Landing a flying saucer on Mars

Terraformer · 2014-04-11 16:01:57

http://www.newscientist.com/article/dn2 … 0hjb4Wa-HY

The idea is to rapidly inflate the saucer to decelerate from Mach 3.5 to Mach 2, then to use parachutes. They're talking about landing up to about 10 tonnes as one payload. Enough for a human team to assemble an inflatable habitat; Sundancer (Bigelow module) is about the mass they're talking of landing.

JoshNH4H · 2014-04-11 19:41:51

Sounds like a great technology, I'm excited to see the results!

Quaoar · 2014-04-12 06:11:59

JoshNH4H wrote:

Sounds like a great technology, I'm excited to see the results!

It may be interesting to confront pros and cons of LDSD v.s ADEPT

GW Johnson · 2014-04-12 09:00:31

I followed the link in post 1 above. The photo there looked like a ballute with some sort of flexible heat shield panel. I'd guess this is ballute technology combined with the inflatable heat shield technology. Not sure what all the connections are, because I haven't followed this very closely, just observing the occasional news story.

Ballutes can be power-inflated. In fact, the should be. Self inflation from ram-air ports has always been rather uncertain. The blunt shape is the drag, but it also has to "tow" stably, that's the real trick. If you have a flexible heat shield material coated onto your ballute, these things become good candidates for aero decelerators in the regime higher than 2.5 Mach, which is just about the fastest you can open a ribbon or ringsail chute successfully.

By providing better aero deceleration at higher Mach than a parachute, is how ballutes can get an big object slowed at an altitude high enough to do some good on Mars. I noticed that the article said "10 tons". This appears to be aimed at surface probes like Curiosity and a little larger. Doesn't appear to be aimed at the even-larger objects that would carry men to Mars. I still think supersonic retro-propulsion, dispensing with chutes entirely, offers more promise in those sizes.

GW

Excelsior · 2014-04-12 10:32:55

Technically that's a falling saucer.

JoshNH4H · 2014-04-12 10:49:40

I think we could reasonably land stuff on Mars in ten tonne packages. What would be bigger than that?

SpaceNut · 2014-04-12 15:50:55

There goes the neighborhood the Earthlings have landed...

All kidding asside the topic has been here on newmars for some time...landing on mars
multiple times throughout the topic

http://www.uh.edu/sicsa/library/media/S … celeraters

Terraformer · 2014-04-13 10:23:11

I was looking for that thread... I expected it to be in this forum though.

Tom Kalbfus · 2014-04-13 12:03:14

JoshNH4H wrote:

I think we could reasonably land stuff on Mars in ten tonne packages. What would be bigger than that?

How much does your house weigh? A ton is 1,000 kg, a person could weigh 100 kg, so ten adult male humans weigh a ton, so ten tons are 100 adult male humans. The tonnage landed is that mass that is left after all the propellents are expended to land the craft safely on Mars, and probably shouldn't include the mass of the rocket engines or the parachutes as those items are of no further use after the landing has been achieved!

JoshNH4H · 2014-04-13 12:35:19

Well, if you figure six people-- and for an astronaut 75 kg is a more reasonable upper limit on mass (Astronauts are short and light, after all). If you have six, that's 450 kg, leaving about 9.5 tonnes for the hab. Zubrin uses less than this, I believe. I'm not saying that it will necessarily be easy to split things up into 10-tonne chunks, but it will certainly be possible.

GW Johnson · 2014-04-13 21:11:10

Whether or not 10 tons is appropriate depends on your mission design. If you want a reusable "Mars ferry" or "landing boat", that will be in the 30-60 ton range.

GW

JoshNH4H · 2014-04-13 21:22:59

Fully fueled, you think? Kind of depends on your payload, obviously, but if you're just looking to send people (Think of a transfer vehicle in a highly elliptical Mars orbit so that almost all of the required delta-V comes from the surface ferry, without having to carry the mass). Let's say you need 5.5 km/s at 3.6 km/s exhaust velocity, your mass ratio is 4.6. This means that your fully fueled vehicle has to be about 80% fuel. If you only want to send up 5 tonnes, budget another 5 tonnes of structure and then 40 tonnes of fuel; There's your 10 tonnes.

