WI: Mankind had taken Space Exploration seriously

[Doug M.]

Oberth around Saturn: d'oh, you're right. Yes, that would help.

(Hm: would you rather do a reaction drive Oberth with a chemical drive or an ion drive? My intuition says chemical, but that seems weird.)

Mars mission reliability has increased drastically since the "Goblin" days of the '60s and '70s. Since 1990, 9 out of 16 Mars missions were successful,

That's true! But note that we reached our current success rate by failing a bunch of times first, and then figuring out why we failed.

As you say, some of the failure modes might have been correctable by a human crew. But maybe not all of them. And that gets us into the very fraught question of what odds of lethal failure are acceptable in a manned mission.


Doug M.

 

[Doug M.]

Incidentally, I picked the old Amundsen-Scott dome because it was about the lightest modern Antarctic base. There are a lot of Antarctic bases --

http://www.wired.com/magazine/2010/04/ff_antarctica/all/1

-- but most of them are well over 1000 tons. The Belgian Princess Elizabeth base (which is probably a good model for a Mars base, being energy self sufficient and recycling its water) clocks in at 1200 tons for a crew of 20, not counting construction equipment.

It's pretty much impossible to find a modern Antarctic station weighing less than a couple of hundred tons. Individual Halley VI modules weigh 80 tons, but they're modules, not a complete base -- the entire complex weighs 720 tons.

Note that (1) bringing stuff to Antarctica is not cheap, so these bases are designed to be as light as possible; and (2) none of these figures include the mass of construction equipment.


Doug M.

 

[Polish Eagle]

We're not really sure how big a Mars habitat will have to be, but 25 tons is certainly much, much too small.

Two comparanda: the ISS (crew of 6) masses just under 400 tons. The old Amundsen-Scott dome at the South Pole (crew of 20) massed about 500 tons empty -- no food, people or fuel, and not including the weight of the construction equipment.


Doug M.

The ISS is also designed with various elements that a Mars spacecraft would not need. Those big trusses? They're about 15-20 tonnes each. Remove those and give the ISS a couple of 1 tonne TOPAZ nuclear reactor, and you save a lot of weight. Docking ports, multiple laboratory modules, each of these add weight that a Mars mission would not need.

A more contemporary example would be the Bigelow Aerospace 330, currently under construction at that company's assembly plant. 330 cubic meters of space, for a crew of 12, at only 23 tonnes. Reduce your crew by 66% and fill the extra space with consumables and scientific equipment, and put it in an aeroshell, and you have a suitable Mars surface habitat.

 

[Doug M.]

The Hab and ERV have all the consumables needed for a 4-person crew during their respective stretches of the mission.

The 4-person crew got thrown overboard back in the 1990s. Here's NASA:

"1.4.5 Crew Complement

"Past studies examined the size and make-up of the crew needed to meet both operational needs and mission objectives (Briggs and Lemke, 1993). The results of these studies arrived at the following general conclusions:

· Skill mix requirements indicate the need for a crew of at least five.
· Peak workload indicates the need for a crew of six (three at the base and three in the field).
· A requirement for margin suggests the need for a crew of seven or eight.

"While no conclusion has been reached regarding the required number of crew members, recent studies have tended to assume a crew of six. Specifically, a crew of four is considered “operationally sufficient (Griffith, 1999), meaning that all skill areas can be covered by four appropriately selected individuals. However, this same study acknowledges that there are operational situations, such as a statistical probability of illness or injury or concurrent EVAs for local and remote tasks, which will require more than four people to accomplish."

Note that the Mars Analog Research Stations all assume crews of six.



Doug M.

 

[Doug M.]

The ISS is also designed with various elements that a Mars spacecraft would not need.

90% of its mass is unnecessary? Really?

A more contemporary example would be the Bigelow Aerospace 330, currently under construction at that company's assembly plant.

That would be the untested inflatable space habitat module, built by the company that was set up as a rich man's hobby, and that has never yet actually put anything in space?

Sure, that sounds good.


Doug M.

 

[Lukkonle]

It's bit telling how some people are fixated on Mars mission.
To me that is a bit old-school, there many more interesting places and science targets in space, which could use funding.

