Nasa: 'Liquid water has been found on Mars'

[Lisias]

More accurate: about 5 years to Jupiter. And you sure don't want to try an accelerated transfer to Jupiter, because a Orbit insertion into a Europa orbit is already costly enough.

My "sources" (aka, pages I found by googling =P ) says somewhat less than 6 years for Jupiter, and about 7 months to Mars.

This value is highly dependant from the date of the departure/arrive, no? Jupiter and Sun will be the closest again by 2022 (right now the distance is about 10% greater), so the [next] launch window for the shortest [low energy] trip would be from next year to 2017...

I found this site where a very nice Solar System Simulator can be found.

---------- Post added at 11:02 AM ---------- Previous post was at 10:48 AM ----------

It is possible to achieve two years to Jupiter; all that's required is a sufficiently powerful rocket. The SLS capable of launching orbiters directly to the outer planets, and maybe even the Falcon Heavy.

You are seeing only half of the problem : getting there. Once there, you must stay there, so if you do a powered approach, you will need to get rid of that velocity or you will overshot.

In order to do that, you will need to carry approximately the same amount of fuel you would spend to accelerate the vessel alone (Mass/Energy conservation). So you will need to spend a huge amount of fuel to accelerate your vessel *and also* the fuel needed to de-accelerate it.

And I'm ignoring the fact of the astronauts probably wanting to go back home eventually.

So you will have to spend a really outrageous amount of fuel in order to accelerate your vessel that will be carrying fuel to deaccelerate it while carrying also the fuel to accelerate back home while still carrying the needed fuel to deaccelerate again, or it will overshot Earth.

I misunderstood the discussion. I saw Ripley arguing about Mars being the next place a human is aiming to set foot on, then boogabooga arguing about Mars not necessarily being the next target, and I took from there.

Unmanned missions don't have to go back home - but powered unmanned missions still have to deaccelerate or it will overshot the target.

 

[Urwumpe]

My "sources" (aka, pages I found by googling =P ) says somewhat less than 6 years for Jupiter, and about 7 months to Mars.

Yes, it depends on the launch window. But generally, you can reach Jupiter in about 5.0 - 5.5 years for a minimum energy transfer, since neither Earth nor Jupiter have much eccentricity or relative inclination.

Practical numbers depend on the mission - for swing-by you generally have a lot of extra-DV, so you reach Jupiter much faster. New Horizons needed only a year and a few days to Jupiter.

Next summer, Juno will reach Jupiter - after about 5 years and a gravity assist at Earth.

 

[Unstung]

As I said: Europa Orbit insertion with a minimum energy transfer to Europa is already expensive enough.

The faster you want to go there, the more fuel you need for slowing down at your target. Using a larger launcher is only the beginning of your problems. If you track the consequences of changing the requirement of a minimum energy orbit insertion into a high energy orbit insertion to all other requirements on your spacecraft, you can quickly see, what a can of worms you have just opened.

Edit: See here for a very good example of the problems:

http://ccar.colorado.edu/asen5050/projects/projects_2003/simmons/

Orbiting Europa is not necessary for most scientific measurements to assess habitability, which is why a multi-flyby mission has been selected by NASA. It also avoids much of the problem with the radiation belts and greatly increases the spacecraft's life expectancy with less radiation shielding. A Jupiter orbiter can utilize a two year transit, and have enough fuel of its own for orbital insertion and maneuvers, just fine.

Nonetheless, I am aware of the complications with entering orbit around a Galilean satellite. It still is a budgetary issue, especially when scientists recommend a $4.7 billion or $16 billion Europa orbiter.

The SLS provides a huge mass margin so the spacecraft can comfortably carry extra fuel, solar arrays, or any number of scientific and engineering instruments. Saving years on the transit time also reduces mission complexity, namely by cutting out planetary gravity assists and not having to design the spacecraft to survive environments both far from and close to the sun.

Yes, it depends on the launch window. But generally, you can reach Jupiter in about 5.0 - 5.5 years for a minimum energy transfer, since neither Earth nor Jupiter have much eccentricity or relative inclination.

Next summer, Juno will reach Jupiter - after about 5 years and a gravity assist at Earth.

Generally, Jupiter can be rendezvoused with in anywhere from 2 to 8 years. Five years is not a magic number nor the most efficient. It usually includes only one Earth gravity assist.

 

[Urwumpe]

It usually includes only one Earth gravity assist.

Wrong. There is no "usually". Especially not today. For example Galileo used a six year VEEGA trajectory because a Hohmann transfer was no longer possible.

