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Help is coming for satellites 'running on empty'

Jonathan Amos | 08:44 UK time, Thursday, 28 April 2011

I’ve come to the Kennedy Space Center to witness the final launch of shuttle Endeavour.

George Nelson (bottom-right) attempts to control Solar Max using the MMU

George Nelson (bottom-right) attempts to control Solar Max using the MMU

It is due to lift off on Friday. The mission will see the delivery of the $2bn Alpha Magnetic Spectrometer to the International Space Station.

It is a strange time to be here. Shuttle retirement has naturally prompted a lot of discussion about the state of the US human spaceflight programme.

Many people have been recalling their most memorable shuttle moments.

For me, some of the most startling images were those of astronauts using the Manned Maneuvering Unit, or MMU.

The backpack seemed to embody what the shuttle was all about and the things it enabled astronauts to do – to work in space.

I recall George “Pinky” Nelson’s attempts in 1984 to retrieve the malfunctioning Solar Maximum Observatory satellite using the MMU.

Floating untethered from the shuttle, he hung on to Solar Max’s solar wings at one point in an effort to bring the rogue platform under control. It didn’t quite work but that wasn’t a problem related to the MMU.

The satellite was eventually grabbed by the shuttle arm and its electronics payload repaired. Twenty-seven years on and Nasa is still interested in satellite servicing as a concept. I’ve been hearing here details of the final shuttle mission – STS-135 Atlantis – which will be taking up a test rig that will allow the Dextre robot on the space station to practise techniques for re-fuelling satellites.

The rig holds a series of tools Dextre can pick up to show how the fuel caps on spacecraft could be released in orbit to allow propellant tanks to be topped up. You can see a promotional video here.

Dextre and the station’s robotic arm are the products of Canadian ingenuity and, in particular, of MacDonald, Dettwiler and Associates (MDA).

The company itself is already pushing ahead with a commercial proposition of its own known as the Space Infrastructure Servicing (“SIS”) vehicle. This is likely to launch in 2015. It’s basically a robotic tanker.

MDA satellite

It will go into near geosynchronous orbit some 36,000km above the planet, where it will service commercial and government satellites in need of additional fuel. Ultimately, MDA hopes SIS vehicles could also find work in moving satellites to new locations, or in carrying out simple maintenance tasks.

The latter might include releasing the antennas on satellites that had become stuck during deployment. Some satellites carry huge antennas that must be packed for launch and they don’t always unfurl correctly when commanded.

But it is re-fuelling that is the primary motivation behind the first mission.

Thierry Guillemin, the chief technical officer of satellite operator Intelsat, told me that shortage of propellant to keep its telecommunications satellites in position is the main reason the company has  to retire the platforms:

”That’s what it is for the majority of them; it’s why re-fuelling is attractive. We actually keep decommissioning perfectly healthy satellites just because they run out of the fuel needed to keep them at their orbital location. To give you an example: in the next couple of years, we will decommission several Intelsat 6 Series spacecraft - satellites that were launched at the end of the 80s, beginning of the 90s. These satellites have more than 20 years in orbit and they are perfectly healthy from the standpoint of both their housekeeping function and their communications payload – but they are running out of fuel.”

Intelsat has agreed to purchase about 1,000kg of the fuel in SIS – about half its total load. It is likely government agencies will take up the other half.

You’ll recall that it was Intelsat last year that temporarily lost control of its Galaxy 15 spacecraft. Dubbed “Zombie-sat” by the media as it drifted past other satellites in orbit, it later became “Phoenix-sat” as engineers managed to regain full command of the wayward platform. But the incident illustrated very well how in-orbit servicing could be a very profitable venture in the future. Thierry Guillemin again:

”Even though we did a pretty good job with Galaxy 15 in avoiding any interference with the 15 or so satellites that we had to fly by, it’s true that the geostationary orbit becomes more and more crowded and the removal or towing of objects is yet another area where the servicer might be used. This one has its own challenges of course because depending on the size of the debris and how it is tumbling in space, it may be more or less difficult to grab it and tow it. But once we start using this service in orbit, designs and technology will evolve and we will learn how to deal with anything.”

Nasa and MDA/Intelsat are not the only ones pursuing the concept of in-orbit servicing. The German Space Agency (DLR), for example, has an idea it is developing called DEOS.

