The Large Hadron Collider has proven to be the boon to particle physics that everyone had imagined to be but it’s far from done yet. We’ll likely be getting great data out of the LHC for a couple decades to come, especially with the current and future upgrades that are planned. However it has its limit and considering the time it took to build the LHC many are looking towards what will replace it when the time comes. Trouble is that current colliders like the LHC can only get more powerful by being longer, something which the LHC struggled with at its 27KM length. However there are alternatives to current particle acceleration technologies and one of them is set to be trialled at the LHC next year.
The experiment is called AWAKE and was approved by the CERN board back in 2013. Recently however it was granted additional funding in order to pursue its goal. At its core the AWAKE experiment is a fundamentally different approach to particle acceleration, one that could dramatically reduce the size of accelerators. It won’t be the first accelerator of this type to ever be built, indeed proof of concept machines already exist at over a dozen facilities around the world, however it will be the first time CERN has experimented with the technology. All going well the experiment is slated to see first light sometime towards the end of next year with their proof of concept device.
Traditional particle colliders work on alternating electric fields to propel particles forward, much like a rail gun does with magnetic fields. Such fields place a lot of engineering constraints on the containment vessels with more powerful fields requiring more energy which can cause arcing if driven too high. To get around this particle accelerators typically favour length over field strength, allowing the particles a much longer time to accelerate before collision. AWAKE however works on a different principle, one called Plasma Wakefield Acceleration.
In a Wakefield accelerator instead of particles being directly accelerated by an electric field they’re instead injected into a specially constructed plasma. First a set of charged particles, or laser light, is sent through the plasma. This then sets off an oscillation within the plasma creating alternating regions of positive and negative charge. Then when electrons are injected into this oscillating plasma they’re accelerated, chasing the positive regions which are quickly collapsing and reforming in front of them. In essence the electrons surf on the oscillating wave, allowing them to achieve much greater velocities in a much quicker time. The AWAKE project has a great animation of the experiment here.
The results of this experiment will be key to the construction of future accelerators as there’s only so much further we can go with current technology. Wakefield based accelerators have the potential to push us beyond the current energy collision limits, opening up the possibility of understanding physics beyond our current standard model. Such information is key to understanding our universe as it stands today as there is so much beauty and knowledge still out there, just waiting for us to discover it.
The Rosetta mission’s journey to comet Churyumov–Gerasimenko 67P spanned some 10 years, nearly all of that spent idling through space as it performed the numerous gravity assists required to get up the required speed. By comparison the mere 60 hours that the Philae Lander, the near cubic meter sized daughter craft of the parent Rosetta satellite, seemed almost insignificant by comparison but thankfully it was able to return some data before it went dead. There was some speculation that, maybe, once the comet got close enough to the sun the lander would have enough power to come back online and resume its activities. Chances were slim though as it had landed in a high walled crater that blocked much of the sun from hitting.
However, just under 12 hours ago, Philae made contact with Rosetta.
To say that the chances of Philae waking up were slim was putting it lightly given the trials and tribulations it went through during its landing attempt. In the extremely weak gravity field of its parent comet the 100KG lander weighs a mere 1g meaning the slightest push could send it tumbling across the surface or, even worse, out into space. This wouldn’t have been an issue if Philae’s landing hooks had fired but they unfortunately failed meaning it had no way with which to hang onto the surface. Thankfully it seems that an outgassing event hasn’t blown our little lander away and, after the Rosetta craft turned on its receiver to listen for it, we’ve finally made contact with Philae.
Reestablishing contact with Philae is a boon to the Rosetta mission as the lander contains a wealth of data that we could not retrieve when it was last active, due to time constraints. After the initial burst of 300 that the ESA was able to retrieve during this first contact after it went dark there are still some 8000 packets left to collect. These will provide some great insight into what happened to the lander during the dark period and what it’s been up to since it finally woke up. Early indications are that Philae has actually been awake before it was just unable to make contact with the Rosetta probe for whatever reason. We’ll likely know a lot more as the ESA team gets more time to analyze the data.
This also doesn’t appear to simply be a spurious occurrence either as the telemetry data indicates that Philae is operating at a balmy -35°C and is generating some 24 watts of power off its solar panels. Considering that its panels were rated for 32 watts at 3AUs from the sun (it is currently 1.4AUs as of writing) that’s not bad considering that it’s in something of a crater which would limit its sun exposure dramatically. This figure can only be expected to increase as time goes on meaning that Philae will likely be able to keep transmitting data and continue the experiments that it was unable to do previously. One such example is drilling into the surface of its parent comet, something which was attempted previously but didn’t prove successful.
Spacecraft coming back from the dead like this are a rare occurrence and it’s an absolute joy to hear that Philae has awoken from its 7 month slumber. It’s brief 60 hour mission will hopefully now be extended several times over, allowing us to conduct the full array of experiments and gather valuable data. What insights it will dredge up is anyone’s guess but suffice to say that Philae’s reawakening is a boon to both the ESA and the greater science community at large.