An Orbiting Atmospheric Gatherer

[paul_klinkman]

<br />"Just a dumb idea that occured. Im sure someone has investigated it. <br /><br />How about a satelite scooping air from the upper atmosphere to save on launch costs for getting hydrogen/oxygen/water into orbit? <br /><br />It would have to recover momentum of course. <br /><br />Apparently electrodynamic tethers can be used to accelerate satelites." <br /><br />--From Kelvin_Zero<br /><br /><br />You had a smart idea. I've been working on it with a project team at Worcester Polytechnic Institute since last September. We presented at the IASTS conference on February 3. The patent is in process. We're out. We're public, up to a point. <br /><br />First of all, we don't "scoop" the atmosphere. Thick atmospheres near the earth's surface can be scooped. Anywhere above 100 km, we must use a molecular pump to gather atmosphere. This gathering can be done. <br /><br />Recovery of momentum is important. We use an electrodynamic tether. Our device operates at altitudes where an electrodynamic tether is functional. <br /><br />A gatherer with a cross section of, say, 10 feet by 10 feet will gather the atmosphere in an area 10 feet by 10 feet by 17,500 miles every hour. If we need 1 ton per year, or 100 tons per year, we size the gatherer to get that much. <br /><br />The gatherer is a vastly more efficient source of liquid oxygen in orbit than launching big dumb boosters. We are tentatively looking into the gathering of hydrogen too, but the profit is in the oxygen so far. <br /><br />We may pump our low value/waste gases such as liquid nitrogen into ion propulsion engines to boost payloads to geostationary orbit. LOX is a high value gas used for lunar landings and for boosting suborbital payloads into orbit after a rendezvous, another profit center. <br /><br />Profit. Can I say that word on this site? <br /><br /><br /><br />"Your work definitely deserves its own thread, not hidden away at the bottom of this one. You should post it in SPACE BUSINESS AND TECHNOLOGY <br /><br />Amazing <br /><br />Als

 

[jimfromnsf]

"and for boosting suborbital payloads into orbit after a rendezvous, another profit center."<br /><br /> This is undoable. An orbital and suborbital vehicle can only rendezvous for an instant (this what KKV's do). The velocity differential is too great, therefore no docking is possible.<br /><br /><br />When people propose new ideas which include glaring mistakes, makes the rest of the idea suspect

 

[rocketman5000]

tone down the hostility....

 

[paul_klinkman]

"An orbital and suborbital vehicle can only rendezvous for an instant (this what KKV's do). The velocity differential is too great, therefore no docking is possible. "<br /><br />There's no good reason why the "orbital" vehicle can't slow down to exactly match the suborbital vehicle's velocity. At this time we regularly aerobrake an orbiting shuttle to a suborbital velocity (and beyond).<br /><br />I'd say that a relative velocity differential of under 200 mph is a minimum target, based on plane landings on aircraft carriers. A nice, easy dock at 1 mph, such as a military plane does with a fuel tanker in midair, might require less hardware and is also practical, but in general we want to dock quickly and surely. <br /><br />One way to steadily work into the suborbital to orbital market is to boost a slightly oversized payload from 17,300 mph to 17,500 mph (or beyond to geostationary orbit), then try a slightly more oversized payload at 17,000 mph, and so on to the point where earth-based propulsion costs equal space-based costs.

 

[kelvin_zero]

How small do you think the prototype could be made? <br /><br />Also, does anyone know if there any labs to test out the conditions on earth? ie suspend a prototype in a vacum and bombard it with air particles at 8km/s?<br /><br />Re suborbital intercept, perhaps the gatherer could use its drag to slow itself to the same suborbital trajectory as the rising ship (gathering a bit more fuel perhaps, though it might not have time to process it) then I guess they have some minutes to dock in freefall. Then the combined pair use the fuel on the gatherer and an engine on either the gatherer or the ship to carry both up to orbital velocity. If they do not manage to dock, the ship simply continues its balistic course and lands, and the gatherer loses some fuel boosting just itself up to stable orbit.<br /><br />This all sounds a bit acrobatic. <img src="/images/icons/laugh.gif" /> gathering gasses in orbit is definitely going to find uses even if not this particular one.<br /><br />I think in future the nitrogen would be very useful to gather too, since it is so useful for life. I remember something about a nitrogen budget for the moon base.<br />