The German DEOS demonstration would show how to capture spinning satellites

The German DEOS demonstration would show how to capture spinning satellites

This is a demonstration mission that will also fly around 2015. It comprises a couple of satellites. One will act as the “servicer” and the other as the “client” spacecraft in need of capture and “repair”.

The purpose of the mission is really to understand how best to approach other objects and practise strategies for grabbing them. This is no trivial matter, Professor Felix Huber, the director of DLR space operations and astronaut training, told me:

”In the longer term, our goal is to be able to capture any satellite with a robotic arm. This might be a satellite that has lost control; it might be spinning or whatever. Usually, if you have a geostationary satellite, you have the apogee engine where you can grab into the nozzle. This is relatively easy. Whereas with DEOS, what we want to demonstrate is that we can grab a satellite anywhere with the robotic hand, even if it is rotating.
"But when you make the grab, what you have to do is un-stiffen the robotic arm - just like when you catch a ball, you kind of decelerate it slowly. Otherwise, if you have a hard touch, it will simply bounce off. Capturing a satellite means that once you have grabbed it, you need somehow to weaken your arm to slow it down gently. You will probably have to rotate the servicer to get rid of the spinning moment, and then you are safe. This will be the future if you have a broken satellite.”

With the space above our heads getting ever more crowded, the long-talked-about proposition of in-orbit servicing has to become a reality sooner or later. And not just servicing, but removing redundant satellites from the sky altogether.

It has been calculated that just removing a few key broken satellites would substantially reduce the potential for collision and a near-exponential growth in space debris over coming decades.

The robotic systems on the space station are key Canadian contributions to the ISS project.

The robotic systems on the space station are key Canadian contributions to the ISS project


  • Comment number 1.

    Retirement of the space shuttle is a good thing. They've been around for a while and quiet frankly are a bit old.

    However, the U.S. is sagging behind as far as space exploration is concerned. Congress needs to stop with making pay rases for themselves and give NASA more funding. After all NASA has rocket scientists. And Congress is full of useless people.

    What was it that Thomas Jefferson said I believe "One useless man is a shame, two is a law firm, and three or more is a Congress."

    He's definantly right.

    Give more funding to NASA and stop spending it on useless ear marks and then coplaining that there is no money.

    At least NASA makes discoveries, Congress is useless.

  • Comment number 2.

    Also Congress need to stop micro managing NASA. An NASA should make sure all projects that aim developed new vehicles and technology are structure similarly to the COTS programme and eliminate the costs plus profits projects that have led to nothing but failures over the years and are usually way over budget.

    I am wondering whether there are any British companies involve on maintaining and decommissioning satelites.

  • Comment number 3.

    Nothing to do with this topic but why on Earth has the BBc chosen to associate the SETI program with UFO hunting? They even use an image of flying saucers here:

    This is total misrepresentation of an important scientific endeavour, come on Jonathan please have a word with your colleagues!

  • Comment number 4.

    The aliens are among us, have you seen Ed Milliband? Lets not even mention Cameron, though a certain Charlie Brooker joke comes to mind, or a line from one of my favorite movies "Casey doesn't have emotions Ripley because she's just made of plastic."

  • Comment number 5.

    On topic. These missions are definitely the slow evolution of space technology but are very interesting nonetheless. The idea of refueling and repairing satellites on orbit has been around since about the time of Apollo but the idea of it actually hapening is very sci fi in a nice kind of way. I remember how incredibly painful NASA's first attempts at satellite repair were, in so many ways things really have come on a very long way.

    Its really only a step away from the old idea of space taxi's.
    With the cost of putting things in orbit its always struck me what a waste it is to de-orbit them so extending the lifetime of any system is a wonderful thing. Maybe even the junk that cant be reused directly could be put into a 'scrapyard' zone or orbit for later reuse or recycling.

    Apart from anything else if we are ever to build say a space elevator the counterweight has a need for hundreds or thousands of tons of ballast. It ultimately needs to go into a very high orbit but the geostationary orbit is over half way there and (I believe) is the best starting point for the construction phase.

  • Comment number 6.

