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New Kind of Orbit Could Ease Mars Communications
japan_dan writes "An interesting way to enable Earth-Mars communication when the Sun occludes the direct radio line-of-sight: ESA proposes placing a pair of continuous-thrusting relay satellites, using a solar electric propulsion system — one in front and ahead of Mars, the other behind and below — with both following non-Keplerian, so-called 'B-orbits'. This means the direction of thrust is perpendicular to the satellites' direction of flight, allowing them to 'hover' with both Earth and Mars in view. Quoting from the Q&A: 'We found that a pair of relay satellites would only have to switch on their thrusters for about 90 days out of every 2.13-year period, and this solution would only increase the one-way signal travel time by one minute, so it could be effective.'" Here is the paper describing non-Keplerian orbits (PDF).
That's good news for the diplomatic Human / Martian relations.
Since there's barely anything useful on the Moon given the cost of getting it, and there's even LESS useful on Mars (again, considering the cost of getting it), is it time to scale back the already neutered-to-the-point-of-a-joke NASA program, and let either private enterprise (?) explore space, or forget it? If you can steal an asteroid, park it at a Lagrange point, then mine it for some super expensive unobtanium thats fine, but do we really need to keep spending money playing robots on the surface of Mars ?
I want to delete my account but Slashdot doesn't allow it.
... to park such a device at L4 or L5, where you wouldn't require *ANY* fuel to keep it in position?
File under 'M' for 'Manic ranting'
Houston> We haven't talked for a day, what's up?
Mars rover> Hey, I moved one meter!
Houston> No shit!
FYI: there is no article on Wikipedia to describe a non-Keplerian orbit.
Even 2 simple diagrams describing the 2 orbits types would help.
Please post more arcane papers. For examples, I highly
recommend arXiv.org:
from the home page: Open access to 565,038 e-prints in Physics, Mathematics, Computer Science, Quantitative Biology, Quantitative Finance and Statistics.
Yours In Yaznogorsk,
K. Trout
Still, there may be something exotic that could be done.
Ruby Neural Evolution of Augmenting Topologies
I understand "behind and below". WTF is "in front and ahead"?
Proverbs 21:19
This is slightly tangential, but worth noting I think:
This will be handy when we can't afford to lose contact with Mars for even a few days, but there's a bigger problem lurking in inter-planetary communications: bandwidth. We don't really have enough Deep Space Network dishes (particularly, the large 70-m ones) to talk to all of our missions as much as we should. We're sacrificing data collection on billion-dollar missions on a daily basis on the grounds that we don't have enough bandwidth to get it back. When we put people or even just more missions on Mars, that'll only get worse.
what kind of latency are you getting?
can you play a fps with mars crew?
can a mars rover host a MMORPG?
intellectual property law is philosophically incoherent. it is your moral duty to ignore it or sabotage it
Sorry, I tried to read the summary but I didn't make it past 'continually-thrusting'.
This article has animations and pictures of everything but the actual type of orbit the paper talks about.
Is it so difficult to actually include such a thing, so that we can imagine it?
Note: I'm not reading the paper, that's too much effort. I'd rather get my information fed to me on a plate. Although I will take the time to write this still.
...we let go of the harakiri you're supposed to commit if you ever go out of cell phone range? I mean, surely we can outfit an expedition that doesn't need 24/7 babysitting from mission control, It's not like Columbus had queen Isabella call him up every night to ask "Are you there yet? Food supply ok? Your blood sugar values are low, you should eat more."
Live today, because you never know what tomorrow brings
A New Kind Of Science...er...Orbit. I wonder if Wolfram will try to take credit for this, too. Maybe there's an automata to describe it.
"Before God we are all equally wise - and equally foolish"
Albert Einstein
"I have sent for you, Dodgers, because we are facing a crisis. The world supply of Illudium Phosdex, the shaving cream atom, is alarmingly low. Now we have reason to believe that the only remaining source is on Planet X, somewhere in this area."
