You are not logged in.
The big question is how the adoption of an SDV will affect the shuttle workforce. For politicians, protecting the workforce is a positive, but it's a big negative for NASA and its industry partners.
My guess is that over 60% of the shuttle workforce deals exclusively with the orbiter. The potential exists for streamlining operations once the orbiter is retired and an SDV is adopted. At the same time, an SDV creates new positions for employment, particularly if the engine pod can be recovered or if an uppe stage is added. Much of the orbiter-only workforce will probably be moved to new aspects of the SDV.
In other words--Energiya should have been our STS.
Imagine if we had been flying that since 1981--with Columbia in Gorky park.
We'd probably have 14 astronauts still with us.
That's a very pompous and callous assertion to make.
I do agree that liquid boosters like those on Energia would have avoided a Challenger-style accident. Yet if Challenger hadn't happened, some type of major shuttle accident would have happened in 1986. The system was just too complex, and NASA was pushing too hard to meet an unrealistic flight rate. Many engineers thought that the accident would occur on the Vandenberg launch or the Centaur flights. The complexity of the orbiter is common to the US space shuttle and the Buran.
As far as Columbia goes, I doubt that Energia-Buran would have been able to avoid a foam-strike incident like Columbia suffered. I haven't been able to get a good answer for this, but I'm assuming that Energia was covered in insulating foam, just like the Shuttle ET.
The major problem is that the shuttle's designers had unrealistic expectations for their ship when nobody had ever built a reusable, orbital spacecraft before. They went straignt from the X-15 to the massive shuttle without taking intermediate steps like the smaller X-20 in between.
I was simply using the RD-0120 as an example of how a hydrogen-burning engine could be converted to burn methane.
It's also worth mentioning, on a tangent, that Pratt & Whitney is buying Rocketdyne from Boeing. The deal is not expected to impact the lines of engines being produced and developed by either firm.
The Russians converted the RD-0120 (the Energia core engines) to run on methane and LOX as well.
Zubrin did an interesting http://www.risacher.org/bh/analog.html]study on using a rocketplane with aerial refueling.
The original idea actually belonged to Capt. Mitchell Burnside Clapp, while Zubrin's firm apparently did some consulting on the concept. An independent review by Boeing found that Clapp's fuel fractions were too optimistic for an SSTO (even with refueling,) but Black Colt survived for a while as the Pioneer Pathfinder.
Clapp has put the Pathfinder on the shelf for now, while his company, http://www.rocketplane.com]Pioneer Rocketplane is trying to build a space tourism craft called XP.
Hydrogen Peroxide+kerosene can achieve Isp's in the 300 sec. range if the engine is designed properly and if it's properly expanded. The problem is that all of the operational H2O2 engines built so far (AR2-3, Black Knight) have not lived up to H2O2's potential.
I used to like aerial propellant transfer for space vehicles, but as I learned about the rocket equation it began to make less and less sense. It allows you to have a lighter landing gear and smaller engines, but the wings have to be sized to support the ship when it's refueling.
Similarly, air launch is impractical for orbital vehicles. The faster you go in the atmosphere, the harder it becomes for the stages to separate. A two-stage rocket, on the other hand, is designed so it reaches the outer atmosphere quickly, and staging becomes easier.
Why not give both contractors the same design and see which one can pull it off using new components so as to limit off the shelf designing from the company that has it putting the other at a disadvantage to coming up with the same product.
That's the same approach NASA tried with the Space Shuttle. The concept was designed at the Manned Spaceflight Center, then the inudstry teams were asked to bring it to fruition. In the end, the result was incredibly disappointing and deeply flawed.
the stage must return near the launch site and be reliable enough to fly without more then a quick check.
I guess this means Integrated Vehicle Health Management (IVHM) is a prerequisite for RLV's.
