8 ms·

A New Way to Reach Mars Safely, Anytime and on the Cheap

118 points by softdev12 12y ago

didgeoridoo 12y ago
My KSP-fu is failing me here... how is it possible to match Mars' circular solar orbit at a slower velocity? Wouldn't a different velocity imply a different orbital distance from the sun?
- dragonwriter 12y ago
  > My KSP-fu is failing me here... how is it possible to match Mars' circular solar orbit at a slower velocity? You aren't actually trying to match it; as I understand this kind of orbit is a slightly slower (so slightly closer, on average) orbit that the vessel achieves somewhat ahead of Mars, so that when Mars passes it, Mars' gravity is enough to capture the vessel. In essence, some of the energy to match the orbit comes from Mars itself (slowing down Mars, but for any realistic spacecraft this is completely negligible because of the enormous mass ratio between the planet and the craft.)
- ashark 12y ago
  Sounds like it's that thing in KSP where you time your insertion to The Mun's sphere of influence just right so you don't have to burn retro to achieve Munar orbit. Basically hit it so that you do gravity-assisted deceleration, and end up in orbit around it—typically badly elliptical orbit, but that's cheap to correct.
- Thrymr 12y ago
  Mars' orbit is not circular, and spacecraft's would not be, either. They would be in slightly different (and intersecting, or nearly so) elliptical orbits, which would allow Mars to gravitationally capture the spacecraft when it approached closely enough.
  - ashark 12y ago
    Is performing a second burn to circularize a craft's orbit to near-sync with Martian orbit really cheaper than a deceleration burn? In fact, that would just be a complete Hohmann transfer. I'd guess the target orbit for a craft performing this maneuver would still have a periapsis in the neighborhood of Earth's orbit, meaning it'd still be very unlike Mars' orbit until the craft was captured by Martian gravity. (googles a bit) It looks like these exploit Lagrange points somehow[1]. Precision maneuvers and weird, long routes to the target body. I'm not quite following how this works with only two bodies (Sun and Mars), versus the Sun-Earth-Moon trio. Wikipedia claims the Mars Orbiter Mission used a low-energy transfer at some point, but I can't figure out whether that was for the insertion into Martian orbit or some earlier maneuver it performed. [1] http://www.gg.caltech.edu/~mwl/publications/papers/lowEnergy.pdf http://www.gg.caltech.edu/~mwl/publications/papers/lowEnergy... [edit] Hoffman -> Hohmann, because I'm an idiot.
wallflower 12y ago
Buzz Aldrin is very passionate about colonizing Mars [1]. He says there are two big things that have to be accomplished before we can colonize Mars. The first is to train astronauts to live in a confined isolated space for 260 days (the length of a journey to Mars) [2]. This alternative journey trajectory increases the 260 days. The second is harder: We need to go to Mars at least three times and bring back the men and women successfully. Once is not enough. Three proves we've mastered the engineering, financial, physical, and physiological aspects. [1] http://www.pbs.org/wgbh/nova/space/aldrin-mars-au.html http://www.pbs.org/wgbh/nova/space/aldrin-mars-au.html [2] http://www.guardian.co.uk/science/2010/jun/03/mock-mission-mars-moscow-hangar http://www.guardian.co.uk/science/2010/jun/03/mock-mission-m...
- debacle 12y ago
  > We need to go to Mars at least three times and bring back the men and women successfully. First we'd need to find a way to bring back pretty much anything else successfully, no? The first is an easy problem to solve, compared to pretty much every other issue. More space (or better space) is a non-linear issue.
  - semi-extrinsic 12y ago
    Unless you're envisioning spacecraft with literally hundreds of astronauts, the first will be anything but easy to solve. Doesn't help having an awesome spaceship if everyone on board goes batshit crazy after six months.
    - diltonm 12y ago
      Bubbleheads are tested in Submarine School for compatibility with the idea of living in the intellectual equivalent of a sewer pipe for months on end with each other. I'd assume NASA would do the same. End of the day make sure you know who holds the keys to the weapons locker.
  - ams6110 12y ago
    Why do we need to bring them back? Pioneers don't normally set off with a guarantee or even likelihood of coming back.
melling 12y ago
Maybe now there will be a Mars X-Prize after we complete the Lunar X-Prize: http://lunar.xprize.org/ http://lunar.xprize.org/
pavel_lishin 12y ago
How much of a given total cost of a launch to Mars is the fuel? According to the article, it shaves 25% off the fuel costs - but what percentage of the total is that, let's say, for the past few missions? It seems that the bigger advantage of this is adding a few months but doing away with waiting for a launch window. Definitely great for equipment, though it would put two months' worth of extra stress on actual human travelers.
- steanne 12y ago
  It might not be great for humans, but it's good for cargo mass. Send the big stuff the slow way earlier and the people the fast way with a later departure.
- tokenadult 12y ago
  According to the article, it shaves 25% off the fuel costs Yes, by the facts and speculation reported in the article kindly submitted here, the headline phrase "on the cheap" is plainly wrong, and "anytime" is an exaggeration, as the overall trip time will tend to be longer for most such missions. The article also notes, "The burn-free, capture altitude is also quite high—some 20,000 kilometers above Mars, far beyond where science satellites set up shop to scrutinize the planet up close. But taking along just a little extra fuel can then gently lower a ballistically captured spacecraft into scientifically valuable, standard orbits of around 100 to 200 kilometers like those achieved with Hohmann transfers—or even onward to the Martian surface for a landing." So one part of the article says that the mission will take less fuel (to leave the vicinity of earth), while another part of the article says that the mission will have to carry along extra fuel (in the Mars exploration modules) to arrive at a location where useful science can be done. The bottom line here is that these missions will still be about as expensive as current missions, and manned flight to Mars and back will be staggeringly expensive.
