The station in space

The European Space Agency (aka the Agence Spatiale Europeene)(ESA), NASA, Russia, Canada and Japan, are the constructors of the International Space Station (ISS), the largest space station science and technology venture ever undertaken. On completion the new space station will be the most sophisticated laboratory ever in space from Earth, with a permanent international manned presence. ISS construction started in space at the end of last year and it is due for completion by the end of 2003. Finished, the station will comprise 420 tonnes of space lab and external attachments for scientific research, both pure and applied as well as technology. At the same time the station will be a test-bed for all manner of developmental work on space necessary systems such as closed-loop life support as well as mundanities as effective storage systems. There will be long term commercial exploitation as well, so that research will not just be pure (for its own sake) but applied. There may well be specialised manufacture even, to take advantage of the sustainable lowgravity environment. For the crew the important aspects will be the effects and difficulties of long term space residence and adaptation (and return to Earth problems). Of especial interest is the planned link-up with academic institutions so that both educators and their students will be able to learn and participate via the Internet. Thus it is arguable that ISS will mark the transition from space race and only for the elite few to colonisation and broadbased accessibility for the universe beyond our planet. That it comes into being as we cross the millenium is fortuitously memorable.

Education

NASA's Pathfinder mission to Mars in 1997 was the first near-interactive space mission. The agency's new willingness to open up access to its workings by allowing anyone on the net to access live pictures from Mars proved irresistible to millions. The access was backed up with well thought out illustrations and clear explanations, so that all could follow what was happening and understand the science and technology involved. With the station it will be possible to observe selected experiments with explanations and educational input from experts. Additionally schools, colleges and universities will be able to access and even input experiments. This will be feasible because of the ease of access thanks to new technology, so that experiments may well be performable at very low cost. As a start-up to the educational programme, ESA is running a SUCCESS competition, for senior students. They may propose experiments for the station, with prizes of internships and thesis opportunities. The winning entries will be considered for actual flight. The results will be announced in October 1999 and details are on http://www.international-space-station.de/.

Living and working in space

Up to seven astronauts at any one time will live and work aboard the ISS, once it is completed in 2003, often for extended tours of duty. Time in space, or even in the microgravity environment of Earth orbit brings with it many physical and psychological hurdles which each must overcome. The human body has been designed to operate at a force of 1g or very close to that figure and any departure from this, whether flying fast jets (when both positive and negative g forces can be experienced in quick succession - and some pilots are able to withstand + or - 9 or even 10g) or in microgravity, produces profound effects. In microgravity, as will be experienced aboard the station, the first effect generally perceived is nausea, caused by the general disorientation of a body in an environment with no familiar 'up' and 'down'. There is no weight perception, only inertial reaction; and balance is disturbed as it relies on gravity. The sense of touch is also altered. Mental pressure comes from being confined closely in a high-risk environment for long periods with other people, working at high pressure and under a need for constant vigilance. Much research will be possible, backing up data obtained mostly from Mir, on microgravity effects not only on the sensory systems of the human body but also on blood circulation, lung performance, fluid distribution and electrolyte balance which all modify. Research is also planned into the effects of microgravity on the body even at the cellular level since changes are perceived even this far down. It is well known that bone density is altered, as prolonged stays in space cause progressive deterioration as bone cell resorption occurs, so that astronauts suffer an effect very like age-induced osteoporosis. Aboard Mir, astronauts lost bonemass at the rate of 1% per month from the lower spine, hips and legs. There was also significant loss of muscle density and tone. Such a significant degredation would tend to rule out prolonged space exposure, such as would be endured on a Mars mission, until it can be satisfactorily combatted. At the same time calcium levels in the astronauts blood rises, which may lead to kidney stones and the calcification of soft tissue. Research into cause and prevention may help the millions of clinical sufferers in to this major cause of disablement and death in old age, as well as in treating the bed-ridden. Loss of the pull of gravity affects the functioning of the heart and circulatory system since there is no longer such a need to 'push' against its effects and the lungs feel the effect through changes to chest wall mechanics. (This results particularly in sleep disturbances). Even with a crew picked for physical health, emergencies will be inevitable, and to support coping with such contingencies the ISS bodies are developing a range of health analysis and support systems for both routine and emergency procedures, based on novel medical information systems, computer diagnostic and virtual reality clinical guidances. These techniques are already cascading down into improvements in imaging and diagnosing for Earth-based healthcare.

Commerce

The ISS will serve as a fixed base test bed for many potential commercial applications as well as research packages. Its big advantage is not simply that it is big and there, but that maintenance, either routine or repair can be very easily performed, even if the package is mounted outside. For example, one of the first experimental applications is the technology exposure facility, which will test superconductor systems destined for satellite communications. These systems will provide power saving and enhanced performance. The module will also be testing electric propulsion for communications systems for orbital transfer manoeuvering, station keeping and attitude control.

