Gravity: Raising space-debris awareness ... perhaps a tiny bit too much

Eager to see Gravity this weekend, which is getting extraordinarily good reviews (98% on the Tomato-Meter, at this writing).

One of the trailers:

While space debris is unlikely to arrive in such pestilential swarms as the movie shows, and probably wouldn't be visible to the eye as it approached (see excerpt from my article below -- the closing speeds are too fast), whoever researched the Gravity script did get some important principles correct. And in any case the movie (particularly in 3-D) apparently does an amazing job of giving the viewer the sense of being up there, and out there.

Setting aside exaggeration for effect, the writers are correct that the biggest threat to manned spacecraft in low earth orbit (particularly the ISS) is man-made debris. It's also worth noting that NASA regarded servicing the Hubble Space Telescope with the Shuttle rather risky (at least after the Columbia loss) because the shuttle had no easily accessible safe haven. The Hubble is in a much higher orbit than the space station.

Here's a link to a NASA report on dangers from space debris.

Following is the introduction from my 1999 space-debris article for Smithsonian on space debris. Coincidentally, that research brought me nose-to-nose with Columbia.

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ANYBODY WHO BELIEVES THAT SPACE IS AS empty as it looks in the movies should spend a few hours with Justin Kerr of NASA and Ronnie Bernhard of Lockheed Martin. It's June and both scientists have flown in from Houston to inspect the orbiter Columbia, which sits in Bay 3 at the Kennedy Space Center's Orbiter Processing Facility. I'm stretched out on an aluminum work platform by Columbia's windshield, under strict orders not to drop pens or notebooks or wedding rings that might damage the fragile tiles below.

Kerr hunkers down to my left and crawls through a playhouse-size aluminum entryway, emerging onto a catwalk with a nice view of Columbia's spacious payload bay. He grasps a lab notebook and a sampling kit, including a chopstick, a bamboo skewer and an orange stick. He directs my attention to a pair of tiny dark craters, each about twice the size of a sharp pencil tip, bored into a white metal frame that holds up one of the spacecraft's antennas. Kerr uses a bamboo stick and tape to gather up the smoky residue from each of the craters. He wraps up the tape and each stick to preserve the soot for microscopic scrutiny.

A shout comes from a platform one level beneath us: others on the NASA debris team have found another impact crater, this time on the right payload door. As we head down, I learn that NASA has logged io6 significant hits on Columbia from this single mission, most of them caused by unwanted man-made particles in orbit. (On most missions, minor damage means that at least one outer layer of window glass is replaced.) Bernhard is crouched under the open door, craning awkwardly to look straight overhead at the white insulated surface with a magnifying glass. He suggests I take a look. Through the tear I see goldish-brown felt that's been singed by the impact; on the white surface of the door smoky soot trails off one side.

These particular craters look pretty small to me, and I ask Bernhard if tiny but fast particles mean much. Yes, indeed, he says.

During a mission in 1995, Columbia took a hit in a payload door that made a gash almost an inch across. If that piece had crossed into the payload bay and punched a big enough hole in the cooling system there, Houston controllers would have ordered the ship back to Earth immediately. One reason it didn't hit at a bad spot was that the NASA debris squad had predicted the risk beforehand, based on earlier shuttle flights, and suggested keeping one payload door partially closed to help shield the payload bay. Bernhard says that, from the metals found in the crater, the culprit on that mission was probably a fragment of circuit board. Where it came from nobody could say, but an explosion is likely. Space has seen its share of silent blasts, some of them quite recently; in 1996 a Pegasus rocket exploded due to a fuel-tank explosion and propelled into orbit at least 700 pieces more than four inches across.

Science writers of the 1950s vividly described the risks to future spacefarers from rocky micrometeoroids near Earth, but the prognosticators missed the boat on what has turned out as a bigger deal, safety-wise. Near Earth, artificial meteoroids now pose a greater risk than the natural stuff. Over the decades humanity has gone Saturn one better by putting up not just a ring but a spherical shell of glittery objects around the planet. It's a layer of camera lens caps, spent rocket boosters, bolts, nuts, buckets of garbage, and countless flecks of dislodged paint and particles of solid fuel from booster rockets.

Even full-sized spacecraft that can be tracked reliably with radar have begun to cross paths, causing encounters that while rare are positively alarming. During his four-month stay on the Mir space station, astronaut Mike Foale received three warnings of approaching space traffic. In the last incident, an obsolete American satellite called MSTI-2 passed less than a thousand meters from Mir.

