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#1 2017-10-29 11:27:02

Oldfart1939
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Registered: 2016-11-26
Posts: 1,805

Deep Space Gateway; a bad joke by NASA?

Ever since NASA announced their latest workfare program for their favored contractors, I've been wondering exactly who came up with this terrible idea. It sounds like a bad medical experiment designed by Josef Mengele for the residents of a concentration camp!

The idea of placing a long-term habitat in cis-lunar space with no provision for shielding from solar flare radiation and GCR, and which makes  no attempts made to alleviate the effects of microgravity, makes me wonder just what they hope to achieve other than killing or seriously injuring the astronauts involved. First proposed by NASA, and now we have the ESA jumping on board the idea along with the Russians. Other than providing something to justify the enormous amount of capital expended on the SLS, it seems to serve no truly useful purpose. It's another NASA let's all get on board and go...nowhere.

This amount of effort and expenditure by  NASA makes me wonder about the ongoing viability of the agency.

Last edited by Oldfart1939 (2017-10-29 11:30:13)

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#2 2017-10-29 13:54:29

RobS
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From: South Bend, IN
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Re: Deep Space Gateway; a bad joke by NASA?

There's a history to the Deep Space Gateway idea. It is close to 20 years old and was first proposed as a way to return to the moon when the Space Shuttle was the prime vehicle for launching people and cargo into low Earth orbit. It is, essentially, a good idea when it costs $20,000 or more to put a pound into low Earth orbit, and since the SLS is just as expensive as the shuttle per pound, it makes some sense with that launch vehicle in mind.

The proposal I am thinking of, which dated to about 1999, proposed that a solar-ion tug be developed using xenon fuel (which is itself horrendously expensive; close to price of gold per ounce!). The shuttle could put about 25 tonnes at a time into LEO, so the ion tug would be designed to mass that much with the xenon and be able to push 25 or 50 tonnes to Lagrange 1 between the Earth and moon (or in lunar orbit; that's another possibility). The first thing placed would be a station called Gateway where supplies would be accumulated and where the astronauts would have a shelter in case of emergency (it was never thought of as a permanently manned facility). Astronauts would fly to Gateway quickly using hydrogen-oxygen (ion propulsion is so slow, they'd fry in the Van Allen Belts). At Gateway they'd transfer to a lunar lander, which would later bring them back to Gateway, where they'd fly home in the ship that brought them to Gateway. Gateway was also a key item in the creation of a base at the lunar poles, where water would be converted into hydrogen-oxygen fuel. It then would be flown to Gateway by an unmanned LH2-LOX tug and would provide the propulsion for the astronauts' return flight.

Elon has rendered the entire idea obsolete. If you can launch stuff to LEO for $1,000 per kilo, can reuse your vehicles, and can refuel them in LEO with terrestrial propellant, you don't need Gateway. You probably can't even harvest lunar water, convert it to propellant, and fly it anywhere--even low lunar orbit--more cheaply than supplying it from Earth, especially if launch prices fall to a few hundred dollars per kilo.

Note that NASA's Mars architecture also assumes ion propulsion. With the massive cost of the SLS, it's the only way to reduce the launch costs sufficiently, until reality sinks in and you abandon SLS! Gateway is a possible launch point to Mars because you could accumulate fuel there via solar-ion tug for the trans-Mars injection. You'd send your vehicle toward the Earth first, or to the moon and then to the Earth--which takes a delta-v of a few hundred meters per second--then perform trans-Mars injection deep in Earth's gravity well.

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#3 2017-11-03 21:40:28

Oldfart1939
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Re: Deep Space Gateway; a bad joke by NASA?

Oldfart1939 wrote:

The idea of placing a long-term habitat in cis-lunar space with no provision for shielding from solar flare radiation and GCR, and which makes  no attempts made to alleviate the effects of microgravity, makes me wonder just what they hope to achieve other than killing or seriously injuring the astronauts involved.

It seems that GW and I have shared concerns about the long-term occupancy of this NASA abortion...

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#4 2017-11-04 04:05:22

elderflower
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Re: Deep Space Gateway; a bad joke by NASA?

