The thread for space cadets!

[bugwar]

And risk turning one dangerous falling object into many?

Then you shoot those too.

 

[Thorgalaeg]

That's a bit exaggerated. Putting some soil between you and the surface is a good idea, but the amount needed to protect against such impact would be much, much bigger. You'd basically need to build deep, reinforced bunkers, which isn't really proportional to the magnitude of the threat.

No the big one but the smaller ones which make 4 m craters or less. IIRC you would need to live 5 meters under the rocks to get protected from radiation anyway.

 

[peter grimes]

http://www.newscientist.com/article...-from-radiation--but-the-trip-there-isnt.html

This article references readings from the surface that show the radiation to be about the same as on the ISS

 

[hobbsyoyo]

Dynetics is rebuilding the venerable F-1 engine with modern 3D printing techniques.

So NASA and it's contractors are already working on development of liquid fuel boosters for an eventual SLS upgrade. The current baseline configuration for the SLS uses two Shuttle-derived solid rocket boosters (they added an extra segment for extra oomph) but that will only provide a lifting capability of ~70-100tons. For bigger, more ambitious missions, they will have to use more powerful boosters.

To that end, Dynetics is working on rebuilding the F-1 with modern fabrication techniques. They call it the F-1B, and as you can see from this sketch, they eventually plan to strap on 2 mini-Saturn V first stages to the side of the SLS.

I interviewed with this company a few days ago and I have to tell you when I found out what they were working on....well let's just say I went from six to midnight lickety-split.

Another article on the project.


ZOOMG THANK THE ALMIGHTY GOOGS FOR MORE ROCKET PORN

There must have been some advances in metallurgy or manufacturing techniques if they are going to go with that simplified gas-generator exhaust duct. On the original F-1, they pioneered a technique to funnel the gas-gen exhaust around the nozzle to cool it during launch (and provide a bit of additional thrust). Apparently they feel they don't need those added benefits anymore or that they are too costly to implement.

One more article.

 

[bhsup]

This title just cracked me up.

Moon punched in the face by a meteorite

CAPE CANAVERAL, Florida — A meteorite as large as 4-1/2 feet in diameter smashed into the moon in September, producing the brightest flash of light ever seen from Earth, astronomers said this week.

...

The moon, with no protective atmosphere, is fair game for celestial pot-shots. The evidence is all over its cratered face and is occasionally recorded by cameras on Earth.

Such was the case on September 11, 2013, when a pair of telescopes in Spain, which were automatically trolling for lunar meteorite impacts, hit pay-dirt with the longest, brightest flash ever observed on the moon.

"At that moment I realized that I had seen a very rare and extraordinary event," astronomer Jose Madiedo, with the University of Huelva in Spain, said in a statement.

...

Scientists estimate the meteorite was between 2 feet and 4.6 feet in diameter and weighed about 882 pounds (400 kg.)

Moving faster than 37,900 mph, the meteorite smashed into a region known as Mare Nubium with the force of about 15 tons of TNT. It likely left behind a 130-foot (40-meter) wide crater.

 

[hobbsyoyo]

....carried over from the rants thread:

NASA just proposed a competition to give Universities/Companies a chance to prove propulsion system feasibility for deep-space CubeSat missions.

Spoiler Background for CubeSats for the uninformed :

CubeSats are modular satellite systems originally developed by some Unversity. Essentially, they offer a standardized satellite package for the general public to use. Basically, a CubeSat is a 10x10x10 cm^3 steel/aluminum cube that you can 'plug' your hardware into to perform experiments on orbit. Even the experiment hardware is standardized to an extent - so in other words you don't have to re-invent the wheel so to speak and invent and build an entirely novel satellite. You just take the basic plan of a CubeSat, find compatible hardware, build it and launch it. Currently, CubeSats are launched as secondary/tertiary payloads on larger rockets because they are so small and light and because they offer a standardized interface bus for rockets (whereas practically every other satellite requires a custom interface bus).

Another advantage of CubeSats is that they can be scaled - such that you can have just one 10x10x10 cm^3 unit (called a 1U) or you can stick multiple units together such that you have a 2U (20x20x10 cm^3) and so on up to about 12U. In the end, the approach is muuuuuuuuuuuch cheaper than bespoke satellites and demand for CubeSat launch opportunities has increased so much that NASA and private companies are designing/building dedicated CubeSat launching rockets to ease the backlog of launch orders.

