Launch Escape Systems on unmanned rockets

[Ultimate Steve]

So, as far as I know, launch escape systems have only been used on crewed rockets so far (I mean, and the ones carrying chimps and stuff, but you get my point).

A while back, I got to thinking about the James Webb Space Telescope and how it has taken over ten billion dollars to develop. It is one of those payloads that cannot fail no matter what.

So, my question is, do you think it would be beneficial if, for super-valuable payloads like the JWST to use some sort of a launch escape system?

For the JWST, I can see a few obstacles.

1. The only place to mount an LES would be above or below the fairing. Above means significant fairing reinforcement would be required, below would mean it would stand a significantly higher chance of being destroyed by the explosion.

2. The JWST may not be able to withstand the high acceleration of a launch abort.

3. It would require significant time put into designing a recovery system. JWST is big and bulky, and might be one of the biggest things we've ever tried to land under parachute - not to mention that it was never designed for recovery in the first place.

So, for the JWST, this late in development, my guess would be "no." At this point, with a ~2% chance of launch failure, it probably wouldn't be worth it.

But, for future $10bn+ payloads, should they be designed with that capability in mind?

Thoughts?

Edited May 5, 2017 by Ultimate Steve

[sojourner]

The G's pulled by a launch abort system would trash pretty much any satellite you tried to save with it.  Designing satellites tough enough to survive a launch abort would be prohibitive  in mass usage. Most of the mass of the satellite would be taken up for a scenario that would be only seconds of it's planned life. It's cost prohibitive.

 

This is why payload customers are perfectly fine with holds and scrubs for the least little variable out of range. Better to wait a day and fix that out of range sensor than take a chance with a multi-million dollar payload.

[p1t1o]

One word: Insurance.

Its much easier to just insure the payload for 10billion, or however much.

https://en.wikipedia.org/wiki/Satellite_insurance

 

[Streetwind]

Also, it didn't cost "more than ten billion to develop". It's approaching 9 billion when including the cost of operating its five-year primary mission.

Just because I have nothing better to do right now than to be a silly nitpick

[magnemoe]

An real escape system would be out of question. 
However with an fully reusable second stage it open the option to let second stage do an return to pad with payload abort,
this require landing bottom first obviously and that the legs can manage the extra weight of the payload and fairing in an emergency.
it will also require you to burn of most fuel before landing but might be smart to have as outside of the landing legs its mostly software. 
 

[StrandedonEarth]

Well, after the mid-flight second-stage breakup of a CRS mission (forget which one) that the Dragon survived until impact, SpaceX added an abort/recovery sequence to the software for that contingency. Hopefully it will never be tested/used. 

[Zeiss Ikon]

On 5/5/2017 at 10:34 AM, magnemoe said:

An real escape system would be out of question. 
However with an fully reusable second stage it open the option to let second stage do an return to pad with payload abort,
this require landing bottom first obviously and that the legs can manage the extra weight of the payload and fairing in an emergency.
it will also require you to burn of most fuel before landing but might be smart to have as outside of the landing legs its mostly software. 
 

I'm pretty sure the second stage of the Falcon 9 isn't capable of 1 G with a near-maximum payload and intact fairing (it's the Vacuum Merlin engine, which is nearly useless at sea level -- and because of regenerative cooling, you can't just use an explosive shaped charge to shorten the nozzle bell to "convert" to a sea level expansion ratio), never mind the roughly 3 G needed for the F9 booster landing profile (a better suicide burn I've never seen).  Even after burning off its fuel, there's just too much mass there to slow down enough.

Carrying landing legs on the second stage isn't likely to happen soon, as every gram of legs, as well as the hydraulics to extend them and operate grid fins, plus the cold gas attitude jet system, comes directly off the allowable payload.  Landing the second stage like the booster would require a ground-up redesign of the second stage (and hence the booster, because of mass gains) to retain existing payload capacity.

[magnemoe]

37 minutes ago, Zeiss Ikon said:

I'm pretty sure the second stage of the Falcon 9 isn't capable of 1 G with a near-maximum payload and intact fairing (it's the Vacuum Merlin engine, which is nearly useless at sea level -- and because of regenerative cooling, you can't just use an explosive shaped charge to shorten the nozzle bell to "convert" to a sea level expansion ratio), never mind the roughly 3 G needed for the F9 booster landing profile (a better suicide burn I've never seen).  Even after burning off its fuel, there's just too much mass there to slow down enough.

Carrying landing legs on the second stage isn't likely to happen soon, as every gram of legs, as well as the hydraulics to extend them and operate grid fins, plus the cold gas attitude jet system, comes directly off the allowable payload.  Landing the second stage like the booster would require a ground-up redesign of the second stage (and hence the booster, because of mass gains) to retain existing payload capacity.

