No, they are a little over 140 degrees of longitude apart, almost opposite sides of Mars.
Spacecraft: Curiosity (USA)
Location: 4.3S, 137.2E
Spacecraft: MER Opportunity Rover (USA)
Location: 1.95S, 5.53W
Google Mars
This map shows location of the various landers, you can see how far apart they are.
Lander (spacecraft)
Using the Mars diameter of 6,779 km, I make that using (140/360)*PI * 6,779 = about 8200 kms apart - have ignored the small difference of about 5 degrees of longtitude there and since they are almost on the equator it is an easy calculation.
Suppose they both approached each other at 200 meters a day for an upper bound, then that makes it (8200*5)/365 = 112 years for them to meet each other (if they could survive that long).
It's a rough calculation - but it would clearly take them at least a century - just traveling all the time, no stops to do science on the way.
Spirit is a fair bit closer - but then on the other hand it is not able to move towards Curiosity to speed up the encounter (it's no longer functioning, contact lost after it got stuck in the sand in an awkward position and didn't get enough solar energy to survive). It's roughly a quarter of the distance from Curiosity to Opportunity. So using the same calculation, that's well over 50 years at top speed.
The reason our rovers are so slow is mainly because of communications with Earth. And they are especially slow because of the low bandwidth. Typically they upload commands each day for the next day of travel based on images from the previous day.
A rover on Callisto, or Titan or Triton or even Pluto could travel just as fast and accomplish just as much per day using that method. The maximum of 40 minutes round trip light time to Mars is hardly a factor at all when it comes to the reason our rovers have such a slow maximum speed on Mars.
It's not practical to download data more often because of the needs of all the other spacecraft, and the deep sky network, and need often to relay through satellites in orbit around Mars that also need to use the available bandwidth for their own data to return to Earth.
So one of the most urgent things for Mars is to find a way to increase the communications bandwidth to Mars perhaps with lasers, or specialized satellites in orbit around Mars just for communications purposes.
If we could do that then we could use the technique of simulated real time, to simulate the Mars landscape on Earth and drive in that simulation -and continually update it with new information as it is received from Mars on the rover's situation and the landscape. Sometimes your data would be uncertain (shown as such visually in some way so you know) but much of the time you might be able to drive at close to normal speed.
We could then design rovers to drive around Mars, eventually perhaps nearly as fast as e.g. the moon buggy with astronauts on board drove around on the Moon.
Then we could do things in days that take years now. The entire 40 km in distance, ten year mission for Opportunity could surely be accomplished within a few months or weeks, and quite possibly be completed in a day or two - at least the travel part of it - with a faster rover and improved communications. Mars Exploration Rovers Update: Opportunity Sets Historic Distance Record and Roves On
And even faster if you could have humans closer to Mars e.g. in orbit around the planet. But this might not even be necessary, which is as well since I think it may well be quite some time before it is practical.
It would help also to have more autonomy for the rovers, able to make decisions themselves, self driving (a bit like the google self driving cars, but adapted to the Mars landscape). ESA is exploring ideas like this for future versions of ExoMars.
Another way we could travel around Mars at greater speed is by balloon, or in flight, though that way you just visit selected spots on the surface itself.
Until we can travel more quickly over Mars then our understanding of ground conditions is rather limited. It has similar land area to the Earth.
Imagine how much you'd find out about the Earth if you had three rovers (corresponding to Spirit, Opportunity and Curiosity) which you could set down on the Earth - but only in flat conditions with a landing ellipse kilometers in diameter with hardly any large boulders or cliffs anywhere within it - and then can move those rovers at 100 meters per day? And three other landers (Viking, Phoenix, Pathfinder) only able to explore the ground within a few meters of the landing site?
You'd end up finding out a fair bit about a few tiny spots within or close to very flat areas of the Earth, and that would be all. That's our current situation on Mars.