    Oh just rereading the article, about a decade ago I did some work on things like robot arms catching (my background is really Strong AI). Yes the arm has to have a way of avoiding rigidity. In my case I used an an algorithm on each joint with a closed loop between a force sensor and motor so that as the arm started to flex the motor would constantly rotate the joint to compensate. Effectively it created an artificial muscle by allowing the joint to rotate flexibly and frictionlessly like a real muscle, allowing the use of a relatively cheap and simple rigid joint and gearbox system.
    The only problem being that if it lost power or anything went wrong the whole thing would instantly lock rigid. Not a very good behavior because a power failure would lead to falling over, at the same time locking the joints rigid at the worst time possible.

  • Comment number 7.

    This comment was removed because the moderators found it broke the house rules. Explain.

  • Comment number 8.


    Just entering the microcosm of atom matter where it is able to absorb and emit energy, still having the possibility to obtain energy from the mass of matter which can be found everywhere. Interestingly, E = mc² does not contain any reference to a particular substance, but there is no need, for one gram of air, water or gram per gram of cosmic particles, is also a gram of mass. So our new role is important to release any material amount of energy in mass that surrounds us and which we use or adapt to the devices and equipment built until now


    Why this huge energy consumption? To overcome the planet's gravitational field and allow a ship to travel in outer space All bodies around the globe are attracted to Earth, the force of attraction called the gravity and acceleration with which these bodies attracted into the gravitational field is called gravitational acceleration g = 9.81 m/ s ². Speed needed to escape Earth cosmic ship is 11000 m / s and can be done with an amount of energy of 2,400 tons of fuel Escape speed from Earth's surface is called the second cosmic speed. With this speed of a ship lifts off from Earth's surface and escapes the planet's gravitational field. Gravitational acceleration surface of Mars is g = 3.75 m / s ² and have an escape speed of 5100 m / s which is equivalent to a fuel quantity of 1055 tons For a trip to outer space or on Mars was built a Kennedy Space Center, a spaceship and made available energy 2400 tons of fuel - liquid oxygen and to overcome the gravitational field of Mars that has g = 3.75 m / s ² and to return to Earth we need a space center, a spaceship and an energy of over 1055 tones of fuel - liquid oxygen


    Stephen Hawking's Warning: Abandon Earthâ Or Face Extinction Let's face it: The planet is heating up, Earth's population is expanding at an exponential rate, and the the natural resources vital to our survival are running out faster than we can replace them with sustainable alternatives. So, according to famed theoretical physicist Stephen Hawking, it's time to free ourselves from Mother Earth. "I believe that the long-term future of the human race must be in space," "It will be difficult enough to avoid disaster on planet Earth in the next hundred years, let alone the next thousand, or million. The human race shouldn't have all its eggs in one basket, or on one planet. Let's hope we can avoid dropping the basket until we have spread the load." Solution to travel in outer space with the same ease as we do by car, bus, streetcar, subway, train, boat or plane is: QUANTIC PROPULSED SHIP

  • Comment number 9.


    There is one which could potentially rule that sort of work, gaining a virtual monoply if it passes the upcoming tests: Skylon.

    It is designed to relaunch two days after landing, it uses runways and it single stage. It has the potential to be able to clean up the junk in space and bring healthy satalites down if in need of more extensive repair and return them as soon as they are fixed.

  • Comment number 10.


  • Comment number 11.

    Congress has little interest in space they just see it as a huge waste of money. However no one wants to be known as the Senator / President who killed it. As a result they keep sending Nasa off on fools errands. Go to the Moon, no orbit, no the Moon, how about Mars?

    As a result Nasa's history is strewn with failures, they got to the moon, but at such a cost it was not possible to stay there, they built a 'space plane' but it was expensive and unreliable, they tried to go back to the moon by copying what they did the first time, but found no one remembered how they did it the first time.

    Hopefully Nasa's new mission which is to use it's hugely talented people to develop new space technologies will finally mean a turn around in Nasa's fortunes.

    In fact one of the new technologies they have been tasked with is the creation of new drive mechanisms. Nasa has made huge advances in Ion and Anti matter drives. This could be hugely advantages not just for long range missions but for keeping satellites in orbit. This would be hugely advantageous to the Satellite industry.

    Chemical rockets, good as the modern ones may be, are very inefficient.

    Sometimes spending money on things people think of as 'a waste of money' is hugely lucrative. Just look at Chris Columbus. I bet a fare few people said that was a waste of money.

    See I was on topic after all!