 

[jimfromnsf]

"There's no good reason why the "orbital" vehicle can't slow down to exactly match the suborbital vehicle's velocity. . "<br /><br />There is a great reason why it can't, it wouldn't be in orbit anymore.<br /><br />"I'd say that a relative velocity differential of under 200 mph is a minimum target, based on plane landings on aircraft carriers. A nice, easy dock at 1 mph, such as a military plane does with a fuel tanker in midair, might require less hardware and is also practical, but in general we want to dock quickly and surely. "<br /><br />200 mph differential is not the difference between orbital and suborbital. Suborbital velocities are around 10,000 mph. Suborbital is not a low orbit that is affected by the atmosphere. It is a lob, a parabola.

 

[rocketman5000]

The most recent Falcon launch was just several hundred mph short of orbital velocity. It didn't make orbit. Its arc didn't look exactly like a parabola. The only thing you need to be suborbital is to be moving less than orbital velocity. if you aren't at orbital velocity you are at a SUBorbital velocity. Say something like 17,300mph

 

[jimfromnsf]

The Falcon launch was several thousand mph short of orbital velocity (it was at 11,000). 17500 mph is not a hard number. It is a function of altitude. A few hundred mph below planned velocity would be a lower than planned orbit, which due to the atmosphere, would be shortlived, either a few orbits or not quite once around. But anyways, a few hundred mph short of orbital would put spacex on the other side of the earth <br /><br />

 

[paul_klinkman]

So, a few orbits at 90 minutes per orbit would give our booster a few hours to dock and then boost the payload. Half an orbit would give our booster maybe 45 minutes to dock. <br /><br />Ultimately, how many minutes (or seconds) would a good, reliable docking maneuver demand? This might determine how slow our space-based reusable boosters can go to pick up payloads.

 

[jimfromnsf]

It would demand a stable orbit, not a suborbital lob. Another issue is tracking, the flight is too short.<br /><br />Also, your are doing it backwards, the second vehicle has to do the chase, not the one in orbit .<br /><br />Just not possible what you are proposing <br /><br />Review some orbital mechanics

 

[thereiwas]

Assume for the moment that the scoopship stays in orbit, and that the hauler actually matches that orbit, docks, pumps out the collected stuff, undocks, and then re-enters.<br /><br />The hauler needs its own fuel to get up there. I wonder if it is worth the trip after that, even though it goes up empty and comes down full.<br /><br />Then the hauler has to somehow land gently with all that cargo on board.<br /><br />I think this idea has greater merit for hauling the scooped gasses away to some other place in orbit or at a LaGrange point for storage and further processing. A refueling depot. It might also be interesting to apply on Titan or one of the gas giants. (Does Titan have a magnetic field? I think you need that for the tether to produce any power.)

 

[kelvin_zero]

That is the plan, to supply objects in orbit where it costs thousands/kg to deliver material from the ground.<br /><br />This intercept discussion is an aside that confuses things and deserves to be in a different thread.<br /><br />Im eager to hear any future news about the gatherer. Im genuinely surprised someone hasnt found a reference that goes back to the 70's. When I searched the internet originally, the only link I found ANYWHERE was one line where someone claimed scooping was often discussed <img src="/images/icons/wink.gif" /><br /><br />

 

[paul_klinkman]

I'd like to announce two upcoming personal visits where we can discuss our atmospheric gatherer.<br /><br />Dr John Wilkes of Worcester Polytechnic Institute and I are both going to be at the RI Space Grant Conference this Saturday, April 28. We're not presenting, but we can answer questions about the atmospheric gatherer over lunch.<br /><br />Finally, Dr. Wilkes is scheduled to present a paper at the AIAA Space 2007 Conference and Exposition on September 18-20 at the Long Beach, CA Convention Center. I may come along for the presentation. It looks like AIAA undergraduate and graduate student prices are pretty affordable, although full price is huge.

