I have my reasons @skyentist, maybe a few months. 
Felt okay about it thanks for asking! I feel confident on 3/4 of them. I wasnât able to complete the fourth because I couldnât figure how to solve for eccentricity with the limited information and lack of time. I was actually going to work on it once I get to the train.
Sure! One question on the exam that I got lucky enough to study beforehand is to find the radius/true anomaly of intersection between a circular orbit and an elliptical orbit. There is an analytical solution to this although this is a simple case because of the circular orbit. From there solve to find their angular difference if both spacecraft start at periapsis at t0 then find the distance of their close approach. For out problem specifically both semi major axis are 20000 km and eccentricity of ellipse is .5. Have fun!
Edit: simple case because eccentricity of circle is 0 and it makes the math easier 
words too
How did the Orbital mechanics midterm go. âŠEdit: 
I didnât the above post first!
And lets get back on topic and talk about all the ideas and points I raised above in my mega post, like the soil layers and how to cover bio-domes on the Moon and Mars. Me me me.
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The tone of this conversation seems to have degraded a bit.
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I see your Moon and Mars, and I raise you⊠Io! Those volcanoes look cuddly, yes?
At a certain point itâs useless trying to reason with Martians. They will not see the common sense of walking before running and will throw every bit of science to back their arguments even though there is an equal amount if not more science to support going to the moon. Besides, we are going to the moon anyway regardless of the endless streams of google science posted so lets enjoy the ride.
The one most important lesson that Iâve learned in several decades of debating and discussing topics in online forums is this:
Never debate anything with someone who doesnât respect you.
If you hear one iota of disrepect, ignore the poster. Move on. You are not going to convince them of anything. At best, you will win Internet Points. These are points which you can spend, well, nowhere.
Life is too short. Find someone with whom you can have a productive debate and go at it. Returning rude for rude will only harm you while legitimizing the practice of being rude.
Note that when everyone stops debating anything with you, you should reconsider your techniques of rhetoric. Or youâre just the smartest guy in the room. Which means that youâre in the wrong room.
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Meant to just reply to thread, not person.
âTrust me, Iâm like a smart personâ
D.J. Trump
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Well, you certainly are a Musketeer. 
As for âTrust me, Iâm like a smart personâ so was Einstein but even he made mistakes. Lets just hope statements like that donât come back and haunt Musk: hubris in this instance can get people killed.
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Iâm unsure what youâre saying with this. The only place to get âperpetualâ light and dark would be the poles of the moon, although I suspect itâs similar to our own poles where they donât line up properly for such. The moon is tidally locked to the earth, so it puts the same side towards earth at all times. This means as it revolves around the earth, the day/night cycle is as long as its orbit, which is to say 27 days. With no atmosphere to refract the light, youâre looking at 13.5 days of day, and 13.5 days of night. The only way to avoid this is to migrate around the moon.
I imagine it will be âdirtyâ water, as youâd have to melt the ice in the soil, unless you have access to the polar craters which might have ice. This means needing to filtrate and then reintroduce salts and minerals, which I imagine is the same on Mars.
I disagree with this sentiment. If anything, the diversity of types of locations actually improves the ability to settle on Mars, because you can choose between soft sand, hard rock, etc. A uniform surface only gives you one choice to work with.
I donât understand what youâre trying to say here. The fine particulate on Mars is probably the most problematic of environmental hazards, as it is incredibly fine and will slip into joints on machinery easily and clog filters rapidly. Anything of greater substance should not pose much of a problem beyond what we are accustomed to on earth.
Regarding the creation of bricks using Martian soil, I donât know that it would be of much value outside of creating artificial barriers, like a windbreak. Youâre unlikely to get such a structure airtight.
The gravity on Mars is greater than the Moon, while less than earth. I donât expect it to pose any problems you wouldnât already have with a Lunar base. Regarding the soil types, this is only a problem if your structure is reliant on the soil as an anchor. If you donât need it as an anchor, you donât need to worry about anything other than what youâre coming in contact with.
As discussed previously, the Lunar habitat requirements and the Martian habitat requirements are not all that similar. Something designed for the moon does not have to contend with an atmosphere (and the associated winds), but does have to deal with more extreme temperature fluctuations, two week long days and two week long nights. I was going to say pressure differentials, but after looking up the numbers Mars doesnât offer much more than a vacuum does, so I guess thatâs not terribly relevant.
Basically, you would not design the two habitats to be identical. A Lunar habitat would be designed for the requirements of living on the Moon, and the Martian one would be designed for Mars.
As for commercial viability of hotels and such, I think we are still some time away from having prices low enough to make it a serious consideration. If itâs going to cost just as much to put someone in Low Moon Orbit and back as it does to land on Mars, itâs not going to be something for the masses anytime soon for recreational purposes.
This entire section, and much of what follows, confuses me, as 99% of it is equally relevant between Moon and Mars, but little of it is relevant to a debate between them. Unless youâre just attempting to portray why either is economically viable, but I donât even require economic viability to want to go: I want to go because I want to go.
You do know there is no such thing as a âdarkâ side of the moon, right? The entire lunar surface gets bathed in the day/night cycle of two weeks on, two weeks off. What youâre looking for here is the Earth-Sun L2 point, where a satellite can have the sun permanently blocked by earthâs shadow. There are actually several satellites already out there, for this exact reason.
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I donât know much about science as you can tell, so thanks for breaking it down.
Soil compacted tiles. I didnât mean to be air tight, more a covering to protect from radiation and micro-meteorites. And to better help regulate temperature maybe inside various types of small bio-domes.
