Landing on asteroids may cause avalanches

[Waspie_Dwarf]

Microgravity memory-test for granular materials suggests landing on asteroids may cause long-distance avalanches

Results from a microgravity experiment suggest that the rubble and dust covering asteroids and comets can feel changes in force-chains between particles over much larger distances than on Earth, making these surfaces less stable than previously imagined. Dr Ben Rozitis of the Open University will present findings from the AstEx parabolic flight experiment at the National Astronomy Meeting in St Andrews on Thursday, 4 July.

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[Crashley]

Yeah, not so sure that is a wise idea. Im all for space exploration and discovery, but not to keen on people losing their lives in the process. More research needed. An unmanned mission, perhaps?

[danielost]

A unmanned mission won't work, the vessel wouldn't have the mass of a manned mission would. Also, a robot wouln't need to keep making corrections that a man would. The other problem is the manned ship might have enough mass to pull any loe rocks to it.

As for rock piles we just have to make sure we don't land on one. That I where your unmanned mission would come into it.

[Waspie_Dwarf]

A unmanned mission won't work, the vessel wouldn't have the mass of a manned mission would. Also, a robot wouln't need to keep making corrections that a man would. The other problem is the manned ship might have enough mass to pull any loe rocks to it.

As for rock piles we just have to make sure we don't land on one. That I where your unmanned mission would come into it.

Really!

Then you will have no difficulty in backing up your conclusions with the relevant evidence and mathematics. I look forward to it, because there is nothing in the original article that states that the phenomenon is limited to manned spacecraft or even mention of a minimum mass, so clearly you must have data of your own, not in the original article to be able to confidently come to such a conclusion..

In fact mass is only part of the problem, but I'm sure you will enlighten us with your calculations of kinetic energy.

Unless, of course, you are just making stuff up off again.

[danielost]

I don't have the math and you know it.

But, we have already soft crashed a probe on one. It is still there, not broadcasting.

And this is why I have been avoiding your threads. Your nit picking.

[Bavarian Raven]

Im all for space exploration and discovery, but not to keen on people losing their lives in the process

Exploration has always been a risky business, and lives will be lost. But if we are to survive/expand as a species, we must take those risks. And as of right now, all the people doing these jobs are doing so out of their own free will...

[Shiloh17]

Japan has already landed on an asteroid, collected rock samples and returned to earth. Seems, humans could do that too.

[d e v i c e]

Cool.

[danielost]

Dwarf. I have decided that I don't need math to answer your challenge. I have not read any of the posts after my last one.

All I need is observance. All matter in the universe has gravity from the smallest grain of sand to the galaxies. Planets orbit the sun because it has the largest gravity field. Moons orbit planets because their gravity field is closer and strong enough t over ride the suns. That is why mercury and venus are the only planets to not have moons.

The largest probes we have sent out was the size of an sub. These probes didn't need to return to earth. If you send a manned space ship it needs to be large enough to carry enough fuel to get there and back. The ship also has to be big enough to keep the crew alive. The ship will need to be bigger than a capsule, depeended on how far the trip is. I don't think anyone would be able to live in a capsule for more than a week.

Thus if the ship lands on an asteroid its local gravity might be sdtrong enough to override the asteriods gravity on small things like dust and small rocks near the landing site. Of course we could use as lander like on the moon.

[JesseCuster]

Thus if the ship lands on an asteroid its local gravity might be sdtrong enough to override the asteriods gravity on small things like dust and small rocks near the landing site. Of course we could use as lander like on the moon.

Do you have any idea how weak the gravitational pull of a spacecraft is? Gravity is an ridiculously weak force, it's only when massive amounts of matter clump together that it becomes relevant.

A very small asteroid of only a couple of miles in diameter is going to have a mass of billions of tonnes. For comparison, the Apollo landing modules had a mass of about 10 tonnes.

