Author Topic: SpaceX Falcon 9 : TESS : April 18, 2018 : Discussion  (Read 192392 times)

Offline dror

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Re: SpaceX Falcon 9 : TESS : NET April 16, 2018 : Discussion
« Reply #220 on: 04/14/2018 06:35 pm »
TESS is tiny. Was there ever a point when it was considered a possible payload for the cancelled Falcon-1e?

Also, the Falcon 1e was cancelled long before the award of the TESS launch contract (in Dec. 2014), it was always going to fly on a Falcon 9.

In the TESS video, they said they designed it for a Minotaur and that the Falcon 9 was a "monster" IIRC.  So they designed it for a much smaller rocket and got a F9 in the end.  They would have designed it differently if it were slated for a F9 from the start.

They knew it was F9 since 2014, do you think it had an effect on the final build?
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Offline 2008rlctx

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Re: SpaceX Falcon 9 : TESS : NET April 16, 2018 : Discussion
« Reply #221 on: 04/14/2018 08:46 pm »
So is it a huge let down to all of the engineers, designers, and the like that worked countless hours saving grams off of each piece of TESS that it's now the lightest payload ever flown by Falcon 9 and could have been much more massive?

Offline vaporcobra

So is it a huge let down to all of the engineers, designers, and the like that worked countless hours saving grams off of each piece of TESS that it's now the lightest payload ever flown by Falcon 9 and could have been much more massive?

Only if it seriously impacted its ability to do good science. There's no doubt that a magnitude greater mass allowance would have enabled far greater capabilities, but TESS was built as a Medium-Class Explorer, capping its cost at $180m. That cost does not include the launch vehicle, but it still is subject to the general law that the cost of science instruments held to the same standards will grow (at a minimum) proportionally with mass.


As a fascinating segue: I am truly stunned that with the launch first contracted in 2014 for August 2017, even after vehicle failures in 2015 and 2016, TESS' launch date slipped right EIGHT MONTHS. That feels like an insane achievement, to me.

Offline Joffan

TESS is tiny. Was there ever a point when it was considered a possible payload for the cancelled Falcon-1e?

The F9 is delivering TESS to a 200x 270 000km orbit, just a tiny bit outside the capabilities of falcon 1e.

I thought TESS has a kick stage to take it up from 600 x 600 to 600 x 200,000 km ... is Falcon handling that now?
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Offline Nomadd

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Re: SpaceX Falcon 9 : TESS : NET April 16, 2018 : Discussion
« Reply #224 on: 04/14/2018 10:56 pm »
 I assumed they weren't sending it to lunar L4/L5 because it didn't have a kick stage and the F9 2nd stage would have to fire after several days to do the job.
« Last Edit: 04/14/2018 10:56 pm by Nomadd »
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Offline Joffan

TESS was never going to a Lagrange Point, it has a 2:1 orbit period relative to the Moon. The orbit insertion video (which talks about the kick stage) includes an impressive Moon gravity assist.

https://www.youtube.com/watch?start=216&v=mpViVEO-ymc
« Last Edit: 04/15/2018 12:33 am by Joffan »
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Offline deruch

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Re: SpaceX Falcon 9 : TESS : NET April 16, 2018 : Discussion
« Reply #226 on: 04/15/2018 03:48 am »
TESS is tiny. Was there ever a point when it was considered a possible payload for the cancelled Falcon-1e?

The F9 is delivering TESS to a 200x 270 000km orbit, just a tiny bit outside the capabilities of falcon 1e.

I thought TESS has a kick stage to take it up from 600 x 600 to 600 x 200,000 km ... is Falcon handling that now?

The orbital insertion plan is different now.  Falcon is going to put it in a 200 km x ~275,000 km x 28.5 deg. initial orbit and the spacecraft's thrusters will perform a series of raising and phasing burns to get to the lunar encounter.  No more kick stage.

https://www.researchgate.net/publication/308260951_Monte_Carlo_Analysis_as_a_Trajectory_Design_Driver_for_the_TESS_Mission

http://spaceflight101.com/tess/tess-orbit-design/


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Offline Norm38

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Re: SpaceX Falcon 9 : TESS : NET April 16, 2018 : Discussion
« Reply #227 on: 04/15/2018 03:54 am »
So that is a pretty big benefit of the switch to F9. Eliminating the kick stage must eliminate a fair number of failure modes, a lot of complexity and all the cost that goes with that.
Not having to scrap over every gram can’t hurt either.

Offline wannamoonbase

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Re: SpaceX Falcon 9 : TESS : NET April 16, 2018 : Discussion
« Reply #228 on: 04/15/2018 04:25 am »
So that is a pretty big benefit of the switch to F9. Eliminating the kick stage must eliminate a fair number of failure modes, a lot of complexity and all the cost that goes with that.
Not having to scrap over every gram can’t hurt either.

That and a couple hundred million bucks cheaper.

I look forward to seeing what probes NASA produces when launches are $60 million instead of $200 or $300.

