One day the International Space Station (ISS) – the most expensive object ever built by humankind – will dip down gradually into Earth’s atmosphere and explode into flames.
It will burn until the entire facility – all $155 billion of it – has thoroughly disintegrated.
This demolition project will be completely purposeful, not an accident. And Canadian-made technology will have the distinction of making it happen.
Video – A tour of the ISS
But that momentous day is still many years in the future.
With the ISS currently operating until at least 2016, and a motion currently before U.S. congress to extend operations until 2020, the early days of building humankind’s first outer-space science laboratory will be a distant memory.
Cable news channels will air footage of the demolition thanks to video captured by spacecraft that will eventually play a role in journeys that venture further into the solar system.
And then the National Aeronautics and Space Administration’s (NASA) sites will set its sites on the Moon, readying to return astronauts there after a half-century absence. Further ahead yet, putting boots on Mars stands as the ultimate goal for many space agencies around the world.
But first the ISS will be destroyed.
“The S-band antennae that we’ll be putting up this time around is going to be one that’s used to control the de-orbiting of the ISS,” says Mark Williams, project engineer for the ISS at the Montreal branch of MDA Corp.
The S-band antenna is reflected in an astronaut’s helmet.
The Richmond, B.C.-based robotics manufacturer is well-known for its famous Canadarm extension used on the ISS and the space shuttle.
More recently, its Dextre robot was added to the ISS to help with tasks requiring more precise manipulations.
But less well-known are the company’s antennae that are also affixed to the outside of the orbital outpost.
Through a contract with Boeing, MDA has supplied, and will continue to supply, the channel through which all voice and data communications flow between the space station and Earth.
The S-band antenna is used for typical, day-to-day communications between the ISS and ground based mission control in Houston, Texas.
It can also be used to remotely control the station from the ground. Thanks to this system, the Canadarm and Dextre can be used, and constant adjustments made to the station’s orbital altitude.
And one day those adjustments will steer the ISS slowly into the atmosphere, on a trajectory designed to minimize debris and steer whatever does fall out of the sky into the middle of the ocean.
“It shows the reliability of this unit,” Williams says. “It has to be 100 per cent reliable and something that people can trust.”
The communications black hole
The S-band antenna actually has two antennae that work in tandem. The stationary, low gain antenna picks up communications from the shuttle and from astronauts outside the station on a spacewalk.
The steerable high-gain antenna is a small horn that can be pointed in a specific direction and beams information to three different Tracking Data and Relay Satellite System (TDRS) satellites. Those satellites then relay the communications to mission control.
While the ISS flies about 250 miles above Earth’s surface, all of its communications are routed through the TDRS satellites that orbit at 22,000 miles. By doing this, NASA’s ground control team can keep in contact with the ISS at all times, says Joe Edwards, a client executive with Plano, Texas-based IT services company EDS Corp.
Edwards, a former NASA astronaut has visited MIR, the Russian space station that has since been intentionally destroyed in the atmosphere – the same ultimate fate that awaits the ISS.
The communications system does have one gap over Asia, Edwards says. Out of the 92 minutes it takes the orbital outpost to travel around the globe, there is an eight-minute window of communications blackout.
If NASA really needs to talk to the crew – they bring in a third satellite to relay the communications.
“If they were going to transmit video to mission control and it was important there not be a gap in the video, then they’d utilize the third satellite,” the former shuttle pilot says.
The procedure is par for the course when video linkups are done with the media or for NASA TV.
The communications infrastructure is able to provide astronauts with many of the amenities we’re used to hear on Earth.
Astronauts will be able to access their e-mail and the Internet, and even receive cell phone calls. Edwards says any data exchanged on Earth can be beamed up to the ISS too – even if an astronaut’s busy schedule doesn’t always allow them to surf the Web.
“You end up with a lot less free time to just spend on personal tasks than you do when you are down here on Earth,” he says. “You just don’t have time to devote to things outside the flight plan.”
A NASA diagram shows the communication pathways to the ISS.
