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Cross-Cutting Issues
A number of issues were mentioned in multiple workshop plenary sessions or breakout groups and are thus included here as cross-cutting issues. A detailed treatment of any of the issues is beyond the scope of the workshop; however, summaries are included here for completeness.
SYNERGY VERSUS COMPETITION WITH DECADAL SURVEY
As noted in the statement of task for the workshop, NPOESS/GOES-R mitigation strategies should take into account the plans for execution of the recent National Research Council (NRC) Earth science decadal survey.1 However, it is important to note that the decadal survey covers all of Earth science, including, but not limited to, climate science. Discussions at the workshop focused on climate science; however, the ultimate implementation of NPOESS/GOES-R climate observation mitigation will occur in parallel with NASA’s intent to implement a balanced Earth science program. This will be challenging, particularly because of the very constrained Earth science budget at NASA. As highlighted in the NRC decadal survey report, Earth science budgets have declined significantly in real-year dollars, while mission costs have risen, due to large increases in launch costs, the unanticipated effects of full-cost accounting, and inflation, and as demand for and reliance on Earth science remote sensing observations have continued to increase. Some workshop participants noted that NASA and NOAA will be greatly challenged to find the appropriate balance between maintaining continuity of key climate parameters and continuing to advance Earth science; these participants also argued that this cannot be an “either/or” decision.
It was frequently noted that one way to address the challenge of balance between measurement continuity and scientific advance was to consider areas of potential synergy between options for climate observation mitigation and missions recommended by the decadal survey. As the decadal survey mission concepts mature, these synergies could be further explored to determine areas where synergy—rather than competition for scarce resources—exists.
CONTINUITY OF LONG-TERM RECORDS VERSUS NEW MEASUREMENTS
Just as climate science is one part of Earth science, so also are sustained measurements but one part of climate science. At the workshop, there was discussion regarding the need to find a balance between providing for conti-
nuity of certain key long-term climate records and advancing climate science through taking new measurements to elucidate key climate processes and initialize climate models. Again, this is not an “either/or” decision, and finding the proper balance between sustained and new measurements will be challenging.
Starting with the evident proposition that the climate science program cannot afford to continue all, or even many, remote sensing measurements indefinitely, participants sought to distinguish between measurements that represent state variables that are so fundamental that they must be continued in perpetuity and those that are valuable and have shorter-term measurement campaigns. The list of state variables should be as short as practical to allow for sustained funding commitments without overwhelming the already-limited budget and precluding new or improved measurements critical to advancing climate science. One suggestion was for implementation of a peer-review process that would periodically review the list of essential variables to consider the science justification for continuation of each sustained record, keeping the list to the minimal measurement set practical.
MEASUREMENT TEAMS
The need for sustained attention to the establishment and maintenance of climate data records (CDRs), which can involve many missions over many decades, led numerous workshop participants to suggest the need for climate measurement teams, independent of mission science teams.
CALIBRATION AND CHARACTERIZATION (PRE-, IN-, POST-FLIGHT)
During the workshop it came to the attention of participants that all subsequent flight builds of the various NPOESS instruments were not planned to undergo the extensive preflight characterization expected for the first builds. Many participants felt it was essential to urge continuation of a rigorous preflight testing and characterization program with subsequent flight builds, and to request improved documentation to increase the climate science utility of data returned from later NPOESS platforms (to date this is not currently planned). Pre-flight characterizations would ensure that the sensors are stable, as nearly identical as possible from sensor to sensor, and thus climate relevant.
FORMATION FLYING
Some participants at the workshop discussed the advantages of formation flying and how this concept, demonstrated on the Earth Observing System “A-Train,” might affect mitigation options in the future (Figure 3.1). The principal benefit of formation flying is the ability to combine multiple, synergistic measurement types without incurring the cost, complexity, and risk of large monolithic observatories—as long as sufficient pointing and position knowledge are achieved and orbits are sufficiently maintained. There are, of course, operational challenges associated with formation flight (e.g., maneuver coordination, orbit insertion, and end-of-life considerations), although these can be minimized through careful plans and procedures and by taking advantage of the lessons learned through NASA’s A-train operations. It was suggested by some participants that NASA and NOAA fully consider formation flying, including the requisite orbit maintenance and operations requirements, as a deliberate part of the mitigation strategy for restoring deleted NPOESS and GOES-R climate-observing capabilities.