Essentially, the competition is to prove that CubeSats can be utilized for independent deep-space missions, which would save the entire industry a ton of money and ultimately push science forward a great deal by ramping up the volume of scientific experiments and satellites significantly.

NASA, as you may know, is building a giant Saturn V-class rocket called the SLS (space launch system) with a debut-flight of the Block 0 variant scheduled for 2017. This mission will send a crew of Astronauts around the moon (and back after some orbits) in a fashion similar to Apollo 8. NASA decided this would provide a good opportunity to push forward the CubeSat platform quite a bit by offering a competition for Universities/Companies to ride-share with the SLS out to the moon.

The SLS will achieve a trans-lunar trajectory and then will dump the CubeSats on that trajectory. The challenge is to develop a CubeSat propulsion system capable of breaking the CubeSat into Lunar orbit, a feat that will take somewhere North of at least 500 m/s of deltaV (haven't crunched the numbers yet so that's an educated guess based on Apollo flight trajectories I looked up). This would be a MASSIVE step forward for CubeSats because currently, there are no really viable propulsion systems for that platform, which basically limits them to LEO and keeps them from having any sort of maneuvering capability. Any designs that can prove capable of doing this mission could then be sold to the broader CubeSat maker market which would make the whole platform that much more attractive.


_________________________

What gets me hot and heavy is that I am currently developing just such a propulsion system for CubeSats, I even recently filed for a patent as a co-inventor of the system. Our team has the know-how and resources to do the mission, but I have to prove to my superiors that it's feasible. Even if I prove it's not feasible, that's still a big achievement because I can prove most other systems won't work either.

That's because our system is a cold-gas system with no combustion and relatively low operating pressures. That's essentially the only way to do this mission because NASA isn't going to allow a hydrazine or bi-propellant system ride-share with their astronauts because of their inherent danger and risk. Also, an electric propulsion system is not viable because at best, you will have one side of the CubeSat orthogonal to the Sun at a time and it is extremely unlikely that the solar cells on that side could provide enough juice to run such a system.

Even still, I don't think our system can provide enough deltaV to do the mission, but a group of us are getting together tomorrow to crunch numbers and find out. Worst case scenario, we'll find that it can't do it and will tell NASA that and they will have to adjust the competition. Best case scenario, we can do it and then we'll begin work on making it happen.

 

[LamaGT]

....carried over from the rants thread:

NASA just proposed a competition to give Universities/Companies a chance to prove propulsion system feasibility for deep-space CubeSat missions.

<snip>

Hope you guys can make it! I remember hearing about a tiny satellite with a Nexus S inside, is it this one? In any case it's awesome that space is becoming more available to the masses!

 

[hobbsyoyo]

^^No, this isn't one of those satellites LamaGT.

_____________
SpaceX to Test Landing Legs on Next Falcon Rocket

SpaceX plans to include landing legs on its next Falcon 9 rocket, a key step toward developing a reusable, lower-cost launcher, company officials said on Monday.

Ultimately, the firm, which is owned and operated by technology entrepreneur Elon Musk, would like to fly its rockets back to the launch site where they would land and be reused.

For now, the first stage of the rocket, which is discarded a few minutes after liftoff, falls back into the ocean with so much force it is destroyed.

SpaceX, also known as Space Exploration Technologies Corp., tried in September 2013 to cushion a rocket's fall by restarting its engines during the descent. The test was nearly successful, but the rocket's spinning choked off the flow of fuel, and it smashed into the water.

For its next test, targeted for March 16, SpaceX will again attempt the engine restarts and deploy four landing legs to provide the Falcon 9 with more stability. SpaceX spokeswoman Emily Shanklin put the odds of success at less than 40 percent.

The legs will be attached to the base of the rocket and stowed during flight. They are designed to deploy as the rocket descends back toward the ocean.

"Given all the things that would have to go right, the probability of recovering the first stage is low," Shanklin wrote in an email. "It probably won't work, but we are getting closer."

SpaceX has a parallel program to test precision landing techniques. The company in October completed tests on an experimental vehicle known as Grasshopper which successfully touched down on its launch pad after reaching an altitude of 0.46 miles (740 meters).

