Using Spacecraft To Discover Life in Our Galaxy
Is there life elsewhere in the universe? This question has been asked since humans evolved to the level of looking up at the stars in wonder. As we advanced technologically in the past century we became enabled to consider approaches to begin this quest. We selected and unsuccessfully pursued a radio astronomy-based approach for the past 50 years. While this effort advanced radio astronomy and related disciplines, no meaningful data have been received.
It is time for a better approach. We need to explore recently discovered exoplanets in habitable zones with new technology — using optical rather than radio wavelengths. This can lead to the next scientific revelation.
The approach would consist of a spacecraft with an infrared telescope in solar orbit that would continually receive biological data from exoplanet atmospheres in our galaxy. There would be no waiting and hoping to receive radio signals transmitted by intelligent beings, and the received optical data would not be restricted as with radio astronomy to only intelligence-generated signals. We would be capable of receiving information from all life-form permutations in any evolutionary state, from microbial to intelligent levels, based on biological activity.
Fifty years of waiting and hoping for radio signals from outer space using the Search for Extraterrestrial Intelligence (SETI) program that theoretically is capable of detecting intelligence-generated signals has returned no results. In addition, we spent the same 50 years flying-by, orbiting and landing on planets and other bodies in our solar system using sophisticated instruments to search for life forms. These missions, while highly successful in many aspects, also did not find evidence of any level of life, past or present.
NASA decided it will not look for life on Mars with the Mars Science Laboratory and its surface rover Curiosity, launched in November at a program cost of $2.5 billion. Instead, Curiosity is to investigate whether life could have existed there. This is a major capitulation for discovery expectations. This can be corrected by exploring elsewhere than in our solar system, where it has proved difficult to find life except on Earth. With advancing technology it is expected to be easier to discover flagrant life on exoplanets rather than subtle life in our own solar system.
All of this — the time that has passed, the huge cost, the lack of results from radio astronomy and the current direction of NASA — helped encourage the design of the proposed Exoplanet Explorer Spacecraft. The design offers an immediate and solid probability of data return related to the presence of life forms on exoplanets. No waiting would be required.
The proposed spacecraft would receive spectrographic information of Earth-size exoplanet atmospheric constituents. Viewing meaningful spectrographic wavelengths of exoplanet atmospheres requires a clear view from outside the Earth’s atmosphere. The platform to implement this is the proposed Exoplanet Explorer Spacecraft, consisting of a telescope with a cryogenically cooled digital focal plane operating in a solar orbit.
The telescope would capture spectrographic data in the visible and infrared regions, requiring cryogenic cooling of the focal plane. A spacecraft location shielded as much as possible from the sun’s heat load would maximize the lifetime of the cryogenic supply. There is a unique orbit location at the L2 Lagrange point where the Earth’s disc blocks 85 percent of the sun. This point is on a line extending from the sun to the Earth, 1.5 million kilometers farther away from Earth. Here the spacecraft would orbit the sun in synchronism with the Earth and constantly be partially shielded from the sun. Layers of super-insulating material would provide an effective large-area, lightweight heat shield on the base of the spacecraft, offering protection from the portion of the sun not shielded by the Earth and from Earth and Moon heat radiation.
The received spectra of the chemical constituents from exoplanet atmospheres would be analyzed using the “Lally Life-forms Probability Index” to rate biological activity. A “bioprint” of chemical components would be compiled for each exoplanet. The data would be inserted into a library of spectra templates of atmospheric constituents, conducive to life as we know it covering evolutionary epochs, and compared. The data-fit to biologically active spectra would be rated and the probability index determined for each exoplanet. Seemingly extraneous data also would be retained and analyzed to begin another revelation, that of understanding atmospheric constituents of life as we do not know it, of potential alien and extremophile life forms.
The Exoplanet Explorer Spacecraft design, with low-risk technology, is proposed to redirect efforts by employing spectroscopy to advance our understanding of the existence of life forms outside the solar system, helping to answer the question, “Are we alone”? A positive answer would transform the perspective of our significance in the universe. This would produce the next scientific revelation related to discovering life in a timelier manner than with current ground-based radio astronomy.
Compare this mission with the bogged-down James Webb Space Telescope (JWST), whose prime mission is to look deeper into where the Big Bang originated. Initially scheduled for launch in 2007 at a cost of $1.6 billion, JWST is now scheduled for launch in 2018 with an expected cost of $8.8 billion, and additional schedule slips and cost overruns are possible. Is discovering life in the galaxy more scientifically useful than looking deeper toward the Big Bang’s origin? If so, the Exoplanet Explorer Spacecraft looks like a good direction to turn to.
Eugene F. Lally is a pioneer space scientist originally at the Jet Propulsion Laboratory, where he designed spacecraft for initial unmanned planetary missions. In 1961 he created digital photography for real-time on-board navigation capturing star, planet and asteroid locations. This concept, eventually called “AutoNav,” is used for autonomous navigation on unmanned spacecraft and was a model for consumer digital camera designs, spacecraft cameras and telescopes. This commentary is a summary of three articles published by the American Astronautical Society.