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Comment by BurningFrog | Hacker News Reader

To me, this is a major dysfunction of the NASA model.

Why wasn't 5 Hubble telescopes launched? The marginal cost for the other 4 must have been vastly smaller than the first. Observation time on the original Hubble is still, after 30+ years a scarce resource. With 5 of them, we could have gotten vastly more science done at smaller cost.

I don't have a fully fleshed out theory for why, but part of it is that NASA as a government organization is ultimately a political endeavour, and it will have to optimize for what makes politicians look good in the press, rather than what gives the most science bang per buck.

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> Why wasn't 5 Hubble telescopes launched? The marginal cost for the other 4 must have been vastly smaller than the first.

Economies of scale only apply at, well, scale. Five Hubbles would cost 5x one Hubble to construct. There's very little in the way of savings because most parts are custom fabricated. The parts need to be tested, integrated, then tested after integration. The testing and verification of each subsystem takes the same number of person-hours. So testing 5x the systems requires 5x the time.

You can't just accept a high failure rate of something the size of Hubble just because you've built five of them. If you launched a Hubble and it failed in some Loss of Vehicle fashion after inserted into orbit you've got a big uncontrollable mass of telescope flying around the Earth.

Even if we still had the Space Shuttle (or a fantasy version of the SpaceX Starship) flying an uncontrollable Hubble couldn't necessarily be retrieved. If it wasn't accepting commands and was spinning on some axis it would be too dangerous to approach with another vehicle. Even an unmanned vehicle couldn't necessarily approach it without a collision that causes even more problems. See the recent idiotic Russian ASAT test for an object lesson in what could happen.

This is all to say you don't want some large satellite in a long lived orbit to fail. So there's no savings on testing and verification. Even though at launch Hubble's mirror had problems the satellite itself was fully under control and operable.

Something like Starlink is very different. All the satellites in a given block are functionally identical and fungible. If one fails it's easily replaced by another. They also deploy to a low unstable orbit. If a Starlink satellite fails and is uncontrollable it will de orbit by itself quickly. They must be functional to enable the onboard engines that get them to a stable intended orbit. A Starlink satellite then needs far less testing and verification than a Hubble or JWST, not that they can be poor quality but they don't need to function Or Else Bad Things.

Is that really true? I'm guessing a big part of the cost is figuring out how to actually invent stuff needed for the project. That knowledge is now known. That cost is now 0.

>There's very little in the way of savings because most parts are custom fabricated. The parts need to be tested, integrated, then tested after integration.

To piggy back on the the GP's point, the fabrication research is only one small cost center. Quality control costs much more in aerospace than many people realize. The reason why a bolt may cost $150 is because it has to be tracked, material coupons kept/tracked/tested, held in bonded storage etc. and not because we had to figure out how to make a bolt. Those costs don't come down as much with scale as, say, raw material.

If it were all about knowledge costs, many designs today would be dramatically cheaper because many use technology (and even refurbished rockets) from 50 years ago.

Just because the knowledge exists in the world doesn’t mean that you know it. Consolidating knowledge is a non-trivial exercise.

> I'm guessing a big part of the cost is figuring out how to actually invent stuff needed for the project.

We're talking about marginal costs, not development costs. So the cost to invent a component is already out of the equation. The high production cost of something like Hubble comes from testing and validation more than materials or fabrication.

The failure modes for something big in space can be extremely dangerous. Even a tiny "cheap" cubesat requires a lot of relatively expensive testing so there's a reasonable assurance it won't fail in some catastrophic fashion and destroy the entire rocket.

Testing space hardware is additionally difficult because you can only just approximate the hardware's operating environment on the ground. Space hardware also can't be easily repaired or repaired at all once launched. So you've got to test actual flight hardware and if it fails possibly rebuild it from scratch testing and validating the entire way.

Developing space hardware and high precision science instruments is expensive and difficult. But it's just a small portion of the overall mission cost for something like Hubble or JWST.

I defer to your knowledge, i'm not trying to be a jerk. But Hubble took like 30 years? or so to develop and build? How long would a second Hubble take? I'd have to imagine it's less than 5 years, no? That has to be a huge cost savings. The testing process would have to be more streamlined or efficient, i would think. You have a much better understanding of failure modes.

The Hubble took a little over ten years to build and develop. It's launch was postponed to 1990 because of the Challenger disaster.

> The testing process would have to be more streamlined or efficient, i would think.

Why do you automatically assume testing for a complicated and delicate machine is inefficient or not streamlined? That's a pretty bold assumption with zero evidence.

Understanding failure modes doesn't help test and validate something any faster. There's a finite number of hours in a day and components need some proscribed amount of testing.

