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Conservatism and innovation in spacecraft design
Doug M.
post May 6 2014, 01:26 PM
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Would it be fair to say that we're in the middle of a fairly conservative period with regard to spacecraft design? By this I mean that we haven't seen major innovations in propulsion, communications, power sources, shielding or avionics in the last decade, and we're not expecting to see major innovations in these areas in the next ten years. We are seeing a lot of ongoing advances in mission design, in payload, and in instrumentation. But the spacecraft themselves are changing much more slowly, and their design is increasingly dominated by heritage technologies.

Would this be a broadly true statement, or is there actually a lot of significant innovation in these areas that's going underreported? I'm sincerely curious.


Doug M.

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machi
post May 6 2014, 01:43 PM
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What about Sabre engine (for Skylon) and plasma aerobraking?
BTW, I don't think, that we saw major innovation in instruments in past decade.
Most developments are improvements of older technologies and not something entirely new.


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mcaplinger
post May 6 2014, 02:13 PM
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QUOTE (Doug M. @ May 6 2014, 06:26 AM) *
Would it be fair to say that we're in the middle of a fairly conservative period with regard to spacecraft design?

What would you give as an example of a less conservative period?


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Disclaimer: This post is based on public information only. Any opinions are my own.
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Floyd
post May 6 2014, 02:57 PM
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Obviously 1957-1968 was the time when rockets propulsion got refined to a very high level in a short period of time. However, the backup computer for the moon missions was an HP65 hand held programmable calculator. So all things computer have continued to evolve rapidly, but for reasons of reliability and radiation hardening, at a much more cautious pace than consumer electronics.

Examples of change--see DAWN mission (ion engine) and the recent launch of SpaceX (takeoff and land at same spot)


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dvandorn
post May 6 2014, 03:36 PM
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There have been noticeable advances in computer systems on spacecraft, particularly in both on-board data storage/processing and in architecture. For example, remember how Phoenix's image handling, running on basically the same system as that used for MPF and MPL, seemed so clunky and kludgey after we'd had the pleasure of the more advanced architectures of the MERs for several years? And while not quite as big of an increase in capabilities, MSL has an even more advanced system than the MERs, doing more on-board imaging caching and processing.

Also, Mars landing systems have been innovative for the past 20 years. The airbag landing concept was quite innovative in comparison to what had been used successfully before, and we used it to land three probes on Mars successfully. And while it's just a reworking of existing technology, the descent stage/skycrane maneuver used by MSL was definitely innovative. I'd call it anything but conservative.

Also, while not using any really new technologies, Cassini has an innovative combination of sensors -- for example, flying a radar imager solely for the Titan encounters was not a conservative choice, though it was driven by the science needs of the mission.

So, I guess it all depends on what you consider conservative vs. innovative...

-the other Doug (with my shield, not yet upon it)


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Gerald
post May 6 2014, 03:56 PM
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QUOTE (Doug M. @ May 6 2014, 02:26 PM) *
... I mean that we haven't seen major innovations in ... communications ...

I'd count LADEE's 620 Mbit/s LLCD uplink data rate via laser communication as a major innovation.
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djellison
post May 6 2014, 04:09 PM
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QUOTE (Doug M. @ May 6 2014, 06:26 AM) *
By this I mean that we haven't seen major innovations in propulsion, communications, power sources, shielding or avionics in the last decade,


Last decade alone.....

Communications:
MRO transmitting at up to 6 Mbits/sec ( 40x the rate of previous Mars orbiters ) from Mars
MSL UHF relay at up to 2 Mbits/sec - 8x the rate of MER->ODY
LASER demo from LADEE at 620 Mbits/sec
OPALS about to be tested on ISS
Continued transition towards more Ka band 32Ghz DSN comms.

Power Sources
Increasingly efficient solar arrays enabling the first dedicated Jovian mission to fly with Solar Power ( Juno )
Development of the ASRTG ( currently on hold, but near completion )

Propulsion
Dawn's Ion engine has given it more than 6km/sec of Delta V - more than any other spacecraft in history -and may reach a total of 10km/sec
First interplanetary solar sail ( IKAROS )

Shielding
Juno's vault
Orion spacecraft student lead shielding experiment

Avionics
Transition from RAD6000 to RAD750
New avionics of SpaceX Falcon 9/Dragon (triple redundant with much COTS hardware)

Plus:
LDSD program including SIAD test program for increased EDL capacity to Mars ( potentially doubling the delivery mass of an MSL EDL like architecture )
Continued revolution in miniaturization. RACE scientific cubesat (among many, many others) , the INSPIRE cubesat BEO program.
HD color video from the surface of Mars. 1600 x 1200 MARDI movie.
Proven EDL performance increased from a 400lb rover in 2004 to a 2000lb rover in 2012


Is your statement broadly true? No. Not even slightly.
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Doug M.
post May 6 2014, 07:41 PM
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I'm delighted by djellison's response, since there's a lot of stuff here I wasn't aware of. That said, I think some items on his list are a bit speculative. I believe that OPALS is still in development. So while it is certainly worth mentioning, it probably shouldn't be given as much weight as stuff that's been tried (even in prototype) and has actually worked. SIAD, even more so: I believe that the first high-atmosphere test of that system will come later this year. Well and good, and I hope it works, but there's many a slip etc.; I don't think you can claim something as an advance in spacecraft design until someone has actually put it on a spacecraft.