At the request of Russian controllers, Foale interrupted his exercise-bike workout to join the cosmonauts in the Soyuz (a Russian spacecraft that can return the cosmonauts to Earth) for a few minutes as a safety measure in case Mir was punctured. "We always looked outside [during the close passes] to spot them and it was inevitably futile," he says now. "Imagine trying to see a small dot ten kilometers away over your left shoulder, and a second later it's right next to you, and another second later it's ten kilometers over your right shoulder."

Howl of the Rena: Updated link from Maritime NZ

Back by popular demand, perhaps because people are thinking of how to use it for Halloween, here's the updated web address with the eerie howl recorded two years ago inside the wreck of the containership Rena as waves tore it apart on a reef offshore New Zealand. There's a spine-tingling shriek starting 34 seconds in.

I haven't heard audio recorded from inside Concordia (hydrophone or microphone) as the strand jacks pulled it upright. I'm sure it was noisy inside. Does anyone know of a link?

FYI on the status of Rena: the bow is gone, but the stern is mostly intact and sunk on the reef, and the highest section is within 30 feet of the surface.

One Risk in Parbuckling the Costa Concordia: Crushing the corner

A good animation is here from Crowley Maritime, which owns Titan Salvage.
 
Using snapshots from that film, which is a head-on view of the ship in which the starboard, or right side is on the left of the image, I labeled the major parts mentioned in this post.

This diagram may help explain some risks that salvors off Giglio will be managing tomorrow (if the weather holds), when they'll have to keep a close eye on concentrations of stress in the hull as it rotates under pull from the parbuckling cables and later the weight of the sponsons. The salvors have been pretty clear that things will bend and break during the process ... hopefully not the bigger things.
 
I'm guessing one risk they'll be watching will be a temporary concentration of weight on the starboard edge of the hull (see yellow arrow, below). The concern is weight of steel not fully offset by displacement in water: that's hull, fittings and the new sponsons, which will be mostly out of the water at that point.



Ship designers sometimes call this area of the hull, where horizontal plating meets vertical plating, the "turn of the bilges." It's the location of a stabilizing fin called the bilge strake, depending on vessel details. Here's a diagram from bestshippingnews.com -- see the highlighted yellow portion.

 

 

Recall that no seagoing cranes will be attempting to hold the weight of the hull off the seafloor. That's the nature of parbuckling: the structure has to hold up while a lateral, rolling force is applied.

 

But the good news is that a world-class crew is on the job. Wreckmaster for Titan-Micoperi is Nick Sloane of South Africa, who came to this job from the wreck of the Rena off Tuaranga, NZ, which I've covered in a series of posts including this one.

Parbuckling on the Costa Concordia: Historical Origins

You've probably seen the term parbuckling in connection with the Concordia work, as on The Parbuckling Project website. The website is partly correct in its description of early parbuckling as a way to roll heavy casks uphill.

That was one meaning in 1800, but “parbuckling” goes back earlier, and concerns artillery instead. Parbuckling was a way to haul heavy cannon from the base of a hill to the top, say when building a new fortification. Relocating heavy wheeled cannons across rough landscape proved such a problem during the Seven Years War in Canada that the Royal Artillery added rough-ground rigging to its curriculum for new cannoneers, and set up obstacle courses to train them.

As an example, a common parbuckling job for artillerymen was to remove the gun tube from its carriage (which can be done without a major effort by tilting the carriage forward until the muzzle is on the ground), then rolling the tube uphill, using ropes, blocks, and wooden runners. The carriage was brought up separately, on its wheels.

  

While it may seem that the gun crew could have saved some trouble and used whatever wheeled carriage the gun came with, when it came to the bigger guns, those carriages were only usable on a level, hard surface. Otherwise the carriages were top-heavy and the wheels dug in. If dragged across rough and steep ground, the carriage and mounted gun would likely mire or tip over on a slope, rolling over and freeing the tube's trunnions from their mounts, at which point the cliche “loose cannon” takes on real meaning.

So it was best to pull the gun tube from the carriage at the start of the operation and roll it along the ground, using parbuckle ropes, then remount it at the destination. For very heavy tubes, the gun crews laid wooden rails along the ground to ease the job.

Parbuckling is one of many ingenious rigging methods worked out by combat engineers through the centuries. Many are still in use, such as the gin pole I saw used by tower workers when I visited a tower-building job for Smithsonian.