Time and space

According to the theory of general relativity, gravity is a property of space-time. A French package will be using the microgravity of orbit to provide meta-accurate time keeping. A huge body such as the sun modifies local space by its presence, leading to a bending of light as it passes by the star. The light is also retarded and there is a frequency shift. At present the most efficient clock is a cooled atomic clock, in which caesium atoms are cooled to about 1k by a laser system. Then a microwave frequency is locked into the extremely narrow resonance frequency of the cold atoms and the accuracy comes from measuring the length of time that an atom can interact with the microwave field. On Earth, gravity causes the atoms to increase their speed rapidly when the lasers are switched off for signal interrogation, but by moving the clock assembly into microgravity it is expected that the accuracy will increase hugely. The French package will be including reference clocks and microwave and laser links down to Earth to provide globally unprecedented accuracy widely available. Other applications will include greater accuracy in measuring long baseline radio interferometry observations and greater precision in global navigation systems and geodesy measuring to millimetre precision.

Pure research

The station will carry probes to examine cosmic dust and cosmic rays, it will be able to search for and study gravitational waves, and research for the background remnants of the Big Bang. The French time-keeping package will allow new accuracy to be achieved in the study of the red shift in astronomy and of the measurement of the accuracy of the bending of light by the sun. An attempt to measure the weight of the anti-proton is to be made. Collecting and studying some of the 'stuff' floating round in orbit may well shed light on the origins of life on Earth, as it will be possible to search for the building blocks among the debris of comets and other bodies. At the same time it is likely that the station will be used to keep a sharp look out for space bodies which may pose a threat to Earth.

Conclusion

Since the Apollo programme ended (and Neil Armstrong's landing on the moon 30 years ago next month) man has not strayed beyond the orbit of his home world. Research into the surmountable obstacles placed in the path of solar system exploration will be accelerated and enhanced by the work planned for the ISS. W

We couldn't leave home without it.

Update July 3 2000

New dates have been announced for the remaining 43 missions required to build the International Space Station.

Two elements of the Station - the Russian-built Zarya module and the US's Unity module - are already in orbit. The third element, the Russian service module named Zvezda ("star" in Russian), will now be launched in November from Baikonur, Kazakhstan. It is currently undergoing testing at the Baikonur cosmodrome. Zvezda will serve as the crew living quarters over the next four years while the Station is being assembled.

The module will be equipped with the first piece of European hardware on the Station, an ESA-developed onboard computer that will act as Zvezda's brain Zvezda will also carry the antenna for the European Global Time System, the first experiment on the Station. It will broadcast experimental chronometric signals whose proposed uses range from automatic adjustment of clocks and watches between time zones to remote immobilisation of stolen vehicles. The Columbus laboratory, Europe's main contribution to the Station, is now scheduled for launch on board the US Space Shuttle in February 2004, Another key European system, the European Robotic Arm, built for the Russian Science and Power Platform, is set to be launched in November 2001. The 10-metre arm will be used to assemble the Russian segment of the Station. It is currently undergoing flight qualification.

The first European, ESA astronaut Umberto Guidoni, is now scheduled to set foot on the Station in June 2000. His Space Shuttle crew will deliver up to 10 tons of equipment, experiments and supplies to the Station, transporting the material in a multipurpose logistics module developed by the Italian space agency ASI.

'All Right' says Fred (Update May 2001)

Fred is the unmentioned member of the ISS crew, presently keeping his crew mates safe from radiation. Fred has no arms. He has no legs.

Fred is the Phantom Torso, a 95-pound, 3 foot high mock-up of a human upper body. Beneath Fred's artificial skin are real bones and Fred's organs -- the heart, brain, thyroid, colon and so on -- are made of a special plastic that matches as closely as possible the density of human tissue.

The dummy is spending the next four months on board the ISS to measure the radiation to which astronauts are exposed. High-energy particles that pass through the human body can disrupt the way cells function. Although no astronaut has ever been diagnosed with space radiation sickness, excessive exposure could lead to health problems.

"We believe the current dose is too small to be of concern," says Dr. Gautam Badhwar, the study's principal investigator at the Johnson Space Centre. "The one possibility for radiation sickness might be an EVA situation during a solar event, if perhaps a crew member couldn't be brought back inside safely." But there's still lots to learn, he added, and that's where Fred can help.

The Phantom Torso is designed to do three things, explains Badhwar. First, it will determine the distribution of radiation doses inside the human body at various tissues and organs. Second, it will provide a way to correlate these doses to measurements made on the skin. "In the past we've typically recorded doses only on the skin," explains Badhwar, "whereas the risk to crew members is established by exposure to internal organs." Finally, the Phantom will help check the accuracy of models that predict how radiation moves through the body.