One animation showed an retractable engine bell.
An favorite in this forum is an bolt on nose with heat shield, engines and landing legs
And yes any recovered upper stage would give you an falcon heavy with falcon 9 performance but with full recovery and an fast turnover it would probably work out, more so as you can sacrifice parts to increase payload up to super heavy lift. 

My thought was that an tail landing would give the return payload to pad theoretical option who customers and fans would like 
 

[tater]

For delicate payloads inside a fairing, such a system seems pretty unlikely for reasons already mentioned above. It's not a fundamentally bad idea, however, it seems to me that all things being equal, partial recovery must be worth something. 

F9 payloads already have to endure launch loads of -2 to +6 g axial acceleration, and +-2g lateral (according to the F9 Payload User's Guide). Presumably they are fabricated with at least a little slop as margin. D2 launch abort is actually well within that at around 4 gs as tested on the pad, anyway.

Edited May 6, 2017 by tater
typo

[tater]

New Horizons experienced 14g on the burn out from Earth, apparently (!).

The problem is not likely load, it's salt water, as it's landing where it lands.

Edited May 6, 2017 by tater

[magnemoe]

8 minutes ago, tater said:

New Horizons experienced 14g on the burn out from Earth, apparently (!).

The problem is not likely load, it's salt water, as it's landing where it lands.

Forget water simply enough, second stage will have an significant boost back performance anyway, so much it will probably do propulsion braking and still has to burn fuel before landing. 
Any fail to second stage would be fail anyway. 

[Motokid600]

Is a heavily damaged satellite cheaper to refurbish then it is to build a new one? How about time? JWST is like a decade in the works now, right? So even if it gets damaged surly it would take less time to refurbish then to build a new one.

[Steel]

12 minutes ago, Motokid600 said:

Is a heavily damaged satellite cheaper to refurbish then it is to build a new one? How about time? JWST is like a decade in the works now, right? So even if it gets damaged surly it would take less time to refurbish then to build a new one.

To be honest I'd imagine it's probably a case that any damage to the mirror and you're back to square one

[kerbiloid]

11 hours ago, tater said:

The problem is not likely load, it's salt water, as it's landing where it lands.

Kazakhstan has a lack of salt water (as also of any water). But LES still isn't used for unhuman payloads.

11 hours ago, tater said:

New Horizons experienced 14g on the burn out from Earth, apparently (!).

And unlikely this could be a compliment for the flight planners.

[tater]

Light spacecraft that went from Earth to the Moon in what, 3-6 hours? The 14 g was the second stage, it was very much planned.

[Motokid600]

On 5/6/2017 at 4:22 PM, Steel said:

To be honest I'd imagine it's probably a case that any damage to the mirror and you're back to square one

Id imagine even if one mirror were to survive that's one less thing you have to do for a rebuild. Im sure you know JWST is made of multiple mirrors. Either way... this mission may be the most white knuckle launch since the first space shuttle when it does go off.

[StrandedonEarth]

3 hours ago, Motokid600 said:

this mission may be the most white knuckle launch since the first space shuttle when it does go off.

It'll be white-knuckle-fingernails-chewed-to-the-quick until First Light. So they should put it on the first launch of the F9H... NOT!!

[PrathamK]

I don't know how many but, i know to LES-Abort was engaged by USSR on a Soyuz (Manned) and on N-1 L3 (Unmanned), its Lunar Payload was successfully recovered after the Largest Non-Nuclear Explosion by Worlds Largest and Most Powerful Rocket. Lunar payload was however Heavy and Tought not lioe JWST. Rocket Failure have less chances depending on Launcher (Which Launcher is to use To launch JWST?). They may make sure to causes and Six Sigma.

On 5/7/2017 at 9:34 AM, kerbiloid said:

Kazakhstan has a lack of salt water (as also of any water). But LES still isn't used for unhuman payloads.

I don't know how many but, i know to LES-Abort was engaged by USSR on a Soyuz (Manned) and on N-1 L3 (Unmanned), its Lunar Payload was successfully recovered after the Largest Non-Nuclear Explosion by Worlds Largest and Most Powerful Rocket. Lunar payload was however Heavy and Tought not lioe JWST. Rocket Failure have less chances depending on Launcher (Which Launcher is to use To launch JWST?). They may make sure to causes and Six Sigma.

[kerbiloid]

L-3 was a mockup of a crewed ship, so it was equipped with LES as it would be in a crewed flight.

https://translate.google.ru/translate?sl=ru&tl=en&js=y&prev=_t&hl=ru&ie=UTF-8&u=http%3A%2F%2Fwww.buran.ru%2Fhtm%2Fgud%2019.htm&edit-text=

Edited May 10, 2017 by kerbiloid

[PrathamK]

N-1 was used to launch Super-Heavy payloads to Moon. And even a Crew for Lunar Landing.

https://en.m.wikipedia.org/wiki/N1_(rocket)

See Launch History and LES pulls out the Spacecraft.

Edited May 10, 2017 by PrathamK

[kerbiloid]

L3 complex from N1-L3

Spoiler