The program has since relocated from SpaceX's test site in McGregor, Texas, to New Mexico's Spaceport America near Las Cruces for higher-altitude flights.

SpaceX’s Musk Argues for More Competition in Security Satellite Launches

At this point, only United Launch Alliance, a joint venture between Lockheed Martin and Boeing, is cleared to bid for Department of Defense military satellite missions.

Update: According to his full statement, which SpaceX released here, Musk said:

In [fiscal year 2013] the Air Force paid on average in excess of $380 million for each national security launch, while subsidizing ULA’s fixed costs to the tune of more than $1 billion per year, even if the company never launches a rocket. By contrast, SpaceX’s Falcon 9 price for an [evolved expendable launch vehicle] mission is well under $100 million &#8212; at least a $280 million per launch difference, which in many cases could pay for the satellite and launch combined &#8212; and SpaceX seeks no subsidies to maintain our business.

SpaceX, the private spaceflight company in Hawthorne, Calif., believes the third successful launch of its upgraded Falcon 9 rocket in January should qualify it to compete for such launches.

Late last month, the Air Force signed off on the first of those launches, on Sept. 29, 2013.

&#8220;This flight represents one of many certification requirements jointly agreed to between the Air Force and SpaceX,&#8221; said Lt. Gen. Ellen Pawlikowski, Space and Missile Systems Center commander.

The Air Force continues to assess the launches on Dec. 2, 2013, and Jan. 6, 2014, and Musk said on Wednesday that the certification process is proceeding.

But SpaceX isn’t sitting still in the meantime. Last week, Musk tweeted pictures of the company’s Falcon 9 rocket with four landing legs attached. SpaceX plans to test the system in a &#8220;splashdown&#8221; in the Atlantic Ocean following a flight scheduled for March 16, as it works to develop a reusable launch system that could dramatically lower costs.

In an interview with Bloomberg TV ahead of the Senate appearance, Musk also argued that the United States shouldn’t rely on Russian spacecraft to transport U.S. astronauts to the International Space Station.

&#8220;We’re being forced to pay over $70 million dollars per seat to the Russians just to go to the Space Station and they have us over a barrel,&#8221; he said, according to the publication’s transcript. &#8220;Being at Putin’s mercy is not a good place to be, so we want to have restored the American ability to transport astronauts to the Space Station, maybe beyond someday, and do so as soon as possible and it’s going to, I think, be a better product for a lot less money, and it’s just kind of embarrassing that the United States has to thumb rides from the Russians.&#8221;

______________

I drafted that design review (from my previous post) and submitted it to the team, it went over really well and we are now working on trying to make the lunar launch a reality for our team.

 

[hobbsyoyo]

SpaceX Postpones Cargo Supply Launch to Space Station
CAPE CANAVERAL, Fla. &#8212; The next supply run to the International Space Station has been delayed.

SpaceX was scheduled to launch a a Falcon 9 rocket carrying a cargo ship from Cape Canaveral, Fla., before dawn on Sunday. But on Thursday, the private company said it needed more time and postponed the launch for two weeks, until March 30.
The unmanned capsule named Dragon holds about 2 tons of supplies and experiments. It will also take up a pair of legs for the humanoid robot at the space station. Until now, Robonaut has been stuck on a pedestal.

The delivery will be the fourth for California-based SpaceX. It is one of two companies hired by NASA to take goods to the space station. (The other is The other is Dulles, Va.-based Orbital Sciences Corp.)

"Both Falcon 9 and Dragon are in good health," SpaceX officials said in a statement. "Given the critical payloads on board and significant upgrades to Dragon, the additional time will ensure SpaceX does everything possible on the ground to prepare for a successful launch."

This Nov. 13, 2013, photo made available by NASA shows the Robonaut with legs at a lab in Houston.

 

[peter grimes]

I'm reading up on basic orbital mechanics, and I have a couple of questions.

http://physics.info/orbital-mechanics-1/

I think Hobbs could be the author of this page, but it's not current.

First, I understand that the LaGrange points are solar orbits with a period equal to earth's sidereal year. I understand that L1, L2, and L3 are colinear, on a radian with the earth and sun. But L4 and L5 are trickier.

