Another NASA fail...

louis · 2014-06-29 12:47:01

http://www.bbc.co.uk/news/science-environment-28080838

Why are NASA making such a meal of the landing issue?

Fundamentally the problem is little different from lunar landing.

Musk has made good progress with retro landing rockets.

NASA seems incapable of focus and that is why despite their multi-billion dollar budget we see so little progress.

RobS · 2014-06-29 13:09:04

No, it's more complicated than that, Louis. The Martian atmosphere is thick enough to make retrorockets hard to use (unless they are canted to the side like Musk's, but that technology is not yet proved) and too thin to use parachutes for very large vehicles. Probably Musk's system will prove effective, but we still aren't sure.

JoshNH4H · 2014-06-29 13:35:12

Especially because the use of retrorockets to decelerate all the way down from Martian hyperbolic entry to the ground (louis' usual approach) is prohibitive from a mass standpoint.

The interesting thing about this test, by the way, is not the failure of the parachute (parachutes are notorious for the difficulty and expense of their design) but rather the success of the extendable drag shield, which is new technology.

We could do entry on Mars in much the same way as we do it on Earth, in principle. The issue is that because of Mars' thin atmosphere you need larger heat shields, which won't fit on existing launchers. This technology is pivotal because it eliminates that limit, and thus in combination with parachutes and perhaps an enlarged sky crane at the end, could very well be the technology that lands us on Mars.

RobertDyck · 2014-06-29 14:35:23

NASA talks about the difficulty landing large mass on Mars, but they've already worked out how.
Adaptive Deployable Entry and Placement Technology (ADEPT) for Human Mars Missions
I've posted this before...

Slide 6 for ADEPT has a little graphic to land on Mars, with 4 options to land 40 MT (assume metric tonnes) landed payload.
#1: 23m umbrella heat shield during aerocapture, then expand to 44m at transition between hyper- & supersonic, then subsonic retro-thrust. Finally terminal descent and landing. Total mass before entry: 90mT
#2: 33m aerocapture, remain 33m during hyper- & supersonic, begin retro-thrust at transition between super- & subsonic. Terminal descent and landing. Total mass: 87mT
#3: 23m aerocapture, remain 23m hyper- & supersonic, supersonic retrothrust. Terminal descent and landing. Total mass: 81mT
#4: 23m aerocapture, parachute opens supersonic, subsonic retrothrust. Terminal descent and landing. Total mass: 78mT

So the lowest mass solution is #4. This drops a lander larger than Mars Direct hab or ERV.

JoshNH4H · 2014-06-29 14:56:53

That's still under 50% of the payload at Mars that gets landed on the surface, though. I'm not claiming its prohibitive or anything, but I'd sure like to see less. What is all that mass? And for that matter, how much mass do we need on the surface at any given time?

RobertDyck · 2014-06-29 15:23:38

The ADEPT chart shows 78 metric tonne mass for 40 metric tonnes landed on the surface. That's for aeroshell with heat shield, parachute, retro-rockets and propellant. That's just a hair over 50% landed payload. However, I think legs are included in "landed payload". Mars Direct habitat had a mass budget of 25.2 metric tonnes, so 40 metric tonnes is bigger.

JoshNH4H · 2014-06-29 15:50:55

At 78 tonnes we're already talking about quite a hefty launcher. Scaling down a bit, a total mass of 53 T means a landed payload around 27 T, so I could see a couple or a few of those (one for the hab, one for the MAV, and a smaller lander for extra scientific equipment?) Being a very good landing technology for the mission.

