Author Topic: How many Opportunity Rovers could Falcon Heavy fly to Mars?  (Read 4489 times)

Offline Oersted

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Opportunity is heading into her thirteenth year of a three-month mission:
https://forum.nasaspaceflight.com/index.php?topic=42774.0

You should think it would make sense for SpaceX to contract the JPL to build quite a few more Mars Exploration Rovers, with just a few basic updates to solar cells, batteries and cameras, and plop them down on various locations of Mars. I cannot think it will ever be possible to make a more economical and dependable design (in view of the amazing longevity of Opportunity and to a slightly lesser extent Spirit). The science package should be focused on SpaceX' goal of identifying a good place for a colony, of course.

The Rovers that were sent in 2003 were limited to landing at certain lower altitudes of Mars. I think progress since then (low-weight heat shield, stronger parachute) would probably make it possible to target a wider variety of landing spots.

But, basically, send slightly updated versions of this time-honoured and well-proven design. How many could a FH take to Mars?

No need (and time) to re-invent the wheel when there is already a great mobile exploration rover design.

Online IanThePineapple

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Well, I think the Martian orbiters will be used for finding the best landing spots, it would cost a LOT to build and launch a handful more rovers.
Proud creator of Ian's Paper Model Rocket Collection:
https://forum.nasaspaceflight.com/index.php?topic=42383.0

Offline Oersted

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I added a "tag" to my posting, specifying that I am talking about the necessary ground truth that only surface assets can deliver. Of course the initial reconnaissance will be done - and already is being done - by orbital assets.

(Don't see the tag now, tho... - Maybe I didn't make it correctly)

Offline Phil Stooke

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Superficial answer:

(mass deliverable to Mars by FH)/(mass of MER in cruise configuration)

A better question would really be whether this is possible - suppose the answer was 6 MER rovers.  Do we have the downlink capability to gather the data each day, and do we have enough engineering and science people to staff six rovers at once? 

Also, is MER really the design you want?  The rovers are actually quite small.  They were enough to do the required science, but can they carry enough instruments (or experimental ISRU equipment etc.) to do what would be needed here? 

Don't get me wrong, I think it would be good to explore these issues.  But I don't think asking how many a certain rocket can deliver is really getting at the important issues.


Offline savuporo

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Don't get me wrong, I think it would be good to explore these issues.  But I don't think asking how many a certain rocket can deliver is really getting at the important issues.

Horizontal vs vertical scaling. There is room for both, and in early days of spaceflight horizontal approach was far more common, out of necessity.

Orion - the first and only manned not-too-deep-space craft

Offline guckyfan

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To really get a lot done better communicaton infrastructure would do a lot. Existing orbital capabilities like high resolution photography is limited by the ability to send data back to earth.

Surface capabilities need to be a lot different than existing rovers. Bigger batteries, stationary solar arrays to recharge and the ability to cover km/day at least on known tracks.

Offline zodiacchris

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Stack the rovers in a dispenser magazine in a Red Dragon on top of a FH, land the thing in an area of interest identified by orbital assets, and have the rovers swarm out in a search pattern after deployment. That would skip the whole individual coast and EDL per rover, and would deliver high density information of 100s of square km of target area. Plus likely to be cheaper than building 6 individual spacecraft...

I'd be surprised if RDs would not take rovers of some description along, likely with some DNA of Spirit and Opportunity.  :)

Offline Oersted

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Superficial answer:

(mass deliverable to Mars by FH)/(mass of MER in cruise configuration)

A better question would really be whether this is possible - suppose the answer was 6 MER rovers.  Do we have the downlink capability to gather the data each day, and do we have enough engineering and science people to staff six rovers at once? 

Also, is MER really the design you want?  The rovers are actually quite small.  They were enough to do the required science, but can they carry enough instruments (or experimental ISRU equipment etc.) to do what would be needed here? 

Don't get me wrong, I think it would be good to explore these issues.  But I don't think asking how many a certain rocket can deliver is really getting at the important issues.

Thanks Phil, great answer!

Very true that transmission rates may be the real bottleneck. Perhaps a couple of relay satellites tagging along in the FH payload stage would alleviate the issue? Musk has already mentioned that he wants broadband and geolocation sats in orbit around Mars to help with comms and pinpoint landing capabilities. But of course that complicates the mission, and relay sats do not solve the problem of an eventual downlink bottleneck on Earth.

Something to remember before calculating how many MERs can be lofted to Mars on a Falcon Heavy is that they might very well share one single navigation stage for the coast phase. All else being equal that should make it possible to stack a few more in there. Judicious release of the various MERs from the stage in the few hours leading up to EDL should be able to ensure that their landing ellipses remain small.

