The way we get most of the scientific data back from the rovers we currently have on Mars is through an indirect method. Currently there are four probes orbiting Mars (Mars Odyssey, Mars Express, Mars Reconnaissance Orbiter and MAVEN) all of which contain communications relays, able to receive data from the rovers and then retransmit it back to Earth. This has significant advantages, mostly being that the orbiters have longer periods with which to communicate with Earth. Whilst all the rovers have their own direct connections back to Earth they’re quite limited, usually several orders of magnitude slower. Whilst current rovers won’t have their communication links improved for future missions having a better direct to Earth link could prove valuable, something which researchers at the University of California, Los Angeles (UCLA) have started to develop.
The design is an interesting one essentially being a flat panel of phased antenna array elements using a novel construction. The reasoning behind the design was that future Mars rover missions, specifically looking towards the Mars 2020 mission, would have constraints around how big of an antenna it could carry. Taking this into account, along with the other constraint that NASA typically uses X-band for deep space communications like this, the researchers came up with the design to maximise the gain of the antenna. The result is this flat, phased array design which, when tested in a prototype 4 x 4 array, closely matched their simulated performance metrics.
With so many orbiters around Mars it might seem like a better direct to Earth communications relay wouldn’t be useful however there’s no guarantees that those relays will always be available. Currently mission support for most of those orbiters is slated to end in the near future with the furthest one out slated for decommissioning in 2024 (MAVEN). Since there’s a potential new rover slated to land sometime in 2020, and since we know how long these things can last once they’ve landed, having better on board communications might become crucial to the ongoing success of the mission. Indeed should any of the other rovers still be functioning at that time the new rover may have to take on board the relay responsibilities and that would demand a much better antenna design.
There’s still more research to be done with this particular prototype, namely scaling it up from its current 4 x 4 design to the ultimate 16 x 16 panel. Should the design prove to scale as expected then there’s every chance that you might see an antenna based on this design flying with an orbiter in the near future. I’m definitely keen to see how this progresses as, whilst it might have the singular goal of improving direct to Earth communications currently, the insights gleaned from this design could lead to better designs for all future deep space craft.
