From: American Astronomical Society
Posted: Friday, November 9, 2001
TITLE: Instrument Technology Development
AUTHORS (AFFILIATION): James Hoffman (JPL), Jeffrey Piepmeier (NASA/GSFC)
CONTRIBUTIONS (alphabetical): Torry Akins (JPL), Andrew Berkun (JPL), Frank Carsey (JPL), David DeBoer (SETI), Wendy Edelstein (JPL), Heidi Hammel (SSI), Ralph Lorenz (U. Arizona), Bruce Macintosh (LLNL), Roy Tucker (NOAO)
The Instrumentation Technology Development Panel (ITD) has attempted to identify the areas of recent innovations and continuing deficiencies in instrument technology as it pertains to planetary science goals and missions. Collaboration between science and technology aspects of all planetary science disciplines is crucial to the success of this task.
We conclude that the technology advances most necessary for the success of future missions (Mars Sounders, Europa Orbiter, Venus Landers, Titan Landers) are increased downlink capacity (i.e. Deep Space Network), improvements in radiation hardened and extreme temperature electronics, increased aperture sizes for radio science, on-board processing power, and increased collaboration with principle investigators.
Current State of Knowledge
While it is obvious that mission success, even mission plausibility, is strongly dependent on technical capability, it may be less obvious that improvements in technology can also lead to a greater number and/or new types of missions. Therefore, we are interested not only in identifying new types of instrumentation, but also in improving existing (even mature) technologies by reducing size, complexity, and cost. Improvements of this type not only lower mission costs, but also enable more complex instrument suites to be considered for advanced data fusion measurement concepts.
We sought to identify the short-term and long-term technological needs (new instruments) and bottlenecks (better instruments) for each of the planetary science disciplines.
Advances in Instrument Development
Advances in instrument development may benefit from work in basic research, device research, instrument sub-system development, and instrument system development. Almost by definition, the returns on investments into basic research are difficult to predict. The planetary science community has neither the resources nor the impetus to invest substantial resources in basic research that may benefit instrument development. However, investments in device development may yield substantial returns to planetary science. One reason for this is the divergence of interests between commercial and science communities. With profit margins intimately linked to the cost of large quantities of inexpensive devices, which may sell for pennies to dollars per unit, commercial interests seek ever less expensive low power devices with statistically acceptable yields. Obviously, this is not a proper business model for space-based instrumentation development. For this reason, the success of the commercial electronics market might be hindering the advance of technologies suitable to extreme environments.
While it is true that the commercial markets emphasis on cost, power, and size is increasingly in line with current space mission philosophy, the very technologies that enable cost and size reductions work to preclude their use in extreme environments. For example, CMOS (Complementary Metal Oxide Semiconductor) technology is favored by the commercial markets; it is reliable, inexpensive, and widely available. Space qualifying individual chips, however, is time consuming and costly. Serious effort needs to be expended on identifying nascent semiconductor technologies that will meet the needs of the next decade of space exploration. It is possible, given current trends, that the commercial markets will have little impact on improving the quality or capability of electronics for space-borne instruments over the next decade. Indeed, the market for space-qualified electronics is a tiny fraction of the global semiconductor market. Therefore, whether success is found in CMOS, MEMs, Silicon Carbide, Gallium Nitride, or some other semiconductor technology, the burden of advancing these technologies for space applications may fall on the science community. While direct financial support for research into low-level device technology may not be practical for planetary science interests and budgets, formal and informal lobbying for support into this research would be a way to ensure future needs of planetary science are met.
By its very nature it is difficult to predict the capabilities of an entirely new device, however, a number of new technologies are currently showing great promise. Microelectromechanical Systems or MEMS technology shows great promise as a building block for extremely small, highly rugged instrumentation. Some recent examples of MEMS applications pertinent to the planetary science community are listed:
Adaptive Lenses for Microwave Antennas
MEMs may be able to address some of the difficulties associated with instruments for extreme environments, such as the high-temperatures of Venus, the low temperatures of the outer planets, or the radiation belts of Jupiter. Missions currently under serious consideration by various researchers include the environments described above.
Since it is far easier to envision the utility of systems-level instrument development, as opposed to basic research or even device development, members of the planetary science community, but outside of specific instrument developments, were able to aid in identifying improvements that would lead to the success or enrichment of missions in their own areas of expertise. Therefore, this section contains both general input into the direction of systems-level instrument development and suggestions for improvements with specific science goals in mind.
Some obstacles to improved instruments are fairly obvious and highly dependent on device technologies and applications, such as lower power, higher resolution, increased sensitivity. Many of these traits involve trade-offs, with limitations imposed by optimization around more pressing traits. Such trade-offs are the purview of the particular instrument designer and principle investigator. However, from our survey, we have identified some of the main bottlenecks that, if improved, would yield specific increases in science volume or quantity.
Improvements to Ground-Based Systems
Unlike space-borne instrumentation, ground-based instruments are freely capitalizing on the consumer electronics market. Distributed Computing and consumer electronics may enable order-of-magnitude increases in capabilities for ground-based systems, such as the Deep Space Network (DSN) and Radio Telescopes.