In any case, Opportunity has traversed 44+ kilometes by now, and progressed well beyond its landing ellipse. The MERs are well capable of driving to a specific location on Mars for on-site analysis as long as they bounce down within their landing ellipse. Their longevity suggests that they may even survive for long enough to serve as landing beacon for later missions.

As for ISRU experiments (Sabatier reaction etc etc) I imagine they would be done from a landed Red Dragon on another, perhaps simultaneous, mission. The MERs would exclusively serve to characterize specific, promising landing locations.

Looking forward to seeing someone try to fit the MERs and associated heatshields within a Falcon Heavy fairing, and perhaps estimate the weight budget.

Offline LM13

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Superficial answer:

(mass deliverable to Mars by FH)/(mass of MER in cruise configuration)


Slightly less superficial: FH payload fairing volume/volume of MER cruise stage (modeled as cylinder of height 1.6 m and diameter 2.65 m). 

An MER, at TMI, massed 1.063 tonnes.  Round up to 1.100 tonnes (for any kind of metal frame between the rovers).  FH TMI payload is 16.8 tonnes (expendable?), suggesting 15 MERs. 

Internal payload fairing diameter is 4.6 m (possibly outdated--taken from old user's guide).  This tapers a bit at the nose, but still seems to stay above 2.65 m for at least 8 meters, so you could launch 5 MERs at a time.  I suspect this would be a mostly-reusable FH.

Of course, this seems to be a variant of the "rebuilding the Saturn V" problem--we have the blueprints, but getting the production line back together could be troublesome.  Suppliers may well be out-of-business by now, parts might be out-of-stock. 

Offline Zed_Noir

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Superficial answer:

(mass deliverable to Mars by FH)/(mass of MER in cruise configuration)


Slightly less superficial: FH payload fairing volume/volume of MER cruise stage (modeled as cylinder of height 1.6 m and diameter 2.65 m). 

An MER, at TMI, massed 1.063 tonnes.  Round up to 1.100 tonnes (for any kind of metal frame between the rovers).  FH TMI payload is 16.8 tonnes (expendable?), suggesting 15 MERs. 

Internal payload fairing diameter is 4.6 m (possibly outdated--taken from old user's guide).  This tapers a bit at the nose, but still seems to stay above 2.65 m for at least 8 meters, so you could launch 5 MERs at a time.  I suspect this would be a mostly-reusable FH.

Of course, this seems to be a variant of the "rebuilding the Saturn V" problem--we have the blueprints, but getting the production line back together could be troublesome.  Suppliers may well be out-of-business by now, parts might be out-of-stock.

Not too big a manufacturing hurdle to handle. The CTO of the company that provide the FH have side businesses manufacturing electric car & comsats. So if you can persuade him that building new MER size rovers have merit, than he can conjoured up some mini rovers.  ;D

Offline Oersted

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Re: How many Opportunity Rovers could Falcon Heavy fly to Mars?
« Reply #10 on: 05/09/2017 09:17 AM »
Superficial answer:

(mass deliverable to Mars by FH)/(mass of MER in cruise configuration)


Slightly less superficial: FH payload fairing volume/volume of MER cruise stage (modeled as cylinder of height 1.6 m and diameter 2.65 m). 

An MER, at TMI, massed 1.063 tonnes.  Round up to 1.100 tonnes (for any kind of metal frame between the rovers).  FH TMI payload is 16.8 tonnes (expendable?), suggesting 15 MERs. 

Internal payload fairing diameter is 4.6 m (possibly outdated--taken from old user's guide).  This tapers a bit at the nose, but still seems to stay above 2.65 m for at least 8 meters, so you could launch 5 MERs at a time.  I suspect this would be a mostly-reusable FH.

Of course, this seems to be a variant of the "rebuilding the Saturn V" problem--we have the blueprints, but getting the production line back together could be troublesome.  Suppliers may well be out-of-business by now, parts might be out-of-stock.

Thanks, LM, for that very informative first assessment. Five, that's pretty good! And with lots of extra mass capacity so it could possibly allow for reuse of at least the side boosters.

I was wondering if there would be room to pack the MERs around a central bus, perhaps three to a side and on two levels, making six in total? That could be useful when deploying. Or they could fly a couple together with a Red Dragon.

I realise it would be quite a huge undertaking, but reconnoitering the Martian surface will IN ANY CASE be a momentous job. Not starting from zero but actually utilizing presently used flight- and surface-operations-hardware could be a useful shortcut, I think.

As for the "rebuilding Saturn V"-issue, well, I don't think it is too bad. JPL is extremely diligent about documenting their work and test procedures. CAD files exist of all hardware. The people are alive and the companies that built the rovers are still here as well, AFAIK.