Strikes me that the proposal is devised to justify their new big, but not big enough, rocket so that the trough keeps getting filled.

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#5 2017-11-04 08:43:18

Oldfart1939
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Re: Deep Space Gateway; a bad joke by NASA?

elderflower wrote:

Strikes me that the proposal is devised to justify their new big, but not big enough, rocket so that the trough keeps getting filled.

Exactly! This is a feeding program for ULA, and nothing more.

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#6 2017-11-06 21:35:57

SpaceNut
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Re: Deep Space Gateway; a bad joke by NASA?

I guess that I am the one that miss directed the topic with the images of mars so lets get back to the deep space exposure to which we seem to have one product that could be a good addition to the protection but its not enough unless we can alter what is placed in between each thin layer of the material to cause the scattering effect that we would want. The protection must be strong for the journey in both directions of the mission to mars.
The regolith is metal oxides for the most part so, what types would be the best to add to each layer of the BNNT liners for the deep space habitat and other areas of the vehicle?

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#7 2017-11-07 06:06:39

elderflower
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Re: Deep Space Gateway; a bad joke by NASA?

For early missions: Sandbags with stones, sand and water. Probably in 3 layers amounting to about 40/50 cms overall thickness. Water must freze so that snags don't let it escape quickly. Bags must be strong enough to resist internal vapour pressure with full insolation and must retain vapour for long periods.
For established settlements: something engineered based on available materials, and thick enough to balance a substantial internal pressure in the protected structures.

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#8 2017-11-07 18:52:53

SpaceNut
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Re: Deep Space Gateway; a bad joke by NASA?

With the use of rovers you can increase the level of shielding that the crew is within as well while they travel from location to location.
Another its to stand under a BNNT canopy that is moved as they do the work outside of the rover. Use large wagon wheel like cart open for the crew to move as they walk under it.

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#9 2017-11-07 20:32:12

Oldfart1939
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Re: Deep Space Gateway; a bad joke by NASA?

Robert-
I for one would be willing to go under the Mars Direct architecture. In both The Case for Mars and Entering Space, Robert Zubrin calculated the exposure rates for the journey and working on Mars. As a Nuclear Engineer, I trust his judgments better than I do NASA's.

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#10 2017-11-08 05:28:50

louis
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Re: Deep Space Gateway; a bad joke by NASA?

There's no reason as well why, if they do have to work in the open, they can't do so under a protective canopy with integral lighting.


SpaceNut wrote:

With the use of rovers you can increase the level of shielding that the crew is within as well while they travel from location to location.
Another its to stand under a BNNT canopy that is moved as they do the work outside of the rover. Use large wagon wheel like cart open for the crew to move as they walk under it.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#11 2017-11-08 15:37:43

louis
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Re: Deep Space Gateway; a bad joke by NASA?

It doesn't require us to add mass to the rover delivered to Mars.  You can have a roof rack for ice that would provide v. good protection.

Terraformer wrote:

Adding shielding to a rover means adding mass to it. A rover cannot be anywhere near as well shielded as a static hab.

The Martian atmosphere already provides 200kg of shielding per square metre. Any awning that can be put up and move easily isn't going to improve that much.

Given that most of their time is going to be spent in the hab anyway, including a lot of work (analysing samples, maintaining equipment, doing experiments etc), I don't think radiation on Mars is going to be much of a problem.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#12 2017-11-08 20:29:41

SpaceNut
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Re: Deep Space Gateway; a bad joke by NASA?

The science that we are going to be doing on mars will not be ride out to a location, jump out in suits grab rocks, soil sample and get back into rover.... We are going to be out on the surface for hours and longer drilling, digging making a site ready for the next visit... which are long exposure and a temporary canopy made large enough to house the foot print of the work site with layers of shielding would make the exposure less as for what we intend to do that work when not in our habitat.

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#13 2017-11-09 04:37:10

louis
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From: UK
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Re: Deep Space Gateway; a bad joke by NASA?

