Project Blue: Looking for Terrestrial Worlds at Alpha Centauri

Eduardo Bendek’s ACEsat, conceived at NASA Ames by Bendek and Ruslan Belikov, seemed to change the paradigm for planet discovery around the nearest stellar system. The beauty of Alpha Centauri is that the two primary stars present large habitable zones as seen from Earth, simply because the system is so close to us. The downside, in terms of G-class Centauri A and K-class Centauri B, is that their binary nature makes filtering out starlight a major challenge.

Image: The Alpha Centauri system. The combined light of Centauri A (G-class) and Centauri B (K-class) appears here as a single overwhelmingly bright ‘star.’ Proxima Centauri can be seen circled at bottom right. Credit: European Southern Observatory.

If we attack the problem from the ground, ever bigger instruments seem called for, like the European Southern Observatory’s Very Large Telescope in conjunction with the VISIR instrument (VLT Imager and Spectrometer for mid-Infrared) that Breakthrough Initiatives is now working with the ESO to enhance. Or perhaps one of the extremely large telescopes now in the works, like the Thirty Meter Telescope in Hawaii, or the Giant Magellan Telescope in Chile.

And if we did this from space, surely it would be an expensive platform. Except that ACEsat wasn’t expensive, nor was it large. It was designed to do just one thing and do it well.

While NASA turned down Bendek and Belikov’s idea for Small Explorer funding, the striking thing is that it would have fit that category’s definition. ACEsat was designed as a 30 to 45 cm space telescope (you can see a Belikov presentation on the instrument here, or for that matter, read Ashley Baldwin’s ACEsat: Alpha Centauri and Direct Imaging). The small instrument now being proposed by an initiative called Project Blue builds on many of the ACEsat concepts. It would run perhaps $50 million even though the original ACEsat was a $175 million design.

In other words, compared to the $8 billion James Webb Space Telescope, Project Blue’s instrument is almost inexpensive enough to be a rounding error. A privately funded initiative out of the Boldly Go Institute, in partnership with the SETI Institute, Mission Centaur, and UMass Lowell, the telescope shows its pedigree both in its low cost and big scientific return. It seems the ACEsat concept is just too good to go away.

So now we have Project Blue, which is all about seeing the blue of an Earth-like world around one or even both of the Sun-like stars of the Alpha Centauri system. No one discounts the value of the planet already discovered around Proxima Centauri, but the project hopes to find an Earth 2.0, a rocky planet in a habitable zone orbit around a star like our own. That would mean no tidal locking, no small red dwarf primary, and a year measured in months rather than days.

Image: An Earth-like planet around one of the primary Alpha Centauri stars, as simulated by Project Blue.

The project’s new Indiegogo campaign has been set up to raise $175,000 to help establish mission requirements, including the design of an initial system architecture to which computer simulations can be applied by way of testing ideas and simulating outcomes. The launch goal of 2021 is ambitious indeed, as is the low $50 million budget profile, but the project’s backers believe their work can leverage advances in the small satellite industry and imaging systems to pull it off. An explicit goal is to engage the public while tapping the original NASA work.

The project’s connection to NASA is in the form of a cooperative agreement explained on the Indiegogo site:

The BoldlyGo Institute and NASA have signed a Space Act Agreement to cooperate on Project Blue, a mission to search for potentially habitable Earth-size planets in the Alpha Centauri system using a specially designed space telescope. The agreement allows NASA employees – scientists and engineers – to interact with the Project Blue team through its mission development phases to help review mission design plans and to share scientific results on Alpha Centauri and exoplanets along with the latest technology tests being undertaken at NASA facilities. The agreement also calls for the raw and processed data from Project Blue to be made available to NASA within one year of its acquisition on orbit via a publicly accessible online data archive. The Project Blue team has been planning such an archive for broadly sharing the data with the global astronomical community and for enabling citizen scientist participation.

And I notice that Eduardo Bendek is among the ranks of an advisory committee (available here) that includes the likes of exoplanet hunters Olivier Guyon, Debra Fischer, Jim Kasting and Maggie Turnbull. But have a look at the advisor page; every one of these scientists is playing a significant role in our discovery and evaluation of new exoplanetary systems.

Thus we can say that ACEsat lives on in this new incarnation that will benefit from the input of its original designers. The spacecraft would spend two years in low Earth orbit accumulating thousands of images with the help of an onboard coronagraph to remove light from the twin stars, along with a deformable mirror, low-order wavefront sensors, and control algorithms to manage incoming light, enhancing image contrast with software processing methods.

Unlike the major observatories we’re soon to be launching — not just the James Webb Space Telescope but the Transiting Exoplanet Survey Satellite (TESS) — the Project Blue observatory will be dedicated to a single target, with no other observational duties.

A photograph of an Earth-like planet 40 trillion kilometers away gives us a sense of the changes in scale that have occurred since Voyager 1’s ‘pale blue dot’ photograph. But we already knew that Earth was inhabited. Now, gaining spectral information about a blue and green world around a nearby star would allow us to determine whether biosignature gases could be found in its atmosphere, potential signs of life that would mark a breakthrough in our science. The degree of public involvement assumed in the project makes the quest all the more tantalizing.