New Mars Forums

The size of SRB’s used also has to considered. It’s the size of the SRB’s on the Ariane 6 that make them so expensive, resulting in the Ariane 6 itself being so expensive. Solid side boosters are commonly 1/10th the size in mass of the core stage they’re attached to. This is true of the Delta IV and Atlas 5 SRB’s, and continues to be true with the new Vulcan Centaur with its GEM 63XL side boosters.

Notable exceptions were the Space Shuttle system and the Space Launch System with their huge SRB’s, with both systems being financial disasters.

The SRB’s on the Ariane 6 instead of being 1/10th size of the core are the same size as the core in mass.

Imagine what the cost of the Delta IV would be if each SRB used was made 10 times its current size.

  Bob Clark

Because of the high thrust solids are good at liftoff, but only if they are small. And this is commonly the case like the solids used for the Atlas 5 or Delta IV, where the solids were only about 1/10th the size of the core stage. They become a poor choice when they are made large like happened with the Space Shuttle and SLS. Their large size, each comparable to the size of the entire core stage mass, contributed to both of those being financial disasters.

The large SRB’s on the Ariane 6 also are financial disasters. They are also each comparable in size to the entire core stage. They are the sole reason why the two versions of the Ariane 6 are so expensive, which will likely lead to ArianeSpace going bankrupt if they go ahead with fielding them at 2 to 3 times higher price than the going rate of the Falcon 9’s used price.

  Bob Clark

Avi Loeb describes the search for the remnants of the interstellar meteorite here:

Corroded Iron and Volcanic Debris in IM1’s Path.
Avi Loeb
https://avi-loeb.medium.com/corroded-ir … bf317bcb0e

I’m surprised they were able to get the expedition up and running so quickly.

   Robert Clark

Just saw this, though I wouldn’t call Loeb a Pentagon researcher:

Pentagon UFO researcher finds something very strange in the Pacific!
https://youtu.be/JgxarjzvLOo

  Bob Clark

Got this response when I asked ChatGPT what is the difference between “Old Space” and “New Space”:

______________________________________________

The terms "Old Space" and "New Space" are not widely recognized or universally defined. However, they may refer to different eras or approaches within the space industry.

"Old Space" could be used to describe the traditional space industry that emerged during the Cold War era, dominated by government space agencies like NASA and Roscosmos. This period focused on large-scale, government-funded space exploration and scientific missions.

On the other hand, "New Space" typically refers to the more recent emergence of private companies and startups in the space industry. These companies, such as SpaceX, Blue Origin, and Virgin Galactic, aim to commercialize space activities, reduce costs, and develop reusable space systems. They have introduced innovative approaches to space exploration, satellite launches, and space tourism.

While "Old Space" often involves national space programs with substantial government involvement, "New Space" emphasizes private sector initiatives and entrepreneurial efforts to expand the boundaries of space exploration and exploit its commercial potential.

It's important to note that these terms are not universally defined, and their meaning can vary depending on the context or perspective of the discussion.
______________________________________________

A fairly reasonable explanation. I would only quibble about the not universally recognized part. That’s probably true about the general public but anyone in the industry and anyone familiar with the industry would know what they mean.

The key problem though with these big government-paid projects is the Old Space companies serving them believe the costs also need to be big - and they’ll do whatever it takes to keep them so.

  Bob Clark

There are also considerations of cost, and reusability. All of the new launch start-ups in both the U.S. and Europe are using all-liquid propulsion, as of course SpaceX also does. And all the new start-ups  are focused on reusability. No future launch company is going to be able to compete with SpaceX prices without reusability. ULA was driven to the brink of bankruptcy by denying reusability. ArianeSpace likely will also by fielding non-reusable rockets priced 2 and 3 times higher than the SpaceX going rate of $40 million for the reused Falcon 9.

About that cost issue and why the solids are so much worse for the Ariane 6 compared to those on for example the Atlas V and Delta IV, the GEM SRB’s used on the Atlas V and Delta IV are only ~30 tons prop load, this in relation to the 300 tons and 200 tons of the cores on the Atlas V and Delta IV, respectively.

But for Ariane 6, the prop load on the side boosters is ~140 tons, nearly 5 times higher than the GEM SRB’s. The Ariane 6 solids are nearly the size of the entire core stage in prop mass. So the two solids are about twice the mass of the Ariane 6 core, and the four solids version about 4 times the size of the core in mass.

GW, look up the price of the GEM SRB’s. Now imagine the cost for the Ariane 6 SRB’s at 5 times larger size.

  Robert Clark

The greatest mass of the SRB version of the Ariane 6 is those SRB’s so if those are removed you have much less mass the two or three Vulcains would have to loft. Actually, three Vulcains would be preferred because you can then use larger upper stages and so get a larger payload. Its just that that might require more strengthening of the tanks due to the higher thrust.

