OPINION: NASA needs to start investing in Mars comms network
By practically every metric, NASA’s Mars Reconnaissance Orbiter (MRO) has been an incredible success. Launched on August 12, 2005, MRO has spent more than ten years orbiting the Red Planet, both as a science-gathering platform and as a communications relay for other Mars-based assets. In its science role, it has contributed to significant findings on the planet, and returns more science information from Mars in a single day than the weekly total of all other Mars missions.
Indeed, in the time it has been active in the Martian system, MRO has transmitted more than 264 terabits (33,000 gigabytes – more than 7,000 DVDs) of data, which is more than all other interplanetary missions — past and present — combined. Not only that, but it has done so at data rates ranging from less than 500 kilobits per second (Kbps) when Mars is at its furthest from Earth (approximately 250 million miles) to 4 megabits per second (Mbps) when the two planets are a “mere” 60 million miles apart.
In its role as a communications relay satellite, MRO has no equal in the Martian system. Its 10-foot diameter high-gain antenna, combined with the 100-watt X-band radio, makes for the perfect partner to relay critical telemetry and science data from other spacecraft in-system. Beyond the obvious benefit of having a large antenna with which to communicate with Earth, being able to use MRO’s comms assets can translate to inbound spacecraft needing smaller – and less massive – comms systems of their own. This mass savings may have a significant impact on the type of science instruments included on the spacecraft, or perhaps may allow for a great fuel load, thus extending the usable life of the craft.
If that weren’t enough, MRO can also act as a “homing beacon” to incoming spacecraft. Unlike Earth, there is no GPS system on Mars, so properly-equipped inbound spacecraft make use of MRO’s Electra communications system to determine speed and distance relative to Mars, significantly increasing navigation precision.
But MRO is aging.
Already well-past its primary science phase, and nearly four years into its SECOND extended mission, the orbiter cannot last forever. Though no one knows when a critical failure may end MRO’s functional life, it has already had some minor malfunctions that had an impact on science gathering. Additionally, several key systems have had issues that impacted both navigation and operation.
Though the agency is aware of the need to ultimately replace MRO, no new orbiter is slated to be launched until at least 2022…and perhaps even later than that. If NASA hopes to send crewed missions to Mars in the 2030s, it will need to have a robust communications infrastructure in-place to support them. In my opinion, that means having more than a single relay satellite. Preferably, there should be adequate coverage to ensure a crewed spacecraft is never unable to communicate with Earth.
This problem is more than just one of continuity. Though the tremendous distance between Earth and Mars will always impart a significant latency – approximately 4 minutes when the planets are closer together, and nearly 24 minutes at maximum separation – bandwidth will also be a significant constraining factor. While a robotic explorer may be content with a sporadic 4 Mbps connection, it’s my guess that a crew of people will need something a bit more than that. Be it for concurrent science ops, spacecraft telemetry, and/or personal data needs, increasing bandwidth should be a top consideration.
Maybe that means a constellation of communication satellites with laser-based comms systems orbiting the Red Planet, be they large craft like MRO, or perhaps something more akin to the MarCO comms CubeSats that will be employed for the InSight mission. Or something between the two.
Whatever the solution may be, it’s not too early to begin working on it. With orbital alignment between Earth and Mars only presenting a favorable launch opportunity every 26 months, there are very few chances to mitigate communication inadequacies between 2022 and the arrival of crew in the 2030s. It’s time to get busy.