Surely there are scientists day dreaming about what payloads they can put on a FH.

Do a great job on this one SpaceX and you're on your way.

The TESS data is going to be amazing too, can't wait.
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Offline Zed_Noir

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Re: SpaceX Falcon 9 : TESS : NET April 16, 2018 : Discussion
« Reply #229 on: 04/15/2018 02:01 pm »
So that is a pretty big benefit of the switch to F9. Eliminating the kick stage must eliminate a fair number of failure modes, a lot of complexity and all the cost that goes with that.
Not having to scrap over every gram can’t hurt either.

That and a couple hundred million bucks cheaper.

I look forward to seeing what probes NASA produces when launches are $60 million instead of $200 or $300.

Surely there are scientists day dreaming about what payloads they can put on a FH.

Do a great job on this one SpaceX and you're on your way.

The TESS data is going to be amazing too, can't wait.

Maybe a few million bucks cheaper. The TESS was baseline on the Minotaur-C (re-branded Taurus) or the Athena IIc with a Star-37FM kick motor added.

AIUI TESS was originally designed for higher acceleration of a solid launcher, so the F9 upper stage will not be throttling back as much like for other payloads. Maybe SpaceX will over-performed with final orbital insertion burn and add many more years of service life.

Offline gongora

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Re: SpaceX Falcon 9 : TESS : NET April 16, 2018 : Discussion
« Reply #230 on: 04/15/2018 02:40 pm »
AIUI TESS was originally designed for higher acceleration of a solid launcher, so the F9 upper stage will not be throttling back as much like for other payloads. Maybe SpaceX will over-performed with final orbital insertion burn and add many more years of service life.

When your orbital maneuvers require interacting with the Moon's gravity it might not be great to be dropped off too far from your calculated destination.

Offline as58

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Re: SpaceX Falcon 9 : TESS : NET April 16, 2018 : Discussion
« Reply #231 on: 04/15/2018 03:21 pm »
As a fascinating segue: I am truly stunned that with the launch first contracted in 2014 for August 2017, even after vehicle failures in 2015 and 2016, TESS' launch date slipped right EIGHT MONTHS. That feels like an insane achievement, to me.

I'm not sure what you mean. TESS development schedule determined the launch date, so why should launch failures be expected to change it? Sure, if a failure happens shortly before the expected launch, then there would probably be a delay until the rocket gets cleared to launch again, but that's not the case here.

Offline OnWithTheShow

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Re: SpaceX Falcon 9 : TESS : NET April 16, 2018 : Discussion
« Reply #232 on: 04/15/2018 06:39 pm »
Quote
For TESS, 30 second launch window is for COLA (Collision Avoidance).  Should a COLA be needed, they can shift the launch time by as much as 30 seconds to the right.

Collision with what? Uncharted space debris? How would it be detected and relayed to the launch team?

Offline jcm

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Re: SpaceX Falcon 9 : TESS : NET April 16, 2018 : Discussion
« Reply #233 on: 04/15/2018 07:26 pm »
On updates thread, statement was made that F9 does 40 minute coast before stage 2 SEIG-2, and that
TESS separates at launch plus 44 minutes. One of these is wrong... I suspect SEIG-2 at  launch + 40 min, not SECO-1 + 40 min?

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Offline Joffan

Great (double) question Chris, sounded like you hit something he really wanted to talk about :) and I got a Twitter question through as well on crowd-sourcing / citizen science - we could just dominate these briefings... :D
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Quote
SpaceX will try to bring rocket upper stage back from orbital velocity using a giant party balloon

April's Fools was two weeks ago, so he's a bit late.

Offline Robotbeat

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Re: SpaceX Falcon 9 : TESS : NET April 16, 2018 : Discussion
« Reply #236 on: 04/15/2018 11:20 pm »
Quote
SpaceX will try to bring rocket upper stage back from orbital velocity using a giant party balloon

April's Fools was two weeks ago, so he's a bit late.
I think he’s serious. Kinda. I mean, doubt it’s a party balloon, for instance.

We’ll see. Musk likes to troll the tech media.
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Offline Mader Levap

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Re: SpaceX Falcon 9 : TESS : NET April 16, 2018 : Discussion
« Reply #237 on: 04/15/2018 11:25 pm »
I think there was some discussions about doing some shenanigans with second stage (not full recovery) in past. Maybe whatever mechanism they will use resembles giant party balloon if you squint hard enough.
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Offline rockets4life97

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Re: SpaceX Falcon 9 : TESS : NET April 16, 2018 : Discussion
« Reply #238 on: 04/15/2018 11:28 pm »
A super light payload seems like the right opportunity to try it out. Lots of margin to try and maneuver the second stage in whatever way best helps with re-entry.

Offline jimbowman

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Re: SpaceX Falcon 9 : TESS : NET April 16, 2018 : Discussion
« Reply #239 on: 04/15/2018 11:32 pm »
helium balloon or something?

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