Space-track.

NORAD   SATNAME   INTLDES      PERIOD      INCL   APOGEE   PERIGEE
43435   TESS         2018-038A   10244.32   29.54   299450   296

Did they overperform? I remember apogee target of 270k km.

Keep in mind that the apogee of such an eccentric orbit is very sensitive to final velocity
error of a low height burn. That also means very little delta V by TESS to change it.

The actual "concern," if one could call it that, isn't about the delta-V requirements for TESS--which are very small--but about the phasing with the moon to allow both the S/C and the moon to be in the proper positions for the flyby.  That is exactly why TESS's mission planners wanted to have a few orbits before going for the flyby.  It allows them time to deal with any dispersions in orbit injection and gives them a series of opportunities for trajectory/phasing correction. 
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Offline rickl

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Re: SpaceX Falcon 9 : TESS : April 18, 2018 : Discussion
« Reply #346 on: 04/21/2018 01:18 AM »
If you mean getting to final science orbit without a lunar flyby, Falcon 9 could not do it. It would require firing at the apogee and F9 second stage doesn't have the capability to coast for such a long time (at least tens of hours if I'm not wrong) and start the engine.

Does Falcon 9 have the capability of sending TESS directly to the lunar flyby without the need for phasing orbits?  I don't know how long the third "disposal" burn was.

Although I would think that using TESS' small onboard engine allows for more precise control of the approach than the F9 MVAC.


Edit:  I see that deruch addressed my second point already.   :)
« Last Edit: 04/21/2018 01:20 AM by rickl »
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Offline deruch

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Re: SpaceX Falcon 9 : TESS : April 18, 2018 : Discussion
« Reply #347 on: 04/21/2018 01:23 AM »
It seems they gave TESS a little more as reserve. Inclination is listed as 29.54 degrees, planned were 28.5 though it might be possible that TESS already tested its own engine.

I don't think it was planned for 28.5 in the end.  In the pre-launch mission briefing, Hans Koenigsman said this about the launch azimuth, "The first burn is pretty much like a geo transfer burn. That's how it's going to look from here. Due east, more or less. Not quite."  It's the "not quite" that indicates that they were targeting an inclination close to 28.5 but actually slightly off.
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Offline TorenAltair

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Re: SpaceX Falcon 9 : TESS : April 18, 2018 : Discussion
« Reply #348 on: 04/21/2018 01:48 PM »
@deruch.  Yes, sorry about my wording. SpaceX planned this for sure, what I meant was that TESS was planned for a 28,5 degrees inclination according to their mission profile. So it might be that they adjusted the profile for the larger F9 to get a few months/weeks of extra observation time.

Offline rickl

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Re: SpaceX Falcon 9 : TESS : April 18, 2018 : Discussion
« Reply #349 on: 04/21/2018 11:20 PM »
I saw a NASA tweet saying that the first TESS orbital burn should occur today.
https://twitter.com/NASA_TESS/status/987687144847179777


But that was early this morning and I haven't seen any updates.  From the announced orbit, it should take about 3.5 days to reach apogee, which would place it sometime early Sunday morning.  Could this tweet have used the planned 6-day orbit?
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Offline rickl

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Re: SpaceX Falcon 9 : TESS : April 18, 2018 : Discussion
« Reply #350 on: 04/22/2018 01:22 PM »
That tweet is now 24 hours old with no updates.  Does anybody know when apogee is expected?  Based on the announced orbit, I guesstimate that it should have occurred about an hour ago, around 8:13 am EDT or 1213 UT.

[/size]Actual TESS orbit before first apogee burn according to Space-track.
NORAD   SATNAME   INTLDES      PERIOD      INCL   APOGEE   PERIGEE
43435   TESS         2018-038A   10244.32   29.54   299450   296
« Last Edit: 04/22/2018 01:31 PM by rickl »
The Space Age is just starting to get interesting.

Offline TorenAltair

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Re: SpaceX Falcon 9 : TESS : April 18, 2018 : Discussion
« Reply #351 on: 04/22/2018 10:02 PM »
Quote
The @NASA_TESS first apogee maneuver (A1M) was successfully completed yesterday. This burn was a 50 second checkout burn to characterize the performance of the #TESS thrusters.

Quote
[email protected]_TESS current speed (at about 22 Apr 2018 15:46 UTC / 11:46 AM EST) was approximately 0.373 km/s. It will be increasing until #TESS reaches perigee at about 25 Apr 2018 05:42 UTC / 1:42 PM at which point it will be approximately 9.51 km/s.

Offline Brian45

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Re: SpaceX Falcon 9 : TESS : April 18, 2018 : Discussion
« Reply #352 on: 04/23/2018 12:47 PM »
Has there been any mention of the Roomba being used on this landing?

Offline Tomness

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Re: SpaceX Falcon 9 : TESS : April 18, 2018 : Discussion
« Reply #353 on: 04/23/2018 12:55 PM »
Has there been any mention of the Roomba being used on this landing?

Check out the Drone Ship thread.
Mention of it by SpaceX yet.  No
Sightings of it being used on this mission. Yes.
https://forum.nasaspaceflight.com/index.php?topic=39766.2460

Offline vanoord

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Re: SpaceX Falcon 9 : TESS : April 18, 2018 : Discussion
« Reply #354 on: 04/23/2018 03:33 PM »
Er...

https://forum.nasaspaceflight.com/index.php?topic=42511.440

OctaGrabber was indeed allowed out to play, but it looks as if only three of the four arms were connected.