  - pavel_lishin 12y ago
    But the trip time is only 2 additional months - which sure beats waiting over two years for the next launch window!
- 12y ago
r109 12y ago
I hate all the fluff in this article. TL;DR: Ballistic Capture aka "Low-energy transfer" is being rekindled by NASA, Boeing, Belbruno, Topputo and colleagues. Fly the spacecraft ahead of Mars in formation of the planets orbit relative to the sun allowing gravity to gradually slow the spacecraft down. This saves on fuel/weight for entering orbit at high velocity.
- iwwr 12y ago
  Unfortunately, Belbruno's work may stay unused because he has a penchant for patenting it. The idea of low energy transfers aren't new and Belbruno didn't invent them, but you can apparently patent individual trajectory strategies. That also means any commercial venture would shy away from talking to him for fear they may be litigated against (which has happened). Another thing to notice is these trajectories are no good for manned travel as they can take years or decades extra, they are even slower than the more traditional multi-planet slingshot maneuvers.
- disputin 12y ago
  "I hate all the fluff in this article." Glad to hear it, because if that's considered clever and impressive then the rocket industry needs me.
markbnj 12y ago
I was surprised that they described a Hohmann Transfer as a "brute force approach to attaining orbit." I would have described it as the non brute-force approach to changing orbits.
- theoh 12y ago
  Yeah, exactly. It also seems like this low energy technique is more or less a Hohmann transfer to a different point in Mars's orbit. The energy is saved by not arriving at Mars with a big velocity relative to the planet, which feels kind of extraneous to the question of whether a Hohmann transfer is used or not. Maybe it's the final Hohmann transfer into orbit around Mars they are referring to? That would make sense. Or is that obvious?
  - markbnj 12y ago
    Honestly I think they just got the terminology wrong. The only difference between this and a normal Hohmann is the means used to get the final change in velocity at the end. By which time the whole "transfer" part of the show is over. Otherwise it's just a normal transfer orbit.
nazca 12y ago
Anyone have a gif/video of the 'ballistic capture' method?
- nazca 12y ago
  FYI - here is a video of a Hohmann transfer. https://www.youtube.com/watch?v=uNdB3nmAl_0 https://www.youtube.com/watch?v=uNdB3nmAl_0
- stefantalpalaru 12y ago
  No, but these static images describe it pretty well: http://ccar.colorado.edu/asen5050/projects/projects_2012/truesdale/intro.html http://ccar.colorado.edu/asen5050/projects/projects_2012/tru...
  - japaget 12y ago
    This link describes "Halo Orbits" about the L1 Lagrangian point of the Earth's orbit around the Sun. Mars isn't even mentioned.
    - stefantalpalaru 12y ago
      That's because using it with Mars is a novel concept. The mechanism, though, is the same.
blisterpeanuts 12y ago
https://en.wikipedia.org/wiki/Nuclear_pulse_propulsion https://en.wikipedia.org/wiki/Nuclear_pulse_propulsion With nuclear pulse propulsion, we could send a craft to Mars in 2-3 weeks, safely, any time, and on the cheap. The mass that can be transported is quite enormous, so we could piecemeal launch the components of a huge habitat and vast amounts of supplies into an outer orbit of Earth, robotically load them onto the pulse ship, and then shoot that baby to Mars. Probably the slowest part of the plan would be launching the stuff into orbit. They scrubbed the idea of launching using nuclear pulse propulsion because of the dangers of radioactive fallout. Too bad, because that would have made things even simpler.
kartikkumar 12y ago
The paper itself provides much more insight into the actual physics behind this [1]. The article doesn't really do the paper justice in my mind, based on my knowledge of the subject matter (although I appreciate the intent of providing an accessible means to introduce the topic). I wrote my MSc thesis on weak capture trajectories and the concept of the Weak Stability Boundary [2] that was introduced by Ed Belbruno. It's a fantastic aspect of the gravitational 3-body problem and has been probed from a number of different perspectives over the last two decades, including tying in the phenomenon of weak/ballistic capture into our understanding of the structure of invariant manifolds and the periodic orbits about the Lagrange libration points. Disclaimer: Francesco is my boss but I haven't spoken to him yet about the paper. [1] http://arxiv.org/pdf/1410.8856v1.pdf http://arxiv.org/pdf/1410.8856v1.pdf [2] http://en.wikipedia.org/wiki/Low-energy_transfer http://en.wikipedia.org/wiki/Low-energy_transfer
kristianp 12y ago
Web design tip (that I just made up). If you're going to have an annoying, large header bar appear above the text when the user scrolls, don't put a drop-shadow under it. It looks like an object is hiding the text, which it is, but is very distracting compared to a flat border.
- dwaltrip 12y ago
  I've gotten into the habit of doing: right click, inspect element, and then "delete node" on these headers. I really should create a chrome extension to reduce the friction in doing this.
  - kristianp 12y ago
    That would be cool. It would be nice to have an extension with a database of sites to automatically remove these space-wasters.
nicholasreed 12y ago
For a fun (fictional) take about life on Mars, I'd recommend reading The Martian by Andy Weir ( amazon link: http://www.amazon.com/The-Martian-Novel-Andy-Weir-ebook/dp/B00EMXBDMA http://www.amazon.com/The-Martian-Novel-Andy-Weir-ebook/dp/B... ). The book was a wild read, and does a tremendous job showing the myriad difficulties humanity must overcome in order to colonize Mars.
Animats 12y ago
What this really means is that cargo deliveries to Mars can be made any time in the orbital cycle; it's not necessary to wait for a close approach. The trip takes a few months longer, but can be started at any time. Useful if there are ever any significant operations on Mars.