"And you want me to find Planet X, eh?"
"Can you do it, Dodgers?
"Indubitubly, sir, because there's no one knows his way around outer space like... Duck Dodgers, in the twenty-fourth and a half
century!"
To clarify - this sort of "orbital" motion (not really "orbital" since it actively powered) is hardly a new idea. What is relatively new is the fact that you have engines that permit you do do it without prohibitive fuel consumption. It's different from a hovering rocket-propelled lander (like the DC-X) only in scale. The key feature, not clear in the article, is that you are intentionally thrusting along the local vertical, in the direction of gravity, to modify its effects. That was possible and everybody knew about it since, well, Newton figured out gravity. What we haven't been able to do is to maintain it for more than the briefest periods due to excess fuel consumption.
The new part here is the Hall Current thruster, which is ~factor of 10 more efficient than traditional engines. The specific impulse of these is around 1800 seconds (lb-sec of impulse per lbm of fuel- hey I didn't invent the units, I just use them...) compared to maybe 180 for a hydrazine monopropellant thruster. These are not exactly "new" either, the Russkies have been using them for decades. Only recently has the western world begun to develop them, so it's new only in that sense. So the solution they are looking at is now looking reasonably practical, although no doubt still significantly limited by the fuel consumption.
Brett
Slightly off-topic, but I have a question for the word-geeks out there. Now, I know that technically "Occults", used the way it is in this context, is technically correct (in fact, as far as I can tell, this is the *original* meaning of the word, and the other meanings have developed off of the original meaning, later). However, given that most people probably associate the word "Occult" with mysticism, mightn't it have been better to describing the Sun blocking communication by using the word Occlude, instead of Occult?
Why won't anyone just put a relay above the sun?
Put one below it too, and one orbiting the horizontal plane and you pretty much have 360 degree coverage of the solar system, outside of being on the shadow side of planets.
Surely there is a stable point somewhere above the sun?
Would it?
Mars has an aphelion (maximum distance from sun) of 250 Gm, and the Earth has an aphelion of 150 Gm. So when the sun is occluding their line of sight, they are on opposite sides of the sun and are separated by at most 400 Gm. If you had a satellite in the Earth's L4 or L5 point, then this would form a 150,350,400 Gm triangle with Mars. Thus the total signal distance would be 500 Gm. This would add 100 Gm, increasing the transit time by 5.5 minutes (from 22.2 to 27.7 minutes). Not as good as the solution presented but not twice as long.
Placing these in the Earth's orbit, rather than Mars', would have the added advantage of solving the solar occlusion problem for anything we send out into the solar system, not just for things on Mars.
An entire planet of nigh omnipotent interior decorators, and they chose "desolate, barren red rock..."
Can you be Even More Awesome?!
I doubt Vilos Cohaagen would agree...
I wonder what the ping times are like?
Confucius say, "Find worm in apple - bad. Find half a worm - worse."
First: What is the purpose of 24 hour communications? If you need SOS messaging, signal recovery, or a simple heartbeat, use the sun as the point-of-reference.
Second: A fleet of solar communications satellites could provide a solar GPS system.
Third: These satellites could use Solar Propulsion and "hover" at a fixed distance from adjacent satellites. Solar sails could serve as a foundation for power generation (focused beam) and for data reception.
Downsides: the sun is a noisy place for communications, as well as a dirty place to park objects with large surface areas.
If we're THAT CLOSE to the sun, it would be interesting to see how big a solar sail would need to be for a 364.245 day parking orbit. Use the dark side of Mercury as Network Control.
Correct, HALT! Collaborate and listen,
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Gelsacs, grab ahold of them tightly,
Speared with a harpoon, goo will flow rightly,
Will it ever stop? Glarg, no!
Pink things from Blue world, you just don't know,
Your robots are a problem the Council's resolvin',
VICTORY FOR MARS, 'round LaGrange you're revolvin'.
Mars, Mars, bitches, too cold. (too cold...)