There were also some delays in getting going after the core landed, but no indication of whether this was OctaGrabber-related or not.

Offline Brian45

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Re: SpaceX Falcon 9 : TESS : April 18, 2018 : Discussion
« Reply #355 on: 04/23/2018 05:08 PM »
Thanks, I tried a search for Roomba but didn't come up with anything recent. I should have used "OctaGrabber"

Glad to see another part of the puzzle coming together!

Offline gongora

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Re: SpaceX Falcon 9 : TESS : April 18, 2018 : Discussion
« Reply #356 on: 05/02/2018 02:43 AM »
From the 2018 GAO assessment of NASA projects

Quote
The project did not meet its expected March 2018 launch date due to certification delays for its launch vehicle, the SpaceX Falcon 9 upgrade known as Block 4. Certification is necessary because it will be the first time that a NASA instrument will launch on the Block 4 version of the vehicle. The TESS project expected that NASA’s Launch Services Program would certify the Block 4 in September 2017, 7 months before TESS is scheduled to launch. However, NASA needed additional time to investigate the Falcon 9 second stage pressure vessel, which was involved in an anomaly that caused an explosion in September 2016. SpaceX also required extra time to meet NASA’s Launch Services Program requirements.
« Last Edit: 05/02/2018 02:29 PM by gongora »

Offline CorvusCorax

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Re: SpaceX Falcon 9 : TESS : April 18, 2018 : Discussion
« Reply #357 on: 05/02/2018 04:04 AM »
From the 2018 GAO assessment of NASA projects

Quote
The project did not meet its expected March 2018 launch
date due to certification delays for its launch vehicle, the
SpaceX Falcon 9 upgrade known as Block 4. Certification
is necessary because it will be the first time that a NASA
instrument will launch on the Block 4 version of the vehicle.
The TESS project expected that NASA’s Launch Services
Program would certify the Block 4 in September 2017, 7
months before TESS is scheduled to launch. However,
NASA needed additional time to investigate the Falcon 9
second stage pressure vessel, which was involved in an
anomaly that caused an explosion in September 2016.
SpaceX also required extra time to meet NASA’s Launch
Services Program requirements.

Correct me if I'm wrong, TESS booster was the last Block 4 SpaceX ever built, right?

Just like Jason3 launched on the last 1.1 ever launched.

Duh, this certification stuff really seriously lags behind SpaceX innovation speed.

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Re: SpaceX Falcon 9 : TESS : April 18, 2018 : Discussion
« Reply #358 on: 05/02/2018 04:23 AM »
From the 2018 GAO assessment of NASA projects

Quote
The project did not meet its expected March 2018 launch
date due to certification delays for its launch vehicle, the
SpaceX Falcon 9 upgrade known as Block 4. Certification
is necessary because it will be the first time that a NASA
instrument will launch on the Block 4 version of the vehicle.
The TESS project expected that NASA’s Launch Services
Program would certify the Block 4 in September 2017, 7
months before TESS is scheduled to launch. However,
NASA needed additional time to investigate the Falcon 9
second stage pressure vessel, which was involved in an
anomaly that caused an explosion in September 2016.
SpaceX also required extra time to meet NASA’s Launch
Services Program requirements.

Correct me if I'm wrong, TESS booster was the last Block 4 SpaceX ever built, right?

Just like Jason3 launched on the last 1.1 ever launched.

Duh, this certification stuff really seriously lags behind SpaceX innovation speed.

It was delayed by *a month*.

How much does SpaceX routinely delay its manifest (for completely valid reasons, I'm sure)? Or is it just that some faction in SpaceX "seriously lags behind" another SpaceX faction's "innovation speed"?

Let's not go all fanboi into a SpaceX vs NASA discussion again. The reason reviews weren't done faster isn't stated, and I would guess having mission assurance oversight in order to prevent mishaps is something desirable, not the contrary. It doesn't matter if it was the last Block 4, the review on S2 COPVs (which caused two LOMs so far) wasn't mature on time.
-DaviD-

Offline CorvusCorax

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Re: SpaceX Falcon 9 : TESS : April 18, 2018 : Discussion
« Reply #359 on: 05/02/2018 04:35 AM »

It was delayed by *a month*.

How much does SpaceX routinely delay its manifest (for completely valid reasons, I'm sure)? Or is it just that some faction in SpaceX "seriously lags behind" another SpaceX faction's "innovation speed"?

Let's not go all fanboi into a SpaceX vs NASA discussion again. The reason reviews weren't done faster isn't stated, and I would guess having mission assurance oversight in order to prevent mishaps is something desirable, not the contrary. It doesn't matter if it was the last Block 4, the review on S2 COPVs (which caused two LOMs so far) wasn't mature on time.

My point wasn't so much the delay, but that more or less for a second time in a row, certification wasn't complete until after the vehicle in question was already out of production in favor of a not yet certifued successor.

This has nothing to do with NASA vs. SpaceX in particular, its rather a common symptom seen in fields with fast innovation cycles.

In my last job, we build wireless sensors, which we needed to put through a certification process due to radio emissions. We had it more than once that by the time we finally had a device iteration certified, one of the chips used in the design was already marked "obsolete" by the manufacturer, Especially in the field of telco microelectronics, some components meanwhile have a generation life of under 1 year. From the time a chip becones available for the general public for prototyping.until end of production is sometimes less than 6 months.

Thats might be OK for smartphone manufacturers who are used to it, but not enough to complete cert tests and paperwork for a small startup, and ramp up production.

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