Hubble took ~12 years from initial funding to launch with the challenger disaster postponing it 4 years out of that. Additionally if the decision was made to use traditional mirror techniques the Hubble was predicted to launch in 5 years already, instead of the difficulty they found with the alternative method but they didn't know that at the outset.

You will encounter different bias the second time around. Although maybe this kind of stuff is less common in space industry. People could want to correct the mistakes of the first time. Spend time optimising things and taking more time. And people could take learned knowledge for granted and assume success was based on that.

If they had built five Hubbles that each had defective mirrors and all of them needed a shuttle visit to correct the issues and make them usable...

The US absolutely could've built 5 Hubbles - because it did, they just don't look at Space - they look at Earth. The Hubble is basically a KH-11 spy sat chassis. NASA was given a gentle suggestion that if the optics package was a particular size, there was definitely a company in the US which could polish lens and mirror packages of exactly that size.

[1] https://en.wikipedia.org/wiki/KH-11_KENNEN

There was. Sort of.

https://en.wikipedia.org/wiki/KH-11_KENNEN

In particular some of the manufacturing tooling for the mirrors were shared, leading to the HST mirror being downsized to 2.4 meters.

Its surprising how many people don't know this all these years later. Hubble is repurposed spy satellite. The main cost of the vehicle isn't in the spacecraft itself though its the optics which are different from those used on KH-11. What is good for looking at Russian military bases doesn't directly translate to looking at galaxies.

In fact, the NRO donated two Hubble-like KH-11s in 2012, on the condition that they not be used to observe Earth.

https://en.wikipedia.org/wiki/2012_National_Reconnaissance_O...

One of them forms the base of https://en.wikipedia.org/wiki/Nancy_Grace_Roman_Space_Telesc....

The person or persons, at the NRO or whatever other clandestine agency, who championed this donation, over what must have been very considerable hand-wringing about the consequences of giving this technology to civilians, are very fine people.

The story from the astronomy side was that the 2.4 meter mirror was mysteriously inexpensive compared to anything else in the R^2 mirror cost curve.

It's a little odd how people re-tell that story, but ok.

The techniques and tooling can be fit for both purposes but the telescope you build to look at something 250km away at high resolution and illuminated by the sun and the one you build to look at galaxies thousands of light years away that are fainter than can be seen with the naked eye are very very different.

Hubble's optics also weren't easy to produce and notoriously were faulty which had to be later corrected in orbit with a Shuttle mission. The bid being lower than expected could just as easily be explained by the contractor massively under bidding to win the contract. I've never heard anyone claim the Perkin-Elmer also made the optics for the KH series before now. Its not outside the realm of possibility but unless you have some compelling proof then I have no reason to believe that. I think the fact they screwed up indicates they probably weren't because if they had done the optics for the KH-11 series then they would have been well practiced at making mirrors that size by the time Hubble was built.

NASA was trying to get some form of series production for base system bus for long distance probes in late 1980s.

What happened was that pretty soon the budget got slashed, and the out of the prototype two units they barely scrambled to have one of them flown, with very complex process to balance the budget in face of constant attempts to cut it by Congress.

Maybe if NASA's budget was allocated in different process, things would be different. As it is now, the people controlling the purse strings care about their reelection so they will at best jerk projects around to send money to their states, or to place their own spin on things, etc.

I'd expect the largest part of why is that the marginal costs of launches to space unfortunately don't go down. Each launch is nearly as expensive as the first. The marginal cost on the ground is one thing, and it sounds like Nasa often builds things in triplicate or more on the ground, but then uses the parts in training exercises or for debugging purposes. Nasa probably made three or four equivalents to Hubble. Probably plenty more than that to do all the underwater training on the incredible repair missions for Hubble that extended its lifetime from a projected 5, then a sad "failed mission", then finally the 30+ years we should be grateful to have gotten at all.

They just have never had the budget in launch costs to ever launch more than one.

> the marginal costs of launches to space unfortunately don't go down

Until recently, neither launch nor satellites had economies of scale. With reusability, launch does. And with common platforms and constellations, satellites are beginning to.

>marginal costs of launches to space unfortunately don't go down.

Some aspects certainly do, like ground-support-equipment and basic launch infrastructure.

Even in the Hubble days, launch costs were a relatively small piece of the pie compared to the costs of actually building the thing. I think for Hubble it was less than 10% (depending on how you count the servicing missions). For Webb it's significantly lower.

Even in high school robotics we built a main chassis and a 1:1 spare for testing and hot swapping parts.

That would require staffing up for the production run and then firing them when the contract was finished. There is a limited volume of sporadic work available for contractors to bid on. Increasing production capacity doesn't increase demand. At the end of the day public investment into science is always a jobs program first.

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