I was just wondering whether the blimp thing could be sent there on Falcon Heavy.
So the idea is to use the blimp to survey the Martian surface, but to inflate on the way down from orbit, to save you the weight of a heatshield.Could the larger surface-to-weight ratio of a blimp be suitable for aerobraking without suffering the destructive heating of usual blunt-body atmospheric entry?
Regarding the skipping-stone effect and bouncing off the Martian atmosphere at interplanetary speeds, wouldn't multiple stone-skips then help to break up the thermal and mechanical loads, to make re-entry easier?I realize that you'd have to get your trajectory just right, in order to avoid bouncing out of the Martian gravity well, but if you could avoid that, then wouldn't multiple stone-skips be better?Fine, it's taking you longer to descend/aerobrake, but wouldn't atmospheric entry be much gentler?
Quote from: sanman on 04/27/2011 04:45 amI was just wondering whether the blimp thing could be sent there on Falcon Heavy.Why just FH?!!!!!!!!!
Quote from: Jim on 04/27/2011 11:22 amQuote from: sanman on 04/27/2011 04:45 amI was just wondering whether the blimp thing could be sent there on Falcon Heavy.Why just FH?!!!!!!!!!$$$$$$$$ ?
Regarding destination:Venus first. Mars can be explored in many other ways, but Venus really requires balloons. ...
Yeah, and plus a deflated blimp would likely be pretty large in both mass and volume
Okay, cool, and plus on Venus you could probably use some photoeletric skin to harvest all the solar energy you'd need. Might be a better way to study the Venusian surface and morphology to help answer more questions about the planet. It seems that we know far less about Venus than we do about Mars.
You keep mentioning only the lower Martian air pressure, while ignoring the lower gravity, and the greater relative density of displaced Martian CO2 compared to H2, which could be used as a lifting gas.I remember having a detailed discussion on this while on the NewMars forum, before it went offline, and we found that a Martian balloon or blimp was quite doable.Here's a quick java applet I found (at the bottom of the page)http://quest.nasa.gov/aero/planetary/atmospheric/balloon.htmlIt uses Helium, but H2 should generate slightly better lift (not much better, tho)Arguably, wheeled/tracked vehicles would be a much more efficient mode of transport, terrain-permitting. But sometimes surface terrain may be too difficult.
Quote from: sanman on 05/12/2011 06:22 pmYou keep mentioning only the lower Martian air pressure, while ignoring the lower gravity, and the greater relative density of displaced Martian CO2 compared to H2, which could be used as a lifting gas.I remember having a detailed discussion on this while on the NewMars forum, before it went offline, and we found that a Martian balloon or blimp was quite doable.Here's a quick java applet I found (at the bottom of the page)http://quest.nasa.gov/aero/planetary/atmospheric/balloon.htmlIt uses Helium, but H2 should generate slightly better lift (not much better, tho)Arguably, wheeled/tracked vehicles would be a much more efficient mode of transport, terrain-permitting. But sometimes surface terrain may be too difficult.Sorry I didn't meant to sound as though it wouldn't "work" at all, just that it's more difficult overall for a "classic" blimp or dirigable. In part that's why something like the Pelican or other "aerodynamic" models would have to be used in conjunction with LTA-lift. (Now that I re-read my post it DOES look like I'm saying it won't work... Sorry about that I was trying to point out that you end up NEEDING both rather than one or the other!) The static lift of the LTA allows lower landing speeds which is a good thing as well as less power required for propulsion for aerodynamic flight.Yes the Co2 atmosphere and lower gravity help, but I still suspect that flying on Mars is going to be a rare thing and people are going to have to get used to driving, walking, or taking a train Now Venus on the other hand..... Randy
Speaking of trains........ No, better not. OT.Mick.
Trains? I don't get it.
And yes, VERY much so Mars has always seemed to hold the larger fascination which leaves both Venus and Mercury as the "almost-was" planets. Thankfully they have been getting more attention of late but I'd like to see a LOT more interest. Venus has a huge number of questions that need to be looked into and frankly could use some intensive study from close up inside the atmosphere...
Quote from: RanulfC on 05/05/2011 09:06 pmAnd yes, VERY much so Mars has always seemed to hold the larger fascination which leaves both Venus and Mercury as the "almost-was" planets. Thankfully they have been getting more attention of late but I'd like to see a LOT more interest. Venus has a huge number of questions that need to be looked into and frankly could use some intensive study from close up inside the atmosphere...Venus is scary. On top of the extreme temperature and the acid clouds, it's essentially a miniature gas giant...(Not that I disagree with you. But still... you can stand on Mars.)