 

[paul_klinkman]

One more chance for detailed questions. I'm going to be attending the ATWG conference on May 22 and May 23, Tuesday and Wednesday.

 

[paul_klinkman]

"Assume for the moment that the scoopship stays in orbit, "<br />It doesn't scoop in a high vacuum, it gathers with a molecular pump. The craft generates thrust against the earth's magnetic field to stay in orbit.<br /><br />"and that the hauler actually matches that orbit, docks, "<br /><br />Not too hard to do.<br /><br />"pumps out the collected stuff,"<br /><br />Actually, the gatherer does the pumping straight into the space tug, which you have called a hauler. <br /><br />"undocks, and then re-enters."<br /><br />"The hauler needs its own fuel to get up there. I wonder if it is worth the trip after that, even though it goes up empty and comes down full.<br /><br />Then the hauler has to somehow land gently with all that cargo on board." <br /><br />The space tug re-enters the outer atmosphere at best. It doesn't land on the earth, or come close. Propellant in orbit costs about $10,000 per kilogram to ship upstairs. Bringing propellant down to earth reduces the propellant's value to maybe $1 per kilogram. We're not carrying coals to Newcastle. We're hauling payloads from low earth orbit to geostationary orbit, supplying propellant for lunar landings, and taking over the last 10% of boosting any payload into orbit. Is the picture clearer?<br /><br />

 

[jimfromnsf]

GSO is not a good staging point, it take more energy to get there than it takes going to the moon

 

[paul_klinkman]

"It would demand a stable orbit, not a suborbital lob. Another issue is tracking, the flight is too short. "<br /><br />A barely orbital lob of 17,400 mph might stay in space for a couple of orbits. That's long enough to track and long enough to dock. <br /><br />The remaining question is, how many minutes (or seconds) would be needed for a rendezvous if we had plenty of practice? 30 minutes? 60 seconds someday? The faster the rendezvous and lock-on, the more money we can save. With thousands of dollars at stake, do you think anyone can learn to lower the rendezvous time from 2 hours to 30 minutes?<br /><br />What I won't know for quite a while is the bare minimum time needed to track and snag a payload that wants to be found and snagged.<br /><br />"Also, your are doing it backwards, the second vehicle has to do the chase, not the one in orbit . "<br /><br />If either vehicle is fueled, either can participate in the rendezvous. Traditionally the vehicle coming up from earth has done the chasing precisely because it has the propellant, but what if the orbiting vehicle has the cheapest propellant for a change?

 

[paul_klinkman]

"GSO is not a good staging point"<br /><br />My best gas collecting point is roughly around the elevation of the International Space Station. I can agree that anywhere in LEO is a better staging point than GSO.

 

[paul_klinkman]

"We're hauling payloads from low earth orbit to geostationary orbit, supplying propellant for lunar landings, "<br /><br />Clarification: we're tugging communications and weather satellites from low earth orbit to geostationary orbit. We never intended to set up any kind of transfer base at GSO.

 

[jimfromnsf]

