Mars 9 tons at a time.

[thereiwas]

Ok, 8t mass, 20m ballute, slows to 94.4 m/s at 137m. But we are talking over 500 kN of thrust to stop it. Raising engine start to 300m requires a peak thrust of more like 240 kN, but consumes nearly twice as much fuel (assuming fuel consumption is linear with thrust level).<br /><br />For comparison the SM engine on Apollo only put out 92 kN of thrust. May need solids anyway for main braking impetus. I am looking at a touchdown speed of 1.4 m/s.<br /><br />Some details: at 300m descending at 94.4m/s, you have just over 3 seconds to stop. To slow from 94.4m/s in 3 seconds is 30 m/s/s. (3 G's; I don't think we want to go higher.) Imparting 30 m/s/s to 8t needs (F=ma) 240 kN, unless I am making some simple mistake in the equations.

 

[keermalec]

No you are right, slowing down from 94 m/s in 3 s requires 3G of deceleration. Five RL-10B-2 engines, the most efficient engine existing today, would weigh 1.5 tons for 550 kN of thrust.<br /><br />Scaling linearly, if we need only 240 kN thrust at 300m altitude, the engine(s) would weigh 660 kg and burn 53 kg/s of fuel. If the burn lasts 6 seconds, this would equate to 320 kg of fuel. I would double the fuel mass for safety considerations (6 more seconds to hover around) to 640 kg so we are talking about an engine-fuel mass of around 1.3 tons.<br /><br />The RL-10B-2 is a re-useable LOX/Lh2 engine. If we use data from the R40-B, a one-use N2O4/MMH engine, engine mass would be only 440 kg but fuel mass would be 950 kg for a 12 second burn. Overall mass 1.4 tons. <div class="Discussion_UserSignature"> <p><em>“An error does not become a mistake until you refuse to correct it.” John F. Kennedy</em></p> </div>

 

[gunsandrockets]

< My question is whether the smooth, rippled, highland area on the eastern area of Elysium is a glacier?><br /><br />My question is -- if there are glaciers buried there, how deeply are they buried? <br /><br />I suspect it is way premature to assume we have found an easily accessed source of water-ice at a low latitude of Mars. <br />

 

[j05h]

<i>> My question is -- if there are glaciers buried there, how deeply are they buried? </i><br /><br />They aren't buried, they are dust covered. 1m of dust or so. <br /><br />Scientists discussing Mars glaciers and ponds:<br /><br />ftp://www.lpi.usra.edu/pub/outgoing/lpsc2005/full97.pdf<br /><br />Compare this to Luna with trace readings of hydrogen. The water is where the money is.<br /><br /><i>> I suspect it is way premature to assume we have found an easily accessed source of water-ice at a low latitude of Mars. </i><br /><br />It is not premature, it is fact. Or so close to fact as to be unavoidable. Elysium Planitia has frozen ocean on it. It might be slightly funny water, but it is water. <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[gunsandrockets]

[My question is -- if there are glaciers buried there, how deeply are they buried? I suspect it is way premature to assume we have found an easily accessed source of water-ice at a low latitude of Mars.] <br /><br /><They aren't buried, they are dust covered. 1m of dust or so...It is not premature, it is fact. Or so close to fact as to be unavoidable. /><br /><br />The link you provided made for interesting reading but contained zero evidence of how deep those glaciers are buried. The only reference I could find was a statement that it was possible for a glacier at low lattitude to remain stable and not evaporate away if it was covered by as little as 1m depth of debris. But nothing about just how deep the glaciers at Elysium are buried.<br /><br />Perhaps I missed it and you can indicate the page on the document where it states the known depth of the debris covering those glaciers.<br /><br /><br /> <br /><br />

 

[thereiwas]

Two years after the initial paper and I have not been able to find the MARSIS radar confirmation. MARSIS was delayed in deployment because of some concern about the antenna, but it has been working for a year now.<br /><br />This HiRISE image and this one are from the same spot, and their description of it says the blocks are lava, something Muller et al disagree with. <br /><br />One of the pro-ice arguments is that the surface is very very flat. (see pp5-6) But still no smoking gun.