A single Earth gravity assist is actually the minority of the trajectories that aim for Jupiter. Most missions that flew past Jupiter had Jupiter as first gravity assist (Cassini is the exception there, which needed a VVEJ trajectory for reaching Saturn)

 

[Andy44]

Wow, water on Mars.

 

[K_Jameson]

No way of building a colony on Venus

Actually, some high strata of the Cytherean atmosphere are the most friendly environment in the entire Solar System besides Earth...

 

[fred18]

Actually, some high strata of the Cytherean atmosphere are the most friendly environment in the entire Solar System besides Earth...

Time to build this then!

 

[Lmoy]

Actually, some high strata of the Cytherean atmosphere are the most friendly environment in the entire Solar System besides Earth...

Indeed, the atmospheric pressure and temperature at 50 kilometres altitude at Venus is very close to Earth's, making it a lovely place to visit. That is if you ignore the sulfuric acid rain and wind speeds of hundreds of kilometres per hour. You'll also have to devise a way to keep from falling down.

 

[Artlav]

You'll also have to devise a way to keep from falling down.

Balloons?

 

[Lisias]

Back to the water, I found this interesting:

NASA's Curiosity rover is only about 50Km from one of the sweet, I mean, water spots, but they aren't going to send it to there.

NASA can’t use the Curiosity rover to examine water on Mars because of contamination fears

It appears to me that they will, probably, send Curiosity exactly the opposite way - just in case.

 

[Urwumpe]

It appears to me that they will, probably, send Curiosity exactly the opposite way - just in case.

No, 50 km distance means, they will just follow the mission up the Aeolis Mons as planned, without any exciting detours. Its a geology mission, after all.

 

[Lisias]

No, 50 km distance means, they will just follow the mission up the Aeolis Mons as planned, without any exciting detours. Its a geology mission, after all.

As long as there's no chance of getting near a water flow, I'm guessing. Curiosity is not certified to get near water. Of course, I don't have a clue about what is "close" to NASA standards.

Crossing a (at the moment) dry water flow would be a problem? Or better yet, how much time are needed to consider a water flow "safely dry" once the water stops flowing? There're any chance that a water flow exists on (or near the) Curiosity's route?

 

[Urwumpe]

As long as there's no chance of getting near a water flow, I'm guessing. Curiosity is not certified to get near water. Of course, I don't have a clue about what is "close" to NASA standards.

Crossing a (at the moment) dry water flow would be a problem? Or better yet, how much time are needed to consider a water flow "safely dry" once the water stops flowing? There're any chance that a water flow exists on (or near the) Curiosity's route?

Its rather sounding like a saline flow, a saturated solution of salt in water.

Still, I doubt it could become a threat for Curiosity directly. There is a small chance of mud shortening a drive motor. Much worse is the danger that the underground could become unstable by the flow and the rover could get stuck or trigger a mudslide by driving too close to it.

And much more significant is: Curiosity lacks the science tools to examine such flows chemically. It could only photograph them.

Also the known details of Aeolis Mons geology suggest that there is no chance of such water flows since no ice or salt is expected to exist there. The next feature to be closely investigated is a layer of hematite.

 

[Lisias]

Still, I doubt it could become a threat for Curiosity directly. There is a small chance of mud shortening a drive motor. Much worse is the danger that the underground could become unstable by the flow and the rover could get stuck or trigger a mudslide by driving too close to it.

I think we got out of compass.

The concerning is that Curiosity was not sterilized enough to be used on a water rich environment without risking local contamination.

NASA classifies the missions in categories, and for each category appears to exist environmental requirents to be met.

I wondering if the presence of water about 50Km from Curiosity would impair its mission by some requirement that no one thought it would be needed.

 

[Urwumpe]

The concerning is that Curiosity was not sterilized enough to be used on a water rich environment without risking local contamination.

I doubt it is a real concern beyond the interests of some scientists. There are many such flows on Mars it seems, some possibly where other rovers have been (Gusev crater for example could also be a potential location).

But yes, Curiosity is only category IVb, not the full IVc like the Viking probes.

http://www.npr.org/sections/thetwo-...t-send-over-a-rover-to-look-for-water-on-mars


Interestingly, if you think further about the implications of the latest discovery: The previous rovers could actually already have been contaminating Mars.

 

[K_Jameson]

Indeed, the atmospheric pressure and temperature at 50 kilometres altitude at Venus is very close to Earth's, making it a lovely place to visit. That is if you ignore the sulfuric acid rain and wind speeds of hundreds of kilometres per hour. You'll also have to devise a way to keep from falling down.

http://www.science20.com/robert_inventor/will_we_build_colonies_that_float_over_venus_like_buckminster_fullers_cloud_nine-127573