I got a little carried away with hotels, but I do think there are serious plans being worked on by Japanese corporations (I think) and other large companies to at least get something in Earth orbit for paying guests. I thought it would be only logical to guess that something on the Moon would follow not long after. Providing there are no fatal accidents. Like you said - I want to go because I want to go. Corporations will also be going almost at the same time I think.
Learning to work on the Moon I thought would be a good grounding for learning to work on Mars. But with the safety net of being close to Earth. Learning generally to do things on the surface off-world so to speak. Of course I realise Mars and Moon soils are very different.
Learning to lay fields of solar panels and wire it all up in such a way it can all be very easily maintained. Creation of walk ways between habitats which might reduce the fine dust build up on suits if just moving between domes or lander craft. Service areas and storage facilities. Surface vehicle docks to safely work in pressured heated area. Similar in some respects to the things needed to sustain a Earth polar science outpost. The fine particulate on Mars you mentioned will get into the machinery and on solar panels. Large fields of solar panels either on mounted stands or flat on the surface, will all need to be cleaned on Mars especially after dust storms. Whether done by robotic cleaners or humans, still quite an operation to over see.
And I think I wanted to say about the dark side, other places near the poles are always in dark shadows. The bottoms of some deep craters may be dark shadows all of the time. Where water ice should be located. A base or outpost build overlapping these regions.
Earth-Sun L2 point - yes your correct.
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For the most part, I agree with your post. I see what you mean regarding the âearthenâ (martian?) tiles now, as a potential solution to issues caused by the environment. It would be something like all of the perks offered by making your base underground, but without having to actually tunnel.
The part I quoted, however, is where I am going to have to disagree. There is some degree of safety offered by being on the Moon instead of Mars, but all of these events should have been well practiced on a far more forgiving location in the years leading up to landing. Locations such as Antarctica, Death Valley, etc. I say this because we can emulate everything except for the gravity well here on the surface of earth: by pressurizing the living quarters and suits to 1atm + pressure differential at final destination, you get almost exactly the same effects on the hardware as you would on the Moon/Mars, without the pesky problem of if everything ruptures you donât immediately die of oxygen deprivation.
Even the low gravity is something we know about, though. Weâve been working in microgravity for decades now, and have progressed a long way in creating tools and practices to compensate for it.
My point in all that is ultimately to say that, in a properly equipped and planned mission, any emergent situations should have contingency plans in place already. The only situations that should require external rescue are those where external assistance will be too late: immediate catastrophic failure of a system that allows no room for recovery.
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Fascinating how is everyone annoyed lately. Not just here.
Anyone following solar weather these days ?
Itâs never a pretty sight when Moonies and Martians meet. 
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We beltalowda need to stay togetha. Them inners donât know anything about life in space!
Donât mind them, beratna. We superior!
⊠story of this argument âŠ
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I want very much in my lifetime to have our own first foot on the Moon moment, when someone first steps onto the Martian surface out of the lander. (A female this time maybe). Either climbing down a ladder or coming down in some elevator. It will be one of the best moments, for me at least. Streamed in 4K with multiple camera angles to chose from I also hope, inc hovering rovers in and around the lander craft. Deployed just after landing to assess the area and also establish some great wide and mid shots of the moment.
It doesnât matter who gets us there in the end, just as long as we are all part of the moment.
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Iâm with you there. Being alive to experience a shared moment like that of the original Apollo 11 landing must be pretty special.
I would love to witness a moment like that in my lifetime. The first human to set foot on another planet would be a unique moment in human history and a privilege to watch for a space-nut like me!
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Elon Musk did an AMA for the BFRâŠ
And now I realize why this is going to be so much better than the shuttle in terms of reuse. The delta âwingsâ arenât true wings. Theyâre simple heat sheilds that are shaped for aerobraking, while the space shuttle had wheel wells and complexities for subsonic flight, which means that it took a shitload of money to repair the thing.
This is happening⊠Holy shit, this is really going to happen.
Holy shit, the BFR can get to LEO on its own. My god, you could make a personal fucking spaceship that you refuel in orbit to land!
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Itâs also worth mentioning that Elon Musk clears up âwhy Marsâ indirectly. The fuel depot is the keystone element to the mission. Without the fuel depot, itâs not happening at all.
So, you all can quit your discussion post BFS/BFR announcement because itâs Elon Musk deciding to take SpaceX to Mars with SpaceXâs money. And, itâs going to happen that way or not at all. I guess âor a new way as SpaceX figures out.â So, thereâs no fruitful argument left to be had.
Theyâre picking low altitude landing spots to maximize aerobraking with lots of ice for fuel production.
Pretty cool stuff.
I like his comment about radiation âBuzz Aldrin is 87â like âyeah, it can cause cancer but seriously people will be fine.â
I had forgotten about it, but Europe is actually developing a hydrolox-powered passenger spaceplane named SpaceLiner (what did you expect from âVery Large Telescopeâ Europe?) since 2005. Unlike Skylon, it uses conventional rocket engines, so the tech is mostly there. For what I gathered, it uses a (reusable) booster for vertical take-off and glide back to its destination at the present concept.
The problem is that they lack financing, so they donât expect to start flying passengers before 2040. I really hope Musk convinced Europe to seriously finance this project. I want my passenger spaceplanes!
It seems more practical than a passenger BFR: it can take off from and land on more or less conventional airports (no need to go out to sea platforms), max acceleration is 2.5g which doesnât require any particular training, it can recover much better in case of emergency.
On the other hand, I suspect re-entry stress may make it require costly maintenance between flights.
And honestly, I find passenger rockets much more romantic.
Letâs hope both projects succeed, the more variety and competition, the better.