Downmass

The word "stevedore" has a great heritage. It comes from the Spanish word "estevador," for "one who stuffs things." Being a stevedore was an occupation for many people working at seaports, where loads of cargo needed stuffing into the holds of freight ships.

Stevedores getting ready to stuff the stuff in with the other stuff on the ship.

 The job of stevedore shouldn't be confused with that of the longshoreman. Longshoremen unload freight ships, stacking the cargo on docks for delivery to warehouses. It's a different skill set, and actually made for two distinct unions during the 19th and 20th Centuries.

Most of us have only a cinematic understanding of  modern dock operations. We think not much has changed since the days of On the Waterfront, where burly, Vic Taybeck-looking guys would offload a ship full of wooden crates with hand-held freight hooks and hemp rope hoists.

If containerized shipping had been established in the 50's, maybe Lee J. Cobb
wouldn't have gotten into that big fist fight with Marlon Brando on the Hoboken docks.

The world's moved on, though. Since 1969, when the US Department of Defense established a standard size for containerized freight, a revolution in cargo transport has changed every job at ports throughout the world. Gone are the days of guys shoving wooden crates into excelsior-lined hulls. Today, the roles of both stevedore and longshoreman have been combined into that of crane operators, a mechanical method of loading and unloading ships without requiring a bunch of guys to crawl all over the cargo. While the number of folks employed by the dockside industry has declined, the amount of merchandise and material shipped worldwide has grown exponentially, expanding employment in related fields such as logistics, transportation, and warehousing.

Today: less Elia Kazan movies, more Denny's Claw games

All this leads up to something going on in outer space next week. On October 7th, SpaceX will launch the first production mission of its Dragon cargo ship to the International Space Station. The previous launch of Dragon was an experiment to see if the process would work - - this time, the cargo is for real.

SpaceX Dragon: this time, it's professional.

Why are the Dragon missions so important? Besides being the precursor to future manned American trips to the ISS, the Dragon is unique among its cargo-carrying rivals (Europe's ATV, Japan's H-III, and the stalwart Russian Progress modules) in that it not only can bring cargo to the ISS, but also bring equipment back to Earth. The other cargo ships are built for one-way trips. They don't have heat shields, parachutes, or any method of surviving re-entry. Even the manned ship, Soyuz, is only capable of returning less than 110 lbs of station equipment back to Earth, and that would only be small things that could fit through the Soyuz's narrow 27-inch hatch.

Puny 27" Soyuz hatch.

Dragon, by comparison, is a proverbial supertanker of downmass cargo. Instead of using the Soyuz probe-and-drogue connector, or even the Shuttle's old PMA linkup, the hatch to Dragon connects directly with any available Common Berthing Mechanism (CBM) port, which allows for a full 50-inch pass through width for equipment. H-III and ATV also use the CBM ports, but as I said before, they can't bring anything back home. The Dragon's downmass capacity (6,614 lbs) equals half the amount it can carry into orbit (13,228 lbs); in fact, this first production ship is going to bring more down than it carries up.

Un-be-freakin'-lievable 50" Dragon CBM hatch.

 How is this such a game changer? Simply, because it's brought the return of downmass capability to ISS operations back to the station program that's been missing since the retirement of the Shuttles last year. Experiments that didn't fit through Soyuz's tiny hatch, or weighed more than 110 lbs were stuck in orbit or doomed to fiery destruction in the old one-way cargo ships. Dragon, built specifically to accomodate the standard ISS experiment rack, makes possible the completion of dozens of station experiments that can now be studied back on Earth. Equipment is now capable of making round trips, so expensive, disabled hardware can be returned to Earth, repaired, and sent back into orbit on a future freight run - - all at a cost about 1/100th of a Shuttle mission.

Round-trip ticket, baby.

A dozen cargo missions by Dragon are scheduled for next year, followed by manned Dragon missions six months to a year after that. The routine-ness and simplicity of Dragon missions will finally make ISS missions safer and more affordable. Like its ocean-going counterpart, the two-way containerization of space cargo will change the economics of space -- for the better.

