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#1 2018-08-13 20:54:14

EdwardHeisler
Member
Registered: 2017-09-20
Posts: 357

Bridenstine: "SLS is unmatched in the world and will remain unmatched"

Guess James Bridenstine isn't familiar with SpaceX and their BFR project.   Oh he is just spreading some more Trump b.s.

[Excerpt from article]

NASA Administrator Supports Trump’s ‘Space Force’ Proposal
THE ASSOCIATED PRESS (KEVIN McGILL)
August 13, 2018

NASA Administrator Jim Bridenstine expressed full support Monday for President Donald Trump's proposed military "Space Force" but added that it will have a role separate from NASA.

Bridenstine was touring the Michoud Assembly Center, where workers are putting together major parts of systems that are planned to return Americans to the moon and, eventually, take them to Mars. In a towering building, Boeing workers are building parts of the 322-foot (98-meter) rocket known as the Space Launch System. Lockheed Martin workers are building the spacecraft called Orion.

Bridenstine praised workers at Michoud for their work on the Orion spacecraft and the SLS rocket that will launch it into space, saying their efforts are helping the U.S. get ahead and stay ahead of other nations in space.

"This is a brand new, very large project that is unmatched in the world," he said. "And it will remain unmatched for a very long time."

https://www.bloomberg.com/news/articles … e-proposal

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#2 2018-08-14 04:28:20

louis
Member
From: UK
Registered: 2008-03-24
Posts: 7,208

Re: Bridenstine: "SLS is unmatched in the world and will remain unmatched"

Isn't the SLS somewhat larger than the BFR? But given neither is operational, it's a moot point.

EdwardHeisler wrote:

Guess James Bridenstine isn't familiar with SpaceX and their BFR project.   Oh he is just spreading some more Trump b.s.

[Excerpt from article]

NASA Administrator Supports Trump’s ‘Space Force’ Proposal
THE ASSOCIATED PRESS (KEVIN McGILL)
August 13, 2018

NASA Administrator Jim Bridenstine expressed full support Monday for President Donald Trump's proposed military "Space Force" but added that it will have a role separate from NASA.

Bridenstine was touring the Michoud Assembly Center, where workers are putting together major parts of systems that are planned to return Americans to the moon and, eventually, take them to Mars. In a towering building, Boeing workers are building parts of the 322-foot (98-meter) rocket known as the Space Launch System. Lockheed Martin workers are building the spacecraft called Orion.

Bridenstine praised workers at Michoud for their work on the Orion spacecraft and the SLS rocket that will launch it into space, saying their efforts are helping the U.S. get ahead and stay ahead of other nations in space.

"This is a brand new, very large project that is unmatched in the world," he said. "And it will remain unmatched for a very long time."

https://www.bloomberg.com/news/articles … e-proposal


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#3 2018-08-14 07:34:50

EdwardHeisler
Member
Registered: 2017-09-20
Posts: 357

Re: Bridenstine: "SLS is unmatched in the world and will remain unmatched"

The answer to your question is no.  It is smaller and will have far less power than the BFR if it is every completed and launched.

And the NASA administrators claim that the SLS is "a brand new project" is not true.   More b.s. from the Trump government.

The BFR will begin testing next year the  SLS may never make it off a launch pad.

It will not be a "moot" issue next year.

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#4 2018-08-14 08:07:06

louis
Member
From: UK
Registered: 2008-03-24
Posts: 7,208

Re: Bridenstine: "SLS is unmatched in the world and will remain unmatched"

Apologies. Got that wrong. I did however agree that the SLS might be overtaken by the BFR. Need to take account of pork barrel politics though...maybe there will be an agreement for the ULA to build variations of the BFR under licence.

EdwardHeisler wrote:

The answer to your question is no.  It is smaller and will have far less power than the BFR if it is every completed and launched.

And the NASA administrators claim that the SLS is "a brand new project" is not true.   More b.s. from the Trump government.

The BFR will begin testing next year the  SLS may never make it off a launch pad.

It will not be a "moot" issue next year.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#5 2018-08-14 15:46:42

EdwardHeisler
Member
Registered: 2017-09-20
Posts: 357

Re: Bridenstine: "SLS is unmatched in the world and will remain unmatched"

Apologies not needed.   Some are suggesting that the SLS be cancelled and that NASA simply use the BFR and pay SpaceX for seats and payloads using the BFR rather than spend another 10 billion for the SLS.

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#6 2018-08-14 16:54:49

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 28,747

Re: Bridenstine: "SLS is unmatched in the world and will remain unmatched"

When you total in the 4 tankers that must go to refuel the second stage then we are not looking at the same apples to apples. A rocket that can not do anything once in orbit is useless. I am not sure that it can even retropropulsion land on earth as no parachutes are able to perform to that much mass..

SLS even with its expensive dollars are at least capable of doing something once there.

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#7 2018-08-14 17:18:17

GW Johnson
Member
From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 5,423
Website

Re: Bridenstine: "SLS is unmatched in the world and will remain unmatched"

BFR/BFS is supposed to be a fully reusable system,  with a fly-back booster (BFR) and a fly-back second stage (BFS) that doubles as an interplanetary spacecraft if refuelled on-orbit. 

