Monday, June 23, 2008

The DIRECT Route?


Government programs tend to grow in weight, size and complexity. The Space Shuttle began with the dream of a reusable Spaceship launched on a winged booster. Budget cuts eliminated the flyback booster, replaced by Solid Rocket Boosters (see Challenger) and a foam-covered external tank (see Columbia). To fit all customers the payload diameter was increased to 5 meters. Heavy drag-inducing delta wings were added to give crossrange capability, which has never been used. High wing-loading led to the TPS tiles, which are a maintenance and safety nightmare (see Columbia again). The dream of airliner-like service led to an expensive and ungainly system.

The Space Station was conceived as a stepping stone to other worlds. The US decided to save money by assigning major components to Russia. That caused delays in getting the Russian modules ready, and forced ISS into a high-inclination orbit serving Kazakhstan launch sites. The Space Station enjoyed the nice view of New Zealand we saw yesterday, but is useless as a stop for the Moon or Mars.

The Vision for the Moon and Beyond called for new boosters using existing technology. Constellation conceived of a Ares I with an SRB as the first stage and a J-2 powered second stage. A larger Ares V would have 2 SRB's attached to a center stage derived from the Shuttle External Tank. Studies then showed that 4-segment SRB's would not suffice, we would need 5 segments for Ares I and possibly 6 segments for Ares V. Building longer SRB's means a long testing process. The long skinny Ares I has vibration issues, as the rocket acts like a giant organ pipe. This may require heavy isolation machinery in the spacecraft.

Even with lengthened SRB's doubts exist whether Ares I could carry a loaded Orion, leading to a drastic effort to save weight. Capability to land on solid ground may be sacrificed for more water landings, requiring another Navy task force each time. The Essex-class aircraft carriers that recovered Apollo don't exist anymore, so a Wasp or Nimitz-class carrier might have to be diverted from the battle group's normal duties. Has anyone from the US Navy brought this up? Hello?

Ares I could not reach orbit without its J-2X powered second stage. The new engine would be an expensive and time-consuming project. Ares V now increases diameter of the External Tank, requiring new tooling. A sixth engine may be needed. The booster would be so heavy that it would exceed limits of the crawlerway leading to pads 39A and 39B. The pads themselves would have to be rebuilt to accommodate a wider vehicle, the VAB would have to be reconfigured...and so on.

The five-year gap between Shuttle and Ares I would mean thousands of NASA and contractor job losses. As happened in the 1970's, talented people would become unemployed and their expertise lost forever. Ares V would be a very expensive project that would be easy for a future administration to cut. This would leave the US where it started, stuck in Low Earth Orbit.

Presently NASA is determined to develop Ares I and V. In April 2009 an unmanned demonstration of Ares I-X is planned. This test will use 4-segment boosters, a dummy second stage and Orion that will not reach orbit. While it will be spectacular to watch, the test will be far from the vehicle that would carry humans. No doubt with enough time and money the engineering issues could be patched. The Ares I and V designs are capable of reaching the Moon, with work.

Any NASA employee would support Constellation and do whatever possible to make it work. However, a few have quietly been developing an alternative. Last month this writer was in the room for their presentation at ISDC. Yesterday the DIRECT plan reached the front page of the local Orlando Sentinel.

NASA remains silent on a rocket that could rescue the Cape.

"Indeed, an unfinished internal NASA study -- shut down and disowned by the agency last fall -- showed Direct 2.0 would outperform Ares, which the agency is designing for its Constellation program to return astronauts to the moon. The initial results showed Direct 2.0 was superior in cost, overall performance and work-force retention -- a big issue for Florida."

DIRECT 2.0 (website) would make maximum use of common hardware. Jupiter-120 would use 2 standard Shuttle SRB's, around a core built from the Shuttle ET with two currently available RS-68 engines. The crewed spacecraft would match the cargo ability of Shuttle. Jupiter-120 could easily lift Orion into orbit with payload to spare.

The larger Jupiter-232 would add a third RS-68 and an upper stage powered by a J-2 engine, to carry cargoes to the Moon and Beyond. Possibly it could be upgraded to carry payloads up to 140 tons. With a similiar footprint to Shuttle, these new boosters would use NASA's existing launch infrastructure. DIRECT backers claim the system would carry humans to the Moon by 2017, two years sooner than Ares.