Glandu · 2014-04-14 03:16:32

In the late 990s, landing more than 150kg was sci-fi. Recently, we landed nearly one ton. That's positive. Though I notice designs are getting more and more exotic. There is probably a limit to what we can do - but current progress is encouraging.

GW Johnson · 2014-04-14 14:25:45

The Rube Golberg rig on Curiosity was the bandaid required to get high enough end-of-hypersonics altitude to use a chute effectively, and still land a 1-ton rover with a fixed total spacecraft mass budget. There's a lot of things coming together constraining that problem.

The ballute being discussed in this thread is an alternate bandaid required to make chutes feasible with even bigger masses to be landed. The bigger the mass, the earlier in the entry hypersonics your ballute has to be deployed, and the more it looks like its own inflatable heat shield. Whether you tow it behind or ride behind it makes no real difference, except that riding behind eliminates your heat shield at the cost of inherently-poor vehicle attitude stability.

There is a completely different approach: supersonic/hypersonic retro propulsion. Great big items will come out of hypersonics at local Mach 3 (about 0.7 km/s) somewhere near 5 km altitude on Mars, instead of the 15-30 km needed to make a chute work. But around a gee or two of retro thrust can take you from that 0.7 km/s to zero in those 5-15 km of slant path length.

Folks are afraid of it because we haven't tried flying this way yet. It's just "new". But I believe you can land objects approaching 100 tons this way. I think there are fundamental solutions to all the design issues.

GW

Last edited by GW Johnson (2014-04-14 14:28:31)

louis · 2014-04-14 15:16:12

JoshNH4H wrote:

I think we could reasonably land stuff on Mars in ten tonne packages. What would be bigger than that?

I agree.

Sounds like this could be the way forward. My only quibble with the article is where they talk about a mission involving 40-100 tonnes. Why on earth would you need 100 tonnes? 100 tonnes of what?

I would say 40 tonnes was very much the upper limit - and you don't need to land it all in one go. Probably 25 tonnes would be good enough for a first time 6 person mission where you were just experimenting with agriculture, smelting and so on, rather than trying to achieve near self-sufficiency straight away.

JoshNH4H · 2014-04-14 16:01:06

I would say it's pretty easy to get to 100 tonnes if you don't do ISRU fuel production.

Having said that, it would be nice to be able to land 100 tonnes on Mars. We do it on Earth, with shuttle; I'm still not convinced that the same technology is not applicable. I've posted this image before, but it shows the speed of the shuttle as a function of altitude:

The altitude, on Earth, corresponding to the same pressure as the surface of Mars is about 40 km. This appears to correspond to a speed under 2 km/s, even when entry speed is 8 km/s instead of 4. I would expect that it should be very possible to slow down to 1 km/s using the Martian atmosphere, even with 100 tonne payloads, and that from there either inflatables or simple retro fire would be doable. Mass ratio for a 1 km/s burn with Methlox is 1.33.

Edit: Just to be extra-clear, I'm agreeing with you, louis, and I don't think 100 tonnes is remotely necessary. But when the time to colonize comes around, it would be nice.

GW Johnson · 2014-04-15 08:39:06

It all depends upon what you are trying to accomplish. For one-way deliveries of habs and supplies, there's little need for anything over around 10 tones.

For a two-way reusable "Mars ferry" or landing boat, something needed when you delivering a permanent base or a real colony, vehicles like that start somewhere around 30 tons, and go up. It doesn't matter whether you fuel it from orbit or the surface, you still have a big velocity requirement for the flight up, plus a smaller one for the landing.

I think that the "minimalist" notions of just landing habs and supplies will lead to another Apollo-like problem. The government or consortium of government agencies that sends the first mission will not send another. It's the "been there and done that" excuse, used to cancel Apollo in the middle of the planned landings.