The DSN is not a new piece of technology, but is currently being upgraded. Even so, with its limitations in capability and availability, data rates will become an increasingly important technology driver for designers of space-based instrumentation. It is incumbent upon the space science community to push for increased capacity of the DSN if large numbers of data intensive instruments are to be viable. Imaging instruments of any type (i.e. SAR, optical, IR) tend to be popular with scientists and the public alike, but are notorious for generating copious amounts of data return. Serious consideration should be given to increasing the capabilities of the DSN further and to developing new communication technologies such as optical communication systems.
An example of new instrumentation for ground-based technology is the SETI Institutes Allan Telescope Array (ATA). The designers of this array are leveraging consumer electronics technology to construct an advanced instrument. The ATA will be capable of covering the spectrum from 0.5 to 11.2 GHz, with up to four concurrent users. This will enable its use as both a science instrument and as a possible tracking station for multiple Mars missions. The base technology for this instrument is derived from commercial satellite broadcasting. Of course the necessary modifications and integration issues are nontrivial, but by leveraging off the commercial product, the designers take advantage of market driven technology innovation, which no science mission, regardless of funding level, could hope to match.
Improvements to Space-Based Systems
The limits placed on the resolution of radio frequency, microwave, and millimeter wave instruments by fundamental physics demand larger aperture sizes. To meet the demand for space-based instruments of this class, serious efforts need to be expended on developing technologies such as large (10s of meters) deployable antennas and antenna constellations. More development is also required for efficient far-infrared detectors and antennas. Research into this area would make possible or improve missions to detect sub-surface water on Mars, sub-ice oceans on Europa, high-resolution mapping of the surface of Io, Triton, and other interesting moons.
Along with antenna technology, these same missions/instruments will require increased DSN time unless on-board processing technology can be improved and approved. This means that so-called smart systems must not only be developed, they must be pressed into service in actual science gathering missions. High-resolution passive or active imagers produce large data sets that are cumbersome to down link. Efficient compression algorithms can reduce data rates, but only so far. More efficient lossy compression algorithms are available, but some within the science community deem their use unacceptable. On-board processing must be employed if large numbers of high-resolution imagery missions, such as Mars and Europa missions, are to be successful. Such on-board processing requires more than simply research into computer models or so-called artificial intelligence agents; to fly it requires hardware. Further investment into radiation-hardened solid state RAM and programmable logic, such as field programmable gate arrays (FPGAs), are required before serious consideration can be given to missions that envision long-term investigation of high-value targets such as Europa. Space qualified programmable logic devices are useful because one device can be targeted to many applications. For example, specific microprocessors can be programmed into an FPGA, or software algorithms conventionally executed on a CPU can be implemented in hardware using a programmable logic device. Qualifying one line of FPGAs can make many different processors and algorithms functionally available to space flight systems designers.
Another option for relieving the strain on the DSN, enabling order of magnitude increases in data rates, is optical communications. Many technological challenges currently make this option difficult to implement, but success in this area would bring real returns in data collection capacity.
Missions to extreme environments require devices and systems capable of withstanding those environments. Research into alternatives to standard silicon technology, such as GaN, SiC, and MEMs, are necessary to mounting serious missions to extremely hostile locations. Ultra-low temperature electronics are required for in-situ missions to Titan (~95 K) or Triton (~50 K). Ultra-high temperature (~500 K) electronics are required for in-situ missions to Venus and perhaps to Ios volcanoes. For mission concepts, such as the Titan Aerobot (and various Mars Scout mission concepts), these devices must be light and low power, as well as rugged. As previously stated, current technology may allow one to optimize one of these parameters, but meeting all requirements is possible only with advances in technology.
A popular concept for planetary research is the use of multiple sensors/craft (anywhere from a handful to many dozens) to blanket large areas with detailed in-situ sensor coverage. This requires advances in almost every technology area previously mentioned. Lightweight, low power probes have been envisioned to cover sections of Mars, Europa, and Venus, and to swarm through the atmospheres of the Gas Giants, Mars, and Venus. These missions, while extremely interesting, require advances in autonomy (even if the probes are dumb, the mothership must have some decision making capability), lightweight electronics, low power electronics, and down link capacity. Every year, interesting missions of this type are proposed, at least on posters, but are limited in their plausibility and utility by lack of technology and risk aversion.
Maintaining Capabilities for the Future (and Outreach)
Even highly motivated students may find difficulty pursuing careers in technology development in the specific market of space exploration. University research laboratories routinely receive large donations in money and equipment in exchange for research into high-risk commercial ventures. This practice benefits the university, the commercial interest, and usually the student, but funnels future researchers into highly specific commercial fields. Increasing expenditures to university researchers is an obvious remedy, but difficult for the decreasing budgets in planetary science. A less expensive approach is to develop and nurture programs to expose interested students to high-profile missions.
Another approach to expose students to technology development for planetary exploration is through leveraging existing programs, such as E-Week (National Engineers Week), which occurs around February each year. Since engineering students are the most likely to get involved in technology development, this type of exposure would bring high visibility. The involvement of the planetary community could be as great as sending representatives to individual E-Week activities are as little as sending information regarding technology development to E-week organizers.
Similar programs for younger students could also benefit from increased support from the science community. Technology competitions, such as NASAs FIRST Robotics competition, are excellent opportunities for high-profile scientists to show their support for advancing technology for space exploration
A valuable (and inexpensive) way to increase support for technology development is to increase communication between the planetary science community and the technology development community. A few versatile people make serious contributions to both fields and should be sought as conduits for information flow.
Summary of Technology Needs
Currently identified areas (non-inclusive) requiring technology development:
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