Given the challenges to reaching the Moon, DIRECT 2.0 deserves official consideration. A new adminsitration will certainly reassess NASA's progress. In the 1960's a few brave engineers proposed Lunar Orbit Rendezvous, which got the US to the Moon in time to meet Kennedy's goal. Presently NASA engineers are working on DIRECT in their spare time without knowledge of their bosses. There may be time to change direction, and possibly get us to the Moon sooner.

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7 Comments:

Blogger Red River said...

DEC had a desktop computer long before Intel or MS ever dreamed of it. And the VMS operating system was mature and secure.

Now we have Windows and Linux, neither of which is anywere near where VMS was in its heyday.

Every generation sneers at the one before, imagining its solution to be better. But they have to walk the same road - using up precious time and resources to rework the same ground that was once plowed for free.

Its a design flaw in humans.

7:48 AM  
Blogger CarlBrannen said...

Turns out I learned to program assembler on a Dec 2060 with VMS. At that time (1979) it was very far from "mature" or "secure". We hacked it from one end to the other.

But all the operating systems since then have been downhill. What I really miss is the nice simple keyboards (ADM3A) but complicated editors (emax) we used at that time. Now keyboards have piles of keys I never use, and there are many many editors, few of which are both common (and free), and designed for computer programmers.

8:24 AM  
Blogger L. Riofrio said...

I miss this thing called the brain which could do math calculations nearly as fast as the computer and had creativity to boot.

6:15 PM  
Blogger Seneca the Younger said...

Assuming that's you in the picture, I see where the blog title comes from.

In any case, though, L, you're missing the point: people should think, computers should compute. We're not best served by doing our own arithmetic.

Carl, you mean "EMACS", and you can get it today; a lot of us old folks still use it.

8:36 AM  
Anonymous Tony Smith said...

Wasn't VMS know as VoMitSystem in the old days?

Didn't Microsoft use VMS as the basis for
its Windows New Technology (WNT)
that replaced MS-DOS
and on which XP, Vista, etc were based?
Alphabetically,
VMS is to WNT
as
HAL is to IBM.

Tony Smith

5:10 PM  
Anonymous chimpanzee said...

What do you think of non-government efforts for space, like SpaceX? (although, they got a 300 million dollar NASA contract) Unfortunately, SpaceX seems to be run by a nut (2 failed launches, 3rd attempt any day now), who is simultaneously fouling up Tesla Motors.

I like Burt Ruttan/Scaled Composites effort, & their anti-establishment mantra:

"NASA is screwing us [ overpriced solutions ]"
[ which is why I left NASA/JPL 20 yrs ago, it was a joke ]

which got private funding from Paul Allen (MS founder), & Virgin Space is stepping up.

A friend of mine (astronomy instructor at Cal State LB) worked on Saturn V Apollo hardware while at Lockheed (?) in the late 60's. He recently told me how the Moon landings marked the end of govt funding for "blue sky projects". His exact quote:

"..all of sudden we're all out of work, flipping burgers"

!! ex-rocket scientists reduced to menial mind-numbing labor.

12:50 PM  
Anonymous chimpanzee said...

I learned assembler on an IBM 360, when taking a systems programming course in '75 (UIUC). Punchcards, remember that? Dialup using 300 baud, TTY (teletype machines). I still have my Processor Technology SOL 8080 microcmputer system, & "basic" keyboards. I still have 1 of the highly desired Microswitch keyboards, very high quality (not the lowly keyboards of today).

Back in 70's at our lab, it was Decsystem 10 (running Tops-10?). Later upgraded to Dec VAX systems. They changed over to the "hot" Unix system. But, scientific users soon found out the lack of support for Fortran was a pit. They switched back to VMS. When I did my PhD in '82-'84, our lab was using PDP-11/40 (magnetic core memory!!). I still have a Dectape system in my garage, along with a Dec PDP-12 rack. Also, a DEC VR17 vectorscope CRT display (2 of them). I vaguely remember using Unix "vi" (?) as the text processor to write my thesis, outputting to daisywheel printer.

When I got to NASA/JPL in '84, the Macintosh was just introduced. VAX machines were used at our lab, & Sun minicomputers (running Solaris) were beginning to take a hold. These days, computing solutions are portable/cheap (laptops), & available to the general public. Staples office store just had a Compaq desktop (no display, Intel Dual Core) on sale for $249!!

1:04 PM  

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