A New Way to Reach Mars Safely, Anytime and on the Cheap
Ballistic capture, a low-energy method that has coasted spacecraft into lunar orbit, could help humanity visit the Red Planet much more often
By Adam Hadhazy | December 22, 2014A newfound, lower-energy means for spacecraft to attain Martian orbit could help make Red Planet voyages cheaper, safer and therefore more frequent.
Credit: NASA
Exploring Mars: Secrets of the Red PlanetGetting spacecraft to Mars is quite a hassle. Transportation costs can soar into the hundreds of millions of dollars, even when blasting off during "launch windows"—the optimal orbital alignments of Earth and Mars that roll around only every 26 months. A huge contributor to that bottom line? The hair-raising arrivals at the Red Planet. Spacecraft screaming along at many thousands of kilometers per hour have to hit the brakes hard, firing retrorockets to swing into orbit. The burn can require hundreds of pounds of extra fuel, lugged expensively off Earth, and comes with some risk of failure that could send the craft careening past or even right into Mars.
(Hohmann):
This brute force approach to attaining orbit, called a Hohmann transfer, has served historically deep-pocketed space agencies well enough. But in an era of shrinking science budgets the Hohmann transfer's price tag and inherent riskiness look limiting.(Ballistic):
Now new research lays out a smoother, safer way to achieve Martian orbit without being restricted by launch windows or busting the bank. Called ballistic capture, it could help open the Martian frontier for more robotic missions, future manned expeditions and even colonization efforts. "It's an eye-opener," says James Green, director of NASA's Planetary Science Division. "It could be a pretty big step for us and really save us resources and capability, which is always what we're looking for."The premise of a ballistic capture: Instead of shooting for the location Mars will be in its orbit where the spacecraft will meet it, as is conventionally done with Hohmann transfers, a spacecraft is casually lobbed into a Mars-like orbit so that it flies ahead of the planet. Although launch and cruise costs remain the same, the big burn to slow down and hit the Martian bull's-eye—as in the Hohmann scenario—is done away with. For ballistic capture, the spacecraft cruises a bit slower than Mars itself as the planet runs its orbital lap around the sun. Mars eventually creeps up on the spacecraft, gravitationally snagging it into a planetary orbit. "That's the magic of ballistic capture—it's like flying in formation," says Edward Belbruno, a visiting associated researcher at Princeton University and co-author, with Francesco Topputo of the Polytechnic University of Milan, of a paper detailing the new path to Mars and the physics behind it. The paper, posted on arXiv, has been submitted to the journal Celestial Mechanics and Dynamical Astronomy.
"A delicate dance"
Ballistic capture, also called a low-energy transfer, is not in of itself a new idea. While at NASA's Jet Propulsion Laboratory a quarter century ago, Belbruno laid out the fuel-saving, cost-shaving orbital insertion method for coasting probes to the Moon. A Japanese vessel, called Hiten, first took advantage in 1991, as did NASA's GRAIL mission, launched in 2011.Belbruno worked out how to let the competing gravities of Earth, the sun and moon gently pull a spacecraft into a desired lunar orbit. All three bodies can be thought of as creating bowl-like depressions in spacetime. By lining up the trajectory of a spacecraft through those bowls, such that momentum slackens along the route, a spacecraft can just "roll" down at the end into the moon's small bowl, easing into orbit fuel-free. "It's a delicate dance," Belbruno says.
Unfortunately, pulling off a similar maneuver at Mars (or anywhere else) seemed impossible because the Red Planet's velocity is much higher than the Moon's. There appeared no way to get a spacecraft to slow down enough to glide into Mars' gravitational spacetime depression because the "bowl," not that deep to begin with, was itself a too-rapidly moving target. "I gave up on it," Belbruno says.
However, while recently consulting for the Boeing Corp., the major contractor for NASA's Space Launch System, which is intended to take humankind to Mars, Belbruno, Topputo and colleagues stumbled on an idea: Why not go with the flow near Mars? Sailing a spacecraft into an orbital path anywhere from a million to even tens of millions of kilometers ahead of the Red Planet would make it possible for Mars (and its spacetime bowl) to ease into the spacecraft's vicinity, thus subsequently letting the spacecraft be ballistically captured. Boeing, intrigued by this novel avenue to Mars, funded the study, in which the authors crunched some numbers and developed models for the capture.