118 points by softdev12 12y ago

My KSP-fu is failing me here... how is it possible to match Mars' circular solar orbit at a slower velocity? Wouldn't a different velocity imply a different orbital distance from the sun?

dragonwriter 12y ago
> My KSP-fu is failing me here... how is it possible to match Mars' circular solar orbit at a slower velocity? You aren't actually trying to match it; as I understand this kind of orbit is a slightly slower (so slightly closer, on average) orbit that the vessel achieves somewhat ahead of Mars, so that when Mars passes it, Mars' gravity is enough to capture the vessel. In essence, some of the energy to match the orbit comes from Mars itself (slowing down Mars, but for any realistic spacecraft this is completely negligible because of the enormous mass ratio between the planet and the craft.)
ashark 12y ago
Sounds like it's that thing in KSP where you time your insertion to The Mun's sphere of influence just right so you don't have to burn retro to achieve Munar orbit. Basically hit it so that you do gravity-assisted deceleration, and end up in orbit around it—typically badly elliptical orbit, but that's cheap to correct.
Thrymr 12y ago
Mars' orbit is not circular, and spacecraft's would not be, either. They would be in slightly different (and intersecting, or nearly so) elliptical orbits, which would allow Mars to gravitationally capture the spacecraft when it approached closely enough.
- ashark 12y ago
  Is performing a second burn to circularize a craft's orbit to near-sync with Martian orbit really cheaper than a deceleration burn? In fact, that would just be a complete Hohmann transfer. I'd guess the target orbit for a craft performing this maneuver would still have a periapsis in the neighborhood of Earth's orbit, meaning it'd still be very unlike Mars' orbit until the craft was captured by Martian gravity. (googles a bit) It looks like these exploit Lagrange points somehow[1]. Precision maneuvers and weird, long routes to the target body. I'm not quite following how this works with only two bodies (Sun and Mars), versus the Sun-Earth-Moon trio. Wikipedia claims the Mars Orbiter Mission used a low-energy transfer at some point, but I can't figure out whether that was for the insertion into Martian orbit or some earlier maneuver it performed. [1] http://www.gg.caltech.edu/~mwl/publications/papers/lowEnergy.pdf http://www.gg.caltech.edu/~mwl/publications/papers/lowEnergy... [edit] Hoffman -> Hohmann, because I'm an idiot.