On earth there are already big mining operations taking place with almost no human involvement.

https://www.technologyreview.com/s/6031 … th-robots/

I am sure that on Mars similar operations will take place but on a smaller scale using suitably sized rovers.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#14 2017-11-09 05:02:36

Terraformer
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Re: Deep Space Gateway; a bad joke by NASA?

louis, adding ice to a rover means adding mass to it. Mass which has to be hauled around. You're still not going to get anywhere near the protection you'd get in the hab.


"I guarantee you that at some point, everything's going to go south on you, and you're going to say, 'This is it, this is how I end.' Now you can either accept that, or you can get to work." - Mark Watney

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#15 2017-11-09 05:09:29

elderflower
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Re: Deep Space Gateway; a bad joke by NASA?

Your rover might be better for a bit of mass. It would improve traction in some circumstances in the low gravity environment. Also rovers have to carry some water and other consumables to allow for return to base or rescue with a recycling system fault.

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#16 2017-11-11 11:44:42

GW Johnson
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Re: Deep Space Gateway; a bad joke by NASA?

I think I have suggested this before on these forums.  Passive radiation shielding is easy to test unmanned in the Van Allen belts,  as a fair approximation to solar flare radiation.  All you need are instrumented test modules with detectors inside,  all docked together.  Put a suitable propulsion module on one end to take them 1000-2000 miles up,  and circularize there.  Then just read the telemetry. 

This is something anybody really serious about deep space travel should have already done.  If the modules aren't too big and heavy,  the second stage of a Falcon-Heavy could likely do this job.  I would think that Spacex,  Bigelow,  and the rest of "new space" ought to be talking to each other about doing just exactly that as company-funded R&D. 

My own preference for one of the test modules is a shadow shield cluster of water and storable propellant tanks around the outside of the module.  The idea is to make something you already have to have,  serve another purpose,  too.  THAT is the essence of efficient design!  I tell you,  it'll work!  Although until it's tested,  that's just my opinion.

"New space" has to do this on its own,  because NASA and "old space" sure as hell are NOT going to do this.  That is because they make more money "studying the problem" than by actually going anywhere or actually doing anything real.  ("New space" ain't on corporate welfare,  yet.)

GW

Last edited by GW Johnson (2017-11-11 11:53:18)


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#17 2017-11-11 18:48:07

SpaceNut
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Re: Deep Space Gateway; a bad joke by NASA?

The trick then is to get some one of the companies to put something like the cygnus or inflateable as suggested with the proper design structure for the test gear inside it for sending back the telemetry data. The question for the test then is do we have the gear ready for this test on the shelf flight ready without anything new to design.

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#18 2017-11-19 20:44:24

SpaceNut
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Re: Deep Space Gateway; a bad joke by NASA?

http://www.sslmda.com/

SSL Selected to Conduct Power and Propulsion Study for NASA's Deep Space Gateway Concept

The gateway will be a human crew-tended spaceport in lunar orbit that functions as an access point to the Moon and deep space. The power and propulsion element (PPE), which will be the first gateway module launched, will serve as a building block to provide all power, maneuvering, attitude control, communications systems, and initial docking capabilities for the gateway. The SSL design for the PPE is expected to demonstrate the value and reliability of the company's spacecraft capabilities, which includes a long track record of success in power and propulsion systems, and more commercial satellites operating in geostationary orbit today than from any other manufacturer.

High power solar electric propulsion will be used to efficiently maneuver the PPE into its orbit and subsequently adjust the orbits of the gateway as needed. To meet the high level of power required for the gateway, SSL will leverage its extensive experience with solar electric propulsion, which includes 30 spacecraft on orbit today. The SSL concept includes the application of a Roll Out Solar Array (ROSA), which is a modular and scalable solar array system that rolls up for launch instead of folding like an accordion. ROSA was recently tested on the International Space Station and is qualified for use on the SSL 1300 spacecraft platform.

http://www.spacenewsfeed.com/index.php/ … ay-concept

ssl-2.jpg

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#19 2017-11-21 11:43:43

kbd512
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Re: Deep Space Gateway; a bad joke by NASA?