 

[JonClarke]

The problem is the frozen sea at Elysium may simply be a lava flow.<br /><br />It mightr be better to look for ice elsewhere. If you don't mind mid latiudes Dao Vallis is one site with glacier like features. If higher latitudes are acceptable, there are some nice icy craters near the Martian north polar cap.<br /><br />Otherwise people should consider water reaction from hydrated minerals. Some magnesium sulphate minerals are 50% water. Much of the sediment at Meridiani contains 5-10% water by mass which could be liberated by heating to 150 degrees and condensing the vapour.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[thereiwas]

Another little gem from the Braun paper: <font color="yellow">"Only entry systems with Beta<50 have the ability to deliver payloads to subsonic conditions, and then only at altitudes near the surface (below 10km)"</font><br /><br />So solving the Beta formula for Area we get A=m/(Cd*Beta) where Cd is the drag coefficient. For the traditional sphere-cone the hypersonic Cd is 1.68, so substituting values, A = 8000/(1.68 * 50) or A=95 square meters. So 11m diameter minimum.

 

[j05h]

<i>> Perhaps I missed it and you can indicate the page on the document where it states the known depth of the debris covering those glaciers.</i><br /><br />That paper doesn't cover debris depth, but media sources have said as thin as a few centimeters. It's a crust of volcanic ash over ice. Check pages 5,6 and 15 for other glacial flow features.<br /><br />"It has probably been protected from complete sublimation by a surface sublimation lag formed from suspended sediment exposed by early loss of the surface ice." p. 5<br /><br />My reasoning that the ice is still there, independent of the science record is simple observation. Some craters in Elysium have the distinct "splat" ejecta apron that indicates impacting ice. These craters are embedded in an identifiable surface feature that includes pack-ice like blocks.<br /><br />josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[thereiwas]

The original announcement "splat" picture can be seen in this JPG photo (currently my desktop). Those sure are unusual looking craters - the ejecta does not look like what you would expect if they were in basalt slabs. And notice how smooth the craters are inside. <br /><br />By the crater-counting technique they judge this area to be 3 to 7 MY old. Also, the most recent axis flip is thought to have happened within the last 10 MY years (according to William Hartmann's book). So they propose one hypothesis that this ice field dates from that last flip, when this was <i>not</i> in the warmest part of the planet, and the poles were getting a lot warmer. (Still equatorial, but the axis can move quite a bit more than Earth's does.) It hasn't had time to sublimate yet, being protected by the blanket of ash and dust.<br /><br />Still, no confirmation by other means yet. <br /><br />Oops, another interpretation. The craters were there first. See how the blocks break up downstream of the craters? The ESA people mention the breakup, but not the splash. Can't have it both ways. The blocks, whatever they are made of, are covering up what the real ejecta blanket is, if the craters are older.

 

[j05h]

Not only are the craters unusually smooth, some of them have a distinctive, flat bottom, that looks like the bowl is half-full and frozen. <br /><br />My argument is that the terrain these "splats" are in is extant ice, because the impacts represent a core sample of the ice. The difference between the splat impacts and impacts in basalt are obvious. <br /><br />There are pre-existing impacts that imagery shows ice "clumping" in front. Check the LPRI link above. The dual-crater ESA image is of fresh, post-flood impacts. There are several different ages of craters in the are, check mars.google.com, especially in visible light. Cerebus Fossae must be amazing when it's erupting - we would be lucky to see something on Mars erupt in our lives.<br /><br />No, there aren't any radar confirmations or OMEGA findings. The area could use ground truth. The visual evidence is of vast reserves of frozen liquid, separate from lava (which is also visible on Cerebus Fossae). <br /><br />If not Elysium then Aram Chaos, Louros Valles, Ruell Crater, whatever works. Elysium makes for simplified planning, stable environment and regular days - unlike polar regions.<br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[thereiwas]

First job of a landing party in Elysium is a trip to Cerberus F, clearly!<br /><br />I guess the craters could have formed while the ground was wet, resulting in the typical soft appearance, and then later the ice blocks begin to move, giving the trail effect behind the craters.<br /><br />The smooth crater interiors are also unusual, even for "sploosh" craters, possibly because they are too young to have slumped much.