SpaceNut · 2014-06-29 17:13:30

Been away for a while but it seems that the topic is about the most recent "Test of Mars reentry technology a qualified success" From Spacetoday.net

NASA declared Saturday's test flight of a Mars reentry technology demonstrator a success although the vehicle's parachute failed to fully open. The Low Density Supersonic Decelerator (LDSD) lifted off on a balloon from the Hawaiian island of Kauai at 2:41 pm EDT (1841 GMT) Saturday, raising to an altitude of more than 35 kilometers. At 5:05 pm EDT (2105 GMT), the LDSD separated from the balloon and ignited its rocket engine, accelerating to Mach 4 and an altitude of 55 kilometers. While one of the key technologies being tested by LDSD, an inflatable ballute designed to slow the vehicle down, did appear to work, another key system, a large parachute, failed to open fully. Project officials still declared the mission a success since the primary objective for this flight was to test the technologies for getting LDSD to the desired velocities and altitudes. Two additional LDSD test flights are planned, with the next in mid-2015. NASA hopes LDSD will successfully test technologies that can eventually be
used to land large spacecraft on the surface of Mars.

The saucer was to expand from 15 ½ to 20 feet in width which is still less than a 10 meter which is what most designs target. The expansion was to increase the aerodynamic drag enough to slow the saucer to Mach 2.5, at which point a 100 foot wide supersonic parachute was to deploy and lower the test hardware to the Pacific Ocean.
From what I understand the parachute did not fully inflate which should have been easy here on earth but goes to show how hard using them on mars will be.

Last edited by SpaceNut (2014-06-29 17:23:05)

louis · 2014-06-29 18:39:11

RobertDyck wrote:

The ADEPT chart shows 78 metric tonne mass for 40 metric tonnes landed on the surface. That's for aeroshell with heat shield, parachute, retro-rockets and propellant. That's just a hair over 50% landed payload. However, I think legs are included in "landed payload". Mars Direct habitat had a mass budget of 25.2 metric tonnes, so 40 metric tonnes is bigger.

But why does anyone think you need to land 40 tonnes on the surface in one go?

We have the technology to land multiple small loads over a number of years, climaxing with the landing of a self-erecting hab unit.

I doubt the human lander has to be much more than 2 tonnes, and of course we can have two for a total six person mission, with 3 in each.

NASA are over-complicating the problem and thereby making it much more challenging that it needs to be.

louis · 2014-06-29 18:43:07

SpaceNut wrote:

Been away for a while but it seems that the topic is about the most recent "Test of Mars reentry technology a qualified success" From Spacetoday.net
NASA declared Saturday's test flight of a Mars reentry technology demonstrator a success although the vehicle's parachute failed to fully open. The Low Density Supersonic Decelerator (LDSD) lifted off on a balloon from the Hawaiian island of Kauai at 2:41 pm EDT (1841 GMT) Saturday, raising to an altitude of more than 35 kilometers. At 5:05 pm EDT (2105 GMT), the LDSD separated from the balloon and ignited its rocket engine, accelerating to Mach 4 and an altitude of 55 kilometers. While one of the key technologies being tested by LDSD, an inflatable ballute designed to slow the vehicle down, did appear to work, another key system, a large parachute, failed to open fully. Project officials still declared the mission a success since the primary objective for this flight was to test the technologies for getting LDSD to the desired velocities and altitudes. Two additional LDSD test flights are planned, with the next in mid-2015. NASA hopes LDSD will successfully test technologies that can eventually be
used to land large spacecraft on the surface of Mars.
The saucer was to expand from 15 ½ to 20 feet in width which is still less than a 10 meter which is what most designs target. The expansion was to increase the aerodynamic drag enough to slow the saucer to Mach 2.5, at which point a 100 foot wide supersonic parachute was to deploy and lower the test hardware to the Pacific Ocean.
From what I understand the parachute did not fully inflate which should have been easy here on earth but goes to show how hard using them on mars will be.

Quite - more risky on Mars = more risk to the life of the crew.

I think we already have the technology to land an Apollo style craft on Mars. Get the crew to the surface and then they can decamp to the hab unit ready and waiting for them. They will have emergency rations with them in the lander and also in the hab. But over the first few days they can then bring in supplies from other pre-landed craft. I envisage maybe 8 separate landings with 2-4 tonnes of supplies.

We've already landed close to a tonne. I don't think it's beyond our ability to do this.

