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#1 2021-07-18 10:54:12

Oldfart1939
Member
Registered: 2016-11-26
Posts: 2,221

Nuclear Thermal rockets and an update.

Here's an interesting review and an update on where we are going.

https://www.youtube.com/watch?v=9DPndCZ1o3Q

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#2 2021-07-18 12:04:29

GW Johnson
Member
From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 4,571
Website

Re: Nuclear Thermal rockets and an update.

At the Dallas 2011 Mars Society convention,  I got to meet David Buden,  one of the last 3 or 4 surviving engineers who worked on the Rover program that led to NERVA.  Buden was in his 80's at that time,  and so would seem unlikely to still be with us.  At the time Nixon killed Apollo in 1972,  he really killed all human spaceflight outside Earth orbit. 

Nixon was no fan of manned space,  and wanted the manned program to only fiddle with spaceplanes and space stations.  And that is exactly what we did,  even long after Nixon was gone.  There are so many Saturn-5's on display,  because we built hardware to fly moon missions through Apollo-22,  when Apollo-17 was the very last one because of Nixon.

The NASA manned Mars mission,  way back then then slated for the 1987 opposition,  thus got killed by Nixon,  and accordingly NASA killed Rover,  because "who needs the engine if we aren't going to go?"  NERVA was baseline for that Mars mission.  As of program termination in 1973,  it was ready for its first test flight,  as the engine for an alternate third stage for Saturn 5.  The thing was literally flight test ready!

I am glad to see renewed government interest in nuclear thermal propulsion after half a century in limbo,  but I do not yet see a credible plan with a clear goal.  The first thing you would do is build and fly NERVA using the plans and technologies ready to fly back then.  But at the same time,  you would work on improved designs with the technology improvements identified over the last half century,  getting them into ground testing.  One or more of those could supplant the old NERVA design,  as soon as they become flight ready.

And,  as a parallel effort,  you start working on the two approaches to gas core nuclear thermal,  hoping to make one of those flyable down the line,  to supplant the improved NERVAs.

You get to start flying nuclear "right now",  and as the years go by,  you get to fly better and better nuclear devices.  But unless you do it as multiple parallel tracks,  starting with what actually worked long ago,  you will never fly anything nuclear. 

And so we have not,  not in half a century.  It's bad planning like that which tells me "the government" does NOT want to go,  only certain groups within it.

GW

Last edited by GW Johnson (2021-07-18 12:06:46)


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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#3 2021-07-18 12:41:02

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 23,078

Re: Nuclear Thermal rockets and an update.

Nixon's choice was control of the high ground to leaving science exploration not part of the plan in that cancelation not realizing that a détente in space would occur several years down the road.
The historic handshake between Russian Aleksei Leonov and American Tom Stafford on their 1975 mission marked the beginning of the end of the space race  formally ended on July 17, 1975.

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#4 2021-07-18 12:59:10

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,742
Website

Re: Nuclear Thermal rockets and an update.

I have to say I really hate that guy's voice. I'm interested in nuclear propulsion, but why that guy? He keeps trying to sound like Jack Nicholson. And he's got that length and annoying opening sequence. TV shows have opening credits, but one reason for the internet is to get away from the crap from TV. At least my ad blocker works with YouTube. That's why I use a browser and not the stupid YouTube app. And I really hate when someone says "we're going to talk about..."! Just say it already! Angry astronaut? I have short patience for someone yelling and always angry. So why him?

Oh! He also claimed nuclear electric propulsion can reduce transit time to Mars from 6 months to 100 days or less. Later in the video he talks about a 3 month, then 2 month journey. Really! Let's see some math to prove that.

This guy emphasizes nuclear electric propulsion. But that has major problems. Nuclear electric requires conversion of heat into electricity, with heat transfer and radiators. Nuclear thermal uses cold propellant directly to cool the reactor, with direct heat transfer from reactor core to propellant. No radiators, no converter. Nuclear thermal is smaller and lighter because it's simpler. Robert Zubrin calculated nuclear electric using available space reactors, and found it has greater launch mass than chemical rockets resulting in slower transit. The mass of the reactor is greater than any propellant saving due to higher specific impulse. I have asked Dr Zubrin to recalculate using SAFE-400 because that's the newest and lightest reactor, but he refused. Frankly, I expected the same result. The reason I asked Dr Zubrin to do this is to avoid someone else using the claim that new reactor design changes everything.

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#5 2021-07-18 13:29:32

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,742
Website

Re: Nuclear Thermal rockets and an update.

GW Johnson wrote:

There are so many Saturn-5's on display,  because we built hardware to fly moon missions through Apollo-22

Apollo 22? The Saturn V intended for Apollo 19 is currently on display at the Johnson Space Center in Houston, Texas. The first and second stages of the Saturn V intended for Apollo 18 were used to launch Skylab. The Saturn V current on display at the Kennedy Space Center in Florida consists of the 3rd stage for Apollo 18, the 2nd stage for Apollo 20, and the 1st stage is actually test stage: S-IC-T, an all-systems test stage, used for static test firing at Marshall Space Flight Center. It's fully complete in every way, but not intended to fly in space. The 1st stage for Apollo 20 was stored at the Michoud Assembly Facility in Louisiana for many years, current on display beside the road between Michoud and the Stennis Space Center in Mississippi. There's another Saturn V on display at the U.S. Space & Rocket Center in Huntsville Alabama. That one is all test stages: the 1st stage is SA-500D, with 1 real F-1 engine and 4 boiler plates. Used for vibration tests. S-II and S-IVB stages were also test stages. Here's an image of the 1st stage from the time in the 1960s... (click image for Wikipedia page)
250px-S-IC-D_positioning_for_shake_test.jpg

Here's what it looks like today... (click image for museum website)
picture3-9e8bfa666c-original-220x220.jpg picture2-3484243262-original-220x220.jpg one-pager-1-4014c1bc12-original-220x220.jpg

Saturn V intended for Apollo 20 was known as SA-515. Third stage of that was converted to a backup Skylab, also known as Skylab B. It's currently on display at the National Air and Space Museum. (click image for Wikipedia page)
240px-Skylab_B_Smithsonian.jpg

Skylab itself was converted from the upper stage for Saturn 1B launch vehicle SA-212. First stage was scrapped. SA-213 and SA-214, only the first stage was built, and they were scrapped. SA-207, SA-208, and SA-208 ferried astronauts to Skylab. SA-209 is on display at the KSC rocket garden. SA-210 was used for Apollo-Soyuz. SA-211 on display at Alabama Welcome Center on I-65 in Ardmore, Alabama.

CSM-115 intended for Apollo 19 was never fully completed. Don't know what happened to it, probably scrapped. CSM-115a intended for Apollo 20 on display at JSC. CSM-116, CSM-117, CSM-118 used for Skylab missions. CSM-119 on display at KSC.

Lunar Modules: LM-13 intended for Apollo 19 on display at Cradle of Aviation Museum (Long Island, NY). LM-14 never completed, most likely scrapped. LM-15 intended for Apollo 20, was going to be converted to Apollo Telescope Mount for Skylab (or Skylab B?), scrapped.

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