If you don't establish a first base (to be left running on automatic) on that very first trip, then it is unlikely that anyone will do that job for many decades, just like what happened with the moon. But if you do leave an operable base, a visionary private concern might go back sooner, and put it to good use.

Landing 10 ton habs and supply modules shot direct from Earth is probably not the best way to do that job. For one thing, there is the "we missed the aim point" problem (too far away is simply wasted). For another, there is the landing area collision problem: you might hit something already there, or damage it with your rocket blast. And, there is the difficulty of assembling the base from payloads you have to transport over rough ground.

I may be wrong, but it seems more sensible to me to use a bigger landing boat to make fewer trips down with bigger cargoes, from a bunch of stuff you sent to Mars orbit. Fewer trips with bigger cargoes reduces the probability of incurring the two problems cited above, and it reduces the effort needed to transport stuff over rough ground for base assembly.

That base needs to be more than just a hab. It needs to be a place to experiment (manned and unmanned) with all sorts of ISRU and crop greenhouse stuff. Otherwise, why go back?

There is a longer-term danger here if you think too small. It already hurt us with the moon.

GW

Tom Kalbfus · 2014-04-15 13:20:51

Any reason why would couldn't scale up a sky crane? The whole idea of landing something on Mars is basically to get the object your trying to land to match the velocity on the ground only for the few seconds required to make solid contact. I believe the latest rover, Curiosity was landed by sky crane. Couldn't an larger sky crane land an entire hab? Lets say we lower the hab from a cable attacked to the sky crane as its retro-rockets fire. a lower extremity of the cable extends below the hab so that it makes contact with the ground first, that way the sky crane knows exactly how high off the ground it is and at what speed it can safely lower the hab onto the ground. Once the hab is on the ground, the sky crane disconnects and crashes itself a safe distance away using the remaining fuel it has to get there.

I think an inflatable hab would be best, one that unfolds to a 15 meter radius disk, and a plastic dome inflates on top of that using pumps to pump the Martian atmosphere inside. One can crack the carbon-dioxide to produce a sufficient quantity of oxygen, then we keep on pumping more Martian atmosphere, we freeze out the carbon-dioxide, and see what gases are left, the idea is to accumulate nitrogen and water vapor. If you freeze out the Martian atmosphere , there is a small quantity of nitrogen that does freeze, so this gets left inside the dome, Since water freezes at a higher temperature than carbon-dioxide, we can freeze out the water and store it in tanks. Slowly over time we can accumulate the gases we need to support the astronauts that are to arrive later.

louis · 2014-04-15 17:42:34

GW Johnson wrote:

It all depends upon what you are trying to accomplish. For one-way deliveries of habs and supplies, there's little need for anything over around 10 tones.
For a two-way reusable "Mars ferry" or landing boat, something needed when you delivering a permanent base or a real colony, vehicles like that start somewhere around 30 tons, and go up. It doesn't matter whether you fuel it from orbit or the surface, you still have a big velocity requirement for the flight up, plus a smaller one for the landing.
I think that the "minimalist" notions of just landing habs and supplies will lead to another Apollo-like problem. The government or consortium of government agencies that sends the first mission will not send another. It's the "been there and done that" excuse, used to cancel Apollo in the middle of the planned landings.
If you don't establish a first base (to be left running on automatic) on that very first trip, then it is unlikely that anyone will do that job for many decades, just like what happened with the moon. But if you do leave an operable base, a visionary private concern might go back sooner, and put it to good use.
Landing 10 ton habs and supply modules shot direct from Earth is probably not the best way to do that job. For one thing, there is the "we missed the aim point" problem (too far away is simply wasted). For another, there is the landing area collision problem: you might hit something already there, or damage it with your rocket blast. And, there is the difficulty of assembling the base from payloads you have to transport over rough ground.
I may be wrong, but it seems more sensible to me to use a bigger landing boat to make fewer trips down with bigger cargoes, from a bunch of stuff you sent to Mars orbit. Fewer trips with bigger cargoes reduces the probability of incurring the two problems cited above, and it reduces the effort needed to transport stuff over rough ground for base assembly.
That base needs to be more than just a hab. It needs to be a place to experiment (manned and unmanned) with all sorts of ISRU and crop greenhouse stuff. Otherwise, why go back?
There is a longer-term danger here if you think too small. It already hurt us with the moon.
GW

I think there's a compromise position for the first couple of missions. It would be wrong to aim for complete self-sufficiency from the start, but we can certainly make progress. We can begin food production, metallurgy, brick production, water mining and so on. But I think we need to build to effective self-sufficiency over several missions.

