22 thoughts on “Europa”

  1. I have some nagging questions about how a small solar-powered satellite with a 150 Watt transmitter and 750 lbs or so of scientific instruments like cameras and magnetometers can cost $2 billion dollars, not counting launch costs. Mars Global Surveyor only cost $150 million.

    They were going to use 150 kg of titanium for radiation protection, but at $26 a pound that only comes to $8,580. They might have switched to gold bars, but that would only add $6 million to the price. Is it possible they’re using Amazon stock certificates for shielding?

    1. Isn’t it too far out for effective solar panels and we have to depend on the Russians for Pu-238 isotopes if we go RTG? …At whatever price they demand.

      1. That’s not the case for Europa Clipper. It uses only solar cells and batteries for power. They considered RTG’s, looked at their limited plutonium stocks, and decided to go with solar, which just barely works out that far. They’d never work at all for Saturn unless they were used as part of a parabolic solar concentrator.

        Which reminds me that the other day I looked at a parabolic radio antenna for a deep space probe that also serves as a solar concentrator.

        At Jupiter, the Earth is never more than about 11 degrees from the sun, so the parabola could be aimed to split the difference, with both the Earth and sun 5.5 degrees off axis, at most. The microwave horn and solar cells could either be oversized (the safest option) or they could shift back and forth over the course of the year, so each tracks its target.

        The solar cells will of course be far past the focus and behind the microwave equipment because the sun is just a dot in the sky at that distance (0.1 degree angular size), and could potentially be brought to a tight enough focus to burn through a solar cell.

        To get Earth normal illumination levels, you’d concentrate the sunlight by a factor of 27. So if you needed 1000 Watts from solar cells that would generate 350 W/m^2 in Earth orbit, you’d need the Jupiter dish to be 32 feet in diameter and concentrating the light on a six-foot diameter solar array.

        For Saturn, the maximum Earth-Sun angle is only six degrees, so the off-axis angle would top out at three degrees. For the same 1000 W output, the dish would need to be 60 feet in diameter, concentrating on the same six-foot solar array.

        I think something similar has been suggested as a long-term communications relay for any probes we send, though I haven’t looked anything up.

    2. I agree that there is the usual NASA cost inflation at work, but I can’t think of a 6,000kg probe as being a “small satellite.” That’s actually more mass than either Cassini-Huygens or the Chandra X-ray Obervatory.

  2. Similar to Clipper, the Lander mission will likely face shortages in skilled technical staff given that it is competing with five other major projects at JPL, including Clipper, for the same resources, putting planned activities at risk.

    A criticism that I haven’t seen made about the Trump administration’s proposal for yearly lunar robotic missions is that the ground staff making use of all the data collected will be expensive. This is especially true assuming the equipment they place on the lunar surface has as long a life span as other similar missions.

    It is a good criticism of anything NASA will do on the lunar surface as they will be expected to actually do stuff and none of it will be cheap. And it is all a big unknown.

  3. I read the report, and was stunned to see that NASA estimates the lead time for an SLS core stage at 52 months. After that, there’s 6 months of integration time. I’ve looked through various sources, and they’re pretty much unanimous that the Saturn V’s lead time, from contract award to flight, was 42 months.

    How can that be? After all, those benighted 60s people had only half a dozen IBM 360 computers, a slew of slide rules, no cell phones or electronic slide projectors (for briefings), no lean six-sigma wisdom, etc, etc, etc…in short, primitive tools, and none of the things you really need for efficient production! How did they do it?

    1. Well, those long lead times are actually quite comforting. It means a NASA contractor can start working on a particular SLS build while his child in high school decides which college to attend. While dad is working on that one rocket, his child can go to MIT, graduate with an aerospace engineering degree, get a job with NASA, and help dad finish that rocket.

          1. Back in 2016 Gwynne Shotwell said they were ramping up to build 30 Falcon 9 cores a year on six first-stage production lines. That would be five cores a year on each line, or 72 days per core. I’m sure they’ve ramped up a lot since then, since they were just shifting to high rate production.

            The SLS production line apparently will take 4.3 years to build a core, assuming no schedule slips. They’re attaching four first-stage engines instead of nine, and the engines they install are RS-25s, just like they used to remove, refurbish, and remount for each Shuttle mission.

            It sounds like there wasn’t much input about manufacturability, as if they’d never been involved with high-volume, high-rate production before.

            But yes, the SLS isn’t even going to be in the game, even if they don’t cancel it.

            I find it ironic that we have a bunch of multi-millionaires and billionaires pursing space flight as vanity projects, yet building serious, re-usable, affordable hardware, while it’s the serious space professionals at NASA who are building a vanity rocket that is financially unworkable and nearly useless because of the boutique nature of its low flight rate.

            I think Bridenstein is completely boxed in by what he’s got, and I think anyone in his position would be in the same box. NASA has one path they’re committed to, the SLS, and deviating from it by switching to commercial boosters would likely be its death blow.

          2. Going back to that chart posted the other week, looks like they can only build three cores at a time. In order to meet the launch schedule, already have two under construction with a third starting this year.

            IIRC, that would be all the left over engines. I don’t think SLS will survive but who know how it goes out. Hopefully it is before AR gets too far down the road of producing new engines.

            2020 is the year to watch, or what ever year 2020 slips to, as that is when they need to start using the new engines.

            That is just my guess. I am sure someone who is familiar with their workflow has a better idea when that decision takes place.

          3. They contracted for new RS-25E production some years ago, and paid an enormous one-time sum to upgrade the production lines.

            NASA Spaceflight story from last year.

            Long-lead items for the six flight engines in the contract are already being fabricated and by the time the first new “certification engine” is fully assembled, the first of those flight engines will be lined up behind it.