Space Pedantry

I apologize: I'm a nitpicker. I'm pedantic, to use the crossword puzzle term. Little things make me twitch like Herbert Lom in the Pink Panther movies.

Nothing gets me more nitpicky than errors in space reporting. People who write technical articles about space are supposed to simplify explanations so that the general public can understand matters of orbital mechanics and engineering, but it doesn't mean that the writers need to be inaccurate.

My latest twitchiness revolves around the COTS-2 Dragon spacecraft, due to meet up with the International Space Station on Friday. Dragon is a history maker, being the first commercial cargo ship to arrive with a billable payload for the ISS.

Where does the craziness erupt? It's when TV reporters describe the linking as "docking" the spacecraft to the station. It's not a docking. In fact, avoiding a docking situation is exactly why the Dragon is such an attractive ship to both NASA and the other space station partners. Dragon has been built specifically NOT to dock with the station.

Docking is when a ship under its own power connects with another ship. Think of a boat on the water as it pulls up to, well, a dock: the boat steers and alters its speed so that it can connect with the cleats on the pier deck. The Apollo Command and Lunar Modules docked in lunar orbit.

Docking

Berthing is when something at sea is snatched out of the open water and placed in a slip, or on a deck. Imagine a cargo ship being unloaded in a harbor. The harbor crane is berthing the cargo containers by stacking them in piles on the shore.The cargo containers are not under their own power - - the crane is doing all the work. The Dragon spacecraft is berthed with the ISS.

Berthing

This doesn't seem like it should be a big deal - - docking vs. berthing - - but in the history of space station operations, it's a best practice when the cargo can be berthed instead of docked.

Why? Because way back in 1997, a docking collision almost wiped out the Mir space station, and the six people on board. Progress ship M-34 had a stuck thruster and wound up ripping a gash in the starboard side of the Mir station, causing a sudden vacuum in the Spektr module and a series of lengthly repairs for the station. Although Russia still uses Progress ships to resupply the ISS, they use minimal thrusts to bring the spacecraft within the "danger zone" (the KOS or "Keep Out Sphere") of the station.

Progress SMASH!

Newer ships are designed around a berthing model. First, the ship will arrive from the underside, or R-bar axis of the station. Why? Let's take a look at the R-bar and see:

The R-bar is a line that runs from the bottom of the station through the center of the planet Earth. Any ship arriving from this direction will fall back towards Earth as the thrust is reduced. So, it's a safe vector if you want to get close to the space station without bumping into it.

Dragon will climb up the R-bar line until it crosses inside the KOS. Astronauts on board the ISS will reach out with the Canadarm and tuck the ship into a port on the bottom of the Harmony module. The connector for the ship and the station is called, aptly enough, a Common Berthing Mechanism, or CBM. Dragon's port hinges will click into place with the ISS mechanism, and -boom- mission accomplished!

So, if you get up early Friday morning to watch all this orbital ballet, you'll be able to yell at the TV with a sense of authority as you correct the woefully misinformed news reader. Hooray for you!

When I Heard the Learn'd Astronomer...

Captain Girlfriend and I went to a nearby library today for a lecture about Apollo 11. The fellow giving the lecture was a retired engineer who worked at MIT's Instrumentation Lab. He helped design the alignment telescope used in the Lunar Module.

Here's a picture of what the alignment telescope looked like inside the LM:

 

That camera looking thing behind the yellow guard rail was the Alignment Optical Telescope. It was a critical piece of hardware used to figure out where the Lunar Module was in relation to the Earth and the Moon. By pointing the telescope at two bright stars, the guidance computer could figure out where the ship was located in space. Quite an amazing bit of machinery that's often forgotten when looking at all the marvelous Apollo equipment developed during the same project.

The telescope and associated software cost $15 million for each unit delivered. The speaker told about how, when he was freshly hired at MIT, he was sent to give a demonstration of the new telescope to NASA. His sample telescope was placed on a table near a lectern, and several other engineers from other companies were also given space on the table to present their hardware projects. One of the other engineers got up to explain his system, and bumped into the table. The telescope began rollling... and rolling... and the speaker was sitting TWO ROWS away from catching the thing. Fortunately, nothing wound up broken, and the MIT folks didn't fire him for not wrapping himself around the scope 24/7.