GW Johnson · 2014-04-16 08:41:59

I quite agree with Louis: self-sufficiency isn't possible in the first mission or two, it will have to be developed over a long time.

My point is that there will be one (and only one) government-funded manned mission to Mars. That's just politics-of-money, which is the controlling factor for government efforts, as was so clearly demonstrated by the truncated Apollo program.

What that one-and-only government mission accomplishes has to be attractive enough to draw visionary private concerns into doing missions two-and-on. If you don't do that, expect at best a half-century hiatus, just like the moon. Or worse, we never go back.

Just landing a hab (however that is accomplished) won't be enough to do that job of placing something "attractive" on Mars. Just-a-hab is tantamount to an Apollo-style flag-and-footprints stunt. To do this "right", you have to try out every imaginable ISRU technique while you're there, and leave the best ones running on automatic when you go home. You have to set up multiple greenhouse approaches while you're there, and leave the best one "running" when you go home, to see if it really balances and self-sustains.

The equipment to do all of that is voluminous and it is heavy. You don't get that from landing one-to-three 10-ton hab modules shot direct from Earth. It'll take a whale of a lot more than that. That's why I think the total payload to be landed is nearer a minimum of 100-to-300 tons than it is 10-to-30 tons. You can land it in small chunks, of course, but I think it would be safest to do that with a reusable landing boat from Mars orbit (however it is fueled).

GW

SpaceNut · 2014-04-17 18:02:28

Landing is key puzzle in Mars trip plans: experts

Where Curiosity weighed one ton, engineers estimate a supply capsule to prepare for a manned landing would weigh somewhere around 40 tons.
Such a mission would require not only food, water and oxygen for the astronauts, but a vehicle powerful enough to get them back to their spaceship, which would likely remain in orbit.
Atmospheric pressure at 25 miles (40 kilometers) altitude on Earth is equivalent to just six miles up (10,000 meters) on Mars -- which leaves little time to slow the faster-than-sound speed of a Mars lander, Braun said.

Campbell's supersonic retropropulsion concept will be briefed at agency headquarters this week, he says.

Human Mars Lander Must Break New Ground

Entry-descent-and-landing (EDL) experts who spoke at a Humans To Mars symposium here say the “sky crane” that landed the robotic Curiosity rover on Mars last year will not scale to the huge sizes need for humans. And even if it did, the “seven minutes of terror” controllers at the Jet Propulsion Laboratory experienced at a distance during the first sky-crane landing may be a little too tame for a human mission.
To land a house-sized cargo carrier or human habitat on Mars, Steltzner says, it probably will be necessary to go directly from hypersonic speeds to propulsive deceleration—essentially firing some kind of rocket to slow down enough to land. And that, the experts say, will be as difficult to accomplish as developing efficient radiation protection, the traditional long pole in the tent for a human trip to Mars.
Kendall Brown, an EDL expert in the Exploration and Mission Systems Office at Marshall Space Flight Center, said a cross-agency study using then-current design reference missions (DRMs) took parachutes entirely out of the landing sequence for a human expedition. Instead, either a rigid or inflatable aerodynamic decelerator would slow the entry vehicles from hypersonic speeds to supersonic speed in the Mach 2.5-3 range. At that point, the EDL system would shift to rocket propulsion for the remainder of the landing. It will not be easy to ignite a set of downward-facing rocket engines as they fly through the Martian atmosphere at three times the speed of sound.