I recall seeing quotes of a 25% savings of fuel. It can come with a time price however. Extra months perhaps in some cases. However, for sending pre-positioned supplies the time issue may or may not be an issue. However in one of my previous links, they cited a way, (Which I don't fully comprehend), where in the Martian, the supplies needed could have been sent sooner, significantly sooner than with a hohmann transfer.
Now, I am ignorant. It will do no good for you to do a can-can't argument with me, because I actually don't know. I can read however, and the material I am reading seems to indicate that a hohmann transfer is not necessarily the always best method.
Please dispute the links I have posted, and educate me about it if I need a further education. Really. I don't know if I am being trolled by Boeing and NASA Perhaps they have nothing better to do with money than to BS me on this stuff for fun.
]]>Sometimes storage in space has advantages over storage on a planet's surface. You could store hydrogen tanks in space for example, and if you shade it properly, the hydrogen can be kept cold much more easily than on the surface of Mars, you might also want to keep it well away from Mars, that way you only need to shade it from the Sun, and not have to worry about reflected radiation from the surface of Mars that might boil off your hydrogen. I think Space is a good place to store rocket fuel. You need that rocket fuel to return to Earth. Maybe the interplanetary transfer vehicle can be kept in a trailing orbit behind Mars, and then when needed it can enter low Mars orbit for a ascent vehicle to reach, and then transfer to Earth.
Should the ship that brought you to Mars also bring you back? Seems to me that the Mars Hab could be lived in on the way to Mars, then land the hab on Mars, the ship that brought you is disposed of along the way, and another ship waits in a trailing Mars orbit ready to bring the astronauts back to Earth when called for. What do you think of this idea?
]]>Anyway, there you go, no humans harmed, as this is play time, not an actual mission.
]]>My presentation in the last post had some errors. I think I understand the following link much better.
http://www.scientificamerican.com/artic … the-cheap/
This brute force approach to attaining orbit, called a Hohmann transfer, has served historically deep-pocketed space agencies well enough. But in an era of shrinking science budgets the Hohmann transfer's price tag and inherent riskiness look limiting.
Now new research lays out a smoother, safer way to achieve Martian orbit without being restricted by launch windows or busting the bank. Called ballistic capture, it could help open the Martian frontier for more robotic missions, future manned expeditions and even colonization efforts. "It's an eye-opener," says James Green, director of NASA's Planetary Science Division. "It could be a pretty big step for us and really save us resources and capability, which is always what we're looking for."
The premise of a ballistic capture: Instead of shooting for the location Mars will be in its orbit where the spacecraft will meet it, as is conventionally done with Hohmann transfers, a spacecraft is casually lobbed into a Mars-like orbit so that it flies ahead of the planet. Although launch and cruise costs remain the same, the big burn to slow down and hit the Martian bull's-eye—as in the Hohmann scenario—is done away with. For ballistic capture, the spacecraft cruises a bit slower than Mars itself as the planet runs its orbital lap around the sun. Mars eventually creeps up on the spacecraft, gravitationally snagging it into a planetary orbit. "That's the magic of ballistic capture—it's like flying in formation," says Edward Belbruno, a visiting associated researcher at Princeton University and co-author, with Francesco Topputo of the Polytechnic University of Milan, of a paper detailing the new path to Mars and the physics behind it. The paper, posted on arXiv, has been submitted to the journal Celestial Mechanics and Dynamical Astronomy.
"A delicate dance"
Ballistic capture, also called a low-energy transfer, is not in of itself a new idea. While at NASA's Jet Propulsion Laboratory a quarter century ago, Belbruno laid out the fuel-saving, cost-shaving orbital insertion method for coasting probes to the Moon. A Japanese vessel, called Hiten, first took advantage in 1991, as did NASA's GRAIL mission, launched in 2011.Belbruno worked out how to let the competing gravities of Earth, the sun and moon gently pull a spacecraft into a desired lunar orbit. All three bodies can be thought of as creating bowl-like depressions in spacetime. By lining up the trajectory of a spacecraft through those bowls, such that momentum slackens along the route, a spacecraft can just "roll" down at the end into the moon's small bowl, easing into orbit fuel-free. "It's a delicate dance," Belbruno says.
