“As an original co-founder of DIRECT…”

Your team made a good proposal. I originally liked DIRECT because of the level of reuse that you did, but ultimately realized that there wasn’t enough demand for an HLV at this time – regardless who builds it.

“So I’m not an AJAX advocate. However, it does strike me [as a non-rocket-engineer] as having some nice advantages compared to, say, Ares or DIRECT.”

If Congress insists on building an HLV, then AJAX is an interesting proposal, and maybe more palatable to me than DIRECT. I would rather use rocket boosters that already have commercial demand (Atlas CCB’s) than boosters that only have one use (DIRECT Shuttle SRB’s). I guess we’ll see which way the wind blows from NASA.

Yes, it probably isn’t just a “shiny new thing” reaction. I think the following quote from NSF’s clongton shows one point of view:

“[someone else’s quote: Yes, I think that is one of the great strengths of your AJAX concept. From my vantage point, quite superior to what is coming out of the RACs.]

As an original co-founder of DIRECT, please allow me to add my agreement to that statement. The Jupiter was designed to replace the Ares with a LV that completely complied with the then legislation, which required using the SRB. So long as that requirement remained absolute, there is literally *NO* better SDHLV design available than the Jupiter. But remove the *absolute* requirement for the SRB, which the current legislation did, and AJAX becomes the superior design.”

From my point of view, it would be better to not have an SLS at all, and to use those funds for exploration technology demonstrations, robotic precursor missions, fully funded commercial crew, ISS use, robotic science missions of various sorts, human research, perhaps very modest enhancements to existing rockets, etc. So I’m not an AJAX advocate. However, it does strike me [as a non-rocket-engineer] as having some nice advantages compared to, say, Ares or DIRECT.

It was designed as a 3 core booster.

There are no additional pumps in crossfeed.

> There are several

Thank you.

Now there’s a truly radical concept. Actually having a reason to fly the vehicle, other than “mine’s bigger than yours”.

The next breakthrough will be leaving enough money to actually fly the rocket and achieve the mission.

It will turn out to be amazine how much we can explore with current rockets, if we care more about exploring than rocket-designing.

There are several and they aren’t always obvious as the discussion sometimes gets mixed in with LV & policy debates.

One particular thread that I’ve been watching is this one:

http://forum.nasaspaceflight.com/index.php?topic=24842.0

This particular thread discusses a multi-launch lunar surface archetecture using only 50t launchers.

The ‘Advanced Spaceflight’ and ‘Orion and Exploration Vehicles’ forums are the best places to look. Otherwise, new spacecraft/payload threads tend to appear in launcher-specific forums (such as the ESA forum for ATV applications, the OSC forum for Prometheus and Cygnus and so on).

Could you recommend NSF threads that discuss potential payloads, please?

I think that you are mis-characterising the debate over on NSF.

Looking back historically to when the DIRECT concept first emerged, it was in a debate about streamlining the Ares Launch System. The reason what eventually evolved into the DIRECT Jupiter concept was so popular, even with some NASA engineers, was that it was so very much simpler and cheaper than the orthodox ALS (even at this time, when SSME and the four-seg RSRM were being considered for Ares-I).

At no time have DIRECT claimed that their ideas were the best option available. If you read the preamble for the 2009 AIAA presentation, you will see that the team acknowledges that any kind of SDLV has its draw-backs. However, they go on to explain how several items of legislation demanded that NASA use legacy hardware as far as possible (yes, that wasn’t an innovation of the 2010 Re-authorisation Act). Because of this legislation and the political needs of a major program, it was their assessment that any non-SD concept was a non-starter, no matter how better it might be in terms of technology and cost-efficiency. The objective of DIRECT always was to find a way to align the stars of political backing, operational requirements and legacy technology in such a way as to provide the required operational capabilities quicker, better and cheaper.

Since then, the debate has moved on. The Augustine Commission’s report concentrated a lot of minds. It has also become increasingly clear that NASA itself does not have the capability to build anything of the sort of a heavy lifter without incurring massive extra costs and schedule slips due to an inefficient bureaucracy and methodology. Because of this, the debate on NSF is moving on to how to make the program ‘no-frills’, seeking even simpler, lower-cost solutions. The current watch-phrase is to leave enough money in the kitty to pay for payloads as well as rockets. Hopefully, this would enable more to be done than, say, fly an Orion on top of a shuttle-derived launcher before the end of the 2020s.

One movement, as has been pointed out, is AJAX. I admit to not being a fan of that design. The T/W ratio at launch is marginal at best and this issue seems to be being hand-waved away by the concept’s fiercest partisans. Another major grass-roots movement on the site has been to attempt to develop an exploration architecture using the Falcon Heavy and the ~50t IMLEO derivations of the EELVs (sometimes known as the ‘Phase-1′ upgrades).

I want to emphasise that this is not in any way a ‘Ooh! Shiny new thing!’ mind-set. If NASA had shown any hint that it was capable of building a D-SDLV In-line in a way that reduced costs or fit in a reasonable time-scale, I believe that it would have more support in the NSF community. As it happens, NASA seem determined to build the most expensive possible interpretation of the SLS using the slowest and least cost- and time-efficient development path. Frankly, we’re getting the impression that NASA don’t want to do it and won’t do it. The race is thus on to find something that either NASA can and will do or something that doesn’t require them.