Quote from: 93143 on 05/17/2011 09:36 pmQuote from: RanulfC on 05/05/2011 09:06 pmAnd yes, VERY much so Mars has always seemed to hold the larger fascination which leaves both Venus and Mercury as the "almost-was" planets. Thankfully they have been getting more attention of late but I'd like to see a LOT more interest. Venus has a huge number of questions that need to be looked into and frankly could use some intensive study from close up inside the atmosphere...Venus is scary. On top of the extreme temperature and the acid clouds, it's essentially a miniature gas giant...(Not that I disagree with you. But still... you can stand on Mars.)Except for the carbon dioxide content, there are zones in the Venusian atmosphere where the air pressure is earth normal and the air temperature is earth temperate; excellent places for floating labs, exploration centers or small outposts or stations.
I am, in fact, aware of that, and have been for some time. I also seem to have this weird phobia of falling into an atmosphere that will kill me long before I hit anything solid...
Quote from: MickQ on 05/13/2011 08:54 amSpeaking of trains........ No, better not. OT.Mick.No, no, go ahead... after all how often does a thread around here STAY on-topic for any great length of time Randy
Quote from: RanulfC on 05/17/2011 01:19 pmQuote from: MickQ on 05/13/2011 08:54 amSpeaking of trains........ No, better not. OT.Mick.No, no, go ahead... after all how often does a thread around here STAY on-topic for any great length of time RandyWell....... I was just wondering how fast a Maglev vehicle would travel in 1/3 G and 1.0 % Earth atmospheric pressure. Would it be ballistic speed or would the low grav and pressure force a more sedate pace Mick.
I was similarly thinking that a blimp would similarly face much less forward air resistance in Mars' 1% Earth atm.
Except for the carbon dioxide content, there are zones in the Venusian atmosphere where the air pressure is earth normal and the air temperature is earth temperate; excellent places for floating labs, exploration centers or small outposts or stations.
I am, in fact, aware of that, and have been for some time.
I also seem to have this weird phobia of falling into an atmosphere that will kill me long before I hit anything solid...
Another advantage A N2 O2 Earth type atmosphere is an effective lift gas on Venus.Both of these can be easily obtained from the atmosphere.The balloon it's self can store atmosphere maybe even be used for recreational space.
The hard part would be getting the airships and station in Venus' atmosphere and deployed.Maybe a reverse of the airship to orbit plan of JP aerospace not sure it could be used for the way back up.http://www.jpaerospace.com/
Some good news they won't have to be as gossamer as a high altitude station on earth and instead could be more like an old Zeppelin in their construction.
As for coming and going maybe NTR SSTOs with a jet mode.There would be no good abort modes except to orbit or the floating base.Some good news a blimp could be used as an escape device.
Actually, I've liked (in an academic sense) the Venus aerostat idea for a while. Transport to and from orbit is a problem, though... Earth-normal gravity has its disadvantages, as any rocket scientist will tell you...
Hmmm... how high is Mount Maxwell? How long can you hold your breath?
we have equipment that can both stand the heat and pressure.
We do? Or do you just mean stuff like the Venera probes?I'd love to see a fusion-powered refrigerated base on Venus, and refrigerated rovers and hardsuits and such. It does seem like a disproportionate level of effort...
Remember that Venus is nearly the same size as the Earth and has a gravity well just as deep as Earth's. Once landed on the surface, any human crew is going to need a very big launch vehicle to return to orbit. Baring being lowered from a floating platform high in the atmosphere, I doubt human crews will visit the Venusian surface anytime soon.
Well....... I was just wondering how fast a Maglev vehicle would travel in 1/3 G and 1.0 % Earth atmospheric pressure. Would it be ballistic speed or would the low grav and pressure force a more sedate pace Mick.
Quote from: MickQ on 05/18/2011 07:51 amWell....... I was just wondering how fast a Maglev vehicle would travel in 1/3 G and 1.0 % Earth atmospheric pressure. Would it be ballistic speed or would the low grav and pressure force a more sedate pace Mick.To think it a bit forward: it is much easier to create an evacuated tube on Mars, then on Earth. And there is that "little" Mount Olympus, which simply reaches space. Wouldn't it be nice to build a long evacuated tube, going up on(in) the side of Mount Olypmus, and so launching the spaceships from Mars surface to Mars orbit?
Actually, Mars atmosphere lowers it pressure slower than Earth. At "zero" altitude (not so easy to define on Mars), it's equivalent to 70km on Earth. So somewhere around 250km, the pressure's are the same. After that, you have higher pressure on Mars than on Earth. Which is a problem since actual orbits tend to be lower in Mars. So MEO has actually more reboost requirements than Earth.
I don't have the slightest idea. Mars has an incomplete Van Allen belt. So I'm not sure the process works like in earth. In fact, I'm pretty sure there's a mission being designed to understand exactly that. I've seen a program where thay shoved a simulation, where the interaction of the incomplete magnetic belt with solar flares, created pockets of atmosphere, that where expunged to outer space. So the Martian atmosphere doesn't have to behave like Earth's.But this got me thinking. What about a blimp only to travel through the Valles Marineris? Those are deep, so pressure should be higher. An there must be some very well defined currents.