 

[Petike]

Here's one good argument why investing in above-LEO spacetech isn't futile nonsense :

A 20 km asteroid is discovered and is supposed to hit us in say... 10 years.

Now what ?

1. Frantically scatter all available resources to send an umanned mission there to push it out of collision orbit ?

2. Just contemplate our navels and wait for the bitter end ?

 

[Doug M.]

Wait -- Bigelow has put two unmanned modules in orbit. My bad. Genesis I and Genesis II. They're basically balloons in orbit without power supply, navigation or life support systems -- nobody lives in them and they don't actually do anything -- but fair is fair.

That said, the original point stands: rich man's hobby company, never yet built anything that anyone had to live in.

-- You know how Bigelow made his millions, yes? Started off with cheap hotels, expanded into being a slumlord. Reclusive, secretive, eccentric. Two obsessions: paranormal investigations and space advocacy.

"Even by the standards of reclusive zillionaires and would-be space entrepreneurs, the 63-year-old is particularly odd. Take his obsession with secrecy. He has never sent an email in his life — not secure enough, he says. Neither he nor any of the 120-plus staffers have office voicemail. Until a few years ago, Bigelow didn't allow pictures of himself to be printed. A framed sign in the guard trailer reads KEEP YOUR WORK AND THE WORK OF COWORKERS VERY PRIVATE FROM PEOPLE OUTSIDE THE COMPANY.


"His signature quirk, however, is an obsession with space that extends beyond his business interests. In addition to the $100million Bigelow has already put into BA (and the $400million more he has promised), he has doled out millions to fund research into alien abductions and UFO sightings. He's done some of the work himself, personally interviewing hundreds of people who claim to have had extraterrestrial encounters. In fact, one of the main reasons he's so eager to get his stations launched is that he thinks they might provide a step toward making contact."


"Over the past decade, Robert Bigelow has continued his backing of paranormal research. He created the National Institute of Discovery Science in 1995 to investigate border phenomena... The NIDS website provides news and investigations into such wide-ranging topics as 'Black Triangle' sightings, cattle mutilations, consciousness studies and crop circles....

http://www.wired.com/science/space/magazine/15-11/ff_spacehotel#ixzz13YhFhikS​

In fairness, I suppose a team of engineers employed by a weird, secretive, creepy slumlord can design a module just as well as a team of engineers employed by NASA. That said, I'd want to see some people actually live in his stuff before saying "ooh, we've found a model for Mars!".


Doug M.

 

[Doug M.]

Here's one good argument why investing in above-LEO spacetech isn't futile nonsense :

A 20 km asteroid is discovered and is supposed to hit us in say... 10 years.

That's impossible. There's nothing out there of that size that could hit us within that time frame.

You do know that we've been surveying the sky for potential Earth-striking asteroids since the 1990s, right?

At this point we can say with very very high confidence that there's nothing bigger than a couple of hundred meters across that could possibly hit us within the next decade. We're not perfectly safe yet -- we could still be surprised by a rock in the ~50 meter range sneaking up on us -- but at this point we're talking impacts that might take out a city and give the rest of us spectacular sunsets for a few months, not dinosaur-killing world-enders.

And the window is closing; within a decade we'll have the inner Solar System mapped down to the little rocks too.

That doesn't mean that impacts won't occur. But it does mean that the warning time for large impacts will be on the order of decades, not years.


Doug M.

 

[Dathi THorfinnsson]

That's impossible. There's nothing out there of that size that could hit us within that time frame.

True

At this point we can say with very very high confidence that there's nothing bigger than a couple of hundred meters across that could possibly hit us within the next decade. We're not perfectly safe yet -- we could still be surprised by a rock in the ~50 meter range sneaking up on us -- but at this point we're talking impacts that might take out a city and give the rest of us spectacular sunsets for a few months, not dinosaur-killing world-enders.

And the window is closing; within a decade we'll have the inner Solar System mapped down to the little rocks too.

Not so true.