wallflower 12y ago

Buzz Aldrin is very passionate about colonizing Mars [1]. He says there are two big things that have to be accomplished before we can colonize Mars. The first is to train astronauts to live in a confined isolated space for 260 days (the length of a journey to Mars) [2]. This alternative journey trajectory increases the 260 days. The second is harder: We need to go to Mars at least three times and bring back the men and women successfully. Once is not enough. Three proves we've mastered the engineering, financial, physical, and physiological aspects. [1] http://www.pbs.org/wgbh/nova/space/aldrin-mars-au.html http://www.pbs.org/wgbh/nova/space/aldrin-mars-au.html [2] http://www.guardian.co.uk/science/2010/jun/03/mock-mission-mars-moscow-hangar http://www.guardian.co.uk/science/2010/jun/03/mock-mission-m...

debacle 12y ago
> We need to go to Mars at least three times and bring back the men and women successfully. First we'd need to find a way to bring back pretty much anything else successfully, no? The first is an easy problem to solve, compared to pretty much every other issue. More space (or better space) is a non-linear issue.
- semi-extrinsic 12y ago
  Unless you're envisioning spacecraft with literally hundreds of astronauts, the first will be anything but easy to solve. Doesn't help having an awesome spaceship if everyone on board goes batshit crazy after six months.
  - diltonm 12y ago
    Bubbleheads are tested in Submarine School for compatibility with the idea of living in the intellectual equivalent of a sewer pipe for months on end with each other. I'd assume NASA would do the same. End of the day make sure you know who holds the keys to the weapons locker.
- ams6110 12y ago
  Why do we need to bring them back? Pioneers don't normally set off with a guarantee or even likelihood of coming back.

melling 12y ago

Maybe now there will be a Mars X-Prize after we complete the Lunar X-Prize: http://lunar.xprize.org/ http://lunar.xprize.org/

pavel_lishin 12y ago

How much of a given total cost of a launch to Mars is the fuel? According to the article, it shaves 25% off the fuel costs - but what percentage of the total is that, let's say, for the past few missions? It seems that the bigger advantage of this is adding a few months but doing away with waiting for a launch window. Definitely great for equipment, though it would put two months' worth of extra stress on actual human travelers.

steanne 12y ago
It might not be great for humans, but it's good for cargo mass. Send the big stuff the slow way earlier and the people the fast way with a later departure.
tokenadult 12y ago
According to the article, it shaves 25% off the fuel costs Yes, by the facts and speculation reported in the article kindly submitted here, the headline phrase "on the cheap" is plainly wrong, and "anytime" is an exaggeration, as the overall trip time will tend to be longer for most such missions. The article also notes, "The burn-free, capture altitude is also quite high—some 20,000 kilometers above Mars, far beyond where science satellites set up shop to scrutinize the planet up close. But taking along just a little extra fuel can then gently lower a ballistically captured spacecraft into scientifically valuable, standard orbits of around 100 to 200 kilometers like those achieved with Hohmann transfers—or even onward to the Martian surface for a landing." So one part of the article says that the mission will take less fuel (to leave the vicinity of earth), while another part of the article says that the mission will have to carry along extra fuel (in the Mars exploration modules) to arrive at a location where useful science can be done. The bottom line here is that these missions will still be about as expensive as current missions, and manned flight to Mars and back will be staggeringly expensive.
- pavel_lishin 12y ago
  But the trip time is only 2 additional months - which sure beats waiting over two years for the next launch window!
12y ago

r109 12y ago

I hate all the fluff in this article. TL;DR: Ballistic Capture aka "Low-energy transfer" is being rekindled by NASA, Boeing, Belbruno, Topputo and colleagues. Fly the spacecraft ahead of Mars in formation of the planets orbit relative to the sun allowing gravity to gradually slow the spacecraft down. This saves on fuel/weight for entering orbit at high velocity.

iwwr 12y ago
Unfortunately, Belbruno's work may stay unused because he has a penchant for patenting it. The idea of low energy transfers aren't new and Belbruno didn't invent them, but you can apparently patent individual trajectory strategies. That also means any commercial venture would shy away from talking to him for fear they may be litigated against (which has happened). Another thing to notice is these trajectories are no good for manned travel as they can take years or decades extra, they are even slower than the more traditional multi-planet slingshot maneuvers.
disputin 12y ago
"I hate all the fluff in this article." Glad to hear it, because if that's considered clever and impressive then the rocket industry needs me.

