Sunday Space Blogging – 25 Oct 2009

TDRS-1

TDRS-1

NASA Retires Pioneering Tracking And Data Relay Satellite

After a rocky start and then a stellar 26-year performance, NASA’s Tracking and Data Relay Satellite – 1 (TDRS-1) is scheduled for decommissioning on October 28.

Communications equipment that links TDRS-1 to the ground has failed and without this capability it can no longer relay science data and spacecraft telemetry to ground stations located at the White Sands Complex in Las Cruces, N.M., and on Guam.

Insecurity in Space
Space once was ours. Then came the space junk, collisions, and dangerous interlopers.

The recent expedition of space shuttle Atlantis on a major Hubble repair mission illustrated the dangers also.

Traveling up to the Hubble telescope’s altitude required transit through a major debris field. As Palowitch described it, the worst debris in LEO is right in the Hubble’s band. The known debris put Atlantis “at a one-in-200 chance of being totally destroyed by impact in flight,” he said. When it landed, Atlantis was pockmarked with more debris hits than any other shuttle in history.

Several factors contributed to the pummeling. First was the transit through debris fields. Then, once in position, the complex repairs required Atlantis to spend more time in the junk-strewn orbit.

More space blogging below!

Speaking of space debris: J002E3

J002E3 is the designation given to a supposed asteroid discovered by amateur astronomer Bill Yeung on September 3, 2002. Further examination revealed the object was not a rock asteroid but instead the S-IVB third stage of the Apollo 12 Saturn V rocket.

The object left Earth orbit in 2003 but will return in 2032. Check out this cool animation of the 2002-2003 encounter. Here is a lengthy write-up of the S-IVB stage.

The World’s Largest Stick of Dynamite

While NASA personnel have done an admirable job in handling the SRB’s up to this point, it’s sobering to know that just one mistake could cost a lot of lives and pull the plug on the nation’s manned space program. The Ares 5-segment SRB will be the world’s largest stick of dynamite, and that risk should never be lost on anybody who works in the space business.

Meanwhile, the Ares I-X test vehicle has rolled out and is in place on Pad 39B:

Ares I-X on Pad 39B<br />Credit: collectSPACE/Robert Pearlman

Ares I-X on Pad 39B
Credit: collectSPACE/Robert Pearlman

That, my friends, is the future of the US manned space program.

I wish it were something we could be proud of and excited for.

Comments

  1. Murdoc:

    We need something that gets men into and out of orbit reliably. And we need something to loft heavy cargos into orbit.

    Ares I and V will do that.

    The casualty rate for the Shuttle program was just too damned high … and the only thing the shuttles could do that Ares can’t is retrieve things from orbit. Once you pay through the nose to get mass up there, bringing it back is kinda senseless. The NRO no longer needs film retrieval flights.

  2. @Kristopher:
    Keep in mind that the Ares I uses the STS SRB system stacked to five segments instead of the four of the Shuttle; the entire first stage is nothing but an SRB stack with an additional joint to potentially fail. HALF of your “casualty rate for the Shuttle program” was CAUSED by a faulty SRB segment joint that burned through the bottom of the ET, resulting in the loss of Challenger. Granted, with the redesign of the joint, the SRBs are more reliable that they were, but solid propellant motors have other unique problems that frighten manned spaceflight engineers.

    The Ares I first stage was designed with no real “roll” control – it relied in large part on the second stage RCS system alone, placing roll stability in question during boost. A lot of experienced engineers questioned Ares I’s longitudinal stability during first stage boost, fearing that resonant frequencies might be so close between the stack and motor exhaust that the whole stack would violently “pogo.” Apparently, some in NASA felt the engineers were right and worked on pogo mitigation “kludges” like interstage vibration dampers, anti-pogo motor devices, and even stregthening the crew protection in the CEV to prevent vibration-related injuries.

    That doesn’t appear to be “something that gets men into and out of orbit reliably.”

    On the other hand, the Falcon series of launchers from SpaceX are very promising and have been developed for a fraction of the Ares budget. For that matter, we already have the heavy-lift Delta and venerable Atlas 5 launchers that could have been adapted for manned-exploration flights – also for a fraction of Ares’ budget – both with proven reliability records.

    An offshoot for the Falcon booster development is the potential to bring the per pound to orbit expense down based on commercially developed low-cost-per-flight RELIABLE launch systems. Even NASA admitted as much in the Augustine Report.

  3. I would add that the only reliable and more safe method of boosting payloads is with solid fuel motors. Liquid propellant was forced onto the US Space program by the damned Germans who came along with Von Braun. We kow-towed to their interests because we were afraid of falling behind the Soviets. Now we have paid a terrible price in both blood and treasure for that mistake.

    Let’s get out of the liquid-fuel business and into the solid-fuel business.

    After that, let’s clean house at NASA and turn over space exploration and space operations to commercial ventures, where they belong.

    respects,

  4. @AW1 Tim,

    There’s more to liquid-fuel rockets than just the Germans in general and Von Braun in particular; many of the liquid-fuel systems have pound-for-pound greater propulsion output than the solid-fuel motors. There are other advantages as well: liquid fueled motors can be designed for “ad hoc” propellant-mixture optimization and thrust-output variation (“throttling”) during the burn and can also incorporate an inflight restart capability. Disadvantages include greater overall complexity, fuel-storage difficulties for cryogenics and hypergolics, and more required ground-support equipment.