A small DSG like the one depicted by SpaceNut in his previous post could be delivered to ISS using two or more Falcon 9's, loaded with supplies / mated to a propulsion module / tested / tweaked, and then use the electric propulsion module to send it to the moon.  The astronauts could then ride a capsule there and have a space station to use as an orbital base camp.  There needs to be a "home away from home" so that absolutely everything doesn't have to ship in a single vehicle.

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#20 2017-11-21 22:01:52

SpaceNut
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Re: Deep Space Gateway; a bad joke by NASA?

I was reminded of this other topic 202*? and then there might be 2 stations in LEO which was due impart to the aging station and other issues but Space has stayed stable.

Deep Space Habitat

NASA could make 'Skylab II' first deep space 'home'

gaetanomarano Lunar Space Station

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#21 2017-11-27 19:54:00

SpaceNut
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Re: Deep Space Gateway; a bad joke by NASA?

Nasa has said that it wants the journey to be one of of cooperation with the current international parters of the ISS. The space review articles International cooperation and competition in space (part 1) & International cooperation and competition in space (part 2) which is where they are leveraging the existing modules as made by the ESA partner.

Through a reading of the 2010 National Space Policy, the 2011 National Security Space Strategy, and current authorization legislation such as the Commercial Space Launch Competitiveness Act of 2015 and NASA Transition Authorization Act of 2017, five overarching policy goals are apparent:

    Establish and reinforce norms of best behavior for outer space;
    Preserve the space environment;
    Enhance and protect national security space assets;
    Support the domestic capabilities and international competitiveness of the commercial space sector; and
    Pursue scientific investigation of the Earth and solar system along with human exploration beyond Earth orbit.

Spacedaily article indicates that Japan is along for the ride in the deep space creation....

Japan signals growing support for Deep Space Gateway concept

If the leading space agencies of Europe, Canada, Russia and Japan, now working together at the International Space Station, join the Deep Space Gateway program in exchange for contributing their space modules and transport ships, they could be able to send their astronauts to the future station in the moon's orbit.

NASA, for its part, is offerings to make the outpost available for training future expeditions to the moon's surface.

Space agencies are also mulling the idea of building a landing module to shuttle between the station and the moon.

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#22 2017-11-28 13:57:27

Lake Matthew Team - Cole
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Re: Deep Space Gateway; a bad joke by NASA?

RobertDyck wrote:
Lake Matthew Team - Cole wrote:

A thin layer of high-Z material could be integrated into the water shield

Do you understand why that's a bad idea? First, you're using obscure terminology. 'Z' is simply the last letter of the alphabet, each field of science or engineering uses it for something different. In the field of radiation shielding, it's usually used to refer to atomic number. That is number of protons in the nucleus, or positive static charge of the nucleus. If you mean atomic number, then say atomic number.

Atoms with high atomic number also have high atomic mass. That's a problem, and something we've moved away from. The reason is heavy ion radiation of any sort (high energy or low) and medium ion radiation with high energy both cause secondary radiation on impact with anything with high atomic mass. Both the radiation particle and material from shielding split apart. Each heavy particle (radiation and shielding) becomes multiple smaller particles, each with lower energy. The shower of secondary radiation is far worse than the original radiation. A high calibre bullet becomes a shotgun blast. The shotgun pellets are smaller, lower mass, lower velocity, but there's a lot more of them. If you're at close range so you get impacted with most of the shot, it actually does more damage than the high calibre bullet. Same with radiation.

"High-Z" material is good for shielding against neutron radiation and gamma radiation. There isn't any neutron radiation in space. Any neutron radiation from stars outside our solar system are so far, the radiation takes so much time, that the half-life of a free neutron causes it to decay into a proton and electron, long before it reaches our solar system. Our Sun had nuclear fusion in its core, but no high energy fusion near the surface. I used to think neutron radiation would decay in transit from Sun to Earth, but nuclear physicists tell me the neutrons either are absorbed or decay before they leave the surface of the Sun. Some fancy 21st century instruments have used this, they detect neutron radiation created as secondary radiation from the impact of solar radiation with the surface of the planetary body (Moon or Mars), and measure what comes back. Most of that neutron radiation is absorbed by Mars atmosphere, but enough gets back to low orbit that instruments can measure the difference between high energy vs low energy neutrons. Of course, the Moon doesn't have an atmosphere, so the instrument works even better there; but Lunar Prospector had to be in low Lunar orbit to work. Bottom line: no neutron radiation in interplanetary space.