Even factoring in a much larger lander of 100 tonnes, how is that going to override of the gravitational pull of something with millions of times more mass and attract any matter towards it? And I'm deliberately choosing a very small asteroid.

Keep in mind that a 3km x 3km x 3km body with the same density of water is already going to have an extremely weak gravitational force, of the order of 1/100,000 g according to a quick calculation (does that qualify as microgravity?). I'd say that figuring out how to just attach to it without the lander drifting off into space is a major issue as opposed to the non-issue of a spaceship attracting rocks and dust in the presence of a body millions of times larger in mass.

[danielost]

Did you watch close encounters. When the ship comes down on the site te scientist who are working under the ship were warned to be careful, due to gravety fluctuation. That ship in comparisen to earth would be small rock on the asteroid. I am sure the rocks and dust won't leave the ground, except for what I thrown up from the engines. But, maybe it will slide toward the ship. If, as according to the story, the engines of the ship can cause a avolance on the other side of that rock. Its gravity can't be to strong.

[JesseCuster]

Did you watch close encounters. When the ship comes down on the site te scientist who are working under the ship were warned to be careful, due to gravety fluctuation. That ship in comparisen to earth would be small rock on the asteroid.

Are you talking about the movie Close Encounters of the Third Kind? Please tell me you're not.

I am sure the rocks and dust won't leave the ground, except for what I thrown up from the engines. But, maybe it will slide toward the ship. If, as according to the story, the engines of the ship can cause a avolance on the other side of that rock. Its gravity can't be to strong.

Its gravity isn't strong. It's enormously weak and the gravity of the ship is millions of times weaker than that. That's why gravity isn't any sort of issue in this scenario. The other forces causing the integrity of the asteroid (chemical, electromagnetic) and external forces like the engines of the lander are so much more relevant and powerful (by orders of magnitude) that I don't know what issue you think the gravitational pull of the ship is relevant. Even if a handful of dust got attract toward the ship, what kind of issue could that raise?

[danielost]

There isn' t going to be a rescue, you have to think of everything that can go wrong immagined or real before you go.

[Waspie_Dwarf]

I don't have the math and you know it.

Yes I do know it. I also know you don't have a working knowledge of basic science. So that leads to the question why (in this thread and all the others where you make totally incorrect statements) do you constantly make statements of fact when you don't know what you are talking about? Claiming knowledge when you don't have it is dishonest behaviour on your part. If you would just point out that the posts were simply your opinion then they would still be wrong, but they would at least be honest.

But, we have already soft crashed a probe on one. It is still there, not broadcasting.

And your point is?

You either haven't read the linked article or (more likely) haven't understood it. It says:

Many smaller asteroids are thought to be entirely granular in nature – piles of rock and gravel held together by gravity.

The probe, which you so vaguely refer to, was the NEAR Shoemaker spacecraft and it didn't make a soft crash (that is an oxymoron) it made a gentle touchdown on asteroid 433 Eros, Despite not having been designed to land it transmitted data from the surface for seven days (see HERE).

Eros is an S-type asteroid (see HERE) and therefore mostly iron in composition. Since it is not an asteroid which is granular in nature NEAR Shoemaker's findings can not be applied to this new research.

And this is why I have been avoiding your threads. Your nit picking.

Sadly (as this thread demonstrates) you don't avoid them.

Nit picking would be picking on very small mistakes, not contradicting something which is totally wrong.

The problem is that the difference between what you think you know and what you actually know is huge and hence you make yourself look foolish time and time again. You compound this by never checking things before you post. Have you never heard of Google? You should try it some time. Then you wouldn't post so much rubbish and you would have links to back up your claims (remember links that back up claims? Those pesky things I include every time I rip your nonsense apart).

Dwarf. I have decided that I don't need math to answer your challenge.

YOU don't get to decide what is and what isn't science (neither do I). Science requires empirical evidence and maths. As by your own admission you don't have the maths so you can't possibly meet the challenge, plain and simple.