They can be found at the vertex of an equilateral triangle which has earth and sun at the other vertices. But I don't understand how this is gravitationally possible. My brain keeps trying to bring the points closer to earth rather than 60° ahead and behind our orbit. It seems that the earth's gravity isn't nearly as strong as the sun's, so for the two forces to balance the points would have to be less than 1 orbital radius ahead or behind.

Also, why are L1 & 2 unstable? I would think that they should be slightly less stable than L3 but more stable than 4 & 5. Is it because of the moon?

Why is it called "Argument" of Periapsis ? I don't understand this meaning of the word.

Edit: came across an excellent diagram that shows the stability factors in a simple way:

 

[PlutonianEmpire]

It's called "argument" because astronomers, scientists, and intellectuals in general have such huge egos that they always fight over trivial technicalities. The modernized word for it is "debate", to replace "argument", so they look less snobby or immature, and "argument" was used for orbital definition because orbital mechanics were the main contributors to these fights.

 

[hobbsyoyo]

I'm reading up on basic orbital mechanics, and I have a couple of questions.

http://physics.info/orbital-mechanics-1/

I think Hobbs could be the author of this page, but it's not current.

Nah, there ain't enough crappy MS Paint diagrams to be my work.

First, I understand that the LaGrange points are solar orbits with a period equal to earth's sidereal year. I understand that L1, L2, and L3 are colinear, on a radian with the earth and sun. But L4 and L5 are trickier.

They can be found at the vertex of an equilateral triangle which has earth and sun at the other vertices. But I don't understand how this is gravitationally possible. My brain keeps trying to bring the points closer to earth rather than 60° ahead and behind our orbit. It seems that the earth's gravity isn't nearly as strong as the sun's, so for the two forces to balance the points would have to be less than 1 orbital radius ahead or behind.

Quick and dirty answer: Gravity is not the only force at work. You also have centrifugal force and Coriolis effects at work (though Coriolis effects are minor). The L4 and L5 spaces are where all three principal forces balance each other out and an object placed in these areas (they aren't really 'points' ) will tend to come back toward the center of these spaces if perturbed.



I present: Another crappy MS Paint Diagram

An object at a the L4 and L5 spaces is represented by a blue ball. The three principal forces acting on this object are represented by the three posts of different colors. There is the Earth's gravity (black post), the Sun's gravity (blue post) and Centrifugal force (red post). These posts are all different sizes because they represent forces that are not equal to each other. These forces each act on the object (represented by the lines attaching the posts to the blue ball) with different magnitudes. You can think of the forces acting on the ball (the lines) as giant rubber bands that attach the ball to the three different posts. Even though some rubber bands may be stronger (such as the Sun's gravity being the biggest force), because the ball is linked to all three of them, it cannot move vary far from a position that is suspended between the 3 posts. So for example, if something nudges the ball toward the Sun's post, then the forces from the other two posts are now pulling the ball back toward the center. This is because while the rubber bands from the other two posts are stretched, they pull back with more force, whereas the Sun's rubber band, being slack now that the ball is closer to it, pulls with less force.

This kind of tug-of-war is essentially what is going on at the L4 and L5 points.

Also, why are L1 & 2 unstable? I would think that they should be slightly less stable than L3 but more stable than 4 & 5. Is it because of the moon?

OK so at L4 and L5, an object is moving at the same pace around the Sun as the Earth is since it is essentially on the same orbital path as the Earth. This means that the Centrifugal force of the object as it moves around the Sun acts to balance out the gravity of the two objects, as per the above crappy MS Paint drawing.

However, at L1 and L2..... you know what, let's do this right.
CRAPPY MS PAINT DIAGRAM #2

At the L1, and L2 points, the Centrifugal force no longer acts to balance the other two forces on the object. This is because the objects is now orbiting either closer to the Sun than the Earth or further away, so it has either greater or lesser Centrifugal force than the Earth and perturbing the object means that force is changing yet even more. So in this diagram, the Red Post that represents Centrifugal force, is kind of derpy and no longer attaches to the ball. The Sun and the Earth are still attached to the ball but if the ball is perturbed such that it moves closer to the Sun then the Sun will pull on it harder because it is no longer balanced by the other forces. In fact, even though I'm showing the Centrifugal force as not attached to the ball to demonstrate that the system is out of whack, in reality it is still acting on the ball and if the ball got closer to the Sun, not only does the Sun's gravity pull it closer, but as it gets closer it has more Centrifugal force as it moves faster. Thus, any perturbations from the *precise* point where the forces balance causes the object at L1 and L2 to fly away from that balancing point as 1 or more of the 3 forces swamps out the others.