Unfortunately, pulling off a similar maneuver at Mars (or anywhere else) seemed impossible because the Red Planet's velocity is much higher than the Moon's. There appeared no way to get a spacecraft to slow down enough to glide into Mars' gravitational spacetime depression because the "bowl," not that deep to begin with, was itself a too-rapidly moving target. "I gave up on it," Belbruno says.
However, while recently consulting for the Boeing Corp., the major contractor for NASA's Space Launch System, which is intended to take humankind to Mars, Belbruno, Topputo and colleagues stumbled on an idea: Why not go with the flow near Mars? Sailing a spacecraft into an orbital path anywhere from a million to even tens of millions of kilometers ahead of the Red Planet would make it possible for Mars (and its spacetime bowl) to ease into the spacecraft's vicinity, thus subsequently letting the spacecraft be ballistically captured. Boeing, intrigued by this novel avenue to Mars, funded the study, in which the authors crunched some numbers and developed models for the capture.
Granted, I am still rather ignorant, which is a problem which needs addressing, but rigid dogma is also a problem of equal proportion.
However I will make a further stab at it. If the spacecraft was too far ahead of Mars, then it would follow it's elliptical path, and move closer to the sun, away from Mars, picking up speed. However, if it dips into an approaching (Moving) Martian gravity well, before it can move away from the ~(Martian solar orbit), it may be gently been captured. The spacecraft captures momentum from Mars, and Mars looses momentum. At least this is how I visualize it. I think I might be close this time.
I think you play pretty good almost all the time Tom.
Further thoughts;
Can heat shields be lighter in this method?
Nasa is entertaining a solar orbiting radiation shield for going to Mars. I presume a human occupied spacecraft would connect with it at some point and use it for human health concerns. That one would be in an elliptical orbit. Could you also put one in a near Martian circular orbit? That is abandon the elliptical radiation shield when you approached the circular one, and then move that whole assembly to a condition of being just in front of the approaching Martian gravity well?
This is sort of a partial cycling spaceship method, but it only has some inheritance from cycling spaceships. Would the advantages outweigh the costs? As I see it the radiation shields would be robotic, and have some solar panels, and some electric rocket capabilities.
Oh well.
]]>The shortcut
However, that delay could have been substantially reduced. In late 2014, my colleague Francesco Topputo and I published a new type of route to Mars. This route first appeared in the arXiv, then in Advances in the Astronautical Sciences, Volume 155, and then in Celestial Mechanics and Dynamical Astronomy. One of the more interesting aspects of this new route is that it is not necessary to wait for Earth and Mars to be properly aligned to launch the spacecraft. It can launch at any time.
This is a major advantage. The transfer works in a substantially different way than the Hohmann version, in which the spacecraft travels directly to Mars. Here, the spacecraft is not sent to Mars. It is sent to a point along Mars' orbit about the sun, which can be chosen from a wide variety of points along that orbit, millions of kilometers from the planet. These points are trailing Mars as it orbits the sun, so the spacecraft slowly catches up to Mars.
The spacecraft can be launched from Earth at the right time, depending on where the desired orbital point is located, using a Hohmann transfer. But there are so many of these points, the spacecraft can leave the Earth whenever desired, or conversely arrive at a point when desired.
Now, when the spacecraft arrives at the desired point on Mars' orbit, it is trailing the planet in its orbit about the sun. The engines fire to do a maneuver that increases the speed of the spacecraft, relative to the sun, so the ship can follow a special trajectory from its location to Mars. This trajectory is called a ballistic capture transfer, or a weak stability boundary (WSB) transfer.