SpaceNut · 2014-06-29 19:14:48

The lunar lander was a full powered from orbit but with the heatshield, parachutes and with an atmosphere needs to be more massive in that the structural elements would need to be heavier. We are now looking at a mass that is greater than a 2 person lander....and that does not even come close as we need power, consumables in food, water, air for the duration and return to orbit fuel.

http://en.wikipedia.org/wiki/Apollo_Lunar_Module

Dimensions
Height: 17.9 ft (5.5 m)
Width: 14.0 ft (4.3 m)
Depth: 13.3 ft (4.1 m)
Landing gear span: 29.75 ft (9.07 m)
Cockpit volume: 235 cu ft (6.7 m3)
Masses
Ascent stage: 10,024 lb (4,547 kg)
Descent stage: 22,375 lb (10,149 kg)
Total: 32,399 lb (14,696 kg)

idiom · 2014-06-29 22:38:44

If you can throw more mass then the lander gets cheaper and safer.

Big dumb launchers at the Earth end make things a lot simpler at the Mars end.

JoshNH4H · 2014-06-29 23:04:17

It looks like SpaceX is trying to strike to the heart of things with its reusable rockets, though. I wonder what the reusability prospects are for the falcon heavy. Probably pretty good.

GW Johnson · 2014-09-12 11:52:35

The difficulty of the Mars lander problem depends upon whether you think one-shot or reusable.

It needs a heat shield because you must do hypersonic entry with severe friction heating on descent. It may not need parachutes, as it is likely that its entry ballistic coefficient will substantially exceed 100 kg/sq.m, and there's simply not time enough time to deploy a chute and have it do any deceleration with higher ballistic coefficients. Going straight from hypersonic entry to terminal rocket braking is the better, simpler, and more practical idea in that regime.

You can build a one-shot vehicle as two stages, to increase the delivered payload fraction substantially. With entry aero-deceleration doing the brunt of the work on descent, the terminal rocket braking requirements are actually quite modest at around 1.5 km/s delta-vee, versus nearly 4 to ascend. That means you do the descent and part of the ascent on stage 1, and finish the ascent and the rendezvous with stage 2.

On the other hand, with a lower payload fraction (and larger vehicle for the same delivered cargo), you can do the entire job on chemical propulsion in one stage, because the total delta-vee required of the rocket is only 5 to 5.5 km/s. It looks better with LOX-LH2, but can be done with the other propellant selections in the 300-350 Isp class. That's a lander you can refuel (at either end of the trip!) and fly again, And again, and again, etc. I typically get around 60-90 tons of loaded fueled Mars lander vehicle for a 3 ton cargo delivery. Closer to 30 tons with LOX-LH2.

Myself, I like that second choice (bigger but reusable) a lot better, because it lets you visit multiple sites in the one mission to Mars, in spite of the added tonnage you must send to Mars (landers plus lots of propellant for the multiple landings). That multiple landing sites capability makes a whopping lot more common sense to me than the Apollo model of one mission-one landing. If there's one thing we have learned all these decades with the probes and the Apollo landings, it's that no one site characterizes a planet (surprise, surprise!).

If you can build a thing like that for Mars (and we can, right now), you can build a similar reusable, one-stage chemical lander for the moon. There's less total delta-vee in spite of the all-powered descent, and no heat shield needed, so payload fraction can be quite attractive. I have no idea why NASA thinks they have to build a one-shot two-stage Apollo-LEM-on-steroids to go back to the moon. Except that it looks like they are still thinking Apollo-on-steroids with one mission-one landing. If we go back to the moon, that's not appropriate. We would be going to set up bases and commercial mining, etc.

One other point: reusable landers must have rocket engines capable of many, many restarts, and a long service life. You can use that propulsion to push said lander where you want to go (moon or Mars), drawing from added propellant tanks (not whole propulsive stages!!) for that purpose. If you choose to return the lander to Earth, it can push itself back and enter LEO. The lander's engine is the "service module" engine for a manned capsule. All it needs is refillable propellant tanks besides what it has internally. Reusability spread over multiple missions is a massive cost reducer.