NASA is expected to have found about 90% of the objects 1 kilometre or larger in Earth's neighbourhood by 2008. Smaller objects have been less well surveyed. But because the smaller objects are more numerous, they have a higher chance of hitting Earth.
The US Congress has asked NASA to identify 90% of the smaller objects - down to 140 metres across - by 2020, but NASA says it does not have the money to implement the search

In a quick google search, I didn't find anything newer than the above that was useful.

Still. We've found 90% of the NEA's larger than 1km by 2008. That means that we still haven't found all of them. True, the likelihood of any of the undiscovered ones that size hitting the earth is small. OTOH, NASA has explicitly ruled out being able to find 140m rocks by 2020 (let alone now)... So, we're talking about a lot more than the odd 50m rock.

I think that discussing the threat of 1km rocks is still appropriate, although the threat is low and dropping fast. 20km rocks are right out as you stated at the beginning of the post (unless they are on some really weird, highly elliptical and/or out of the ecliptic orbit - which in turn is pretty improbable).

 

[Petike]

That's impossible. There's nothing out there of that size that could hit us within that time frame.

You do know that we've been surveying the sky for potential Earth-striking asteroids since the 1990s, right?

Of course I know. But it's generally better to be prepared, at least from a theoretical and economic perspective of the problem.

 

[Workable Goblin]

Oberth around Saturn: d'oh, you're right. Yes, that would help.

(Hm: would you rather do a reaction drive Oberth with a chemical drive or an ion drive? My intuition says chemical, but that seems weird.)

Chemical or nuclear. Oberth depends on a lot of acceleration in a short time, so ion or similar high-efficiency low-thrust drives are right out.

That's true! But note that we reached our current success rate by failing a bunch of times first, and then figuring out why we failed.

As you say, some of the failure modes might have been correctable by a human crew. But maybe not all of them. And that gets us into the very fraught question of what odds of lethal failure are acceptable in a manned mission.

Well, the rocket blowing up on the launchpad would definitely be something that couldn't be corrected by the crew, yes. But most of the American failures, for lack of a better word, seem to be "special"--they are some new and inventive screw-up that got invented for the first time there. I'm not too sure how to design those out...if nothing else, a humans to Mars program will probably involve a fair bit of testing for the components.

Wait -- Bigelow has put two unmanned modules in orbit. My bad. Genesis I and Genesis II. They're basically balloons in orbit without power supply, navigation or life support systems -- nobody lives in them and they don't actually do anything -- but fair is fair.

They do have life support systems and power supplies; they're designed to be small-scale tests, and it would be stupid to test the thing without a power supply or life support system, right? It's true that it doesn't have any reboost system (I assume that's what you meant by "navigation," since they do have a guidance and stabilization system), but again that's because they're just small-scale test modules; there's no point in keeping them up there longer than necessary, it would just clutter up LEO even more.

If they just wanted to put a balloon in orbit, they could have looked at the Echo program, instead. Overall, I would rate the Bigelow modules as having a very great reliability rating for something that hasn't flown a full-scale test yet--say, as great as the Space Shuttle in 1980

 

[Doug M.]

To bring it back to the original question:


http://www.planetary.org/blog/article/00002739/

"The major event of the month will be, of course, Deep Impact's flyby of small comet Hartley 2, which happens at 13:50 UTC on November 4. But there's some other things to take note of: Cassini has a very, very close flyby of Enceladus' north pole (not the pole with the plumes, the other one) on November 30. Also China's Chang'E 2 is, as I write, orbiting even closer to the Moon than that, passing just 15 kilometers over Sinus Iridum. November is also the most likely month for the reestablishment of contact with the long-silent Mars Exploration Rover Spirit -- keep your fingers crossed..."

-- She does those updates every month, and they're awesome. Actually, that whole blog is a must-read for anyone who's into this stuff.


Doug M.

 

[Doug M.]

They do have life support systems and power supplies; they're designed to be small-scale tests, and it would be stupid to test the thing without a power supply or life support system, right?

Genesis I was inflated with nitrogen. Genesis II used oxynitrogen, but without rebreathers. If you were up in it, you'd last a couple of hours, then die horribly. I think that qualifies as "without life support", no?

I note in passing that neither one was life-rated. Although in fairness, life-rating covers all kinds of boring sissy stuff like having a first aid kit and some kind of toilet and a water supply and such.