markbnj 12y ago

I was surprised that they described a Hohmann Transfer as a "brute force approach to attaining orbit." I would have described it as the non brute-force approach to changing orbits.

theoh 12y ago
Yeah, exactly. It also seems like this low energy technique is more or less a Hohmann transfer to a different point in Mars's orbit. The energy is saved by not arriving at Mars with a big velocity relative to the planet, which feels kind of extraneous to the question of whether a Hohmann transfer is used or not. Maybe it's the final Hohmann transfer into orbit around Mars they are referring to? That would make sense. Or is that obvious?
- markbnj 12y ago
  Honestly I think they just got the terminology wrong. The only difference between this and a normal Hohmann is the means used to get the final change in velocity at the end. By which time the whole "transfer" part of the show is over. Otherwise it's just a normal transfer orbit.

nazca 12y ago

Anyone have a gif/video of the 'ballistic capture' method?

nazca 12y ago
FYI - here is a video of a Hohmann transfer. https://www.youtube.com/watch?v=uNdB3nmAl_0 https://www.youtube.com/watch?v=uNdB3nmAl_0
stefantalpalaru 12y ago
No, but these static images describe it pretty well: http://ccar.colorado.edu/asen5050/projects/projects_2012/truesdale/intro.html http://ccar.colorado.edu/asen5050/projects/projects_2012/tru...
- japaget 12y ago
  This link describes "Halo Orbits" about the L1 Lagrangian point of the Earth's orbit around the Sun. Mars isn't even mentioned.
  - stefantalpalaru 12y ago
    That's because using it with Mars is a novel concept. The mechanism, though, is the same.

blisterpeanuts 12y ago

https://en.wikipedia.org/wiki/Nuclear_pulse_propulsion https://en.wikipedia.org/wiki/Nuclear_pulse_propulsion With nuclear pulse propulsion, we could send a craft to Mars in 2-3 weeks, safely, any time, and on the cheap. The mass that can be transported is quite enormous, so we could piecemeal launch the components of a huge habitat and vast amounts of supplies into an outer orbit of Earth, robotically load them onto the pulse ship, and then shoot that baby to Mars. Probably the slowest part of the plan would be launching the stuff into orbit. They scrubbed the idea of launching using nuclear pulse propulsion because of the dangers of radioactive fallout. Too bad, because that would have made things even simpler.

kartikkumar 12y ago

The paper itself provides much more insight into the actual physics behind this [1]. The article doesn't really do the paper justice in my mind, based on my knowledge of the subject matter (although I appreciate the intent of providing an accessible means to introduce the topic). I wrote my MSc thesis on weak capture trajectories and the concept of the Weak Stability Boundary [2] that was introduced by Ed Belbruno. It's a fantastic aspect of the gravitational 3-body problem and has been probed from a number of different perspectives over the last two decades, including tying in the phenomenon of weak/ballistic capture into our understanding of the structure of invariant manifolds and the periodic orbits about the Lagrange libration points. Disclaimer: Francesco is my boss but I haven't spoken to him yet about the paper. [1] http://arxiv.org/pdf/1410.8856v1.pdf http://arxiv.org/pdf/1410.8856v1.pdf [2] http://en.wikipedia.org/wiki/Low-energy_transfer http://en.wikipedia.org/wiki/Low-energy_transfer

kristianp 12y ago

Web design tip (that I just made up). If you're going to have an annoying, large header bar appear above the text when the user scrolls, don't put a drop-shadow under it. It looks like an object is hiding the text, which it is, but is very distracting compared to a flat border.

dwaltrip 12y ago
I've gotten into the habit of doing: right click, inspect element, and then "delete node" on these headers. I really should create a chrome extension to reduce the friction in doing this.
- kristianp 12y ago
  That would be cool. It would be nice to have an extension with a database of sites to automatically remove these space-wasters.

nicholasreed 12y ago

For a fun (fictional) take about life on Mars, I'd recommend reading The Martian by Andy Weir ( amazon link: http://www.amazon.com/The-Martian-Novel-Andy-Weir-ebook/dp/B00EMXBDMA http://www.amazon.com/The-Martian-Novel-Andy-Weir-ebook/dp/B... ). The book was a wild read, and does a tremendous job showing the myriad difficulties humanity must overcome in order to colonize Mars.

Animats 12y ago

What this really means is that cargo deliveries to Mars can be made any time in the orbital cycle; it's not necessary to wait for a close approach. The trip takes a few months longer, but can be started at any time. Useful if there are ever any significant operations on Mars.