Not Getting Enough Data From Mars? Set Up A Solar System Pony Express

Getting data in from deep space can be difficult. Almost all of our missions that have flown into deep space use the Deep Space Network, a system of transmitters and receivers that already imposes constraints on the amount of data we can transfer from the far reaches of space. So a team led by Joshua Vander Hook, then at NASA’s Jet Propulsion Laboratory and now at a start-up called, came up with a way to dramatically enhance the throughput of the DSN. In so doing, they gave it a very catchy name – the Solar System Pony Express.

Dr. Vander Hook was initially supported by a NASA Institute for Advanced Concepts (NIAC) grant in 2021. The basic concept utilizes what is known as a “cycler” orbit, where a spacecraft repeatedly orbits between two bodies in the solar system using their gravity wells to swing around in sync with when their orbits pass each other. 

In this case, the spacecraft would consist of a communications relay module that would collect high-throughput data from an observer module parked in orbit around the other body. The observer module would consistently download data from the missions operating in its local area and then, when a relay module gets close, would rapidly send all of that data to the cycling spacecraft. The cycler then returns to Earth, where another rapid download process begins, and the cycle repeats itself.

Fraser discusses some of the problems of communicating with deep space probes – especially those going to other stars.

That sounds like the Pony Express – a system in the 1800s whereby mail carriers would ride physical ponies (or horses) to deliver mail occasionally to remote outposts in the American West. In another homage to that mail carrier heritage, the team named the cycling relay satellites “data mules.”

Those data mules would have a long trip between Earth and their target destination. It might come as no surprise that in much of the literature surrounding the idea that the target destination was Mars. Buzz Aldrin, the most famous proponent of cycler orbits, suggested that cycler “castles” could effectively shuttle people and goods between Mars and Earth. But in this new configuration, instead of physical things, it would be more beneficial to ship data.

Another Depiction of how the observer / data mule interaction would go.
Credit – Marc Sanchez-Net et al.

Calculations described in a paper released last year estimate that with as little as six data mules, the network could provide a bandwidth of 1 petabyte a year from the surface of Mars while only requiring a minor allocation of time on the DSN. That would potentially allow some real-time high-definition video from the red planet, which would undoubtedly be attractive to many of the inhabitants of its nearest neighbor.

However, such high data rates come at a cost. In the case of the Solar System Pony Express, that cost is latency. The high throughput data transfer possible between the observer and a data mule, and then again from the data mule back to a receiving station on Earth, is only possible if they are in physical proximity to each other, as the network would use a type of high-throughput optical communications network. And since cycler orbits can take years, it would be years after the data was collected on the red planet that anyone could use it.

That is not a show stopper – indeed, many people would be okay with waiting for over a year for a high-definition video from Mars if that is the only way for them to see it. But it makes funding such a mission more difficult given the immediate feedback culture prevalent in many of today’s media. Give the authors credit, though – they recognize this limitation and, as all good scientists do, mention that it would be a good topic for further study.

For right now, that further study seems to be on hold. Dr. Vander Hook has moved on to other non-space-related efforts. While there has been some interest from researchers elsewhere, such as a paper from the University of Illinois, there’s currently no clear path forward for the project. But, there will always be a desire for more data transfer from farther out in the solar system. If the Pony Express is the most cost-effective way to get it at the beginning of our explorations, then don’t be surprised if this concept is resurrected sometime in the future.

Learn More:
Pascarella et al – Low-thrust trajectory optimization for the solar system pony express
Sanchez Net et al – Cycler Orbits and Solar System Pony Express
UT – NASA has too Many Spacecraft to Communicate With. Time to Build More Dishes
UT – We’re Entering a New Age When Spacecraft Communicate With Lasers

Lead Image:
Artist’s depiction of a representative cycler orbit.
Credit – Joshua Vander Hook

Andy Tomaswick

Recent Posts

China Names its Capsule and Lander for its Upcoming Human Lunar Missions

In a recent announcement, the Chinese Space Agency (CSA) unveiled the names for its forthcoming…

13 hours ago

If Exoplanets Have Lightning, it’ll Complicate the Search for Life

Discovering exoplanets is almost routine now. We've found over 5,500 exoplanets, and the next step…

16 hours ago

Electrodes in Spacesuits Could Protect Astronauts from Harmful Dust on Mars

To quote NASA associate administrator Jim Reuter, sending crewed missions to Mars by 2040 is…

17 hours ago

Odysseus Moon Lander Sends More Pictures — and We Know Where It Is

Four days after Intuitive Machines' Odysseus lander made an off-kilter touchdown on the moon, the…

19 hours ago

Astronomers Discover a New Meteor Shower. The Source is Comet 46P/Wirtanen

Like many of you, I love a good meteor shower. I have fond memories of…

1 day ago

Surprise! Japan’s SLIM Moon Lander Wakes Up After a Freezing Night

Japan's space agency didn't expect its wrong-side-up SLIM moon lander to revive itself after powering…

1 day ago