I was just thinking about how much pressure there must be on everyone involved in Discovery Class missions. People's entire professional careers, billions of dollars, so much at stake!
Is the pressure something significant, or is it spread across so many people that there is little trouble sleeping at night?
If you built even 15 Europa Clippers the cost per-item would come down enormously (because all of those people's work could be re-used), but since the 1970's NASA has not had the budget for multiple probes per missions. So every mission is bespoke, and has to be done again completely from scratch.
1: The engine was normally used for circularizing the orbit of a geosynch comm satellite, so within a few hours of flight. For doing a Mars Insertion burn it needed to sit fueled for months in outer space, which was not appropriately tested, and probably the fuel tank exploded in flight because of that.
Details on the Europa Clipper budget are at https://www.nasa.gov/wp-content/uploads/2023/03/nasa-fy-2024...
(Edit: fixed billion/million typo)
1: Officially I believe the expectation was "3 minutes" but that was a deliberate under-promise so that a success could be declared as long as they got any message at all from the lander on the surface: I have second-hand accounts that 30 minutes was what the scientists considered the minimum.
2: Even with all that testing, disaster almost struck. It wasn't until after the launch that someone realized even all of this testing had missed something important. The radio communications between Cassini and Huygens would be affected by the Doppler shift of Huygens hitting Titan's atmosphere, which would be unpredictable changes to velocity. After launch they had to rejigger when Huygens would be launched to a time when the signals would be perpendicular to the direction of travel so the shift wouldn't affect the radio waves so much that the Cassini receiver firmware (which could not be modified after launch) could still detect the signals. And also with all of that testing, ESA's instructions to the Cassini probe missed turning on one channel on the receiver and so half of the pictures that Huygens transmitted had nothing listening in and were lost.
Each mission has unique requirements, but since payload mass costs are coming down, ISTM it should be possible to create a standard buss that meets most requirements most of the rime, even if it's heavier than a bespoke effort for any one mission.
Here is an HN post from 2014, "How a Swedish engineer saved a once-in-a-lifetime mission to Titan (2004)" [0]
Since the link has rotted away, here is the archive link to the IEEE story. [1]
[0] https://news.ycombinator.com/item?id=7472495
[1] https://archive.is/3oj6P (archive.org is still not working reliably)
In theory falling launch costs will eventually mean maybe we can make space science missions more disposable so a loss from random failure is no big deal, but we're not quite there yet.
I ultimately decided against pursuing a career in aerospace engineering after talking to engineers who worked a similar time frame on a project only to watch it get killed in 30 seconds' debate in Congress.
When you are on contract for something, you deliver to the contract, and are done when you successfully meet the customer's requirements. So in that sense you don't have the same exposure to the program risks.
However, I've been part of one-off science missions before, and there is a different feeling beyond the contract obligations, though it's certainly abstracted through the many layers of sub-, sub-contracts.
When I took Ae105 at Caltech, the NASA MSL project manager explained it like this (I remember the numbers he used clearly): a mission might cost $500 million with an 80% chance of success, or they can spend twice as much to increase the chance of success to 95% by investing a lot more in upfront testing and R&D. Now, the smart thing to do - given a billion dollar budget - is to take that first option because if it fails you can try again and the probability of both attempts failing is only 4%, compared to 5% for the expensive single mission. Then you’ve got an 80% chance of having $500 million left over for a different mission.
The public and decision makers react irrationally to any failure, putting funding for other missions and the entire program in jeopardy. NASA and ESA have to make some extremely suboptimal decisions to make sure that funding doesn’t get catastrophically cut.
The above is the example the instructor used to easily illustrate his point but he said the real numbers are even more stark. Often times the cost savings of just building a second copy of the payload along with the first means it costs $600 million for the first attempt, and only $200 million for the second (the cost of the launch vehicle and keeping people on staff), saving hundreds of millions overall.
https://en.wikipedia.org/wiki/Comparison_of_satellite_buses
For example, the SSL 1300 apparently has hosted 118 satellites so far:
https://en.wikipedia.org/wiki/SSL_1300
Though maybe the distinction between "satellite" and "spacecraft" bears importance here.