Dawn's ion propulsion is great, but ion engines have been around for a while. Dawn's thrusters, in particular, are modified versions of the thrusters from Deep Space, launched in 1998. In the Dawn white paper way back in 2005, Marc Rayman and the other authors made a point of emphasizing just how innovative they weren't.

IKAROS was certainly innovative, but it's not exactly an innovation that's been seized on with enthusiasm. There was Nanosail D2, and then Sunjammer got cancelled, and there's crowdfunded Lunarsail which IMS is supposed to launch in late 2016, and then... well, that's about it. The major space agencies' attitude towards solar propulsion seems to be profound disinterest.

As to the Advanced Stirling RTG, "currently on hold" seems a somewhat optimistic interpretation of its status. My understanding is that it's more like "cancelled with little hope of a reprieve". If I'm wrong about that I welcome correction. (I'd like to be wrong, since a better RTG would indeed be a great step forward.)


Doug M.



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djellison
post May 6 2014, 08:24 PM
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QUOTE (Doug M. @ May 6 2014, 12:41 PM) *
I believe that OPALS is still in development.

It was launched two weeks ago. It is currently hanging off the side of the ISS waiting for final installation later this week before being powered-up on Saturday.

QUOTE
SIAD, even more so: I believe that the first high-atmosphere test of that system will come later this year.

Both heatshield and parachute's have already been thru initial testing.
https://www.youtube.com/watch?v=3YVOpdqdULU and https://www.youtube.com/watch?v=_jOzxEOlDJg

The first of three atmospheric tests comes later this year.


QUOTE
Dawn's ion propulsion is great, but ion engines have been around for a while. Dawn's thrusters, in particular, are modified versions of the thrusters from Deep Space, launched in 1998.

I know. Dawn increases upon the Delta V of DS1 by nearly an order of magnitude. 1.3km/sec -> 10km/sec. That's revolutionary.



QUOTE
IKAROS was certainly innovative, but it's not exactly an innovation that's been seized on with enthusiasm.

Wrong. The only reason Sunjammer may not fly is budgetary - not conservative engineering or 'enthusiasm'.

There is no shortage of new technology and innovation in spaceflight.

All this stuff is a simple Google away.

We are in a genuinely exciting period of technological innovation in just about every aerospace engineering discipline. The stories are out there if you care to look for them.

I would urge you to do a little research of your own - and ponder Mike's question
QUOTE (mcaplinger @ May 6 2014, 06:13 AM) *
What would you give as an example of a less conservative period?

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vjkane
post May 6 2014, 08:56 PM
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QUOTE (Doug M. @ May 6 2014, 06:26 AM) *
But the spacecraft themselves are changing much more slowly, and their design is increasingly dominated by heritage technologies.

For many spacecraft functions, good solutions exist, so managers reuse existing designs to save money and reduce risk. The basic MRO design has been reused three times (MRO, MAVEN, OSIRIS-REx). However, as Doug E. points out, when there's good reason, managers use new technology and NASA has a pipeline of technologies in various stages of readiness for flight to support future missions.


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Gerald
post May 7 2014, 12:48 AM
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What about chasing a comet with a harpoon?
We don't know yet, whether it will work, and Rosetta launched a little more than 10 years ago.
Harpoons are nothing new, but using them in space to connect to a comet...
At the end of this year we will know, whether it has been a crazy idea, or that it's an innovative technology.

Deep space missions need some time to verify the benefit of new technologies.
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Doug M.
post May 7 2014, 01:54 PM
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QUOTE (djellison @ May 6 2014, 10:24 PM) *
Both heatshield and parachute's have already been thru initial testing... The first of three atmospheric tests comes later this year.


Well and good. My understanding is that Mars missions are booked through the end of this decade. So if it's going on a spacecraft, it's not happening before the 2022 launch window at the very earliest. No?


QUOTE
Dawn increases upon the Delta V of DS1 by nearly an order of magnitude. 1.3km/sec -> 10km/sec. That's revolutionary.


Yes, it is -- but we're discussing design, and Dawn's design is conservative.



QUOTE
The only reason Sunjammer may not fly is budgetary - not conservative engineering or 'enthusiasm'.


Budget cutting isn't some automatic process; there are presumably reasons Sunjammer got cut instead of something else. My point is, while IKAROS provided an impressive proof-of-concept, at the moment nobody is building on it. I don't know of a deep-space mission using solar sail propulsion that's scheduled to launch in the next five years; do you?


QUOTE
I would urge you to do a little research of your own - and ponder Mike's question


Let's compare the current decade, 2011-2020, to another. Picking the 1960s or 1970s would seem a bit unfair, since those were periods of explosive development and experimentation. So let's choose something more recent: 1991-2000. We'll include only missions that launched during the decade, so that leaves out Galileo, Magellan and Ulysses at one end, and Mars Odyssey at the other. From memory and brief googling, here's a partial list of significant missions.