Costa Concordia: Ready for the big pull

Readers of Disaster-Wise may know that I'm a fan of heavy rigging and the related work of collapse rescue, because such projects demand ingenuity, practical knowledge, and nerve. Through the years my writing research has taken me to rigging sites including collapse scenes, tunnels, towers, and derailments.

Photo: Parbuckling Project

 

In the heavy-rigging news this week: almost 20 months after Costa Concordia blundered onto the rocks off the island of Giglio, Italy, drowning at least 32 people, Italy's Civil Protection Department has given the Titan-Micoperi joint venture permission to pull the Costa Concordia upright, which (if the ship holds together) will allow a row of steel flotation boxes called sponsons, welded to the sides and bow like water wings, to ease it off the seabed so that tugs can haul it to a breaker's yard.

Weather permitting, the job of setting Concordia upright could start on Monday morning, September 16, local time. It will take the better part of a day to execute. Rest assured that hundreds of media reps will be watching from land, sea and air, so you won't miss anything.

The salvors will use computer-controlled strand jacks, wire rope, and sponsons to roll the ship very slowly from its capsized position. Right now it's laying on the starboard side, 65 degrees off vertical. If the parbuckling works as intended, the ship will come to rest in one piece, grounded but now upright on a temporarily leveled seafloor. (The leveling work was done with big bags of cement grout and giant steel frames, all of which will be pulled out later. Only anchor holes will be left in the reef, we are told.)

The groundwork should help keep the ship from breaking in half, as it would surely do without the leveling job, since the hull came to rest on two underwater promontories.

Here's my summary of the parbuckling plan. It will need three moving forces:  a row of flotation tanks welded to the port side of the ship that will serve as a downward force when flooded, and two sets of tension rigging on opposite sides of the ship. (By "rigging” I mean the full set of blocks, wire ropes, chains, anchors, and computer-controlled strand jacks.)

Here's a strand jack:

Now for the moving machines.

1) Parbuckle rigging: These are visible as a set of cables on the portside, the side facing the open sea. They will haul the ship upright most of the way, until weight from the flotation tanks (aka sponsons) take over. Specifically, strand jacks mounted on the sponsons will slowly take up cables whose other ends are anchored to underwater steel frames that make up the temporary seabed foundation.

2) Holdback rigging. This will keep tension on the bottom of the hull. Strand jacks will be visible on anchor towers on the starboard side. (Starboard is the side facing the seashore.) The main job of the holdback rigging is to keep tension on the hull nice and even, and to keep the ship from sliding across the temporary seabed, destroying the underwater platforms, and then rolling down the slope in reaction to the pull from the parbuckling cables.

3) Flotation tanks on the starboard side. These will flood to provide seawater ballast at the time of the parbuckling. (Later, for the tow to salvage, they will be pumped out and provide buoyancy for the flooded hull.) Apparently this ballast is necessary to bring the hull down to the seabed, because the ship's compartments will still have some buoyancy as the parbuckling begins.

There are several risks associated with this work, and I'll go into that in another post.

Visiting the B-2 Bomber Wing: A look at weapons loading

For those curious about the nuts and bolts of weapons that might be employed over Syria if the US intervenes, following is information I gleaned during a recent visit to Whiteman AFB at Knob Noster, MO, for Air&Space/Smithsonian Magazine.

The article as printed in August, "Stealth Bomber Elite," is here; this is bonus material.

(USAF / Senior Airman Nick Wilson )

Having heard of the sophisticated rotary launcher available to B-2 mission planners, I had the mistaken idea that such a high-tech bomber must take on its cargo automatically: perhaps a launcher preloaded with munitions elsewhere in the base, then hustled to the aircraft on a trailer and plugged into a B-2 bomb bay a half-dozen bombs at a time … fast and easy, like ramming a clip into the 9mm pistol issued to pilots before each combat mission.

Time with a bomb-loading crew in Whiteman AFB's Weapons Load Trainer straightened me out: While machines substitute for some of the muscle-power, it's very much a hands-on task, from bomb assembly in the weapons depot to loading the plane behind the closed doors of a dock. That goes for the 30,000-pound Massive Ordnance Penetrator to the smallest, a 500-pounder: all are individually loaded.

Conventional bombs can go on board with no more than tail fins and fuses, or they can be enlightened with JDAM guidance packages. The JDAM unit (short for Joint Direct Attack Munition) relies on satellite signals and inertial navigation to steer the bomb with swiveling tail fins and strakes. Because each JDAM-guided bomb is individually cabled to the plane's targeting computer, the crew can reassign targets over enemy territory. Boeing recently announced manufacture of the 250,000th JDAM kit.