Lead or other "high-Z" material has been used for radiation shielding against nuclear bombs or nuclear reactors because they produce so much neutron radiation. Space is different, it has proton radiation and particle radiation consisting of atomic nuclei. Stopping that without causing more radiation than you're blocking requires "low-Z" material, preferably hydrogen.

Please don't pontificate: that was tedious.  And look at the noted research before posting.

Atwell et al. 2013 wrote:

This study investigated the use of Graded-Z materials for radiation mitigation of proton environments.  The results showed some slight dose reductions in using Tantalum or Tungsten with 5 g/cm2 of HDPE in a GCR environment...

Last edited by Lake Matthew Team - Cole (2017-11-28 14:33:45)

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#23 2017-11-28 14:45:10

Lake Matthew Team - Cole
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Re: Deep Space Gateway; a bad joke by NASA?

Wrobel et al. 2017 Fig. 1 provides an existent analogue for the shielding case of "a thin layer of high-Z material... standing within the water volume".  The given polyetheretherkeytone / tungsten design is optimized for electronics shielding (protons + electrons), so it's not directly applicable.  It's just a tangible analogue for consideration, perhaps as starting point for thoughts on graded-Z improvements to the proposed water shield.

Last edited by Lake Matthew Team - Cole (2017-11-28 14:53:03)

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#24 2017-11-28 21:41:39

Lake Matthew Team - Cole
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Re: Deep Space Gateway; a bad joke by NASA?

SpaceNut wrote:

Space is cold so high temperatiure plastic will be brittle...but would work to hold the water....

Well, the additional shielding material would be in or around the water, and the water vessel adjoins crew quarters, so presumably the entire system would be held above freezing, which helps.

SpaceNut wrote:

Another materials is a blanket of Boron Nitride Nanotubes

So to get the water amount down such that we will have that mass for payload we will need more than 1 type of shielding method....

Yes, multiple methods could be used.  If some combination looks promising, we can work up a round-trip flight efficiency profile, to see how the numbers compare with Omaha Trail baseline. 

One complicating factor:  the water shield is transferred between Deimos and LEO, and between LEO and Mars EDL, so it's never included in the payload calculation.  That is, the water is never lifted from a planetary surface.  In contrast, any other, additional shielding material is lifted from planetary surfaces, and must be subtracted from payload.  For this reason any additional shielding material must reduce water mass very significantly, to justify itself. 

Mille-feuille (thousand-leaf)

One conceivable option:  Whereas small satellites might accommodate only a single graded-Z shield, an ITS spacecraft carrying Deimos water would have a much larger space for shielding.  Conceivably many extremely thin high-Z inserts could be stacked within the water vessel, arranged a bit like a mille-feuille pastry.  While each very thin graded-Z unit would give little shielding, the compounded iterative effect on primary and secondary particles might conceivably exceed first-order mass addition.  If, and only if, that proved to be the case, the effect would increase the net shielding beyond that of a single-insert design. 

It's just an idea; I wouldn't know if it's viable.  How to simulate accurately? 

Update:  SPENVIS is an interesting online tool for this purpose.  No guarantees of course, but it's a quick way to compare the merits of shielding ideas.  For example, a quick simulation of a 10-layer mille-feuille of tantalum and water is compared with a single unit of same mass.  First output suggests very similar proton shielding.

Lady-M-Trail-3.jpg

Last edited by Lake Matthew Team - Cole (2017-11-29 00:34:55)

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#25 2017-11-29 08:03:57

elderflower
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Re: Deep Space Gateway; a bad joke by NASA?

How good is liquid methane as a shield?  Or even LOX. I'm thinking in terms of doughnut tanks with a shelter in the middle.

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