To architect Mars mission scenarios with a limited launch cadence and still target a first human landing in the late 2030s, the design community is motivated to maximize the useful payload mass delivered to Mars to support each human mission. The rocket equation shows that staging is a great way to maximize payload for a given launch system capacity. The end result is that the transportation architecture is largely performance driven, relying on expendable, multistage systems, including the Mars lander and the two-stage Mars ascent vehicle. This results in a “boots-on-Mars” or “flags-and-footprints” as the best case mission scenario—a Mars super-sortie, defined as a mission measured in months-to-years, employing only those systems and provisions required to support a single crew. Subsequent missions would attempt to leverage assets or infrastructure from previous missions to eventually evolve to a permanent base, but in general each human mission to Mars surface will cost about the same. For the initial human landing, such a minimalist mission plan is unsafe. Over a campaign, this is unaffordable. Over multiple administrations, this is unsustainable.
The present strategy promotes a developmental approach that minimizes technology investment, maximizes the degree of expendability in the system design, increases risk to the crew, and requires that we bring nearly everything we need from Earth for each mission. This may get humans to Mars surface by the late 2030s, but this program is not affordable or sustainable, nor does it establish the human race as a multi-planet species.There’s a better path forward. An alternative strategy is proposed with the goal of affordably establishing a permanent and self-sustaining settlement on Mars in the next half-century, as a prelude to colonization, with NASA playing a major role. This strategy, referred to here as “Base-First,” briefly postpones early human landings on Mars until key technologies and systems are demonstrated and matured, and a significant amount of infrastructure is established on Mars to safely support humans. In addition, it could leverage emerging commercial capabilities along the way to improve the affordability of the campaign and potentially reduce the timeline for getting humans to Mars thought increased launch cadence and overall capacity.
Base first seems more doable, and ends up with an enduring presence. 1960s tech was not up to teleoperated/robotic base construction but things are different now, we would hope. Refreshing to see this study pointing that out, as well as at least acknowledging that commercial capabilities may increase the scope of what's achievable... but it would seem that while they acknowledge the role of staging, they miss the leverage that refueling via tanker launches can provide.
Quote from: Lar on 10/18/2016 01:16 pmBase first seems more doable, and ends up with an enduring presence. 1960s tech was not up to teleoperated/robotic base construction but things are different now, we would hope. Refreshing to see this study pointing that out, as well as at least acknowledging that commercial capabilities may increase the scope of what's achievable... but it would seem that while they acknowledge the role of staging, they miss the leverage that refueling via tanker launches can provide.Yes, refueling seems to be a huge blind spot in NASA planning in general.Is there some type of 'mandate' that the topic never be mentioned?
Quote from: AncientU on 10/18/2016 01:22 pmYes, refueling seems to be a huge blind spot in NASA planning in general.Is there some type of 'mandate' that the topic never be mentioned?Is it because the type of refueling that was to be considered for deep space missions was deep cryogenic hydrolox transfer, and that was considered to be too much of a technical challenge/ expensive development?Or maybe refueling in general was just viewed as "increasing operational complexity."
Yes, refueling seems to be a huge blind spot in NASA planning in general.Is there some type of 'mandate' that the topic never be mentioned?
The "problem" is of course that NASA's goal is to maximize the science return from its manned missions, not to establish a human presence. Hence expendable landers to different locations with minimal surface infrastructure.Quote from: AncientU on 10/18/2016 01:22 pmYes, refueling seems to be a huge blind spot in NASA planning in general.Is there some type of 'mandate' that the topic never be mentioned?Refueling is part of the EMC's hybrid architecture. Only xenon and hypergolics though.
Quote from: AncientU on 10/18/2016 01:22 pmYes, refueling seems to be a huge blind spot in NASA planning in general.Is there some type of 'mandate' that the topic never be mentioned?I don't know about NASA. But someone reported here on the forum that even mentioning refueling at ULA would get you fired. Even now that they are planning to refuel ACES they don't call it refueling. They use the term distributed architecture instead I believe.
The centerpiece of this plan is the Hercules reusable lander. Exact detail of Earth-side launch are less central to the point of this architecture.
Yes SpaceX would probably top out at 5.5m with a new stage... but so what? They could submit proposal and pros and cons of systems weighed the same as CRS. Or expand the program to allow for 2 competitors for full development , again see CRS and CC. Both could end up with fully reusable system so cost sharing ia mutually beneficial agreement with NASA is possible. I'm sure Masten would love to throw their hat in the ring as well.As an aside costs of the whole system could go way down by not building a dedicated man rated crew landing capsule and instead just using an independent Dragon reentry and landing vehicle. New trunk (if required for launch abort from Mars) and hypergol refuel kit goes as cargo in hercules lander. Handwavey? Yes but not impossible. Is there a way to download the complete document or does it need to be purchased?
Oli provided the study article above at this link:https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20160006324.pdf
The 6.5m diameter of Hercules would be perfect on New Glenn or Vulcan, but would be overly-wide for FH.