            All of the flight engines are planned to be delivered to NASA by July, 2024; the new engines are due to begin flying on the fifth Space Launch System (SLS) launch.

            Six engines is enough to power an SLS and a half!

            I have no idea what SLS flight number six is supposed to use.

            Meanwhile, when I was digging up SpaceX production figures for a comment up above, it mentioned that SpaceX was geared for producing several hundred (300 to 400) Merlin engines a year.

            That strikes me as an entirely different production universe from producing six engines in six years. One engine a day or one a year? One group is producing enough engines for an intense and sustained flight campaign, and even re-using those engines. The other vehicle will throw away four years worth of production each time it leaves the ground.

            Anyway, purely for entertainment, and Orbital ATK (now Grumman) Omega first stage solid (derived from the Shuttle SRB) was tested a couple of days ago, as part of a DoD launch contract. Right at the end of the planned burn the nozzle blew into flying fragments.

            Youtube video, including slow motion

            It includes the post-test press conference. Yep. Something happened right at the end, but no big deal. ^_^

  4. One more thing that will go completely obsolete if SpaceX Starship flies. Musk has already floated an expendable version of Starship (wings, heat shield, and some engines removed) that could land dozens of tons payload on Europa in one go. Or a small payload that could return itself to EML2 (i.e, Europa sample return). There’ll come a time when end of life Starships will be available too.

    1. I hope everything goes smoothly. It doesn’t look like anything will change until it actually flies. I also hope that not too much money is wasted by government and companies in the meantime.

  5. This morning a CNET article said that Bridenstein had ruled out going to the moon with anything other than the SLS, Orion, and the Gateway.

    “I want to be clear about SLS and Orion… SLS and Orion is the only system that gives us any chance of getting there in 2024,” he said. “We’ve looked at everything, we’ve considered everything and SLS and Orion, that is the system. And once it’s developed, we will use it over and over and over again.”


    Bridenstine went on to reiterate NASA’s plans to ready a bare-bones version of the gateway and a lunar lander for the 2024 mission. He touted the reusability of both designs, while also acknowledging, a little ironically, that SLS rockets are not reusable, like a Falcon Heavy.

    “We are trading a little bit of reusability for speed,” he said.

    Yep. Just a little bit…

    I remember many years ago, it seems like a decade ago, when NASA was looking into replacing the SLS’s SRB’s with liquid boosters that were each going to use a pair of Rocketdyne F-1’s. The contractor was even hot firing an F-1 preburner to refine the performance data.

    In a more rational world where technology programs worked like they often do in the private sector, NASA would be flying SLS Block VII, with flyback re-usable liquid strap on boosters and a first-stage a core that lands on a barge.

    1. It looks like another thing they are trading is competition between suppliers. There are a lot of people who think these companies can’t find other customers for their products, so why have multiple companies providing the same service to one customer? I think its a mistake to focus on speed, ignoring that NASA’s plan may not actually be speedy.

      Commercialization of LEO might be the real prize here as the world’s governments spin their wheels on the Moon.

    2. You think that’s a lost opportunity? I was reading Astronautix articles on the Saturn V last night, and ran across the article on the Saturn V-B (http://www.astronautix.com/s/saturnv-b.html). I had never heard of this idea, but it makes a lot of sense. Using a standard S-IC stage, this rocket would have taken off, climbed to a certain altitude, then (like the Atlas) dropped its outboard “booster” engines, then continued to orbit with a singe F-1 engine, there depositing 50,000 pounds of payload. The outboard booster package would be recovered, as would be the rest of the vehicle.

      If you think about all of the weights involved, it makes perfect sense. It would have been a 1 1/2 stage fully recoverable rocket with a 50,000 pound payload. Damn, I wish they had done it!

      1. Hrm…. 1968. They still had the Saturn IB launching on a milk stool, and they had enough of those to fly the Skylab and Apollo Soyuz missions. The Saturn IB had a LEO payload of 46,000 lbs, virtually the same as the Saturn V-B. It may have seemed redundant, and dependent on manufacturing lines that they were going to shut down after the Apollo program ended.

        1. As Astronautix pointed out, “At very minimal cost (36 months lead-time and $ 150 million) the United States could have attained a payload capability and level of reusability similar to that of the space shuttle.”

          1. I had to run a bunch of numbers on it too get a feel for why they would have rejected the idea. At first I thought the performance looks okay, and the cost might be good.

            From a payload growth potential it would’ve been pretty trivial to add an upper stage. I think adding an S-IVB on top ups LEO performance to about 170,000 lbs. Add two upper stages and it’s a Saturn V.

            However, the S-VB configuration only offers the same payload capability as the Saturn IB, but uses 7.5 million lbs thrust at liftoff instead of the Saturn IB’s 1.6 million lbs. The S-IC is a very heavy stage (287,000 lbs) and it would be going into LEO along with the 50,000 payload, so the payload fraction is only 20%. That’s similar to the Shuttle, but it doesn’t have a crew cabin or any way to return them to Earth. If you add those, you’ve got an Apollo CSM on top, no payload, and might as well have used a Saturn I-B.

            However, since a Saturn IB could launch the same payload, why not just replace the first stage of the Saturn IB with a new stage that just uses an F-1 engine, especially one of the post-Apollo F-1’s that were uprated to 1.8 million lbs thrust? Then you don’t have to recover four unnecessary F-1’s.

            I think they looked at those options, too, but the problem was that all the Apollo hardware seemed expensive and they couldn’t point to a cost reduction down the road. In contrast, the Space Shuttle would be almost fully re-usable, cheap, and fly once or even twice a week.

Comments are closed.