Genesis I seems to have used batteries, though it's hard to be sure. It's damnably difficult to find details on these things online beyond the basics: mass, dimensions, orbit. (Is Bigelow the Aerospace company as obsessively secretive as Bigelow the eccentric real estate mogul? Wouldn't that be self defeating?)

Genesis II uses solar panels, fair enough, but they seem to be producing a fairly modest trickle of power -- though, again, I haven't been able to find wattage figures.

Bigelow /is/ trying to build a life-rated module, but apparently it's still in the test bed stage, and at least a couple of years away from launch.

I'd say more like the Space Shuttle in 1976, myself.


Doug M.

 

[Doug M.]

In a quick google search, I didn't find anything newer than the above that was useful.

Still. We've found 90% of the NEA's larger than 1km by 2008. That means that we still haven't found all of them.

Go to this link

http://neo.jpl.nasa.gov/stats/

scroll down and look at the first three graphs, especially that second one.

The number of large (>1 km) NEA discoveries has been falling steadily over the last decade. In 2000 we found 88 large NEAs; in 2005, 41; in the first half of 2010, just 8. Although our observational techniques have gotten better and better, the curve is nonetheless sinking steadily down towards zero. There are just fewer and fewer undiscovered large NEAs left, and the number keeps shrinking every year.

(There's going to be a blip upwards in the second half of 2010, because that's when the WISE data will be credited. But that just goes to the point; there's a finite number of undiscovered NEAs left out there, and WISE is about to take a bunch more off the board.)

Eyeballing the graph, I'd say it looks more like 95% or 98% than 90 at this point, though it obviously depends on how you draw out that slope on the right.

Note that the curve for smaller asteroids has flattened out -- there are still plenty out there to find, but we're well past the bonanza stage. And I'd bet money that if you sorted that first graph by size, you'd find the >300m category has already begun to nosedive.

Within a decade, it's going to be something like 99.9+% for 1-km rocks, and well over 90% for >300m rocks. That doesn't fulfill the Congressional mandate, no, but at that point we're starting to talk "odds of being killed in a terrorist attack" vs. "odds of being struck by lightning twice".


Doug M.

 

[Workable Goblin]

Genesis I was inflated with nitrogen. Genesis II used oxynitrogen, but without rebreathers. If you were up in it, you'd last a couple of hours, then die horribly. I think that qualifies as "without life support", no?

I note in passing that neither one was life-rated. Although in fairness, life-rating covers all kinds of boring sissy stuff like having a first aid kit and some kind of toilet and a water supply and such.

Genesis I seems to have used batteries, though it's hard to be sure. It's damnably difficult to find details on these things online beyond the basics: mass, dimensions, orbit. (Is Bigelow the Aerospace company as obsessively secretive as Bigelow the eccentric real estate mogul? Wouldn't that be self defeating?)

Genesis II uses solar panels, fair enough, but they seem to be producing a fairly modest trickle of power -- though, again, I haven't been able to find wattage figures.

Bigelow /is/ trying to build a life-rated module, but apparently it's still in the test bed stage, and at least a couple of years away from launch.

I'd say more like the Space Shuttle in 1976, myself.

Really? I've found it amazingly easy to find information on it. The Wikipedia articles are heavily referenced; Here and here are two of their sources that pretty much specifically deny some of your claims. The delays in lauching "Sundancer" (their last, and human-rated, test module) are mainly due to delays in booster acquisition, which cannot reasonably be attributed to the module itself.

 

[Doug M.]

I'm sorry, but which of my "claims" are "denied" in those two links? Apparently Genesis I had solar panels after all. Okay. Otherwise, it's all consistent.

One of those pages is a puff piece from Bigelow itself that only talks about their insect habitat. The other is a short page from their avionics contractor that lists what they put on board. Neither of these is exactly chock-a-block with technical details.

And to bring it back: we got off on Bigelow because someone claimed that an untested, unflown Bigelow module would be an /awesome/ model for a Mars base. Throw one of those at Mars, along with an old Soviet nuclear reactor for power, and boom! good to go.

This strikes me as unlikely.


Doug M.