Quote from: philw1776 on 03/20/2017 04:44 pmNot good for solar power in winter. Not exactly exciting topography for settlers. The "fun" factor Elon oft mentions.Perhaps SpaceX wants earliest RD missions to have easiest ice access to validate ISRU tech and then proceed to base selection forays.Also NASA landing site priority criteria are not likely SpaceX's priorities.First of all we don't know the conop for the mission. It might not be intended to survive the winter. Or it might be powered down over winter. Or the panels might be tilted to allow winter operations. We don't even know whether Red Dragon will run on solar power. It might rely on batteries and have a surface mission that lasted only a few days.
Not good for solar power in winter. Not exactly exciting topography for settlers. The "fun" factor Elon oft mentions.Perhaps SpaceX wants earliest RD missions to have easiest ice access to validate ISRU tech and then proceed to base selection forays.Also NASA landing site priority criteria are not likely SpaceX's priorities.
Isn't it "easy" to tip the solar panels making higher latitude almost as good. I would think dust on the panels or in the air might be a more important power consideration.
More on the Space News web site. Gives details of some other landing sites considered - Deuteronilus Mensae, Phlegra Montes and Utopia Planitia - all ruled out because they were too rocky. Interesting that Utopia, where Viking 2 landed, was considered to be unsuitable. Indicates the surface roughness tolerance on the landing system to below Viking 2 levels.See more at: http://spacenews.com/spacex-studying-landing-sites-for-mars-missions/
Quote from: rsdavis9 on 03/20/2017 01:50 pmIsn't it "easy" to tip the solar panels making higher latitude almost as good. I would think dust on the panels or in the air might be a more important power consideration.You can fix the elevation angle, but can't fix the shorter days.I'm with RB here. If we're stuck with solar, maximizing power is the #1 consideration. With water, all you need is to pass a certain threshold, not maximize - and I think you can pass that threshold in many locations.
Quote from: meekGee on 03/21/2017 02:43 pmQuote from: rsdavis9 on 03/20/2017 01:50 pmIsn't it "easy" to tip the solar panels making higher latitude almost as good. I would think dust on the panels or in the air might be a more important power consideration.You can fix the elevation angle, but can't fix the shorter days.I'm with RB here. If we're stuck with solar, maximizing power is the #1 consideration. With water, all you need is to pass a certain threshold, not maximize - and I think you can pass that threshold in many locations.Remember the following:1) We don''t the power requirements, or how it might be supplied.2) Shorter daylight in winter is balanced by longer daylight in summer. Power usage can be adjusted accordingly. Viking 2 data (similar latitude) indicates that surface irradiance varies between 0.3 and 4 kwh/m2. Assuming 30% efficiency that is 0.1-1.3 kwh/day
Quote from: Dalhousie on 03/22/2017 10:16 pmQuote from: meekGee on 03/21/2017 02:43 pmQuote from: rsdavis9 on 03/20/2017 01:50 pmIsn't it "easy" to tip the solar panels making higher latitude almost as good. I would think dust on the panels or in the air might be a more important power consideration.You can fix the elevation angle, but can't fix the shorter days.I'm with RB here. If we're stuck with solar, maximizing power is the #1 consideration. With water, all you need is to pass a certain threshold, not maximize - and I think you can pass that threshold in many locations.Remember the following:1) We don''t the power requirements, or how it might be supplied.2) Shorter daylight in winter is balanced by longer daylight in summer. Power usage can be adjusted accordingly. Viking 2 data (similar latitude) indicates that surface irradiance varies between 0.3 and 4 kwh/m2. Assuming 30% efficiency that is 0.1-1.3 kwh/dayPersonally, I'm hoping they'll go with nuclear, but that's a separate issue.The total energy requirement are reasonably well known. Tons of methane per BFS, liters of O2 per person, etc.
Quote from: meekGee on 03/22/2017 10:41 pmQuote from: Dalhousie on 03/22/2017 10:16 pmQuote from: meekGee on 03/21/2017 02:43 pmQuote from: rsdavis9 on 03/20/2017 01:50 pmIsn't it "easy" to tip the solar panels making higher latitude almost as good. I would think dust on the panels or in the air might be a more important power consideration.You can fix the elevation angle, but can't fix the shorter days.I'm with RB here. If we're stuck with solar, maximizing power is the #1 consideration. With water, all you need is to pass a certain threshold, not maximize - and I think you can pass that threshold in many locations.Remember the following:1) We don''t the power requirements, or how it might be supplied.2) Shorter daylight in winter is balanced by longer daylight in summer. Power usage can be adjusted accordingly. Viking 2 data (similar latitude) indicates that surface irradiance varies between 0.3 and 4 kwh/m2. Assuming 30% efficiency that is 0.1-1.3 kwh/dayPersonally, I'm hoping they'll go with nuclear, but that's a separate issue.The total energy requirement are reasonably well known. Tons of methane per BFS, liters of O2 per person, etc.I don't there is any chance of anything nuclear (except perhaps RHUs) flying to Mars on the 2020 Red Dragon.
The thread comments can be confusing. Some of us are referring to colony site landing sites while others are referring to RD landing sites. The criteria could be quite different, e.g. lack of solar irradiance circa 40 degrees north might not be a big issue for a RD mission, but could be a big negative for an all-seasons colony, assuming no nukes.
Quote from: philw1776 on 03/23/2017 03:21 pmThe thread comments can be confusing. Some of us are referring to colony site landing sites while others are referring to RD landing sites. The criteria could be quite different, e.g. lack of solar irradiance circa 40 degrees north might not be a big issue for a RD mission, but could be a big negative for an all-seasons colony, assuming no nukes.IMO it is a safe assumption that a RedDragon landing site would be chosen to be a likely colony site.Maybe not for a 2018 like mission where landing was the main/only goal. But for 2020 missions. If the choice was right, then a first ITS can use a radio beacon from that landing to home in on.
Nor do I! It makes sense, I guess, to put a Red Dragon with a beacon at the colony site before we start pre-landing the habitat and supplies, but allowing for a wee bit of a delay that would likely be a decade from now (minimum), so all the early dragons will be doing other things. They are already being promoted as delivery of customer cargo, so the sites will be chosen to suit the customers for quite a while.
I just argue from the timeline given. I am aware that the timeline will slip, like everybody is. But presently they are working towards it. That does not leave any room. 2020 for Red Dragon. 2022 for the unmanned ITS. That timeline means the 2020 Red Dragons are direct precursors for the first colony flights. Remember there is the need to build substantial capacity for fuel production at that first landing site. They don't do that randomly for any number of locations until they like one for settlements.That does not mean they would not abandon the first site if it for some reason turns out to be untenable but it would be a major and costly setback.I don't just assume Elon Musk is only talking nonsense about his plans.
Quote from: guckyfan on 03/24/2017 06:47 amI just argue from the timeline given. I am aware that the timeline will slip, like everybody is. But presently they are working towards it. That does not leave any room. 2020 for Red Dragon. 2022 for the unmanned ITS. That timeline means the 2020 Red Dragons are direct precursors for the first colony flights. Remember there is the need to build substantial capacity for fuel production at that first landing site. They don't do that randomly for any number of locations until they like one for settlements.That does not mean they would not abandon the first site if it for some reason turns out to be untenable but it would be a major and costly setback.I don't just assume Elon Musk is only talking nonsense about his plans.When it comes to timelines, he talks nothing but nonsense. There is also a huge difference between a Red Dragon mission which could feasibly launch in 2020 (although may well slip to 2022 based on record) and the ITS fantasies.So let's stick to Red Dragon landing sites.