I have not read any of the posts after my last one.

Of course not, you wouldn't want to actually learn anything would you?

All I need is observance.

By "observance" you mean you are just going to make stuff up again and post more rubbish don't you?

All matter in the universe has gravity from the smallest grain of sand to the galaxies. Planets orbit the sun because it has the largest gravity field. Moons orbit planets because their gravity field is closer and strong enough t over ride the suns. That is why mercury and venus are the only planets to not have moons.

You're actually serious aren't you?

Sorry but you are wrong again with your statement on Mercury and Venus. Whilst it is true that Mercury's small size and proximity to the Sun mean that it has a tiny Hill Sphere (the sphere around a planet where the gravitational influence is stronger than that of the Sun's {see HERE}) Venus is more than capable of holding on to satellites. In fact one of the theories to explain it's slow rotation speed and retrograde rotation requires it to have had a large moon in the past (see HERE).

The largest probes we have sent out was the size of an sub.

A totally meaningless statement given that a Russian Typhoon class submarine displaces 48,000 tons (see HERE).

These probes didn't need to return to earth. If you send a manned space ship it needs to be large enough to carry enough fuel to get there and back. The ship also has to be big enough to keep the crew alive. The ship will need to be bigger than a capsule, depeended on how far the trip is. I don't think anyone would be able to live in a capsule for more than a week.

Really!!!

I think you need to inform NASA of this is they might do something stupid like keep two men in a capsule for 14 days. Opps, too late, they did that with Gemini VII in 1965 (see HERE).

Thus if the ship lands on an asteroid its local gravity might be sdtrong enough to override the asteriods gravity on small things like dust and small rocks near the landing site. Of course we could use as lander like on the moon.

Totally meaningless with out the maths to back it up. I gave you a clue that mass was only part of the problem. You could have chosen to do some research, to have learnt something. Instead you fell back on you belief that what ever facts you happen to invent must be true just because you said so.

It is the energy of the landing that is important, in this case kinetic energy.

E_k = ½mv²

Where

E_k = kinetic energy

m = mass

v = velocity

Let's put in some figures. When the Constellation program was still active it was planned that the Altair Lunar Surface Access Module would have a mass of about 23 tons (21,000 Kg). So let's use a lander of that mass.

Because it would land in a very similar manner to the Apollo Lunar Module it would land with a virtually zero vertical speed, as it would hover and then gently lower itself to the surface. Lets say that it lands at 10 mph (4.47 m/s) (in reality it would be a lot lower than that so I am over estimating the amount of energy).

We can put those figures into the equation and arrive at the amount of kinetic energy transferred from the lander to the surface of the asteroid.

E_k = ½ x 21000 x 4.47²

= 10500 x 19.98

=209,799.5J

= 209.8 kJ

Now you claim that it is impossible for an unmanned mission to replicate the effect of a manned spacecraft landing on the surface of the asteroid.

If you understood the maths you would know that was nonsense. The fact that the velocity term in the equation is squared means that increasing the landing (or impact) velocity has a far bigger effect than altering the mass.

We can take the figure I have calculated and work backwards. Lets go with an easy enough velocity to achieve. Let's see what happens if you hit the asteroid with a probe travelling at the relatively low velocity of 1000 mph (447.04 m/s) and aim to impart the same amount of kinetic energy on the asteroid. We can work out what mass is needed.

Since E_k = ½mv²

then 2E_k = mv²

And therefore m = 2E_k/v²

Putting in the figures:

m = 2 x 209,799.5 / 447.04²

m = 419599 / 199,844.76

m = 2.10 kg

So to hit the asteroid with the same energy as a 23 ton lander touching down at 10 mph all we need to do is hit it at 1000 mph with an impactor weighing just 4.6 pounds. That means not only is it possible to simulate a manned landing with an unmanned mission, technologically it is relatively easy to simulate a manned landing with an unmanned mission.