Astronauts are exposed to three types of radiation while in space:

The most energetic are Galactic Cosmic Rays (GCRs) -- the nuclei of atoms accelerated by supernova explosions outside our solar system. Cosmic ray nuclei can be as light as hydrogen, as heavy as iron, or almost anything in between. Because they lack their surrounding coat of negatively-charged electrons, GCRs are positively charged. The heavier nuclei carry the greatest charge, explains Badhwar. "As the charge increases, the amount of energy that the particle can deposit in tissue increases as well."

The other forms of particulate radiation consist mostly of protons. Most high-energy protons in the solar system come from the Sun. Although their charge is not great and they are less energetic than GCRs, solar protons can still be dangerous when they come in intense bursts known as solar flares.

The third kind of radiation, which surrounds Earth in areas known as Van Allen belts, consist mostly of decayed products from galactic cosmic ray interactions that have been trapped by Earth's magnetic field.

Some of this trapped radiation is confined to a region above the coast of Brazil, known as the South Atlantic Anomaly. "The Space Station goes through that Anomaly roughly five times a day," says Badhwar. The passage takes, at most, 22 or 23 minutes. That's good, he says.

If you go through the trapped radiation belt in less than twenty minutes or so, then for the next seventy minutes the body has time to do some repair to the damage done by the radiation." The radiation from solar flares can actually do more harm, he says, simply because it comes at a rate that doesn't give the body time to recover.

In order to measure space radiation as it propagates through Fred's body, Badhwar and his team have sliced Fred horizontally into 35 one-inch layers. In each section they've made holes for radiation detectors called dosimeters. The torso carries 416 lithium-crystal based passive dosimeters, which simply record the total radiation dose received throughout the mission. Fred is also equipped with 5 active detectors. These, placed at the Phantom's brain, thyroid, heart, colon, and stomach, can track the times that the radiation exposures took place.

"With the active detectors, we can correlate the time the radiation was received with the position of the spacecraft," explains Badhwar. "We can separate out quite reliably when we were in the Anomaly and when we were in the Galactic Cosmic Ray region." This kind of split makes radiation models derived from such data applicable to interplanetary missions, too. To assess astronaut exposure on a trip to Mars, for example, "we'll just switch off the Van Allen Belt particles," says Badhwar.

Radiation models devised by Badhwar and colleagues will be able to estimate how much radiation reaches an astronaut's internal organs simply by looking at the dose on his or her skin. That's important, because while the permissible radiation limits are based on internal exposures, practically speaking, all that can be measured is what occurs on the skin.

Such models are also scalable. Rather than giving a blanket risk assessment for all crew members, they can be customized to each individual in terms of height, weight, and even personal histories: how the astronaut flies an aircraft, or what medical tests he or she might have taken. All this contributes, says Badhwar, to total radiation exposure.

Even our internal bacteria rate a careful look: If a crew member gets too much radiation, it could kill the digestive bacteria essential for breaking down food.

Space station crew members will be sending data from the Phantom's five active dosimeters back to Earth about every ten days. When the device returns to Earth next fall, Badhwar and his team will be able to examine results from Fred's passive detectors as well.

"The thing that we're really going after is to get as good a handle as we can on what the organ exposures really are." he says. The goal is to make sure that the crew is exposed to the least amount of radiation possible.

Astronauts working on the construction of the ISS now have a new tool to help them - a robotic arm built for the station by the Canadian Space Agency (CSA)

Called Canadarm2 it is 'a bigger, smarter and more grown-up version of the shuttle's robotic arm," said Chris Lorenz, CSA's manager of mission operations. "It's part of Canada's investment in the space station program." Weighing 1640 kg (3620 lb), Canadarm2 is 17.6 meters (57.7 feet) long when fully extended and has seven motorized joints. It's capable of handling large payloads and helping dock the space shuttle.

Canadarm2 is surely big and strong, but it's not just a brute. This next-generation robotic arm has some amazing tricks up its sleeve.. Unlike the original Canadarm, which is mounted just outside a shuttle's payload bay, Canadarm2 won't be tied down to one spot. Each end of the new arm has a hand that can grasp an anchor on the space station. By flipping end-over-end between anchor points, Canadarm2 can move around the ISS like an inchworm.

With seven joints, Canadarm2 is more maneuverable than its predecessor on the shuttle and even more agile than a human arm. This is important because the space station is a larger and more complex environment than the shuttle's payload bay.