"1. A barely orbital lob of 17,400 mph might stay in space for a couple of orbits. That's long enough to track and long enough to dock.<br /><br />2. The remaining question is, how many minutes (or seconds) would be needed for a rendezvous if we had plenty of practice? 30 minutes? 60 seconds someday? The faster the rendezvous and lock-on, the more money we can save. With thousands of dollars at stake, do you think anyone can learn to lower the rendezvous time from 2 hours to 30 minutes?<br /><br />3. If either vehicle is fueled, either can participate in the rendezvous. Traditionally the vehicle coming up from earth has done the chasing precisely because it has the propellant, but what if the orbiting vehicle has the cheapest propellant for a change?"<br /><br />1. You don't understand the fundementals of orbital mechanics. 17, 500 mph is not a hard number for earth orbital velocity and actually a lower orbit is faster than that. Earth orbit velocities (no atmosphere)<br />Altitude - velocity<br /><br />30 miles - 17627 mph<br />50 - 17582 <br />100 - 17470<br />200- 17269<br /><br />17,400 mph is at an altitude of around 135 mi<br /><br />2. You are only talking about docking. Rendezvous starts much further away. Time has nothing to do with practice, it is driven by the velocity changes required and the time it takes for changes to affect the orbits.<br /><br />3. It has nothing to do with propellant. the lunar module had less fuel than the CSM and the Gemini had less than the Agena. The rendevous starts with the vehicle that is launching. It must guide itself to the target. If not, it could go into an orbit "unreachable" from the other vehicle (unreachable meaning it would take days and lots of propellant to reach)

 

[j05h]

<i>> 3. It has nothing to do with propellant. the lunar module had less fuel than the CSM and the Gemini had less than the Agena. The rendevous starts with the vehicle that is launching. It must guide itself to the target. If not, it could go into an orbit "unreachable" from the other vehicle (unreachable meaning it would take days and lots of propellant to reach)</i><br /><br />Another way to put this: if the orbiting vehicle performs his "catch up" maneuver, it deorbits itself. Space. It's counter-intuitive.<br /><br />The best ways to harvest atmosphere would be either a vehicle that dives into the upper reaches to collect gases, then is picked up by a bolo-tether to reestablish orbit. The other is for a bolo with a collector at the tips, it collects then uses electrodynamics to raise it's orbit. <br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[kelvinzero]

You should patent it then <img src="/images/icons/wink.gif" /><br /><br />Could another use of 'fuel to burn' in orbit be safer reentry for the space shuttle? If you could fully tank it up before it returned, couldnt it more fully decelerate wrt to the earth before reentering the atmosphere, perhaps to the degree where heat shielding is not required?<br /><br />This could have an immediate benifit before more specialised craft were developed to exploit this cheaper fuel in orbit.

 

[qso1]

Do you have any graphical data or illustrations of how this concept is designed to work. That would help me and maybe a few others to better understand what your trying to accomplish. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[paul_klinkman]

"Another way to put this: if the orbiting vehicle performs his "catch up" maneuver, it deorbits itself."<br /><br />That's correct. Please try not to be hung up on the question of whether a spacecraft is "orbital" or "suborbital" in the long term, because we're dealing with a short-term set of operations. A rocket starts at an orbital velocity. It decelerates in perhaps two minutes to a slightly less than orbital velocity, snags a payload in well under two minutes, then accelerates in perhaps two minutes to its original orbital velocity. If this rendezvous operation took an entire orbit then yes, the rocket might de-orbit. However, waiting more than 1/4 of an orbit for disaster to show up is just not in our plans. We decelerate (or slow down in the outer atmosphere), snag the cargo, and accelerate quickly. <br /><br />If learning how to rendezvous with the orbiting vehicle makes access to space cheaper, someone will learn how to do it. I don't care that it's always been done the other way. That's not a reason. Historically, one space vehicle has been designated the target and the other the pursuer because of fuel use reasons, and now for the first time in NASA's history the fuel source has changed.

 

[jimfromnsf]

"It decelerates in perhaps two minutes to a slightly less than orbital velocity, snags a payload in well under two minutes, then accelerates in perhaps two minutes to its original orbital velocity."<br /><br />Prue fantasy. Physically impossible. There is no "short-term" There isn't enough time to peform the manevuers. And you have no idea of the amount of thrust that would be required.<br /><br />" one space vehicle has been designated the target and the other the pursuer because of fuel use reason"<br /><br />As I pointed out previously, this is not the reason. It didn't apply to Apollo or Gemini. The vehicle on orbit had more fuel than the chaser.<br /><br />Honestly, do you know orbital mechanics? Look at the first orbit rendezvous of Gemini 11. <br /><br />