 

[thereiwas]

Using the Thiokol STAR 48A motor as an example (used as a payload assist on STS missions) I get 2.626 kN of thrust per kg/s of fuel burned. This turns out to be in the middle of the range of a variety of solid motors I evaluated, of all sizes.<br /><br />So I programmed my model to fire an engine scaled from that with 250 kN thrust for 3 seconds when radar detects 2.1 seconds to impact (cutting it close, eh?) while falling at terminal velocity (96.4m/s) on the ballute. This turns out to happen at altitude of 141m. At the end of the 3 seconds of 3G deceleration, we are at 30m alt falling at 5.6 m/s.<br /><br />At that point the liquid engines (based on RL-10B-2) cut in at a gentle 36 kN thrust and slow us the rest of the way to the touchdown. Neat. Total liquid propellant used 1299 kg, liquid engine mass 100 kg, solid rocket mass 286 kg. Some fine tuning is possible to optimize the tradeoffs between solid and liquid.<br /><br />But wait, looking back up the curve I find that at 33 km altitude, moving at Mach 11.4, we were decelerating at a whopping 18G. (This is with the 20m diameter ballute.) My starting point was a reentry velocity of 3550 m/s, which I got for a 1 degree reentry angle from a 150 km orbit.<br /><br />Clearly have to revisit the high-altitude part of the model, with some application of L/D and not coming straight down.

 

[j05h]

I'd propose two or three expeditions for the first 5-year crew at an Elysium Township. The first, after local research and finalizing initial base configuration, is to these features to the west in Cerberus Fossae and Elysium Mons. The base needs to be situated on solid ice or soil, I wouldn't trust the stability around Cerberus - it's patchy warm in infrared but doesn't tell the temp range. The first link below is a candidate area. It has the Elysium floodplain to the right, Cerberus cracks and smaller fragmented flow features. The link is in infrared, so the fine flow features are cold. If you scroll immediately north, it is evident that the are is still active. To the south, more flow features. <br /><br />The second expedition would be later, involving a flight in the reusable lander/ascender to set up a research outpost in Valles Marineris. <br /><br />Last, either a rover trip to Olympus or another hopper trip to a polar region. <br /><br />Google Mars: Cerebus flow features<br /><br />Possible location of base #1<br /><br />Possible location #2<br /><br />The site selection requires a solid (preferably ice) surface to build on/in. Solid helps reduce unknowns in landing. <br /><br /><br /><i>> The smooth crater interiors are also unusual, even for "sploosh" craters, possibly because they are too young to have slumped much.</i><br /><br />This is extremely young terrain - it is fresh. You can also see that the liquid didn't freeze quickly. Compare different craters and you can see the ones that hit slush instead of solid ice. The papers indicate successive flooding, it appears as rings of m <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[thereiwas]

We want good chance of ice close at hand since it is a primary feedstock. I was thinking of up next to (but not on top of) one of the ESA icebergs.<br /><br />What other than grandeur is the reason for a mission to Valles Marineris? It may not be all that grand to the human eye, due to its very wide expanse and the small planetary radius. I think Elysium Mons would tell as much about Martian volcanoes as Olympus. I'd pick a pole as 2nd landing site, then Tharsis as 3rd priority.

 

[j05h]

<i>> We want good chance of ice close at hand since it is a primary feedstock. I was thinking of up next to (but not on top of) one of the ESA icebergs. </i><br /><br />That works, too. The "icebergs" were my first consideration, then I went looking for interesting terrain. <br /><br /><i>>What other than grandeur is the reason for a mission to Valles Marineris?</i><br /><br />Grandeur might be reason enough, but I think Louros Valles could use some ground exploration. Here is a visible light Google Mars Map with visible fog/steam to the east of Louros and jumbled terrain in Ius Chasma to the north. Switching to IR shows it is jumbled, broken terrain. What is boiling off in there? That there is long-term fog along vast stretches of Marineris is reason to explore it. <br /><br />I wouldn't be surprised if different volcanoes have different origins on Mars. Some impacts appear to cause secondary eruptions. Ices may form part of Mars' vulcanism, so Elysium might be an water-mud volcano versus Tharsis' lava vulcanism. Pure speculation but parts of Mars seem to belch water periodically, perhaps in time with the changes in sun inclination?<br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[j05h]

I found the ESA "splat" craters, check it out in IR.<br /><br />Splat Craters on Google Mars<br /><br /> <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[JonClarke]

Why pick Vallis Marineris? Fantastic exposure through the Martian upper crust. Complex and interesting internal sediments, you could get a good over view of much of Martian history from a well-chosen landing.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[thereiwas]

That upper crust is a long way from the bottom. Is the best first visit on the rim and descend on km-long ropes, or to the bottom and look up with telescopes, while also digging in the sediments?<br /><br />I note that looking at it spherically, the north pole is between Elysium and Tharsis.