About the two Vulcain case, I also used a smaller upper stage because of the lift-off thrust constraints. I didn’t use the 30 ton Ariane 6 upper stage, nor the 19 ton Ariane 5 upper stage. I used the 13 ton Ariane 4 H10 upper stage:

ARIANE 4 STAGE 3
Specifications are given in H10/H10+/H10-3 order.
Designation: H10/H10+/H10-3
Engine: single cryogenic open cycle SEP HM-7B
Length: 10.73 m/11.05 m/11.05 m
Diameter: 2.60 m
Dry mass: 1,200 kg/1,240 kg/1,240 kg, excluding interstage 2/3
Oxidizer: liquid oxygen
Fuel: liquid hydrogen
Propellant mass: 10,800 kg/11,140 kg/11,860 kg
Thrust: 63 kN vac/63.2 kN vac/64.8 kN vac
http://www.braeunig.us/space/specs/ariane.htm

Note that in addition to being lighter this has a much better mass ratio at over 10 to 1, rivaling the famous Centaur upper stage. As you know mass ratio or propellant fraction is an important parameter for a rocket stage. A mass ratio greater than 10 to 1 means the propellant fraction is above 90%.

Given these numbers I get a payload to LEO for the two Vulcain case that’s above the 10 tons of the Ariane 62 that uses two SRB’s. The reason the Vulcain’s can give a better payload than using the higher thrust SRB’s is the Vulcains being hydrolox have a much better ISP, ~432s compared to ~270s for the SRB’s.

Actually, after doing a calculation I was surprised to see there is a reason that makes it ABSOLUTELY IMPERATIVE THAT ESA produce the all-liquid version of the Ariane 6. On a key measure that rocket engineers use all the time I was startled to see the resulting all-liquid Ariane 6 would literally be the best rocket ever produced. Better than the Falcon 9, Atlas 5, Delta IV, Soyuz, Saturn V, anything, on this key measure that engineers use to rate rockets. And it’s not just a little bit better; it’s majorly better than any other rocket ever made on this key criterion that engineers use.

So switching to all-liquid Ariane 6 gives a cheaper rocket that’s even cheaper than the Falcon 9, can be made reusable in being all-liquid, is manned flight capable, requires a small development cost compared to the SRB version, and is literally a revolutionary advance on this key measure of rocket efficiency that no other rocket has ever gotten close to.

  Robert Clark

In my blog post I noted the reason why ESA is using the more expensive solid rocket boosters rather than just adding another Vulcain is political. The majority of the development funds and revenues from launch go to those ESA member states producing the solids, more than the amount going to all the other member states combined. If those solids were no longer used that majority of funds would drop down to nearly nothing.

So that‘s a severe political problem for the other member states who might want to go to an all-liquid propulsion form for the Ariane 6. But there may be away to get there anyway. If a member state wanted to spend their own money to build a prototype Ariane 6 core using two Vulcains how could other member states prevent it? It’s their own money. They can spend it anyway they want. Remember quite key to why this is approach is preferable is because how low cost the development costs would be. The example of JAXA adding a second hydrolox engine to the H-II core for ca. $200 million(27 billion Yen) demonstrates this:

In point of fact it’s probably even cheaper than this just to add the second engine. The transition from the H-IIa to the H-IIb actually involved multiple systems:

Then conceivably the development cost just for adding the engine only might be only $100 million or less. But when there is no multi-billion dollar development cost, any of the ESA member states could afford to add an additional engine to an Ariane 5/6 core on their own. It’s so low that even the member states that spent billions developing the solids could also adapt a Ariane core to have two Vulcains at this low cost.

At such a low development cost and each per rocket cost being even lower than the Falcon 9 each ESA member state could have their own independent all-liquid Ariane launchers. And each ESA member state could have their own independent manned flight capable rockets.

Robert Clark

There needs to be an overall independent review of the safety of the SuperHeavy/Starship launch. That independent review needs to include the lax standards the FAA applied to the SH/SS launch. SpaceX and the FAA dodged a bullet in the last launch.

Agencies studying safety issues of LOX/methane launch vehicles. 
Jeff Foust.
May 20, 2023 
WASHINGTON — Three U.S. government agencies are undertaking studies to examine the safety issues associated with a new generation of launch vehicles that use liquid oxygen and methane propellants.
At a May 15 meeting of the Federal Aviation Administration’s Commercial Space Transportation Advisory Group (COMSTAC), FAA officials described efforts that are underway to understand the explosive effects of that propellant combination in the event of a launch accident.
https://spacenews.com/agencies-studying … -vehicles/

Robert Clark

By the largest jumbo jets I mean literally THE largest jumbo jets. That’s the most appropriate comparison to make when SpaceX is proposing to use ONLY the SuperHeavy/Starship for ALL space flight. The point I’m making is there are many smaller but still commercial aircraft making the great majority of air flights. If instead the airlines ONLY offered the LARGEST jumbo jets they would rapidly go out of business.

   Robert Clark