Clementine
Yohkoh
A bunch of early 1990s stuff on MIR that's now mostly forgotten, but was pretty amazing at the time (advanced solar panels, the Rapana truss structure, the Spektr module, etc.)
Mars Pathfinder (and Sojourner; strictly speaking a rover isn't a spacecraft but if we're including EDL architecture, that was definitely something new)
Mars Global Surveyor
NEAR-Shoemaker
Lunar Prospector
Cassini / Huygens
Construction of the ISS involving a whole host of new technologies
Stardust
SOHO
Mars Observer, Mars Climate Orbiter, Mars Polar Lander, Nozomi (not sure we count failed missions, but anyway there they were)
Deep Space 1
Deep Space 2 (ion engine!)
and, right at the end of the decade, the ISS going live as the first astronauts took up residence in November 2000.

I've left out a lot of stuff, obviously. No orbital space observatories, for instance. The 1990s were a crazy time for those, a Cambrian explosion. But I think that gets a little gnarly in definitional terms, so let's leave it be.

Now, this is a list of /missions/ rather than of /design innovations/, and I'll be the first to concede that those are two different things. However, looking at the list, we can see that a lot of these missions involved fairly major advances in design. Cassini, for instance, had to drop a lander on Titan and was the first deep space probe deliberately designed with an eye towards a ~20 year mission. Cassini was originally supposed to be another Mariner mission, but got upgraded and redesigned (albeit at the cost of cannibalizing its sister mission CRAF). So while Cassini certainly uses heritage technology -- its RTG is a standard design that had already flown on Galileo and Ulysses, and its CPU is a 1750A from the early 1980s -- whole chunks of it ended up being rebuilt from scratch. Mars Global Surveyor was deliberately done on the cheap with a lot of heritage tech including lots of stuff recycled from the lost Mars Observer. Nevertheless, it included several design innovations, including the biggest solid state recorder in deep space up until then, a new attitude control system, the first nickel-hydrogen batteries to travel beyond Earth orbit and an upgraded communications system that could downlink at a blistering 85 kbps. And so forth.

So, does 1991-2000 overall look more innovative in terms of spacecraft design than 2011-2020? Less? About the same? It's a sincere question. I'm an interested layman, but many of you are experts. What do you think?



Doug M.

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djellison
post May 7 2014, 02:36 PM
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QUOTE (Doug M. @ May 7 2014, 06:54 AM) *
However, looking at the list, we can see that a lot of these missions involved fairly major advances in design


I see no less or more design advances in that list than the decade after it, or before it.

You've asked the "sincere question" and you've been given the same answer many times over.
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machi
post May 7 2014, 03:20 PM
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QUOTE (Doug M. @ May 6 2014, 03:26 PM) *
....fairly conservative period with regard to spacecraft design?.......we haven't seen major innovations in propulsion, communications, power sources, shielding or avionics in the last decade, and we're not expecting to see major innovations in these areas in the next ten years.....


It's probably good idea to define what you mean by "major innovation", because evidently from your other post it's almost every improvements -

QUOTE (Doug M. @ May 7 2014, 03:54 PM) *
Mars Global Surveyor was deliberately done on the cheap with a lot of heritage tech including lots of stuff recycled from the lost Mars Observer. Nevertheless, it included several design innovations, including the biggest solid state recorder in deep space up until then, a new attitude control system, the first nickel-hydrogen batteries to travel beyond Earth orbit and an upgraded communications system that could downlink at a blistering 85 kbps. And so forth.


This significantly changes answer. In such case almost every new larger mission has something what you call "major innovation".
On the contrary I mean by major innovation something what we can call "game changer" technology.
Such technologies were first X-band, Ka-band or laser space communications, first CCDs, first imaging spectrometers, first long life ion engines etc.
In the past decade (2004-2014) we had landing apparatus for Curiosity (precise landing), Ikaros, first long-range laser communications, first LILT solar cells (Rosetta), first real test for anti-asteroid/comet system (Deep Impact), and almost ASRG (development is still going under ESA?).
And of course lots of other new technologies which are important but I forgot them or I don't know nothing about them.
In the next decade it will be similar. For example large deployable optical structure (JWST) or mechanical cryocoolers (SPICA) will be definitely "game changers".
And of course functional air-breathing rocket engines can be revolution comparable with invention of the space rocket.


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Astro0
post May 7 2014, 11:32 PM
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ADMIN NOTE:

While this thread could be an interesting dicussion on the development of spacecraft technology over the decades, the comments seem to be going around in circles and are running very close to the mark on breaching our standards of 'Acceptable Behaviour' as outlined in the
Forum Rules and Guidelines. In particular: 2.1, 2.3, 2.4 and 2.5

Let's all be mindful of the need to be respectful and non-argumentative. Responses to specific points raised are fine, but avoid rants please.

Thanks all.


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