However, it is possible to have a semi-stable orbit about the L1 and L2 points, these are called Halo orbits as they form a circuit, or halo, around an imaginary point in space for minimum fuel expenditure.
Example:

Spoiler :

Why is it called "Argument" of Periapsis ? I don't understand this meaning of the word.

From one of the lesser-used definitions of the word argument:
5. Mathematics
a. An independent variable of a function.

b. The angle of a complex number measured from the positive horizontal axis.

The argument of Periapsis is pretty much both of these things. It's an orbital element that is one independent variable used to uniquely identify an orbit as well as an angle taken from the Periapsis point of an orbit (though it's not a complex number in the sense of a number with an i component like x +iy)

 

[peter grimes]

Great! Now I need to understand the Centrifugal Force and Coriolis. Isn't Centripetal force just equal to the angular momentum of the orbiting body?

 

[hobbsyoyo]

Well I just spent a few minutes confusing myself on Wikipedia. I really have no idea on that one peter. Sorry. I do know centrifugal =/= centripetal but that's about it.

 

[Winner]

Of them is "fake", i.e. it's only an apparent force. I think centripetal is the "real" one.

Coriolis Force is pretty difficult to understand abstractly, until you see the animated gifs on the Wiki page. Then you start getting the idea I wouldn't be able to explain it though.

 

[hobbsyoyo]

Of them is "fake", i.e. it's only an apparent force. I think centripetal is the "real" one.

Coriolis Force is pretty difficult to understand abstractly, until you see the animated gifs on the Wiki page. Then you start getting the idea I wouldn't be able to explain it though.

It's even messier than that, as centrifugal has 'fake' and 'real' components depending on the reference frame. I think. I dunno, my head hurts.

 

[dutchfire]

NASA and the Ruskies to stop collaborating because of the Crimean crisis. Death blow for NASA?

 

[hobbsyoyo]

Not at all?

They are still working with the Russians wrt the ISS - which is really the only thing NASA depends on the Russians for. Even then, they depend as much on NASA (given the US owns 51% of the station, including the power generation facilities and other vital components) as NASA depends on Ruscosmos for rides.

And the ISS is the major co-operation NASA has with Ruscosmos where there is any kind of dependency on Ruscosmos. Almost all the other co-operative agreements that NASA has with Ruscosmos involves their dependency on NASA. NASA has been subsidizing their space agency for the last decade and a half and without that it wouldn't have survived intact much longer beyond the collapse of the USSR. Even today, NASA still subsidizes Ruscosmos quite a bit.

I expect the Europeans to cut off co-operation with the Russians pretty soon, which would be a major blow to Russia given they launch 'Europeanized' Soyuz launchers from Kororou.

Then factor in all of the launch contracts they are about to lose with western corporations/companies and yeah...it's Ruscosmos that's getting screwed, not NASA, not by a long shot.

 

[hobbsyoyo]

And to show how epically screwed US politics are...

Obama has been pushing a program that has been paying commercial companies to develop systems (capsules and rockets) capable of delivering astronauts to orbit. The idea was they could do it cheaper and possibly faster than the government could and that they could then use the technology they develop for additional commercial ventures.

Since the beginning of the program, Congress has undercut it budgetary. This year, they are looking to cut it even further. As a consequence, instead of flying US astronauts on US rockets this year, as they would have if it had been funded properly, it'll be another year or two before it happens. Meanwhile, we're still buying seats from the Russians to the ISS.

Well last week, Congress brought in Charles Bolden (the NASA top admin) and gave him a tongue-thrashing for still depending on Russian flights to the ISS.

tl;dr

NASA has a program to build American space capsules so they won't need Russian ones
Congress: But but but OBAMA111!!!1!1 NO FUNDS FOR YOU
NASA: Well, we still have to buy seats from Russians
Congress: WHY YOU STILL BUY SEATS FROM RUSSIANS YOU DICK

 

[Crezth]

thank god nasa is always so perfectly reasonable and congress talks in all-caps