Debris in orbit are becoming one of the greatest challenges that we face as we become a space fairing species. You see by the simple fact that something is in orbit means that it has an incredible amount of potential energy, zipping around the earth at Mach 25 ready to wreck anything that might cross its path. Thankfully there’s quite a lot of empty space up there and we’re really good at tracking the larger bits so it’s usually not much of an issue. However as time goes by and more things are launched into orbit this problem isn’t going to get any better, so we need to start thinking of a solution.
Problem is that recovery of space junk is an inherently costly exercise with little to no benefits to be had. A mission to recover a non-responsive satellite or other spacecraft is almost as complex as the mission that launched said object in the first place, even more so if you include humans in the equation. Additionally you can’t send up a single mission to recover multiple other missions as typically satellites are on very different orbits, done so that they won’t collide with each other (although that has happened before). Changing orbits, known as a plane change, is extremely expensive energy wise and as such most craft aren’t capable of changing more than a couple degrees before their entire fuel supply is exhausted. The simple solution is to deorbit any spacecraft after its useful life but unfortunately that’s not the current norm and there’s no laws governing that practice yet.
It’s even worse for geostationary satellites as in that particular orbit things don’t tend to naturally deorbit over time. Instead anything in a geostationary orbit is pretty much going to be there forever unless some outside force acts on them. Geostationary orbits are also particularly valuable due to their advantageous properties for things like communication and location so the problem of space debris up there is of a much bigger concern. Thankfully most geostationary satellites have the decency to move themselves into a graveyard orbit (one just outside geostationary which will eventually see them flung from earth orbit) but this method isn’t guaranteed. Mass that’s already in orbit is incredibly valuable however and DARPA has been working on a potential solution to debris in geostationary orbit.
The DARPA Phoenix program is an interesting idea, in essence a in orbit salvager that cannibalizes other satellites’ parts in order to create new “satlets”. These new satlets won’t be anywhere near as capable as their now defunct donors were but they do have the potential to breathe a whole lot of life back into the hardware that’s just sitting there idle otherwise. Compared to a regular geosynchronous mission something like Phoenix would be quite cheap since a good chunk of the mass is already up in orbit. Such a mission can really only be done in geostationary orbit since all the satellites are in the same plane and the energy required to move between them is minimal. That is our most valuable orbit however so such a mission could prove to be quite fruitful.
Dealing with the ever growing amount of space debris that we have orbiting us is a challenge that we’ve still yet to answer. Programs like DARPA’s Phoenix though are the kinds of projects we’ll need to both reduce the amount of orbital junk we have as well as making the most out of the stuff we’ve already put up there. I’m really keen to see how the Phoenix project goes as it’d would be quite a step forward for on orbit maintenance and construction as well as being just plain awesome.
Almost 2 years ago the Phoenix Lander, was sent on its way to Mars. The Phoenix’s mission was simple, to search the north pole of Mars for the most fundamental building block we know: water. Just like the Spirit and Opportunity rovers it was only designed with a very short mission time in mind, approximately 125 martian days (sols). After that point the solar panels would not produce enough power for it to continue operations and was instructed to shut itself down until conditions improved.
Phoenix however wasn’t designed to endure the harsh martian winters. The solar panels it has are too small to generate any meaningful charge during the winter and the lander has no way of reorienting itself to maximise the small amount of solar energy it gets. The rovers have a one up on the lander in this regard since they can find a hill at the right angle to maximise their exposure or, in the case of the trapped Spirit, digging its wheels into the soft martian soil. So despite its name it looks unlikely that the Phoenix will rise out of the frigid winter ashes, but that doesn’t stop us from hoping otherwise:
Listen up, all you Phoenix lander fans! Beginning Jan. 18, the Mars Odyssey orbiter will start listening for any signs of life from Phoenix, which has been sitting silently on the frozen arctic region of Mars since its last communication in November 2008. The Phoenix team says hearing any radio transmission from the lander is high improbabl[e], but possible. Never say never….
“We do not expect Phoenix to have survived, and therefore do not expect to hear from it. However, if Phoenix is transmitting, Odyssey will hear it,” said Chad Edwards, chief telecommunications engineer for the Mars Exploration Program at NASA’s Jet Propulsion Laboratory, Pasadena, Calif. “We will perform a sufficient number of Odyssey contact attempts that if we don’t detect a transmission from Phoenix, we can have a high degree of confidence that the lander is not active.”
Odyssey will pass over the Phoenix landing site approximately 10 times each day during three consecutive days of listening this month and two longer listening campaigns in February and March. The listening attempts will continue until after the sun is above the horizon for the full 24.7 hours of the Martian day at the lander’s high-latitude site. During the later attempts in February or March, Odyssey will transmit radio signals that could potentially be heard by Phoenix, as well as passively listening.
From the mission onset I always held a slim, illogical bit of hope that the lander would survive the long martian winter. Mars has a track record for killing the majority of space craft we send at it (the “Mars Curse” has seen 50% of the missions planned for it fail in some way, although the Americans by themselves have a 72% success rate) so the Phoenix lander coming back alive after what is considered to be certain death for it would be one of those moments where impossible odds are overcome. Sure we’ve already got almost all the science we wanted out of the lander, but that doesn’t mean there isn’t more useful things we can do with it.
It also brought back another interesting fact about Mars, the number of both active and inactive craft we have on our red neighbour. There’s currently 3 orbiting satellites (Odyssey, Express and the Reconnaissance Orbiter), 2 rovers and a smattering of landers (all inactive unfortunately). Having this much infrastructure on another planet has proved to be a great boon for all missions that go there as the existence of orbiters that can function as communications relays means that we can get more data back to Earth for the same cost. Plus its just plain cool to know we’re capable of such things, and gives me hope that we will one day make Mars our second home (that’s a story for another day!).
So in about a week we’ll start to get an idea of whether or not the Phoenix will rise again. Either way we can still look upon the success of Phoenix with a smile, and should it come around again you can rest assured the scientific community at large will be both surprised and overjoyed.
It’s all a matter of time now.