The Q&A session was disappointing. I like going to popular science lectures to hear what average people want to know about, but it's usually quite depressing to think that most people believe the job of NASA is to redirect asteroids that are going to hit the Earth like a Michael Bay movie. The questions were about asteroid redirection, why America is "no longer in space anymore" and whether America would establish a permanent base on an asteroid. It's difficult to have a dialogue about the state of American manned space exploration when so few people actually follow what's in development at NASA. 

An interesting question from a 15-year-old boy in the audience made me realize how little of the Apollo era has translated to the current generation. The young man could not understand how the Apollo parachutes could have survived reentry. I've never noticed this before, but the landing sequence for Apollo really isn't described in much detail in movies about the missions. The engineer did his best to detail the Interface and Entry process in Apollo, but I'm not sure if the boy completely understood. 

After the Q&A, the small crowd broke up into little groups getting ready to leave for home. One family asked me a few questions, as they had heard some of the questions I had asked the engineer. I explained that there were many manufacturers working with NASA on manned spacecraft, and reading sites such as spaceflightnow.com was a great way to find out what's new. Their son (also about 14 or 15) didn't ask questions but seemed very interested in the topic. I can only hope that his curiosity would turn into the passion so many folks my age still have. 

All in all, a fascinating day.

Uh-huh. Rocket Science

Update: Rocket buddy Ralph Schiano pointed out that the SLS is going to use Space Shuttle Main Engines, fueled by liquid hydrogen for its first stage. Any impressions I made about NASA being smart by using kerosene, please ignore. LH2 is one of the quickest moves I could think of to make this project more expensive than it ever needed to be.

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Yes, I really am a rocket scientist. I have a big piece of paper on my wall with fancy lettering that says so.

The first consequence of being a rocket scientist is that I have many friends who enjoy saying, "Let me ask my friend, Jim. He's a rocket scientist and he'd know." This seems to make a lot of people happy that they know at least one rocket scientist, so I'm fine with that.

The second consequence is that every time something happens in the news concerning rockets, spaceships, astronomy, or satellites, I am asked for an expert opinion as soon as such news appears on the internet. My typical response is "the who in the what what now?" because I'm usually busy doing something else. But then I have to read up about whatever the news was and concoct an opinion, because "I dunno" is usually an unsatisfactory answer for my friends.

Today's Hot Space News Topic concerned NASA's new proposed Space Launch System (SLS), the latest in a near decade-long series of futuristic launch vehicles designed to take astronauts and equipment into deep space. NASA held a press conference, announcing the new design that featured a fat kerosene-and-LOX main stage strapped with two Shuttle-derived solid rocket boosters (SRBs). Here's a pretty artist's conception of the thing:



It looks like someone took an Apollo-Saturn V, removed the second stage, and bolted a pair of Shuttle SRBs to the stack. Wait a minute: if it already looked pretty much like a Saturn V, why would NASA bother with the SRBs? Why wouldn't they just build a newer Saturn V?

The answer is, of course, jobs, money, and politics. The New York Times estimates the cost of building two of these vehicles by 2021 would be about $62 billion That's a lot of Congressional money to kick around in the important districts of the House and Senate appropriation committee members. The primary assembly would be in Florida, the home state of former astronaut and current Senator Bill Nelson - - who also happens to be on the Budget Committee, the Committee on Commerce, Science, and Transportation, and the Committee on Finance. The solid rocket boosters, built by ATK, will be constructed in Utah, home of Senator Orrin Hatch. Hatch is the Ranking Minority Member of the Committee on Finance.

What's the big deal about having segmented solid rocket boosters on the SLS? They're an alternative propulsion system that isn't really needed. The SRBs provide extra lift to move the launch stack up from sea level, but that job could also be handled by making the main stage bigger, adding a second stage, or ratcheting the lift requirements of the launch vehicle down a bit. SRBs are built in segments - - as you'll recall, this segmentation proved to be quite a weakness in design for the astronauts onboard Challenger back in 1986. The SRBs are segmented so that they can be disassembled in Utah and shipped to Florida by rail - - that's the only reason for the segmentation. There are shorter, unsegmented solid boosters in production (Aerojet Corporation makes quite a few) but they aren't built in Senator Hatch's constituency.

