Findings and Recommendations
Key Findings
Piggyback opportunities abound. Prudent mission managers maintain contingency margins. These margins can turn into piggyback opportunities late in the mission development cycle. For example, during payload integration and spacecraft assembly, ballast is often used to correct the center-of-mass. A self-contained piggyback payload with the right characteristics could replace the ballast and provide valuable science data or technology demonstrations. In this way, piggyback payloads can amplify the science return of expensive missions at relatively low cost. Some opportunities of significant interest to astrobiology include:
Mars orbiter and lander missions launching every two years (see Mars Exploration Program and Exobiology Strategy )
Space Station early assembly phases beginning 1999 -- piggyback opportunities on both Space Station and Space Shuttle are available.
Missions to comets and asteroids, especially Near Earth Asteroid Prospector (launching 1999-2000), Muses (2002), Contour (2002), ROSETTA/Champollion (2003)
Europa Orbiter (2003)
Pluto Express (2004)
Solar Probe (2007)
Leonid Meteor Storm 1998-1999
A wide array of Earth sciences missions
Space science missions
Space Shuttle flights
Analog and extreme environments on Earth
The piggyback strategy yields important new primary payload concepts. As workshop members struggled to fit scientifically useful payloads within tight mission margins, miniaturization was the enabling approach. This strategy yielded obvious benefits. By developing miniaturized components, suites of instruments can be used to execute a multipronged attack on the difficult problems of characterizing prebiotic chemical evolution or searching for extant or extinct life. Carried one step further into the primary payload class, suites of instruments may be deployed where only one classically designed instrument used to fit. This approach can dramatically amplify science return on future missions.
Analog environments are necessary for astrobiology science and for missions and technologies testbeds. Extreme environments on Earth, from deep sea vents, missions to the stratosphere (infall of extraterrestrial material, high altitude ecology, and high altitude biota), Arctic/Antarctic, geothermal vents, glacier cores, deep subsurface, caves, etc., help define origin of life issues, evaluate strategies for characterizing habitable zones on other worlds, and characterize the envelope of life as a guide to detecting life elsewhere. At the organism level archaebacteria, extremophiles, metazoans, and organisms most studied for genomics research were cited most frequently as the species-of-choice for a wide variety of astrobiology studies.
Space Station offers a surprisingly broad set of capabilities for astrobiology studies. Exterior payloads on Space Station can collect interplanetary and interstellar dust particles. Using aerogel capture strategies developed for the Stardust mission, some of these can be collected intact enough for organic analyses. The early Space Station is a particularly interesting platform for astrobiology piggybacks exploring co-evolution of life and the environment and testing our understanding of ecosystem dynamics, engineering artificial ecosystems, and sustaining them over prolonged periods of time in extraterrestrial environments. Other studies supported by this platform include definitive characterization of the environment/organism interface in microbiology, and general cell and microbiology studies. Of particular interest to astrobiology is the ability to explore the potential for the evolution of terrestrial life beyond Earth by characterizing the process of the evolution of terrestrial life in space, beginning with the simplest organisms and building the knowledge base over decades to increasingly complex organisms.
Key Recommendations
Embrace miniaturization. Piggyback opportunities are enabled by using tiny, low power, low mass, low volume instruments. These capabilities allow piggyback missions to fit within mission margins. DS2 is an outstanding example of this philosophy. See also Ion Mobility Spectrometer, Sensors 2000 and Mission to the Solar System examples.
Be ready to go. Piggybacks are opportunistic. Because prudent mission managers will hold contingency margins as long as possible, there will be little time to develop either unique instruments or unique interfaces to the mission architecture. Instruments that fit within all the mission constraints and are ready to go will be selected. This implies that technology development needs to be advanced to flight qualification for the highest priority instrument candidates.
Work with the mission managers. Even ballast needs to be planned in space missions. Since piggyback payloads need to interface with spacecraft power, data, communication and other services, they need to be actively integrated into the mission architecture. Therefore, piggybacks will only be deployed with the support of mission management. Again DS2 is an outstanding example of success in this area.
Mine existing data. Data mining is another form of piggyback science opportunities. As our knowledge increases, old data has new meaning and is seen in a different perspective. There is a wealth of data from hundreds of space, earth, and life sciences missions that can be examined in new ways. This examination may yield important new insights. At the least, this data is an important resource for student investigations. Some sources for this information include: NASA Data Archives, Global Change Master Directory, EOSDIS Version 0, and NASA Life Sciences Data Archives
We should no longer conduct planetary missions as if we are only visiting the planets once. Investments in infrastructure (e.g., developing a communication network in deep space, the ability to re-charge batteries on Mars, capability to refuel) dramatically amplify the science return of multiple planetary missions by reducing the necessity to carry redundant infrastructure on each mission. These may also extend the operating life of payloads in situ.