That is a very beneficial fit with generalized modular design (assembly from docked modules) for all the vehicles. The right size of module is 10-25 tons right now, up to twice that when Falcon-Heavy starts flying (two 25 ton modules per Falcon-Heavy, say). Unit prices to low LEO are about $2500/pound right now, and should be near $1000/pound with Falcon Heavy. Unless SLS can get under that unit price (and it never, ever will), there's no point to use it for these missions. That's something NASA and Congress should have considered.

The modular concept leads one almost immediately to the orbital transport idea for Mars, equipped with landers. The landers might be flown there separately, or maybe not. The transport, if shaped as a long "baton" from docked modules, can be spun head-over-heels for artificial gravity. And that solves a whole host of life support issues for a 2.5 year mission to Mars.

There's real benefit available if one stirs up the guts to think outside the old Apollo box.

GW

SpaceNut · 2015-03-18 18:01:54

kbd512 wrote:

RobertDyck wrote:
No, not inflatable. I said several times, used ADEPT. NASA is already working on a carbon fibre heat shield that can be deployed like an umbrella. It's specifically designed for payloads larger than Curiosity.
Has this carbon fiber heat shield ever flown in space? If so, could you post a link?
RobertDyck wrote:
Do you work for Boeing or Lockheed-Martin? Why do you obsess over stupid ideas? What are you trying to sell?
Why is designing a capsule so small we can test it to perfection on small sounding rockets a stupid idea?
Which do you think will cost more money, be more complicated, and take significantly longer to design and test?
A one person capsule capable of descending to Earth from ISS in LEO or to Mars from a MTV in LMO or a far larger four to six person special purpose MAV that has to be landed using technology that has never flown in space, so far as I know, powered by engines that don't exist?
I'd be absolutely shocked if this multi-person MAV costs less than five billion to develop. Why immediately go for the most expensive and technically challenging solution?
The one person capsule has other potential uses, as previously noted, but the MAV will only be useful for landing on Mars or perhaps the moon.

kbd512 · 2015-03-18 19:16:13

I've said it before, but I'll say it again. Start really small. Single person landers are about working with realistic budgets and using existing technology, not giving up on something better.

Money isn't going to fall from the sky to fund heavy lift launch systems and multi-person landers. Absent angel investors with pockets like the Marianas Trench, the kind of money needed to do the types of things we want to do with lander tech just doesn't exist right now or the near future. NASA and Congress squandered available funding on SLS and Orion.

If we're going to pour money into a development project, let's start with the MTV and its propulsion system. Let's design something that F9H vs SLS can lift, even if it has to be assembled on-orbit.

If there's any money left, closed loop ECLSS and active radiation shielding are higher priorities than insanely expensive landers using experimental reentry tech. NASA had its shot to save the lunar and Mars programs by funding a lander program instead of a redundant capsule program.

SpaceNut · 2015-03-18 19:43:26

I should have done a better job of editing the post for the topic of ADEPT a bit better and did copy part of the post to the smallest human lander topic which I think is an interesting thought to get some of the mass down....

kbd512 · 2015-03-18 20:34:21

I think ADEPT is an enabling technology for landing the larger and heavier payloads, like the habitat modules or mobile habitat modules (rovers) on Mars, but let's admit to our reality and concede that this is a very new technology that will require far more testing before it's ready for prime time.

If NASA's manned space flight budget was double what is now, which is what I think a proper level of funding would be, then we'd have sufficient funding to develop the kinds of technologies we'd really like to have, such as multi-person landers, deep space transit vehicles, closed loop ECLSS, and active radiation shielding.

Regarding the presentation, I think approach #3 is the correct approach, even if it gives up a little payload mass in comparison to approach #4, by using more propellant for supersonic retro-propulsion.

Last edited by kbd512 (2015-03-18 21:31:02)

RobertDyck · 2015-03-18 22:01:53

kbd512 wrote:

I think ADEPT is an enabling technology for landing the larger and heavier payloads, like the habitat modules or mobile habitat modules (rovers) on Mars, but let's admit to our reality and concede that this is a very new technology that will require far more testing before it's ready for prime time.