Once the spacecraft is on this transfer, it takes an additional few months to catch up to Mars. Upon arrival at the planet, no more maneuvers are necessary, and the spacecraft is automatically captured into orbit (the ballistic capture). This is much safer than a Hohmann transfer, in which spacecraft need to substantially slow down using their engines, which can be dangerous (NASA's Mars Observer was lost due to this). The ballistic capture transfer could also be designed to go directly to Mars' surface.
Using the ballistic capture transfer, the resupply spacecraft could have left as soon as NASA realized Watney was alive, with a flight time of about 294 days, taking 234 days to reach a point on Mars' orbit. From there, it would need another two months to get to Mars itself using a ballistic capture transfer. The flight time would have been 294 days — a savings of 120 days, giving Watney a much better chance of survival. He would have been relieved. ['The Martian' Rescue Mission Simply Explained In Film Clip ]
It's important to note that WSB transfers have been used several times before, in missions to the moon. The first was completed in 1991, by the Japanese spacecraft Hiten. James Miller and I designed this transfer, which is described in more detail in "Fly Me to the Moon" and the Space.com essay "Painting Our Way to the Moon." Another was completed in 2004 by the European Space Agency (ESA)'s SMART-1 mission, which used a different type of lunar transfer, based on the first one I found in 1986. JPLs GRAIL mission in 2011 used the same transfer type as Hiten. (Read more in Belbruno's key papers.)
But, alas
As it turned out in the book, the resupply craft never made it to Watney. However, if this type of transfer had been known, then the options to get a craft to Mars with supplies could have been executed on a different schedule, decreasing the chance of failure.
If you're a topical expert — researcher, business leader, author or innovator — and would like to contribute an op-ed piece, <a href="mailto:expertvoices@techmedianetwork.com">email us here</a>.
If you're a topical expert — researcher, business leader, author or innovator — and would like to contribute an op-ed piece, email us here.
Credit: SPACE.com
View full size imageWith WSB transfer, a spacecraft with emergency supplies could have been put in Mars orbit about the sun in advance, before Watney and his crew arrived, ready to use in case of a mishap. It could have then been sent to Mars on a WSB transfer in a couple months.
In the book, Watney's crew redirects its ship, Hermes, to Mars since the resupply ship didn't make it. The rescue spacecraft first had to perform a flyby of the Earth to gain the necessary speed to make it to Mars as fast as possible, using a Hohmann-like transfer. This resulted in non-desirable Mars arrival conditions, since the spacecraft was traveling much faster than normal. In this case, the transit time was 375 days. This is still 81 days in excess of the WSB transfer.
Also, the WSB transfer would not have arrived with such a large overflight velocity as Hermes did in the book. As a result, it would not have been necessary to attempt the hair-raising, dangerous rescue for Watney depicted in the novel.
The use of the WSB transfer would have clearly altered the course of this book, offering a number of different options for NASA and Watney. His life would have been much easier.
So, in my own words, I would perhaps have said that this other method/new method, would have the spacecraft enter a trailing orbit of Mars orbit, but then add a bit of speed, and allow/assist the spacecraft to catch up to Mars, using the gravitation of Mars as an assist? Perhaps I am close. Of course I have just read this, I am a featherweight as it comes to these matters at least.
Comments on the movie:
I like to see the movie. Movies have to sell, it is a business.
I think the movie was at least reasonably brave. Some movies, about space exaggerate danger, and in fact the moral of those stories is that moving from point A to point B is dangerous, and the best you can hope for is to circle back home, and end up in the primordial mud, run and hide. Granted, real life sometimes wants that remedy. Not all brave deeds are wise deeds. However, since it is not a real space mission, but play acting about a space mission, the emphasis should be on "Play".
In play mammals in particular rehearse what they will do as adults. Humans even more so. Children should most likely be allowed to have heroic delusions, up to a point. Sci-Fi, is part reality, and part fantasy. One foot on the ground, one flying.
The movie was pretty good that way, and I was happy to see it ended with the notion that there was going to be yet another mission to Mars.
So, seeing that as in the reference I added some other people have additions that could have been made that would change the story, that's all very good. Playtime, necessary for organisms with a greater mind capacity, the capacity to go beyond the emotions of fear, using problem solving.
At least that's how I see it.
]]>