Offline Kaputnik

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Re: How many Opportunity Rovers could Falcon Heavy fly to Mars?
« Reply #11 on: 05/10/2017 08:28 AM »
The science community is not asking for this.
They are asking for sample return.

A much more interesting question is: what would a SpaceX led MSR mission look like?
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Offline Oersted

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Re: How many Opportunity Rovers could Falcon Heavy fly to Mars?
« Reply #12 on: 05/10/2017 08:44 AM »
SpaceX is not focused on Mars to satisfy the science community. They are in it for colonization. Obviously, down the road, Mars colonization will hugely benefit the science community. Specifically there will be huge amounts of sample return.

If MERs were to fly to Mars on a Falcon Heavy they would go with instruments to characterise soil, rock and water.

Do anyone see a better, cheaper and faster way to surface-reconnoiter colony candidate sites?
« Last Edit: 05/10/2017 08:44 AM by Oersted »

Offline Kaputnik

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Re: How many Opportunity Rovers could Falcon Heavy fly to Mars?
« Reply #13 on: 05/10/2017 10:42 AM »
SpaceX is not focused on Mars to satisfy the science community. They are in it for colonization. Obviously, down the road, Mars colonization will hugely benefit the science community. Specifically there will be huge amounts of sample return.

If MERs were to fly to Mars on a Falcon Heavy they would go with instruments to characterise soil, rock and water.

Do anyone see a better, cheaper and faster way to surface-reconnoiter colony candidate sites?

So are you suggesting that SpaceX contract JPL to build them dozens of MERs? At $400m each at 2003 costs?* I'm not even sure what the legal position would be if part of NASA were asked to provide a commercial service like that.

A precursor to manned colonisation would be better served by a different set of instruments, especially large subsurface drills.


*To be fair, the program was initially costed at $600m for a single rover, so the additional cost per rover is 'only' $200m and of we take out the launch cost it's only about $140m. Plus inflation to 2017 costs.
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Offline spacenut

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Re: How many Opportunity Rovers could Falcon Heavy fly to Mars?
« Reply #14 on: 05/10/2017 01:09 PM »
We have only scratched the surface of Mars.  If SpaceX is going, like someone said, a satellite system needs to be installed to globally cover Mars.  Then there may need to be some communication satellites in orbit around the sun to be able to have continuous access to Mars.  Then we not only need rovers, but we need serious ground radar and drilling robots to see what is under the Martian surface, like how much water?, what minerals and chemicals? 

Offline Jimmy Murdok

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Re: How many Opportunity Rovers could Falcon Heavy fly to Mars?
« Reply #15 on: 05/10/2017 01:43 PM »
A JPL solution would be very expensive for SpaceX way of doing things, I can see few JPL advisors into a partial time task force team mostly composed by Tesla and SpaceX employees. Similar to Pica knowledge transfer.

How do you get rid of the expensive plutonium heaters in a fully electric design? ???

Offline Kaputnik

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Re: How many Opportunity Rovers could Falcon Heavy fly to Mars?
« Reply #16 on: 05/10/2017 03:19 PM »
A JPL solution would be very expensive for SpaceX way of doing things, I can see few JPL advisors into a partial time task force team mostly composed by Tesla and SpaceX employees. Similar to Pica knowledge transfer.

How do you get rid of the expensive plutonium heaters in a fully electric design? ???

Buy Li ion cells from Samsung of course.
« Last Edit: 05/10/2017 03:19 PM by Kaputnik »
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Offline whitelancer64

SpaceX is not focused on Mars to satisfy the science community. They are in it for colonization. Obviously, down the road, Mars colonization will hugely benefit the science community. Specifically there will be huge amounts of sample return.

If MERs were to fly to Mars on a Falcon Heavy they would go with instruments to characterise soil, rock and water.

Do anyone see a better, cheaper and faster way to surface-reconnoiter colony candidate sites?

Yes. Build a clean-sheet, customized design for the purpose, rather than make a kludge with obsolete parts and designs.
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Offline Oersted

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Re: How many Opportunity Rovers could Falcon Heavy fly to Mars?
« Reply #18 on: 05/10/2017 03:49 PM »
How do you get rid of the expensive plutonium heaters in a fully electric design? ???

No plutonium in the MERs. That is Curiosity.

Offline guckyfan

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Re: How many Opportunity Rovers could Falcon Heavy fly to Mars?
« Reply #19 on: 05/10/2017 04:06 PM »
How do you get rid of the expensive plutonium heaters in a fully electric design? ???

No plutonium in the MERs. That is Curiosity.

Unfortunately not true. The MERs don't have RTG, but they do have small devices producing heat to keep them from getting too cold over night.

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