Consider an "afterlife" for deep space vehicles. Providing infrastructure in deep space is an expensive undertaking, yet its availability would provide new science opportunities and enable piggyback and other creative new explorations. If possible, spacecraft reaching the end of their missions should be used as part of a communication network in deep space or some other secondary purpose that takes advantage of their unique location and embedded infrastructure.
Some high priority ready to go instrument components are recommended. Certain astrobiology instruments are "givens" for exploring planetary bodies. Similarly, certain biological instruments are givens for Space Station investigations. These should be identified, prioritized, developed, tested, and multiples should be available on the shelf and ready to go. Not only will this amplify flight opportunities, it will allow instrument development to proceed in the most cost effective manner, neither artificially accelerating nor stretching out an optimum development cycle.
Issues:
Enabling access to astrobiologically important sites throughout the solar system is a key challenge -- perhaps the key challenge to answering the highest priority astrobiology questions. In addition to searching for surface sites where fossils of extinct Martian life may be found, it is essential to search for extant water and, if found, to access the hydrosphere to search for extant life. In addition, core samples and/or access to sites that reveal Mars’ chemical evolution and climate history from the origin of the planet to the present are high priorities. (See Exobiology Strategy Report) On Europa, there is keen interest in developing missions and instruments which enable us to detect a subsurface hydrosphere (if any), obtain core samples to assess Europa’s chemical evolution over time, and if water is found, to search for life. On Titan, probes that enter and characterize the atmosphere, the surface, and details of its environment are required. On comets, studies that help determine their chemical histories, especially the extent of their prebiotic chemical evolution, and enable comparative studies among comets (and asteroids), and measurements that reveal the processes that formed our solar system are of significant interest. Regardless of locale, the general approaches for accessing sites of high astrobiology interest involve orbital or suborbital remote sensing, in situ surface instruments at multiple sites, drilling or core samples and in situ studies at various depths, and sample return missions. Accessing all of these astrobiologically interesting regions requires new approaches and technologies and in a number of cases, new mission concepts.
High priority instruments and measurement systems identified for Astrobiology are not ready to take advantage of either important piggyback opportunities or to compete successfully for primary payload space. Readiness to fly is the single most important factor enabling piggyback payloads and is a critical factor in selecting many flight experiments. For piggyback missions, readiness means demonstrating that the payload will not negatively affect the mission and will work as intended in the operating regime. This must be done in high-fidelity simulation environments, if not in space. Development of mission specific interfaces as well as the instrument itself is also required. Sample acquisition, preparation, and preservation technologies are showstoppers because the state of the art lags so far behind the miniaturized sensors and analytical instruments. For example, the life sciences laboratory equipment developed for Space Shuttle biological research has enabled well over 500 investigators to conduct research in space since 1990 at relatively low cost and to respond to unexpected flight opportunities on Mir and other vehicles as well
Inventive mobility systems must be developed for Mars and other worlds. While not a piggyback issue per se, there was general consensus among workshop participants that new means of exploring Mars, including balloons, airplanes, refuelable hoppers, and other devices which can provide greater terrain coverage with higher resolution imaging, were highly recommended. Not only would these be exciting to the public, they would significantly increase general science return and site selection for life detection. The strategy of orbital coverage, suborbital, and ground truth is as important for Mars exploration as it is for Earth studies and this analogy may be extended to Europa and Titan as well.
Fair mechanisms for selecting piggyback payloads are required. This is a challenge because piggybacks will be chosen late in the development cycle. Therefore, selection criteria will be driven more by readiness and mission impact than by any other criteria. However, it may be possible to release a call for proposals early in the mission development cycles to obtain "standby" candidates, develop them, then select a smaller subset to fly based on mission accommodations and constraints later in the mission development cycle.
Conclusion:
Confluence of new miniaturized technologies and piggyback approaches can cause novel payload opportunities to be enabled within missions already planned. Moreover, they make new missions better, faster, cheaper, and smaller. The array of mission opportunities, when coupled with the advances in miniaturized imaging and analysis technologies, increased mobility options, and piggybacking strategies, reveals that the science yield from the suite of planned missions can be significantly amplified.