The first stage booster flies back the same way that Falcon booster stages fly back,  just scaled up larger. 

The second stage flies back an aerobraking entry much like the space shuttle,  but then pitches up for a retro-propulsive landing,  the likes of which we have not really seen before,  except in 1950's science fiction,  such as "Rocky Jones,  Space Ranger".   

Used as a transport to low Earth orbit,  BFR/BFS require no refueling.  The propellants in the BFS second stage get expended reaching orbit,  except for the retro-propulsive landing allowance.  Payload estimates vary,  but are in the same 100 ton class as SLS.  Edit:  that would be something around 100 metric tons delivered to low Earth orbit.  100-ton "class" is anything from 70 to 150 tons actual payload,  far greater than anything flying today,  except Falcon-Heavy,  which comes close,  at over 60 tons. All the rest are under 20-25 tons.

If refuelled from tankers on-orbit,  the very same second stage hardware becomes feasible as an interplanetary vehicle,  and in the same 100-ton payload class all the way to Mars or the moon. Edit:  the differences are (1) that BFS is recoverable and reusable,  and SLS is not, and (2) BFS actually is the interplanetary vehicle that carries the full 100 ton class payload internally,  while SLS must carry the interplanetary vehicle and landing means,  as a separately engineered item,  which in turn subtracts from ultimate payload capability.   

My best estimates are that 6,  not 4,  tankers are required to fully refill a BFS on-orbit in order to send full payload one-way to Mars. What Spacex has posted is unclear about how many such tankers are needed for that mission.

Given propellant production on Mars,  it becomes feasible to refill a BFS once landed on Mars,  so that it can return for a free-return aerobraked/retropropulsive landing on Earth.  In that sense,  reusability is maintained,  something SLS can never,  ever do. 

Without feasible propellant production on Mars,  BFS offers only a one-way,  one-time throwaway use to land 100-ton class payloads on Mars.  The aerobraking entry and retropropulsive touchdown at Mars are similar but not identical to what is planned for free returns from Earth orbit.  Or from the moon.  Edit:  or free returns from Mars. 

My best estimates say that BFS/BFR is capable of landing 100-ton-class payloads on the moon,  and returning for an aerobraking/retro-propulsive landing on Earth,  entirely unrefuelled on the moon.  Refuelling to full capacity on orbit in Earth orbit is required to make this capability real.   

The only shortfall with all of this,  is rough-field landing stability with a vehicle about 3 times taller than the span of its landing legs.  No such lander has ever before been attempted.  All have had landing leg spans greater than height.  Pre-prepared landing zones may (or may not) be required to use this vehicle for such missions. That has yet to be determined.  The stakes are VERY high!

It IS clear that BFR/BFS per-launch costs will be no more than something on the order of $200-300 million per flight (edit: and very probably less,  perhaps a lot less),  while SLS per-launch costs will be at,  or higher,  than $1 billion per flight.   Edit:  the past trend of these SLS cost estimates has been uniformly upward,  with critics claiming about twice NASA's estimates.

Edit:  further,  the second stage BFS vehicle doubles as a spacecraft capable of making landings while carrying the full rated payload internally.  There is nothing about the SLS,  or any payloads yet designed for it,  that can make either of those two claims. 

Edit:  neither vehicle has yet to fly in any sort of experimental test.  If Spacex holds to its intended timelines,  the very first experimental BFS-only short-hop tests will begin in late 2018,  or more likely during 2019.  The latest projections for the first flight of SLS hardware (which inherently has to be the whole vehicle with a less-capable third stage) have pushed first launch back to 2020. 

Edit:  should Spacex meet its projections,  then BFS should be experimentally flying atop its BFR first stage by the time of first SLS flight.  It is pointless to attempt predicting when either vehicle will complete its experimental and development test flights,  and be ready to enter service.  One might assume this will be around the same time somewhere in the early to mid 2020's. 

Edit:  same 100-ton payload class,  sooner first flight test,  far lower cost,  reusability,  and greater versatility (not to mention the general mission usefulness of a second stage that doubles as an interplanetary spacecraft) all speak to BFR/BFS being a much superior system,  as compared to SLS.  I'd like to see both fly,  but the better system will very probably prove to be BFR/BFS,  and fairly quickly,  once both do begin service.

Edit:  those conclusions are merely my own opinions,  but they are those of a rigorously trained mind, with long experience in real-world propulsion and flight vehicle work. 

GW

Last edited by GW Johnson (2018-08-15 13:01:49)


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#8 2018-08-18 09:18:34

kbd512
Administrator
Registered: 2015-01-02
Posts: 7,361

Re: Bridenstine: "SLS is unmatched in the world and will remain unmatched"

GW,

All good points, which is why some of us have repeatedly called for the cancellation of SLS.  Apart from spending our tax money, there's nothing else for that rocket to do.  I think the best use of the SLS core stage would be a second stage for BFR.  That should easily be a 250t to LEO vehicle.

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