I have actually heard cryogenic fuels mentioned in some of the CEV articles I've read. I also feel that hydrogen peroxide / kerosene may make a good propellant combination. It can't match any of the cryogenic propellants, but it's storable, not carcinogenic, and has better performance than hydrazine / nitrogen tetroxide.
Part of the problem with the Aviation Week piece is that it doesn't reveal what the specific mission of the CEV is. If the CEV is supposed to simpy fly to ISS and back, a 20 MT spacecraft should be an easy goal. 20 MT for an Apollo replacement is much more challenging.
Even if the CEV was forced to use its engine for lunar orbit braking and trans-earth injection with a docked LSAM (Lunar Surface Access Module,) I think significant cost savings could be made with regards to Apollo. Solar panels will likely be lighter than fuel cells, and composite fuel tanks have been cited for application to the CEV.
The problem with a two-stage DC-X type vehicle is getting the booster back to the launch site. It would need significant glide range, which probably isn't possible with the DC-X "lifting capsule" approach.
Buzz Aldrin's StarBooster concept (a winged, reusable rocket) envisioned gliding back to base with wings if the boosters separated at Mach 3 or slower. For speeds between Mach 3 and Mach 6, both wings and jet engines were needed.
The reusability of the booster will have to be determined by the trajectory, separation velocity, and separation altitude. The requirements for a booster's return have traditionally been quite different from those for an orbital vehicle coming back to earth. The result has been very different designs being used for orbiter and booster.
The Atlas V has a more powerful first stage engine. In theory (as long as we're talking about a heavier upper stage for the Delta IV) you could put a larger upper stage on an Atlas V heavy and place a larger payload in orbit.
It's interesting to note that the CEV is designed for four occupants and weighs 20 tonnes, versus three occupants and 34 tonnes for the Apollo CSM + escape rocket. I like the idea that modern materials and avionics can result in weight savings over Apollo, but I'm leery of emasculating the CEV by keeping its crew to just four instead of six.
Aviation Week is getting into the act, talking about http://aviationnow.ecnext.com/free-scri … 5top]Delta IV upgrades for Project Constellation. Apparently Boeing is throwing its eggs into the Delta IV basket in spite of concerns about human-rating. I also loved the way the article explains the vehicle's insulation burning at ignition and during part of ascent. I wonder what the astronauts think about that.
I would rather hold out for LockMart and see what the Atlas V heavy (if built) can do. On paper it's a more capable rocket using denser (and cheaper) kerosene propellant. I want to see LockMart build the beast. Having two heavy launchers in the Air Force stable will stimulate competition and give NASA more options for the VSE.
I'm glad to see Spirals 1 through 5 fleshed out. This is the most detail I've seen on the Spiral development plan. Taylor Dinerman at The Space Review should be pleased.
Ariane 5G only failed its first launch, due to loading software for the Ariane 4.
What about the failure of the first Ariane 5 EC-A? The first stage nozzle was deemed to be too flimsy for the flight, as it failed on the way up.
Ariane V has had its fair share of problems too. The challenge for Arianespace is to make sure these are flukes rather than the result of systematic problems in vehicle design, prouction, integration, and launch.
At the same time, I think that NASA could easily do 6-8 SDV flights per year under the current VSE plan. Assuming that each launch will be either a manned lander or an unmanned habitat, three or four missions per year is a realistic goal.
At this stage I think it's important to have a booster that's suited for the needs of CEV, rather than sizing the CEV system to a booster that's already available. Then again, Apollo was sized based on the Saturn V.
I would be interested to see a breakdown of the shuttle army to determine what percentage of those folks work exclusively with the orbiter. My guess is that over half do. I could only support an SDV if it meant a leaner shuttle army. Unfortunately, a lot of politicians would only support an SDV if it meant maintaining the status quo. Still, the imminent retirement of the shuttle orbiter means that none of the standing army will have jobs unless SDV is approved.
One important thing I noticed in the original posts is that Michael Griffin advocated an SDV. I believe that Griffin's name has been floated as a candidate for NASA administrator.