SpaceNut · 2014-04-17 19:57:05

Overall, the latest DRMs estimate a human Mars mission will require launching about 800 tons of payload with the heavy-lift Space Launch System. But estimates of just how much of that mass actually will touch down on Mars range from 20-60 tons, and the most recent DRMs NASA has developed are being held so closely that the National Academies of Science panel studying the future of human spaceflight cannot access them.

Meet NASA’s new supersonic flying saucer, for future Mars landings

NASA is developing two variants of the LDSD [PDF] http://www.jpl.nasa.gov/news/fact_sheets/LDSD.pdf – one with a 20-foot (6m) SIAD for smaller, robotic extraplanetary landings, and one with a larger 26-foot (8m) SIAD for larger, human payloads.
NASA is scheduled to perform a series of LDSD launches from the Pacific Missile Range Facility on Kauai, Hawaii in 2014 and 2015. The LDSD could be ready for missions to Mars as early as 2018, though there aren’t currently any scheduled heavy-payload missions to Mars that could use it.

Quaoar · 2014-04-20 10:22:13

SpaceNut wrote:

Kendall Brown, an EDL expert in the Exploration and Mission Systems Office at Marshall Space Flight Center, said a cross-agency study using then-current design reference missions (DRMs) took parachutes entirely out of the landing sequence for a human expedition. Instead, either a rigid or inflatable aerodynamic decelerator would slow the entry vehicles from hypersonic speeds to supersonic speed in the Mach 2.5-3 range. At that point, the EDL system would shift to rocket propulsion for the remainder of the landing. It will not be easy to ignite a set of downward-facing rocket engines as they fly through the Martian atmosphere at three times the speed of sound.

I think SpaceX solution of putting Super Draco rocket pods backward and canted outward at 45° will work: if rockets are inside the Mach cone, they will not be hited by supersonic stream, and if they are hypergolic, like they are, ignition will be quite easy.
Super Draco pods will be perfect for a hab that has to remain on Mars surface, but not for a MAV, because 45° canted out rockets lost too much delta-V to be useful for orbital ascend. This problem can be fixed munting another ascend rocket in the middle of the thermal shield or using basculant rocket pods that fire at 45° outward douring descend and straight during ascend.

Happy Easter to all!

Last edited by Quaoar (2014-04-20 10:47:58)

SpaceNut · 2014-04-20 10:55:48

So by solving entry descent for larger payload mass we now have a secondary problem of ascent is not achievable.

One way to solve is if the engines are detachable to allow for them to be relocated would the hypregolic fueled engines have the launch power to achieve orbit. Which on a guess would be a no but I will leave that up to others that can compute the values. This also does cause an issue if we are wanting to use methane created fuels for return in the same vehicle that we land in. It is starting to sound like we need a multiple engine system for landing and take off.

Quaoar · 2014-04-20 13:10:09

SpaceNut wrote:

So by solving entry descent for larger payload mass we now have a secondary problem of ascent is not achievable.
One way to solve is if the engines are detachable to allow for them to be relocated would the hypregolic fueled engines have the launch power to achieve orbit. Which on a guess would be a no but I will leave that up to others that can compute the values. This also does cause an issue if we are wanting to use methane created fuels for return in the same vehicle that we land in. It is starting to sound like we need a multiple engine system for landing and take off.

Detachtable enigine may be a solution, but I imagine pivoting pods that stay 45° canted outward for descent and will be extrofletted and pointed straight downward for orbital ascent.
Propellant issue may be solved using hypergolics only for ignition, like almost every Russian's rockets do, then burning other propellant like LOX-CH4, LOX-RP1 or LOX-LH2. It's a very well proven technology.

Last edited by Quaoar (2014-04-20 13:16:43)

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#1 2014-04-11 16:01:57

Landing a flying saucer on Mars

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#10 2014-04-13 12:35:19

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#14 2014-04-14 14:25:45

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#15 2014-04-14 15:16:12

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#16 2014-04-14 16:01:06

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#17 2014-04-15 08:39:06

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#19 2014-04-15 17:42:34

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#20 2014-04-16 08:41:59

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#21 2014-04-17 18:02:28

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