And that, danielost is the beauty of understanding very basic mathematics and science, you can work things out scientifically instead of making pure guesses and looking foolish when you are wrong.

Edited July 7, 2013 by Waspie_Dwarf
typos.

[danielost]

Dwarf you need to take a reading class to comprehend what the words if might and maybe mean. It's ok you have a mphd and a high school dtop out can keep up with you. My gravity field has over powered the earths several times. When a feather gets stuck to you thatis gravity not static electricity, unless you ave done something to get a charge. Somethng with those tiny pellet sized packing bags.I did not make a solid statement about anything except for the gravity keeping earth and moon in their places.

Do you think nasa, had desinged apallo to survive if it blew up. No they didn't, but they did design it incase two things went wrong. They were not thinking of it blowing up and the crew would be calling for help. But apallo thirteen blew up. The only reason they survived was of the triple by pass.

There will be no rescue if something goes wrong in space . Because, it could take a year to send crescue.

[danielost]

I also said an unmanned ship wouldn't be making minute corrections, like one under control by a human. How you going to simulate something that is completely random for each human would handle the controls differently from the others. When the men landed on the moon they used a hopping gate. They didn't practice that on earth. Armstrong found that the best way to move on moon.

Your just like my dad. Your both scared someone might by smarter than you. My dad has gone so far as to believe his own lies about how I did so goood when iwas in school. He held my back oth figerotively and reality. My first grade teacher said iu could go to the seventh graded. My dad put me in the second grade, supposedly so I would be with kids my age. So I understand your problm

Edited July 7, 2013 by danielost

[Waspie_Dwarf]

I also said an unmanned ship wouldn't be making minute corrections, like one under control by a human. How you going to simulate something that is completely random for each human would handle the controls differently from the others. When the men landed on the moon they used a hopping gate. They didn't practice that on earth. Armstrong found that the best way to move on moon.

What has this got to do anything?

I repeat, you have either not read or not understood the original article. It says:

“A lander touching down on the surface on one side of a small, rubble-pile asteroid could perhaps cause an avalanche on the other side, by long-range transmission of forces through chains It would, however, depend on the angle and location of the impact, as well as the history of the surface – what kind of memories the regolith holds, ” said Murdoch.

A lander danielost, not activity by astronauts, there is no mention of that at all, it is simply another one of your inventions. My calculations are based on the work of the scientists, not the guesswork of someone with no scientific ability at all.

Your just like my dad. Your both scared someone might by smarter than you. My dad has gone so far as to believe his own lies about how I did so goood when iwas in school. He held my back oth figerotively and reality. My first grade teacher said iu could go to the seventh graded. My dad put me in the second grade, supposedly so I would be with kids my age. So I understand your problm

This is hardly the place to discuss your psychological problems, it's off topic for a start.

As for me, I know lots of people are smarter than me, that's why I don't go into subjects where I know absolutely nothing and invent stuff to try and look clever, it's a sure fire way of looking very foolish indeed.

[ImMike]

Ok... I created an account just to say this. danielost, you have no idea what you are talking about. Unless English is your second language, your father did you the biggest favor of your life by keeping you in second grade. Your last post made absolutely no sense. Also your gravitational field was never and will never be greater than the earth. I don't care how many feathers you stick to yourself or how big of a lunch you had that day.

[danielost]

Dwarf your mad at me for making a guess and using the words if, might and maybe. The article that your so proud of used the words, might couse an avolance. That makes that a guess. So by your attack on me, that article was a waste of space.

To the other person, I am the only one on this thread that is using his immaganation. Dwarf has a phd and assumes anyone with out one is stupid. I don't know well enough to say why you think I am stupid. But I would GUESS it is because dwarf thinks I am. Now the gravity field is much smaller than earths. If the rock is small enough there might be a chance for an asternaut may lounch himself into space.

Edited to add.

By the way dwarf your math has to do with the amount of force at landing. I was mainly talking gravity fields.