Let's roll the clock back a bit and see how we wound up with this configuration. In 2003, the Space Shuttle Columbia broke up during reentry because its thermal protection system was struck by foam and ice debris during launch. The reason for the debris impacts was because of the poor design of the Space Shuttle launch system. Prior to the Shuttle, manned launch vehicles never had their reentry surfaces exposed to any launch debris. Since there was no way to protect the Shuttle reentry system from impacts, and since NASA was committed by international agreement to complete construction of the International Space Station, President George W. Bush announced that the Shuttle fleet would be retired, following the completion of the ISS construction in 2010.

As an appeasement to both Nelson and Hatch, Bush okayed a new plan for NASA called "Project Constellation," where NASA would strive to land people on the Moon, Mars, and "Beyond," wherever that was. The new Constellation program designers concentrated on reusing as much Shuttle hardware as possible, modifying the external tank, the SRBs, and the Space Shuttle Main Engines (SSMEs). This was supposed to cut down on development costs, because the technology was already in the factories and building this hardware should have been a snap.

Unfortunately, the reconfigurations didn't work, mostly due to a lack of funding by the government and a lack of foresight by NASA management. The first variety of new launch vehicles, known as Ares 1-X, was designed as a super-tall version of a single SRB, with a liquid-fueled second stage as an additional booster. A lack of budget money pushed the timeline of development back for the second stage, so NASA decided to attempt a flight of the Ares 1-X without a working second stage. The result was a disappointing suborbital launch of the Ares-1-X, coinciding with the cancellation of the entire program. Here's a pic I took of the pre-launch preparations for Ares 1-X, with the dummy second stage rising high above the old Shuttle gantry:



Ares 1-X, and the unflown Ares 1 were supposed to be the run-up to the big cargo-hauling ship of Constellation, the Ares V. Ares V was going to stretch out a Shuttle External Tank (ET) add a few SSMEs to burn the liquid hyrdogen (LH) in the ET, and two SRBs to carry the initial stack into space. The biggest problem with this arrangement is that the Ares V would continue the legacy of an LH launch fuel at sea level that plagued the Shuttle flights. Liquid hydrogen is extremely dangerous, and requires extremely low temperatures to be useful at ground level. Remember the spark generators at the base of the Space Shuttle, that would shoot a shower of pyrotechnics just before launch? Those spark generators were there to ignite any stray hydrogen at the launch tower, just so that the rocket ignition didn't detonate trapped hydrogen underneath the Shuttle. It's a really dangerous and complicated practice, and it buys little in the way of efficiencies for larger ships.

Ares V at left, Ares I on right

The new SLS system avoids LH as a sea-level fuel. Instead, the liquid fueled first stage runs on good old kerosene, the same fuel that powered the Saturn V's first stage. Kerosene is also the same fuel SpaceX is using in its deep space launch vehicle, the Falcon Heavy.


According to SpaceX, the Falcon Heavy will deliver only slightly more than 1/3 the payload of the SLS into low Earth orbit, or in other words, about 58 tons of payload. That doesn't seem to be too impressive, until you look at the cost of a Falcon Heavy - - the TOP price is scheduled for about $125 million per launch, about $31.775 BILLION cheaper than the expected SLS price tag per launch. The reason? SpaceX doesn't have to please the constituencies NASA must bow to in every price negotiation. SpaceX (and the other COTS companies) can press for cheaper prices, cheaper solutions, and simpler designs to get their product to market. Without facing competition, and being at the beck and call of irked Congressmen, NASA can't cut corners if it means trimming the fat. So, they'll continue with this $62 billion research project, maybe have one or two launches, then they'll declare success and mothball the vehicle. Don't worry, though - - its job will be completed by private companies with better control of their balance sheets.

Whew, that felt like a lot of spewing about rockets. Let me know if you have other questions about the SLS and I'll try and give you my bestest answer EVARRR in the Comments section.