So you're saying a technology NASA is currently working on and making progress with is not ready, but inflatable heat shields that have had no work what so ever are somehow ready?

kbd512 wrote:

If NASA's manned space flight budget was double what is now...

Oh, sure, I would like to double NASA's budget and slash the military budget. In year 2000 I said we could slash the military budget by 10%, give half to NASA and the other half for tax cuts. That would double NASA's budget. But it didn't happen. But after George W. Bush, utopia would be to cut the military budget to year 2000 plus inflation. Remember, year 2000 was the last year America had a balanced budget. In year 2000 the military budget was $288 billion, but in year 2007 it was $700 billion, and 2008 it was $799 billion. For year 2009, the first budget approved by Obama, it was $901 billion. This raises the obvious question "Are they insane!?!?!??!" And some people wonder why America is broke. It's been cut a bit; for 2015 it's only $628 billion. "Only!" If you take the year 2000 military budget and apply inflation to today, it works out to $390.87 billion. So try doing that. Try telling Congress to stop waging war on the Middle East, slash the military budget to that level, and double NASA's budget. Good luck with that.

kbd512 · 2015-03-19 00:56:03

RobertDyck wrote:

So you're saying a technology NASA is currently working on and making progress with is not ready, but inflatable heat shields that have had no work what so ever are somehow ready?

Inflatables have flown several times now and all tests I am aware of that didn't suffer from a launch vehicle failure have been successful.

Has ADEPT ever flown? Ever? Or is it powerpoint tech with some materials testing behind it? I'm not trying to be a Debbie Downer, but I'm pretty sure that they're still in the feasibility phase with ADEPT.

RobertDyck wrote:

Oh, sure, I would like to double NASA's budget and slash the military budget. In year 2000 I said we could slash the military budget by 10%, give half to NASA and the other half for tax cuts. That would double NASA's budget. But it didn't happen. But after George W. Bush, utopia would be to cut the military budget to year 2000 plus inflation. Remember, year 2000 was the last year America had a balanced budget. In year 2000 the military budget was $288 billion, but in year 2007 it was $700 billion, and 2008 it was $799 billion. For year 2009, the first budget approved by Obama, it was $901 billion. This raises the obvious question "Are they insane!?!?!??!" And some people wonder why America is broke. It's been cut a bit; for 2015 it's only $628 billion. "Only!" If you take the year 2000 military budget and apply inflation to today, it works out to $390.87 billion. So try doing that. Try telling Congress to stop waging war on the Middle East, slash the military budget to that level, and double NASA's budget. Good luck with that.

Yeah, I'm dreaming, I know.

RobertDyck · 2015-03-19 07:08:40

kbd512 wrote:

Inflatables have flown several times now and all tests I am aware of that didn't suffer from a launch vehicle failure have been successful.
Has ADEPT ever flown? Ever? Or is it powerpoint tech with some materials testing behind it? I'm not trying to be a Debbie Downer, but I'm pretty sure that they're still in the feasibility phase with ADEPT.

Yes you are being Debbie Downer. Read the documents. No, it hasn't flown. But it's way past PowerPoint. They've built hardware and tested in a ground lab. That's way beyond any work on an inflatable heat shield. Besides a Balloot is an inflatable heat shield for aerocapture; it isn't good enough for direct entry into the atmosphere of Venus or Mars. That's the two destinations the team for ADAPT are targeting. The Mars Direct mission plan included a heat shield that could be deployed like an umbrella. ADEPT is exactly that heat shield, designed for payloads heavier than Curiosity. Their document states it's capable of atmospheric entry of a payload heavier than the Mars Direct habitat or ERV; so it's more than enough.

kbd512 · 2015-03-20 01:18:15

RobertDyck wrote:

Yes you are being Debbie Downer. Read the documents. No, it hasn't flown. But it's way past PowerPoint. They've built hardware and tested in a ground lab. That's way beyond any work on an inflatable heat shield. Besides a Balloot is an inflatable heat shield for aerocapture; it isn't good enough for direct entry into the atmosphere of Venus or Mars. That's the two destinations the team for ADAPT are targeting. The Mars Direct mission plan included a heat shield that could be deployed like an umbrella. ADEPT is exactly that heat shield, designed for payloads heavier than Curiosity. Their document states it's capable of atmospheric entry of a payload heavier than the Mars Direct habitat or ERV; so it's more than enough.