Once installed the station's crew will control Canadarm2 from two identical consoles (called "Robotic Workstations") located inside the Destiny Lab. Eventually one of those workstations will move to The Cupola -- a module tentatively scheduled for launch in 2005. Like the window-studded "Ten Forward" lounge on Star Trek's USS Enterprise, the Cupola --with eight windows-- will provide astronauts a stunning view of the space around the ISS. It's the perfect spot for direct viewing of the robotic arm and shuttle payload operations.

Plumbing in space

While the basics of human hygiene in space have been solved for many years a more ..civilised approach had to be created for astronauts who would be spending long times aboard the ISS.

Designers of the International Space Station (ISS) had to lay out a complex network of tubes, pipes and ducts between the Station's outer skin and its inner walls. Like veins and arteries in the human body, the Station's plumbing circulates vital liquids and gases that keep the crew and the ISS itself in good health.

Most of the time the ISS -- and its plumbing -- operates as a "ship in a bottle," cut off from the outside world. Between replenishment visits, the Station runs on a fixed amount of air and water. Efficient, leak-free recycling of everything that flows through the pipes is essential.

"This is kind of an ecologist's dream house," said Dave Williams, system manager for Environmental Control and Life Support Systems (ECLSS) at Johnson Space Center in Houston, Texas. "If you built a house this way you would be reclaiming as much water as possible."

For example, while a house on Earth can simply drain its wastewater to lines leading to a municipal treatment plant, the ISS must carry its own miniature water treatment plant onboard.

This equipment must achieve a higher level of cleanliness than its earthly counterparts for several reasons. Unlike most municipal systems, the ISS system recycles the urine of both the crew and the laboratory animals and returns it to the drinking water supply Microbes are a danger even to the Station itself, as exemplified by the problems on Mir with fungal growth. Keeping microbe levels in the water supply to an absolute minimum is an important part of ensuring the longevity of the Station.

Operating "in a bottle" also complicates the plumbing of the Station because the crew can't simply open a window to get some fresh air. Tubes carry pressurised oxygen and nitrogen from the Shuttle to storage tanks on the ISS. Ducts move cabin air from all parts of the Station to the carbon dioxide scrubbers and back, ensuring that the dangerous gas doesn't build up in any forgotten corner.

To be certain cabin air is safe, a mass spectrometer routinely analyses the gas content of the air. Another network of tubes draws air samples from many different spots around the Station and feeds this air to the spectrometer, which looks at levels of oxygen, carbon dioxide, and other gases.

"So if we know, for instance, there's some crew activity in a particular location that day, we can tell the computer to sample more frequently there," Williams said.

The oxygen tanks -- in addition to providing a backup supply of oxygen to replenish cabin air -- attach to yet another set of tubes that supply low-pressure oxygen to the modules. Receptacles in the modules allow the crew to tap into these lines with their emergency breathing apparatuses, extending the 15-minute supply built into the breathing apparatuses so that the crew can take their time handling the emergency.

And this collective network of tubing and hardware, which is far more elaborate than that of the typical house, must be compact, lightweight, corrosion-resistant, leak-resistant, microbe-resistant, and highly dependable. To meet this tall order, the pipes of the Space Station are variously made from titanium, stainless steel, or Teflon wrapped in metal mesh. In comparison, household plumbing is typically made of inexpensive PVC and copper.

Along with the unique demands of a "ship in a bottle," the plumbing on the ISS must operate without the assistance of gravity.

When building a house on Earth, it's enough to just lay the pipe and then let gravity or the pressure of the city water supply create the flow. In the mutual free fall of Earth orbit, liquids and gases would stagnate on their own.

"You have to look at the lack of gravity carefully," Williams said. "Because normally fluids would just sit there, unless you had the head pressure to force them. In a house, you can count on gravity when you flush a toilet to take that water and put it out in the sewer."

To keep the fluids flowing, the ISS plumbing system includes dozens of pumps and fans that create the pressure needed to coax the liquids and gases into moving.

The mutual free fall environment also places special demands on the design of bathroom and tap fixtures. Mass-produced fixtures like those found in a typical home won't work on the ISS.

"With taps, it's a lot different," Williams said. "For getting a drink, we usually keep the drink in a sealed container -- it kind of reminds me of a kid's juice bag or something. You hook the bag up to the dispenser and you select how much you want and hit the button. It dispenses that fixed amount of water and then it will stop. You can't just turn

The lavatory on the ISS looks markedly different than a bathroom here on the ground. A conventional toilet would not function at all without gravity. The ISS uses specialised equipment to meet these bodily needs.

"We have to have active components to help remove the faeces and urine away from the astronaut," Williams said. The two machines that separately handle these two body functions both use air flow created by suction to facilitate waste removal.

3D Pictures of the Space Station. You need 3D glasses for these.