Today we have 50 times as many satellites in orbit as in the 1980s and the price of space equipment has come down; however, we have a thousand times fewer satellites orbiting far away space bodies than locally.

Can't we do 10 Galileo-like missions these days for the price of one space mission in the 1980s? Can't we make 10 copies of a cheap satellite and send them cost-effectively to all the major space bodies?

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    $\begingroup$ see Space Exploration. Why do 10 Galileo missions, we've already done that. You want to think about doing something different, something new. There's no point just doing the same mission over and over again. $\endgroup$
    – James K
    Dec 13, 2023 at 5:49
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    $\begingroup$ Can you give a source for the claim that the cost would be a factor of 10 lower? I can imagine that the R&D costs would be that much lower, but the actual hardware, launch and operational costs would possibly be a bit higher. Good Q though. $\endgroup$
    – ProfRob
    Dec 13, 2023 at 11:26
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    $\begingroup$ The prices that went down most dramatically (launch, chips) were never the largest component of mission costs. You still need the people who know how to plan, build and operate the missions, and things like RTGs have not dropped much in cost. If 20% of the mission cost is 10x cheaper, your mission still costs 82% or what it used to. $\endgroup$
    – antlersoft
    Dec 13, 2023 at 14:23
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    $\begingroup$ Apples and pears. Galileo was a huge mission (6-m, 2.5 tonnes) with 16 scientific instruments and an atmospheric probe, lasting 13-years with loads of novel technology. It was also launched into Earth-orbit on a manned spacecraft, which adds to the cost hugely. $\endgroup$
    – ProfRob
    Dec 13, 2023 at 18:27
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    $\begingroup$ I'm curious as to what bodies you think we should be visiting? In the last 20 years, we've had Cassini (an analogue to Galileo) at Saturn, the New Horizons flyby of Pluto, Messenger and the upcoming BepiColombo at Mercury, the upcoming JUICE at Jupiter, the Parker Solar Probe, Dawn bopping around Vesta and Ceres, multiple asteroid and comet intercepts, about a dozen space telescopes with various missions, and India just landed at the Moon's south pole for the first time. What is it you feel is being ignored or overlooked? $\endgroup$ Dec 13, 2023 at 21:01

2 Answers 2


I can figure out a partial answer:

There was a decline in launches following the end of the spaceshuttle program that we can see here: enter image description here From 2000 to 2015 the launch rate was 50% of what it was in the 80's. enter image description here

Missions have focused on quality and advancement of sensors and equipment, rather than a higher quantity of less sophisticated missions.

The price of launches is perhaps going to change that soon. A launch in 1981 cost 99 times more than in 2020: enter image description here

Compared to the 1980's the CAD design suites, sensor prices, booster technologies, orbital mechanics models, N-body simulations, should contribute to a higher productivity rate, lower design price and facilitate slingshots and other complex mission physics equations.

However, the specialized nature of the extreme equipment used for space exploration and the cost of the skilled workforce counterbalances those effects.

Considering the recent leaps in launch economy, and new space organizations in India, Japan and China, perhaps we will see a higher throughput of lower budget missions soon, perhaps these less well known targets:

  • Europa, Icy Ocean
  • Uranus, Not investigated nearby since Voyager 2
  • Neptune, Also never visited since Voyager 2
  • Enceladus, Active Geysers
  • Titan, Hydrocarbon Lakes
  • Triton, Retrograde Orbit
  • Ceres, Water Ice
  • Charon, Geological Complexity
  • Vesta, Diverse Geology
  • Eris, Distant Dwarf
  • Pluto, very complex hydrocarbon glaciers and cryovolcanos
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    $\begingroup$ I suspect KBOs like Pluto aren't on the menu for extensive study simply because the need to get there in a reasonable time and the desire to slow down and enter orbit are mutually exclusive, and while I'd love to get more looks at the ice giants, they're probably not high on the list of things to do either. I just don't see operating that far from the sun on a budget mission -- long travel time, long distance communication, and engineering for the extreme cold and dark are all going to jack up the price significantly. $\endgroup$ Dec 14, 2023 at 20:20
  • $\begingroup$ It is frustrating to have so many problems that can be solved with huge nuclear reactors and yet be unable to solve them that way. $\endgroup$
    – ikrase
    Dec 15, 2023 at 9:58
  • $\begingroup$ The chart from FutureTimeline.net, while the graphics are nice, is full of misinformation which we should not propagate. I published a paper that covered this topic. project-atlantis.com/wp-content/uploads/2023/05/… $\endgroup$
    – phil1008
    Dec 15, 2023 at 11:09

One reason why there are not multiple outer planet missions is that to run a transmitter powerful enough to get things like high resolution images home you need serious electrical power onboard. Which generally means a nuclear radioisotope generator which tends not to fit small/cheap missions.

  • They are outright expensive because the isotopes require a large nuclear program.

  • The production rate is basically fixed unless multiple new reactors built specially for the purpose, with pretty much all the available material for over a decade being used for two Mars rovers and New Horizons.

  • Facilities to generate, handle and purify isotopes suitable for RTGs are generally part of weapons programs, so attract scrutiny and complications. While spinning up a civil large scale RTG isotope program would be possible, it certainly would not be cheap.

  • If not a major military power budget needs to include contingency for a cleanup.

Juno successfully operates around Jupiter with solar power, but the array weighs 340kg and Juno is a fairly minimalist mission.

So a smaller nation or large organizations can make feasible moon or even mars vehicles, but for Jupiter and beyond only the super powers have the means, and none of them have seen political advantage overcoming the other issues to fly a flock.

  • $\begingroup$ I like this answer. While electronics may be getting cheaper and lighter, I suspect that RTGs needed for outer planet missions are getting more expensive too thanks to more stringent regulations and less plutonium availability. $\endgroup$
    – phil1008
    Dec 15, 2023 at 11:28
  • $\begingroup$ @phil1008 they also do not gain much with tech changes - the thermal power is fixed for a given isotope and the thermal to electric part is pretty well understood and already pretty efficient. The real gains would be someone working out how to have an actual flyable reactor in this weight class. $\endgroup$ Dec 15, 2023 at 11:36

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