 

[j05h]

The areas I linked to in Valles Marineris last night would allow easy(ish) access to various layers by approaching one of the recent collapse sites in Ius Chasma, right near the fog. That would provide access to all sorts of segment s of strata but slightly confused. I'd go for landing in the valley first and working upward one way or another.<br /><br />Following the plan we've been discussing, it'd probably start as a robotic base and have people land there after a few years, both for ISRU and bioprotection. <br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[gunsandrockets]

<That paper doesn't cover debris depth, but media sources have said as thin as a few centimeters. It's a crust of volcanic ash over ice.><br /><br />A few centimeters? Do you have any links to those media sources? The paper you linked to suggested a minimum of 1m depth of debris was neccessary to prevent sublimation at such a low latitude.<br /><br />I think the presence of glaciers at Elysium looks very promising. It still doesn't answer though just how deep below the surface those glaciers are.

 

[j05h]

<i>> I think the presence of glaciers at Elysium looks very promising. It still doesn't answer though just how deep below the surface those glaciers are.</i><br /><br />Some of the frozen terrain isn't "deep", it's on the surface. They are talking about 30+ meters of ice over the original basin of Elysium. If you dug into the ESA "polygon" terrain in eastern Elysium, you'd find increasing moisture until it is equivalent of permafrost. These are forming into the "knobby" terrain like in the northen boreal areas, as moisture boils off. If Elysium flooded by water, there might be blue ice underneath and as the paper suggested just a thin crust of baked dust covering. There are other examples given as well. <br /><br />If you look at the Elysium area in all 3 manners on Google Mars, you can identify several flooding events. They left traces against the highlands to the south and layered flows in both major channels onto the Boreal plain.<br /><br />If you look at the links to Google Mars, the Cerberus Fossae area includes some outflow marks that look like uncovered ice - it shows most dramatically in Infrared. The dark patches on the left don't appear in visible light, but pop in IR. Being black, it is cold. The bright area in IR trailing the large crater to the right is dirt ejected during the larger impact. The craters in the flow feature, including the big one, look like the impacted something softer than the frozen ice fields in Elysium proper. This area may still be active, including liquid/slush near the surface. <br /><br />Those cold, ice-like features (baring contention that it's all lava) are just northwest of the ESA "splat" crater and the very large rafting plates. <br /><br />Here's an example of two craters from different sides of the <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[thereiwas]

You can't read "black" as "cold" on Mars. It's all cold. Black is just "colder than the white parts". Looking at the shading in those IR pictures it looks like we are seeing the sun warming the sides of the hills, and the far sides are still cold.<br /><br />What makes a horizontal surface heat up more slowly? Bare rock heats up more slowly than sand because sand is an insulator so the top inch keeps all the heat. Solid rock is sucking the heat down inside. So those black places could be rock with no sand on top.<br /><br />Taking that into account, and moving just a bit south from your link, we find this. It looks like the ESA blocky tiles but in IR and much larger. This is about 2.5 degrees north of the ESA site. Note how it is in a valley that looks like it flowed from the northeast. The light substance, that is spread all over this area, tapers off at the edges as though it was dust. Would a "sticky' dust break apart in chunks like that? (Look up "duricrust') The ESA blocks do not show up at all on this scale so this may be a different principle in action. And the ESA blocks <i>do</i> appear to have thickness to them. It was their stereo camera that found them, but I have not seen the stereo images published anywhere yet.

 

[j05h]

<i>> You can't read "black" as "cold" on Mars. It's all cold. Black is just "colder than the white parts". Looking at the shading in those IR pictures it looks like we are seeing the sun warming the sides of the hills, and the far sides are still cold.... Solid rock is sucking the heat down inside. So those black places could be rock with no sand on top. </i><br /><br />Good points on bare rock. What I'd really like to see is some high-res spectroscopy maps from Mars orbit. Perhaps my linked images are showing rock. The whole area is fairly flat, so we are looking at the heat-retention issues of flat items instead of hills. <br /><br />Those flow-features look more like pack ice than duricrust, IMHO, but i'm not a geologist. A sticky dust (probably dry/static) might clump and move, but probably not form giant plates like that. <br /><br />If your goal was to build a resource-extracting base, where would you place it?<br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[abcole]

Things are looking good for the Railgun technology. We could supply large amounts of deliveries from Earth to Moon and onward Mars or wherever with the Railgun. This technology is advancing and possibilities are looking much more promising. Groups of smaller Railgun projectile satellites that reassemble in space. Creating one large unit for whatever you can imagine. With the development of high-temperature electronics and incredible transforming alloys. Special thermal coatings with amazing characteristics for launch, within Earth's atmosphere. Laser vacuums in which the payload will be launched through. Yes it is possible. The price is right. I'm not talking mile-long cannons here.