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brellis
Right, I forgot about Mariner Mark II. If only NASA's budget were double its current size, think how many replicas would be moving through production at reduced cost.

Regarding private investment, I wonder if a really longterm partnership with private investment funds could be formed where sample return leads to mining, and manned missions lead to tourism. Are there enough billions out there to do it without draining the global economy?

If I had the choice, I'd rather dedicate my 401(k) to the space program. smile.gif
edstrick
"...Cassini was originally supposed to be the first mission using the Mariner Mark II series ..."

JPL Director Bruce Murray <I think> had a major article in Science magazine in the mid 80's explaining in detail how the newly concieved Mariner Mark II program would provide the basis for continuing low cost planetary exploration. Mission costs <I think> were to be well sub-1-Billion-$, achieved in part by reusing modifications on a common spacecraft bus, much the way Mariners 69, 71, 73 and Viking Orbiters had massive design heritage.

The first missions were to be Comet Rendezvous / Asteroid Flyby CRAF and Cassini.

Well.... as the mission pair cost past umpteen billion, CRAF was nuked and Cassini was descoped to (among other things) a No-Scan-Platform mission.

"The road to hell is paved with good intentions"

I'd really like to see the story of how Mariner Mark II went form good intentions to budget control hell. Watching MSL, I'm getting massive deja vu.
vjkane
The pre-MRO Mars orbiters, as I understand it, shared much of their designs, which helped kept costs down. One idea I have would be if NASA were to design a new platform capable of orbiting Venus, the moon, or Mars (there are some thermal problems, but as Venus Express and several studies have shown, it is possible) and then hold a Discovery-like competition to pick the target and payload for a new mission every two years. I think we could get some really nice missions out of that at a fairly low cost.

Alternately, NASA could complete its just announced partnership to develop cheaper and more capable radar systems and then fly a copy at Mars and Venus to study both the surface and sub-surface.

There are lots of ways to do good science and lower costs. But this approach requires planning a series of missions and amortizing development costs.
nprev
This is the third or fourth time I've seen mass production of planetary spacecraft come up on the forum (I instigated one such discussion). Unfortunately, in order to realize any economy of scale, you not only have to place severe constraints on payload mass & volume that may well severely restrict the type of experiments that can be flown, but you also have to assume a stable budget environment for many years...and historically, the latter has been anything but. sad.gif The third fly in the soup is technological advancement, which tends to obviate long-term configuration control as new methods become available.
mcaplinger
QUOTE (edstrick @ Feb 24 2008, 10:07 PM) *
I'd really like to see the story of how Mariner Mark II went form good intentions to budget control hell.

One big reason is that the Cassini and CRAF missions were not really very similar, so the idea of sharing a common spacecraft was not that valid to start with.

As I have pointed out before when these "common spacecraft" discussions come up, there is huge commonality at the box level. Regardless of how different spacecraft may look on the outside, much of the guts are built out of catalog items.
tedstryk
There was also the problem of NASA's budget not being able to support Mariner Mark II missions at a rate that would make the "assembly line" advantage practical.
Mariner9

One example of design inheritance working well was Rosetta - Mars Express - Venus Express.



Venus express was a nearly identical ship to Mar Express, with almost the same collection of instruments. In fact, the ESA leaders put out the request for proposals of what kind of mission could be flown with the Mars Express vehicle, and do it shortly after Mar Express so they could keep the same engineering teams together to do the work. Thus, Venus Express was born.

Venus Express flew, the cost for that mission was far, far lower than a comparable NASA planetary mission. However, it was limited to be a near repeat of Mars Express, just flown to a different destination. And then mostly with instruments originally selected for a comet mission 10 years earlier.

Typically scientists and engineers identify a mission they want to fly, then design a spacecraft around those requirements. That isn't what happened in this case.

Venus Express was not a mission in search of a spacecraft. It was a spacecraft in search of a mission.

So there is a real downside on "assembly line" spacecraft . You are very limited in how you move forward.

A big part of MSL's problems may have been avoided if they had stuck to a modestly scaled up MER. However, MER was already pushing the size and weight envelope of the airbag delivery system. So you would have been stuck flying another MER, and never get anywhere near to MSL's capabilities. I've expressed a lot of concerns over the MSL cost problems, but I completely understand that in order to move past MER that the engineers had to take some risks.
Tom Tamlyn
>Venus Express flew, the cost for that mission was far, far lower than a comparable NASA planetary mission

One interesting aspect of the cost efficiencies of Venus Express is that they depended to a large extent on assembling the spacecraft immediately after (or indeed, concurrently with) Mars Express. If I recall correctly, a fascinating ESA discussion (can't remember source) said that even a several year delay would have largely vitiated the cost savings of the twin mission approach, due to the ordinary obsolescence of contractor tooling, processes, and parts used in fabrication.

TTT (Heraclitus said as much several millenia ago)
vjkane
QUOTE (Tom Tamlyn @ Feb 26 2008, 03:15 AM) *
One interesting aspect of the cost efficiencies of Venus Express is that they depended to a large extent on assembling the spacecraft immediately after (or indeed, concurrently with) Mars Express. If I recall correctly, a fascinating ESA discussion (can't remember source) said that even a several year delay would have largely vitiated the cost savings of the twin mission approach, due to the ordinary obsolescence of contractor tooling, processes, and parts used in fabrication.

When NASA was considering series of missions, it was always pointed out that a key was to commit to the program up front so that they could make block purchases of critical components, keep the engineering and mission ops teams together, etc.

To get an idea of what a series of orbital missions at Mars could do, look at the 4 proposed MSO focii: "Report from the 2013 Mars Science Orbiter (MSO) Second Science Analysis Group" http://mepag.jpl.nasa.gov/reports/index.html
Steve G
Nasa still needs to eventually land another spacecraft on Mars. Granted, every launch window for Mars has different payload constraints, some are favourable windows, others less favourable, but why not stick the MSL herritage as much as possible? I know the trend is looking towards a sample return mission but the money may simply not be there. If that's the case, keep landing rovers, each with a specific focus and instrumentation, but keep the heritage.
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