Rob,

NASA has developed inflatable tech a little beyond powerpoint, too.

http://www.nasa.gov/home/hqnews/2012/ju … aunch.html

GW Johnson · 2015-03-20 15:11:42

louis wrote:

http://www.bbc.co.uk/news/science-environment-28080838
Why are NASA making such a meal of the landing issue?
Fundamentally the problem is little different from lunar landing.
Musk has made good progress with retro landing rockets.
NASA seems incapable of focus and that is why despite their multi-billion dollar budget we see so little progress.

Those were Louis's original questions or remarks starting this thread. Let me address those.

Landing issue -- the only outfits within NASA who have any experience at all landing things on Mars are the planetary probe guys, mostly the folks at JPL. Once those probes reached about a half-ton mass, they ran into severe problems continuing to do what they have always done: a heat shield-protected aerobrake entry followed by chute deceleration to some sort of final-braking subsonic landing.

This is driven by ballistic coefficient (which is inherently larger at larger vehicle mass) in that near-vacuum Mars has for "air". All that really means is that you have to start doing it differently at higher landed weights. They did: the air-bag bounce landings and that Rube Goldberg "skycrane" for Curiosity. Those guys have never looked at anything over a ton or two.

Heavier still requires more different yet. There are 2 possibilities: some sort of extendible or inflatable heat shield leading to chutes, or supersonic/hypersonic retro propulsion instead of chutes. The second is actually more mature, as Spacex has demonstrated with its Falcon-9 1st stages and its Dragon V2 design. Although they are the only demonstrators of this so far.

Comparison to lunar landing -- not true at all. The bulk of entry speed on Mars is aerodynamically dissipated in hypersonic drag (hot but not as hot as here). That's completely unlike the moon! On Mars, you come out of hypersonics at local Mach 3, which is only around 0.7 km/sec velocities. At high ballistic coefficient, this happens way too low in altitude to get a chute deployed, much less have it do any deceleration good, in that near-vacuum-of-an-atmosphere.

NASA focus -- not all NASA's fault, see the article I posted on "exrocketman" titled "Stagnation in Space?". The main problems are (1) egregious micromanagement by Congress, and (2) overwhelming stultification of an organization-grown-too-large (without a good reason-to-be, and so trying to be everything to everybody, instead).

Musk/Spacex progress with retropropulsion landing -- progress is good, but absolutely no full success has yet been achieved. This'll take a while before they get it "right". BUT, viability of supersonic/hypersonic retropropulsion HAS been established, and in the case of Falcon-9 1st stages, without the engine cant angle that I thought would be required for aerodynamic stability. They "done good".

GW

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#1 2014-06-29 12:47:01

Another NASA fail...

#2 2014-06-29 13:09:04

Re: Another NASA fail...

#3 2014-06-29 13:35:12

Re: Another NASA fail...

#4 2014-06-29 14:35:23

Re: Another NASA fail...

#5 2014-06-29 14:56:53

Re: Another NASA fail...

#6 2014-06-29 15:23:38

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#7 2014-06-29 15:50:55

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#8 2014-06-29 17:13:30

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#9 2014-06-29 18:39:11

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#10 2014-06-29 18:43:07

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#11 2014-06-29 19:14:48

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#12 2014-06-29 22:38:44

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#13 2014-06-29 23:04:17

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#14 2014-09-12 11:52:35

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#15 2015-03-18 18:01:54

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#16 2015-03-18 19:16:13

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#17 2015-03-18 19:43:26

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#19 2015-03-18 22:01:53

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#20 2015-03-19 00:56:03

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#21 2015-03-19 07:08:40

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#22 2015-03-20 01:18:15

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#23 2015-03-20 15:11:42

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