  • Comment number 12.

    Just saw the video sim for refuelling satellites.What a dog's dinner!A bit of foresight and consensus on the part of the 'community' of satellite designers would have made refuelling a simple,standardised task that wouldn't have posed any problems for a ZX Spectrum and saved billions of pounds.It is also clearly cheaper to refuel and/or re-equip an existing satellite than it is to build a new one and put it into orbit.
    Domestic plug sockets and mains electricity are standardised for VERY good reasons.The same logic clearly applies here.Too many 'experts' spoil the broth,I guess!An avoidable problem produced by the vulgar,archaic organisational architecture of academia and companies,yet paid for by all of us.Disappointingly predictable!

  • Comment number 13.

    #chippysteve et al, foresight is something lacking in almost every branch of modern science and tech.

    Remember the millennium bug? that was caused by a huge simple lack of foresight. In the end nothing really happened but that was only because they spent years and millions (billions?) of dollars fixing everything and just in time. If they hadn't every PC in the world would have crashed as its clock reset to 1900 - along with telecoms systems, networks systems, military systems, satellites, and on and on.
    The whole climate change thing was caused by an even bigger lack of foresight in planning things like oil production or the development of real carbon free energy like fusion, more advanced fission, advanced solar, bio-cycle fuels, gasification, etc. Or then there's efficiency improvements in electric grids like DC super high voltage, research on superconducting wires, or at the opposite end CHP systems and generation localization that do away with the problem altogether. Where was the foresight made to focus money and research on any of these even though we knew the problem was serious as long ago as the mid seventies!!

    Most of the biggest and worst places where we are lacking foresight are on the really big things. For instance there seems to be little no real foresight or planning at all in the overall direction in our future in space and space technology. As it is there is plenty of development but little or none of it is moving outside the scope of what we're already doing. If we are serious about ever achieving larger scale mass access to space or developing more advanced technologies then things need to change. The irony is that it often actually ends up being cheaper to do more, for instance with a more advanced engine tech a manned trip to Mars could be done on a budget of about 5 to 10 billion and then repeated for 1 to 2 billion. The money is there but it never moves in the right directions - there are plans are out there but the money yet again is flowing into the development of yet more new rockets on the same old pattern. (I remind everyone that TODAYS rockets are one of the stupidest least efficient inventions ever concieved, achieving a general overall efficiency of about 5% with 90%+ of the system being single use only.)

    For the future the number one goal must be access to orbit, but most of the technologies that could genuinely advance things get little or no funding. - Advanced closed cycle gas core nuclear rocket lifters, - advanced chemical rocket lifters (eg SSTO Skylon, or the super scale Sea Dragon), elevators or Lofstrom loops (launch loops), laser lifters, even a second generation reusable Shuttle.

    Nearer the fringe or the edge are things like gravity engines/mass recyclers, people laugh at the idea but these kind of things only remain impossible because no one will take the idea seriously until someone else gets it to work. I like to work in this area as an amateur but the most likely routes to success all require things way beyond any amateur today. A primary path is in 'neutronium condensate solids' but not only does it require a huge complex lab setup but a source of a lot of free neutrons like a high power nuclear reactor. And add to that if it could be made and kept stable a neutronium solid could be seen as creating a whole new class of nuclear bombs - and we can all imagine the kind of difficulties that would create. :)

    ---- ** ----
    An even more extreme possibility -at least for outer solar system manned missions is 'robotization'. People are already talking about one way Mars missions, robotization simply takes that a step further and offers the possibility of bringing the crew home. The essential idea is the one seen in the film Robocop, a persons brain and CNS is removed intact from their body and placed in an artificial life support system with the nervous connections interfaced electronically to an external waldo body and other systems. Some parts of it are unbelievably complicated but preserving a living brain is already basically possible.
    Why do all this? because a brain weighs a few kilograms, its life support a few tens of kilograms, it uses far less resources and energy than a full person, but best of all it can potentially be shut down for most of the trip without the huge complications normally associated with months spent awake in a confined space. Who would or might volunteer? - maybe people who are already paralyzed, people who are already on the verge of death from disease or cancer or something else, or people simply willing to make the sacrifice for the price of seeing the outer system. (Through most of the 90's I worked in Strong AI and was looking at this from the other side but it was always fascinating wondering if ... )


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