But, as I have said twice now. A robot can not land as a human could, because of the minute corrections you have to make. I am guessing you have never played any of the lander games if you had you would know what I am talking about.

Edited July 8, 2013 by danielost

[Waspie_Dwarf]

Dwarf your mad at me

I not mad with you. It may be personal for you, it's not for me.

I am, however, bored with your posts. I'm bored with them because you repeatedly make statements of fact which are are no such thing and are usually totally wrong. I am bored with them because I have better things to do than correct the nonsensical idiocy you see fit to post in the science sections. I am bored them because you make yourself look foolish with the nonsense you post but don't take responsibility for your own actions, but instead try to blame everyone else.

for making a guess

Guessing has NO place in science.

and using the words if, might and maybe.

I'm also bored with your intellectual dishonesty. Posting complete (and usually incorrect) guesses as if they are fact. Here is your reply to Crashley

A unmanned mission won't work, the vessel wouldn't have the mass of a manned mission would. Also, a robot wouln't need to keep making corrections that a man would. The other problem is the manned ship might have enough mass to pull any loe rocks to it.

As for rock piles we just have to make sure we don't land on one. That I where your unmanned mission would come into it.

Not once did you point out it was only your opinion, not once did you say it is only a guess, and only in the sentence where you show a complete ignorance of the strength of gravity did you use the word might. The rest of the nonsense you presented as fact.

The article that your so proud of used the words, might couse an avolance. That makes that a guess.

No it doesn't. If I say, "if you don't look both ways when you cross the road" it is not a guess. If I say, "if you drop the glass it might smash", it is not a guess. If I say, "if you drive drunk you might kill someone", it is not a guess. These statements are factually correct, it is just that the outcome is not necessarily certain.

So by your attack on me,

I didn't attack you, I attacked the nonsense you posted.

that article was a waste of space.

No!

Your guess is based on nothing. It has no supporting evidence, no observational data, no mathematical calculations to support it, no empirical evidence what so ever. It is made up nonsense by someone who (as demonstrated by the rubbish you have written above) understands NOTHING about how science works.

The original article I linked to is an hypothesis created by experts in their fields based on experimentation and a deep understanding of the principles involved. It combines observations made during experiments with the known phenomenon of force-chains between particles.

They use words such as "might", "possible", "could be" etc not because they are guessing but because they understand the nature of a scientific hypothesis. They understand that any hypothesis is only as good as the supporting evidence. They understand that future missions to asteroids could confirm or refute their claims. They use these words because of intellectual honesty.

The fact that you believe your (wrong) guesses are the equal of the scientific conclusions of a team of scientists who are experts in the relevant fields says volumes about your grasp (or lack of grasp) of what constitutes science.

To the other person, I am the only one on this thread that is using his immaganation.

Imagination is a wonderful thing, but science is EVIDENCE and FACT based. Your guesses are not.

Dwarf has a phd and assumes anyone with out one is stupid.

There you go with making up stuff again. I do not have a PhD, nor have I ever claimed to have one. That in itself should show that second part of your invention can't be true.

I don't know well enough to say why you think I am stupid.

And more invention. Neither I, nor ImMike have said that you are stupid. We have both said you don't know what you are talking about. That is not the same thing at all. For all I know Albert Einstein knew nothing about the history of China in the 14^th century. That would not make him stupid, it would make him ignorant of that subject. If he then went on to make claims about the history of China in the 14^th century based on guess work and ignorance then he would be foolish. Intelligence and knowledge are NOT the same thing.

Now I have warned you enough times in the past about making false allegations against people, I really suggest that you don't do it again.

But I would GUESS it is because dwarf thinks I am.

Ignoring the fact that he didn't call you stupid, it doesn't even cross your mind that the reason he says you don't know what you are talking about is because you don't know what you are talking about does it. You post total nonsense, someone tells you you have posted total nonsense, therefore it's might fault. [sarcasm]Very logical.[/sarcasm]

Now the gravity field is much smaller than earths. If the rock is small enough there might be a chance for an asternaut may lounch himself into space.