    Solids have the advantages of simplicity (no turbopumps or plumbing or tank pressurization) and long-term propellant storage (a real boon for things like SLBMs and AAMs). Disadvantages are lower specific-impulse fuels, inability to throttle, shutdown, or restart in realtime, and things like propellant-grain cracks that can turn a propellant casing into an explosion.

    And don’t forget that it was American Robert Goddard that first got the liquid-fueled rocket literally off the ground. The Germans merely took an American design and adapted it for their use….just like the Japanese with the transistor.

    Each type of motor has its place, depending on what is needed for a particular application.

  5. Well, IIRC, and I believe I do, Thiokol demonstrated the ability to stop and restart a solid motor about 25 years or so ago, with good results.

    I would much rather go with segmented boosters, even with additional strap ons, and those associated risks, than with the Rube-Goldberg affairs that come with liquid-fueled systems.

    What we need is the ability to boost parts into space and assemble the ships up there, rather than down here. It’s the only way we’re ever going to be able to get to Mars and beyond, and solids provide a less-expensive, more reliable solution than liquids, IMHO.

    Having said all of that, the big thing, besides cost, that solids give you is safety. Yes, the O-ring has the potential to burn through, and it has, but the resulting loss of the vehicle and crew was due to the explosion of the liquid center tanks, NOT the burn-through of the O-ring between segments, though that was the reason the centre tank exploded.

    The O-rings have their particular design because of two reasons. One is it allows for easier casting, and two, the end used plans to recycle the segments after ecovery.

    If the end user doesn’t plan to reuse the segments, then an entirely different, and stronger connecting system for each segment can be designed.

    Despite the composition of the solid fuels, there is virtually no chance of a catastrophic explosion due to the star-shaped ignition channel, as well as the open nozzle. If it were completely sealed, then yes, it’s possible, but as long as the nozzle is clear, it will furiously burn, but not explode.

    I admit to a great bias against liquid fuels and in favour of solids. :)

    respects,

  6. JT: That burn through was only a problem because of the proximity of a huge liquid fuel tank … the same fuel tank that dropped a chunk of frozen solid foam through a different shuttle’s wing.

    As for your cost complaints … that is a function of using a government agency to fund space exploration, which is a completely separate issue.

  7. First of all, a word of appreciation. (grin) It’s nice having a spirited discussion with someone on the innertubes over technical issues without a …flame… war.

    I hadn’t heard about the throttle-shutdown-restart work at ATK. I’ll have to look into that; the most recent I’ve read concerning the concept is the liquid-solid hybrid that Scaled was using.

    As far as the “Rube Goldberg” plumbing used for the liquids – it’s a well-understood technology. Most of the SSME difficulties experienced during development involved the concept of reusing the motors afterwards rather than the simple issue of “can we do this.” The SSMEs also incorporated the flow and temp sensors and control systems required to execute a prelaunch shutdown in the event of an off-nominal system alarm – something quite difficult to do with the SRBs. The SSMEs weren’t alone on the LO2-LH2 cutting edge, either; the J-2 proved an LO2-LH2 motor was not only technically possible but overwhelming successful – in the 60’s on the Saturn series.

    I agree with you totally that we need to develop the techniques and tools to perform on-orbit assembly and maintenance of systems for space exploration and development. I think we just disagree whether we want to ride a Ford or Chevrolet uphill. As I said, each technology has its application and place in the grand scheme of things.

    Depending on what you use as a source, the failure rate for solids range in the neighborhood of .7 – 1.2 percent. Several Delta, Arianne and Titan heavy-lift boosters have been lost due to SRB failures via cracked grain, case rupture or nozzle failure. Such failures tend to end rather dramatically (and with the total loss of the vehicle).

    In the case of STS-51L, the O-ring seal failure allowed a case burn-through that severed the lower SRB tank-attachment and caused the ET failure in the lower LH2 tank bulkhead (“dome”) area. The destruction of Challenger was through excessive aerodynamic loadings on the vehicle; the tank never really “exploded” – rather, the sudden “dumping” of the LH2 through the failed lower tank dome area acted like an additional rocket motor that overstressed the entire vehicle stack – and the aero stresses just shredded everything but the SRBs.

    As far as segmented SRBs, it is possible to create single or two-segment motors as large as the STS SRBs – however, it would require ATK to cast them near the launch site so they don’t have to be transported by rail from Utah (somehow I don’t think Florida residents would be happy about that). STS crews report and videos shot during launch on the flight deck reveal the high vibration levels associated with the SRB burn. I’m not sure I’d want to ride a “rough train” all the way to orbit; 140 seconds seems about right to me :).

    Regards.

    PS – You might be interested in a good discussion for Solids vs. Liquids was taking place over at the BA/UT forum over the last several days:
    http://www.bautforum.com/space-exploration/90742-solids-better-than-liquids-will.html

  8. JT,

    Heh.. yes indeed. I admit to my bias. My dad worked for Thiokol, back before it became Morton Thiokol, then ATK.. He was there when they were first starting out, and I grew up watching them test motors out north of Promontory. Worked there for a summer after High School, and got to go all over the mixing and casting areas, even down into the pits. Pretty heady stuff for a young man who grew up with the Space program and around airplanes.

    IIRC, the shut-down/re-start of the solid motors tests were in the late 70’s, but it might have been sooner.

    I’ll check out the other forum debates.

    Thanks much!

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