The TDRS satellites aren’t used only for the ISS, Edwards points out. The first one was launched in 1983 and 19 are in service today, providing various communications to NASA.
The last TDRS satellite was put into orbit in 2002.
Extreme conditions
Keeping IT hardware from overheating is the concern of any Earthly technician. But in space, the prospect becomes even more daunting.
As the space station orbits the Earth, it spends half its time in searing temperatures hotter than an oven, and half its time in frigid temperatures colder than any winter day. Affixed on the outer wall of the ISS, the hardware must survive as the ISS is constantly exposed to the Sun, then shadowed by Earth.
“Space is an extremely hostile environment,” MDA’s Williams says. “You have the thermal aspect, and the radiation that degrades the performance of electrical components, and you also have micrometeorites.”
Nothing a coat of paint can’t handle, he adds.
At least for the searing heat, a special chemical paint can protect from the Sun. An electric heating system keeps the antennae from freezing up in the colder temperatures.
The particularly sensitive electronics are concealed in an aluminum box that is pressurized, Williams says. That helps keep their temperature at the correct levels.
But there’s not much you can do about the micrometeorites – space dust and tiny debris that the ISS routinely flies through. The best approach is a sturdy construction, the engineer says. But one antenna returned to MDA after its life in space came to a natural end showed some wear and tear.
“When you touch it, it’s like sandpaper, the metal is roughed up,” Williams says. “We had one larger impact that made a small dent in the outer skin.”
Temperature control isn’t the only worry that space technicians share with their grounded counterparts.
“You’d always like to have more bandwidth,” EDS’s Edwards says. “No matter how much bandwidth you have, you can always find ways to completely fill it up.”
To get wider data pipes running to the ISS, NASA has started using higher frequencies to transmit their communications. The S-band is the lowest frequency, and so it is limited to mostly voice communications. The KU-band satellites are higher frequency and allow for video and data connections.
The U.S. Military is also working on using a super high frequency EHF band that could further boost bandwidth, Edwards says. Another way to boost it is to have more transponders to increase the data simultaneously transmitted to and from a satellite.
Spare parts for space
The $21 million contract awarded to MDA from Boeing is to build two spare sets of the S-band communications antennae. That’s a break from usual NASA behaviour.
“The original philosophy of the space station was that they’d buy the units they needed and maybe one spare,” explains Bob Barrette, the ISS program manager at MDA. “If a part broke down, they could replace it by returning it to ground on the shuttle and actually having it repaired and sent back up.”
But come 2010, parts as large as the antennae won’t have a lift to space anymore. NASA is retiring its fleet of space shuttles at the end of the decade and getting ready for their new Orion spacecraft that will take astronauts to the Moon and Mars… but the Orion missions won’t start until 2014 at the earliest.
“So the philosophy now is to have extra spares and put them on the station while the shuttle is still flying,” Barrette says.
The last two shuttle flights in 2010 will be mainly to load the ISS up with spare parts. The large antennae will simply be affixed to the outside of the station at an empty spot and outfitted with the heaters to keep them from freezing while they sit dormant.
The Russian Soyuz spacecraft will continue its regular trips into orbit. A less expansive cargo hold means they can’t take any new antennae. But they can take astronauts who will install the spare parts if need be. It’s a matter of performing a couple of spacewalks, Barrette says.
The move away from the shuttle marks the end of an era. NASA is shifting its focus away from conducting missions to Earth’s orbit, and towards the Moon and then on to Mars.
The ISS could play a role as a staging area in that journey, Barrette says. Its life could be extended beyond 2020 if the major international players are willing to keep funding the project.
But one day the inevitable will happen. The antenna supplied by MDA will receive commands that result in the destruction of the ISS. For MDA, that doesn’t mean their communications systems won’t see any more action in space.
NASA has named Boeing a partner in building their Constellation satellite system that will serve as the communications infrastructure for future missions. As a Boeing partner, MDA could be supplying components for those systems.
“We see this as a big step to being a part of that expansion of the communications network to the Moon and Mars,” Williams says.