Whilst true this irrelevant to the problem of force-chain caused avalanches.

By the way dwarf your math has to do with the amount of force at landing.

Yes it was, because that it was the article was about.

I was mainly talking gravity fields.

Yes you were, and demonstrating no understanding of them at all.

continued below...

Edited July 8, 2013 by Waspie_Dwarf
typos and clarifications

[Waspie_Dwarf]

Continued...

But, as I have said twice now.

It doesn't matter how often you repeat rubbish, it remains rubbish.

A robot can not land as a human could,

Yes it can.

because of the minute corrections you have to make.

The corrections required for landing are the same whether carried out by computer or by an astronaut. Physics remains the same in both cases. It neither knows nor cares whether the vehicle is manned or not.

Beside these manoeuvres are totally irrelevant, it is the force imparted on the asteroid at the point of landing (or impact) which matter (go and read the original article). The corrections before landing will play no part.

I am guessing you have never played any of the lander games if you had you would know what I am talking about.

You are joking right? Sadly I suspect you are not. You base your arguments on computer games and the fictional movie Close Encounters of the Third Kind and you wonder why no one takes your posts seriously.

Edited to add:

{b]danielost[/b]

You may wonder why, if I am so bored with your post, I continue to respond to them. It's because I care about scientific truth, I fear that someone may actually believe the stuff you post. One of your fellow countrymen says it far better than I ever could.

Ignorance is a virus. Once it starts spreading, it can only be cured by reason. For the sake of humanity, we must be that cure.

― Neil deGrasse Tyson

... there is no shame in not knowing. The problem arises when irrational thought and attendant behavior fill the vacuum left by ignorance.

― Neil deGrasse Tyson

If you want to assert a truth, first make sure it's not just an opinion that you desperately want to be true.

― Neil deGrasse Tyson

Edited July 8, 2013 by Waspie_Dwarf

[ImMike]

To the other person, I am the only one on this thread that is using his immaganation. Dwarf has a phd and assumes anyone with out one is stupid. I don't know well enough to say why you think I am stupid. But I would GUESS it is because dwarf thinks I am. Now the gravity field is much smaller than earths. If the rock is small enough there might be a chance for an asternaut may lounch himself into space.

I said what I did based solely on what you have written. This thread is the first time I've read what either of you have posted so I don't know why you would think I would take his side for no reason. Your posts are full of typos and many sentences you have written make no sense at all. You are also saying things that are completely untrue and passing it off as fact. Instead of admitting you are wrong or even trying understand what other people are saying, you just come back and spout out more incorrect or irrelevant information.

I also do not have a PHD. I didn't even finish college, and I'm willing to say that there is a lot in this field that is over my head. If someone tells me I'm wrong about something I said, I would try to find out why they are saying that and if I can't come up with anything to disprove it, I would admit I was wrong. You seem to be incapable doing this.

[danielost]

That is your problem. I said a robot cannot land a ship like a human can. I was not talking about the weight of the ship. I was talking about the pilot of the ship.

Did you see the movie apallo thirteen. The scene in which they use the earth as a target to align the ship for its return course. The humans were bouncing that ship all over the place. The final line was we had to learn how to fly all over again. What made that manouver so hard is that there were two humans at the control, instead of one computer. If the domputer had bee up the manouver would have been smooth.

Everything else I said had a quilifing word in it to tell everyone who read it would know it was a guess. Just as the person who wrote the article. Did. Your problem is I am a high school drop out and you have a phd and I am ableto keep up with you. Altho my ablet cannot keep up with me on these long posts

[danielost]

Immike dwarf didn't like the way I said it not what I said.

[Jodie.Lynne]

Welcome to UM ImMike. Keep your eyes and ears open and you can learn some neat things here. There are some extremely clever and sharp folk hereabouts!