Mars, Mars, bitches, too cold. (too cold...)
- K'Breel, Speaker for the Council of Elders and Rapper for the Council of Culture.
(When a junior music reporter said "I'mma let you finish, K'Breel, but you're merely riffing off an Earth song from 20 years ago, and the aerobraked packages of Vanilla Ice CDs were selling better than anything the Council of Culture had produced in all time - IN ALL TIME!", K'Breel had the reporter's gelsacs pressed into discs, vapor-deposited with a think layer aluminum, inscribed with lasers, and placed into a mass driver aimed back at the source of the original Earthican launch site.)
"So will you be pulling your troops out of our city?"
"..."
"Pull your troops out or we will be forced to liberate it ourselves."
"..."
"Are you looking for a fight?"
"Yes."
"You have it then! "
"Don't worry, we will have the troop out in no time"
"No certainly not, we will withdraw peaceably"
"Wait, what!?!"
From what I've read, using quantum techniques to communicate wouldn't be faster than light, but surely that would solve any line of sight issues?
I'm confused. Isn't 90days/(2.13years*days/year) 1?
Just off the top of my head, how about this:
a set of say, four to six, relay satellites placed at the forward and trailing Lagrange points on Venus's solar orbit and the other two placed in Earth's solar Lagrange points.
Line of site is closer to straight line and as others have pointed out it would give us pretty much unrestricted communication to any point in the solar system. There may be some tech issues with this but wouldn't this or a some variant work better than having relay sat.s in powered orbits where they would burn up their fuel quickly?
Wouldn't it make more sense ... to park such a device at L4 or L5, where you wouldn't require *ANY* fuel to keep it in position?
I'll second that.
Jupiter might perturb the Mars L4 & L5 points too much. But the Earth's points should do just fine. They'd also have somewhat more solar power available and would be closer, fuel-wise, for installation, which should help as well.
George O. Smith proposed essentially this solution in the _Venus Equilateral_ series, between 1942 and 1945. He sited his relay at Venus L4 to relay among Earth/Moon and hypothetical settlements on Venus and Mars.
It's a scream to read these days, with a giant manned communications/research station in Venus orbit, using advanced vacuum tube technology and machinery scheduling messages by automatically splicing hyper-fast-moving punched paper tape. But the basic problem (sun gets in the way sometimes) / solution (relay at an L4/5 point to bounce messages around it) is still sound and the engineering thinking and team organization was well portrayed.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
I am not quite sure of what you call this, perhaps orbital mechanics or gravity surfing. Whatever you call it, it has the potential to affect space travel by reducing the amount of energy needed to accomplish a task. Clever use of the Interplanetary Transport Network, LaGrange points, and gravity assists/ gravitational slingshots means that a small amount of force applied with the right vector at the right time and place can accomplish what might take much more energy in other places in time and space.
The technology that humans have so far developed is good at measurement and computation, but not so good at transforming and storing large amounts of power. If humans utilize our strengths in information technology to calculate clever courses through various gravitational fields. See my posts at http://realisticinterstellartravel.blogspot.com
By the way,I kept on logging in and then when I'd go to post, find that slashdot had logged me out. This happens quite frequently. More broken-ness at slashdot, alas, again.
This is a job for Venus Equilateral!
Why not put two satellites 120 degrees in front of and behind Mercury?
-one of them is always visible to both Mars and Earth
-they are Kepler orbits requiring no thrust
-the gravitation pull of Mercury at 120 degress is on average 0.0000000556 that of the Sun. =SunMass/MercuryMass/sqrt(2-2cos120)
Maybe the answer is below
-to get to Mercury-like orbit requires 4.6 times more energy than to get to Mars-like orbit from the Earth. (MercuryMass/MercuryRadius-EarthMass/EarthRadius)/(MarsMass/MarsRadius-EarthMass/EarthRadius)
-adds maximum of about 40 seconds to signal path.(simple pythagorus)