Some very interesting points, particularly regarding CEV acceleration. I still like SDV, but it's too big to be the answer to our need for a CEV launcher. I was thinking that the manned CEV capsule would launch on an EELV while the bulk of the spacecraft would be launched unmanned on the SDV.
At the same time, EELV accelerations should not be a show-stopper. If the problem was fixed for the Redstone, Atlas D, and Titan II, there's no reason why it can't be done for Delta IV and Atlas V.
NASA is looking at 30-33 days for sending up a rescue mission. It was estimated that two weeks would have been enough to send Atlantis on a rescue mission to Columbia, but a lot of testing and safety checks would have to be skipped.
I'm an environmentalist and all, but sometimes it is just better to throw something away.
Let's not forget that, no matter what we do, Hubble will be coming down in 2013 or so. The only question is whether it will be working in the period after 2008 due to a servicing mission.
Sending a shuttle to bring the telescope back to earth has already been nixed, as it would be an expensive mission for creating a museum piece and it would pose unneeded dangers to the crew.
The fact of the matter on http://www.pha.jhu.edu/hop/]The Hubble Origins Probe is that, although it won't be ready until 2010 at the earliest, it will last for a minimum of five years and give us phenominal new abilities like the Very Wide Field Imager. Most importantly, it will enhance our ability to study extra-solar planets.
Technologically, HOP is a cut above Hubble. Whereas HST was based on the KH-11 spy sat designed during the 70's, HOP owes its lineage to the newer Spitzer Space Observatory. It will come in 2,600 kg lighter than HST, orbit at 700 km above the earth, and only require an Atlas V 521 launcher.
The fundamental question is, do we spend the money now to fix the "old and busted" HST, or do we apply it now towards designing and building "the new hotness," HOP?
I vote in favor of financing the future.
I found the answer to the Kistler contract issue in the 2005 Aviation Week sourcebook. Kistler had a contract from NASA for flight data into spring 2004. NASA was then forced to drop it after SpaceX charged that NASA didn't open te contract to competition. The Falcon I is a similar vehicle to the K1, except that the upper stage doesn't come back. SpaceX would have been a viable competitor, but NASA completely ignored it until SpaceX whipped out its lawyers.
If the crippled shuttle still has operational life support systems when it docks with ISS, the astronauts could easily live there for the 30 or so days it would take to launch a rescue mission. This assumes, of course, that the orbiter is equipped with the Extended Duration Orbiter package.
I'm at a loss to explain how NASA can pull it off without EDO installed. Maybe they're not realistically considering the "safe haven" option and instead want to minimize risk through reducing the amount of debris that falls off the ET in the first place.
Air launch will not make any sense until we can fly the mothership at Mach 6 or higher and then have a reliable stage separation.
I support "Son of Hubble" 110 percent. I see no need to risk human lives and the entire manned space program over a telescope, but I'd also like to see the science continue if the robots are deemed unable to to the job.
Hubble II might not look like Hubble I, and I'm perfectly fine with that. Hubble I was based on the KH-11 spy sat, which is long out of production. It might be cheaper to adapt a current generation spy sat into Hubble II, as long as the unflown Hubble instruments could be integrated.
Ideally, the telescope would be in a much higher orbit, but Hubble was placed in a lower orbit so the shuttle could reach it. An expendible telscope that has no chance of being serviced should fly in a higher orbit and take better pictures.
I've also heard that folding optics would make it possible to launch a Hubble replacement on board a Pegasus-class rocket. Maybe this is a technology we should look towards when replacing Hubble.
If Hubble II is the same size as Hubble I, it will need a Delta IV-Heavy or similar booster. Depending on the telescope's orbit, it may require something even bigger, like an SDV. When NASA studied the Magnum booster, a space telescope mission was a reference mission. With Hubble II and Mars providing equal justification, maybe NASA will decide to by an HLLV after all.