On display when I visited the training facility, which is about the size of a high-school gymnasium, were a full range of conventional bombs. That included green-painted free-fallers, and gray glide bombs with wings that swung out, along with a powered version like a small cruise missile. All were practice models, for loaders to use during initial training and recertification.

The demonstration that morning featured a 5,000-pound bunker buster called the EGBU-28: taking it from its perch on a trailer and loading it into a practice version of the B-2, which featured a rotary launcher in the right bay and Smart Bomb Racks in the left.

According to the pair of sergeants giving me the tour, the combination of GPS and inertial guidance on this bomb's JDAM kit would be accurate enough to put the first bomb in the top of a steel drum, then a second bomb in the hole made by the first.

The loaders had a diesel-powered truck with a hydraulic arm designed for bomb loading, a rugged and bulky remote control, hand tools, and a checklist with grease pencil. And a good deal of elbow grease, as shown by the first job: moving the bomb-bay door from a vertical position and pinning it back so that it's out of the way, against the wing.

The green bomb was long and slim, with a rod-like nose.

(USAF / Airman First Class Shelby Orozco)

The driver edged the loading arm under the bomb's midpoint, then raised and rotate it to line up with the truck's direction of travel. A few turns of the steering wheel and it was lined up under the left-hand bomb bay. Each step was called out and repeated. Watched carefully by an airman on an orange ladder wearing a headlamp, the lift arm edged around obstructions to snug the bomb against an open slot on the rotary launcher, called a station.

For a brief moment, as the loading crew released temporary fastenings in preparation for shifting the deadweight to the aircraft, the 2 ½ ton bomb lay neatly balanced on the tip of the loading arm. Now it was time to make all connections and verify that nothing would come loose: a sway brace to hold it in place, a data cable to provide updates from the aircraft, and an explosive cartridge to separate the mechanical fastenings during the run. Loading the bomb took about five minutes. After each bomb goes aboard, a control panel at the stairway to the cockpit activates hydraulic power that swivels the launcher to take on the next weapon.

While the noncoms had good words for the efficacy of this particular bunker-buster, what I didn't expect was their enthusiasm for a lowly 500-pound non-bunker GBU-38 bomb with a MK-82 warhead ... if JDAM-equipped. The B-2 can haul 80 of these in the Smart Bomb Rack, totaling 20 tons, compared to a maximum of 16 one-ton bombs using both rotary launchers.

“With these you can destroy all the facilities on an airfield and leave the daycare center standing,” said one of the non-coms. Because a 500-pound bomb can demolish most targets as well as a one-ton bomb can, having such a big swarm of bombs in the belly might allow a single B-2 trip to take the place of three, or even four, B-2 sorties carrying one-ton bombs. Hard or buried targets could be left for a separate mission carrying bunker-busters.

That's if people and computers can rise to the opportunity without errors along the way. The 80-bomb load hasn't yet been tried in wartime, even in the most recent engagement, the 2011 attack on Libyan airfields. There's a risk that, along with the more sophisticated situational-awareness tools now available to the pilots, the extra capability could over-tax pilots and mission planners back at Whiteman.

Thoroughly Modern Fantasy: Europa Report

Have been working on a wide variety of projects over the summer (the history of DEFCON alerts, a kids' book, and an article on helicopters for a luxury magazine called The Private Journey) but now it's time to catch up on the blog.

Some buzz in the last week in reviews about Europa Report, about the movie rising to an accurate depiction of space exploration.

Hmm - certainly compared to Armageddon, which was lucky to get even a 39% rating in Rotten Tomatoes.

Once the premise is accepted -- that a company would send people out to look for life by landing on the surface of the Jovian  moon Europa -- the procedures are  fine enough. But the plot line isn't accurate in the sense that any such human-led plan will be organized and carried out, now that robots and remote sensing are so capable and offer so much value. The JPL advisers were polite about this, referring in interviews to the importance of robots in planetary exploration.

For an article in Air&Space about "Humans or robots -- who's driving the spacecraft?" I asked former astronaut Story Musgrave his thoughts on the issue. He sees it as a partnership, but with robots touching down first.

"There's a robotics program and a human program, and we've kept them separate," he said. "True exploration of space is not happening. We need to integrate humans with robots." He illustrated with a Mars scenario. "The way to do this is to sent robots first – design and operate so that they lead the way for humans. As opposed to just doing the robot thing."