Spacecraft: Curiosity (USA)
Location: 4.3S, 137.2E
Spacecraft: MER Opportunity Rover (USA)
Location: 1.95S, 5.53W
Google Mars
This map shows location of the various landers, you can see how far apart they are.
from: Water Still Flows Freely On The Surface Of Mars
The equatorial warm dark streaks there are spots that would be very interesting to explore close up, but quite challenging to get to and need a much better sterilized rover than Curiosity to make sure we don't contaminate them with Earth life.
Lander (spacecraft)
Using the Mars diameter of 6,779 km, I make that using (140/360)*PI * 6,779 = about 8200 kms apart - have ignored the small difference of about 5 degrees of longtitude there and since they are almost on the equator it is an easy calculation.
Suppose they both approached each other at 200 meters a day for an upper bound, then that makes it (8200*5)/365 = 112 years for them to meet each other (if they could survive that long).
It's a rough calculation - but it would clearly take them at least a century - just traveling all the time, no stops to do science on the way.
Spirit is a fair bit closer - but then on the other hand it is not able to move towards Curiosity to speed up the encounter (it's no longer functioning, contact lost after it got stuck in the sand in an awkward position and didn't get enough solar energy to survive). It's roughly a quarter of the distance from Curiosity to Opportunity. So using the same calculation, that's well over 50 years at top speed.
The reason our rovers are so slow is mainly because of communications with Earth. And they are especially slow because of the low bandwidth. Typically they upload commands each day for the next day of travel based on images from the previous day.
A rover on Callisto, or Titan or Triton or even Pluto could travel just as fast and accomplish just as much per day using that method. The maximum of 40 minutes round trip light time to Mars is hardly a factor at all when it comes to the reason our rovers have such a slow maximum speed on Mars.
It's not practical to download data more often because of the needs of all the other spacecraft, and the deep sky network, and need often to relay through satellites in orbit around Mars that also need to use the available bandwidth for their own data to return to Earth.
So one of the most urgent things for Mars is to find a way to increase the communications bandwidth to Mars perhaps with lasers, or specialized satellites in orbit around Mars just for communications purposes.
If we could do that then we could use the technique of simulated real time, to simulate the Mars landscape on Earth and drive in that simulation -and continually update it with new information as it is received from Mars on the rover's situation and the landscape. Sometimes your data would be uncertain (shown as such visually in some way so you know) but much of the time you might be able to drive at close to normal speed.
We could then design rovers to drive around Mars, eventually perhaps nearly as fast as e.g. the moon buggy with astronauts on board drove around on the Moon.
Then we could do things in days that take years now. The entire 40 km in distance, ten year mission for Opportunity could surely be accomplished within a few months or weeks, and quite possibly be completed in a day or two - at least the travel part of it - with a faster rover and improved communications. Mars Exploration Rovers Update: Opportunity Sets Historic Distance Record and Roves On
And even faster if you could have humans closer to Mars e.g. in orbit around the planet. But this might not even be necessary, which is as well since I think it may well be quite some time before it is practical.
It would help also to have more autonomy for the rovers, able to make decisions themselves, self driving (a bit like the google self driving cars, but adapted to the Mars landscape). ESA is exploring ideas like this for future versions of ExoMars.
Another way we could travel around Mars at greater speed is by balloon, or in flight, though that way you just visit selected spots on the surface itself.
Until we can travel more quickly over Mars then our understanding of ground conditions is rather limited. It has similar land area to the Earth.
Imagine how much you'd find out about the Earth if you had three rovers (corresponding to Spirit, Opportunity and Curiosity) which you could set down on the Earth - but only in flat conditions with a landing ellipse kilometers in diameter with hardly any large boulders or cliffs anywhere within it - and then can move those rovers at 100 meters per day? And three other landers (Viking, Phoenix, Pathfinder) only able to explore the ground within a few meters of the landing site?
You'd end up finding out a fair bit about a few tiny spots within or close to very flat areas of the Earth, and that would be all. That's our current situation on Mars.
About the Author
Robert Walker
Writer of articles on Mars and Space issues - Software Developer of Tune Smithy, Bounce Metronome etc.Studied at Wolfson College, Oxford
Lives in Isle of Mull
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