Is there room here for making things more reusable? For example, instead of creating one big satellite with tens of instruments, how about they create 10 satellites with one instrument each? or would that still be too bespoke to lower the cost per item?
Since SLS launches are now upwards of $2B per launch by some estimates, how does this math work? Wikipedia also suggests $2 billion saved.
https://en.wikipedia.org/wiki/Space_Launch_System#Europa_Cli...
Which, incidentally, is one of the key reasons SpaceX has had the success they have: they're set up to handle failure and avoid this politics. How many Starships have blown up? If Starship were a NASA program, how many explosions ago would it have been cancelled? And yet this approach to risk is pretty effective!
The whole strategies of exploration haven’t shifted yet to this new paradigm. Hopefully NASA starts making smaller probes and launching them far more often.
For exploration missions and anything in deep space (basically, beyond Lunar Orbit) people have kicked around ideas for common buses, there have been plenty of proposals, but no one seems to have enough value in them to be the third or fourth user of one- everyone has found it better to start from scratch than use someone else's bus design. It is possible if there was a sustained, focused effort at one kind of project, say, something where Mars orbiter launches were guaranteed every 26 months for more than a decade, that the investment in a common bus might pay off. But as long as we are bouncing between Mars, Jupiter, Pluto/KBO's, E-S L2, and inside Mercury's orbit, it just isn't actually reusable.
Just as one point, until the past few years everything in the outer planets had to be RTG powered, which requires a totally different design than something solar. It was only with Juno (and now the Europa Clipper) that solar has been demonstrated for outer planets at all, and it is still not exactly a design you'd have off the shelf, nor would the power design you'd want for outer planets solar be at all similar to the design you'd want for inner planets solar. The same is true for comms, for thermal management, for rad-hardening, etc.
It is possible for a swarm of small satellites to fill niches in space exploration. Closely studying Europa isn't really one of them with today's technology.
Compare the responses to a failure by Boeing or SLS and to a failure by SpaceX.
Also, SpaceX hasn't had a serious non-experimental failure yet (?). I'm sure their PR is preparing for that eventuality, but when non-fans are upset over a bad outcome and then learn about the risk tolerated, they will swing from admiring risk to condemning it. Imagine the Congressional committees.
Even if SpaceX is super-conservative when flying humans (which we shouldn't assume - cultures tend to be consistent), if someone dies then all that risk-seeking behavior will be attacked.
(To be clear, as long as SpaceX can manage risk in production - i.e., with high-value payloads such as people and NASA flagships - I think they and everyone else should use risk efficiently.)
Easier said than done, of course.
There was some talk about using ISS as a base for on-orbit assembly but the orbit (half-way between best orbit from KSC and Baikonur) isn't great for that and it turns out that constant docking and un-docking ruins scientific experiments requiring microgravity, so ISS really isn't a great base for assembly. Ideally, if you want to start on orbit assembly you'd have another station in the right orbit for KSC which isn't doing any microgravity research, but now we're talking about massive up front investment to save money on research satellites, is NASA ever going to get the scale of research budget for that savings to be worth it?
If something like Space Based Solar Power ever become a thing then such an on orbit assembly station would make sense, but the case for assembly for science missions really only closes if you have the station already for something else.
I would also count the Apollo missions. They launched on a single rocket, but the docking between the CSM and Lunar Module was for all intents and purposes equally difficult to assembly on orbit.
There are multiple commercial companies planning to assemble stations over the next few years. This in addition to the on-orbit refueling that SpaceX will be doing should hopefully enable a new generation of larger, assembled interplanetary probes.
But that is closer to what I meant, because they had to worry about separate launches that might fail (GVI, GIX) and find and dock with something you need to use orbital mechanics to approach (basically anything under 30m distance you can just eyeball and fly, but anything over that distance requires the full set of orbital calculations).