STABILITY REQUIREMENTS PARTICULAR TO CLIMATE STUDIES
It was noted that even when there is perceived synergy between climate research and operational needs based on resolution, care must be taken in assessing the stability requirements that are unique to long-term trend studies and that can drive instrument design costs dramatically.
INTEGRATION ON NPOESS VERSUS FREE FLYERS: LARGE VERSUS SMALL PROGRAMS
Small programs often can succeed with a leaner systems engineering and management approach than can larger programs. Given the large national investment already made in NPOESS, agency commitments to allow for
remanifesting of canceled instrument payloads, and spacecraft margins that include on the order of a metric ton of mass, kilowatts of power, millions of bits per second of spare bandwidth, and large, unused parts of the optical bench, it is natural to consider NPOESS platforms for the flight of climate-relevant sensors. However, based on presentations from the agencies to the workshop, it appears that the incremental cost of the accommodation (integration and test, with management and systems engineering overheads) might equal or even significantly exceed the total cost of a free flyer accommodation. The lack of a cost-effective process for integrating climate payloads onto NPOESS, given the significant investment in developing the capacity to fly the payloads once integrated, is a significant impediment in terms of low-cost access to space.
Because of the extraordinarily high cost of integration with NPOESS, free flyers appear to be no more expensive, and may even be cheaper, than reintegrating the demanifested sensors into the existing NPOESS bus. The use of free-flying spacecraft to ensure the continuity of CDRs was frequently suggested as desirable by workshop participants. Free flyers provide increased launch flexibility, which decreases the risk of a gap in the measurements. It was considered noteworthy that none of the climate sensors are considered of sufficiently high priority for sensor failure to trigger the launch of a new NPOESS bus to preserve the data record. However, free flyers are not without risk, as they are typically more susceptible to cancellation compared with a single large, operational spacecraft bus. Some participants also noted that regardless of their desirability, NOAA has no history of utilizing free flyers as operational space platforms.
STRUCTURAL ISSUES ASSOCIATED WITH PROCUREMENT OF SENSORS THAT SUPPORT CLIMATE SCIENCE
Lack of an Enterprise View
Progress in climate research depends on continuous, multidecadal time series measurements for a stable underpinning as well as new measurements to advance process understanding. However, it often appears that the United States lacks such a fundamental enterprise view2 for the maintenance and stewardship of a climate observing system. Some workshop participants noted that communication between NASA and NOAA appears to be improving; however, there was continuing concern because the agencies have yet to demonstrate a pragmatic
success-oriented process that seamlessly ties together cutting-edge research demonstrations with continuity of operational measurements.
In the view of many participants, critical and unique measurement time series, such as that for over-ocean near-surface vector winds, are placed at risk through the lack of a planned transition when an existing instrument (e.g., QuikSCAT) ages and ultimately fails. Not only are improvements to existing Western Hemisphere geosynchronous atmospheric temperature and moisture profiles deferred, but the measurements themselves are also eliminated, due to a lack of agility in the block procurement process. When operational budgets are tight, there is a temptation for NOAA to declare relatively new but demonstrated capabilities (e.g., hyperspectral soundings) as “demonstrations” and then look to NASA for the funding. Similarly, NASA has indicated it would like NOAA to fund the cost of extended research missions that have operational utility. Developing a more effective national and international climate observation enterprise would greatly benefit climate science. Some participants mentioned the Earth science decadal survey recommendation, directed to the Office of Science and Technology Policy, which calls for a national plan to provide for sustained Earth observations.3
Proprietary Nature of Industry Contracts
The competitive process, properly executed, can yield better-value products and services that may be of higher quality, and lower-risk and cost, than those obtained through sole-source acquisitions. Industry invests to obtain, retain, and increase competitive advantages—and so do nations. Much of the climate observing and remote sensing technology has multiple uses. Thus, there is an understandable need to safeguard proprietary intellectual property, and a corresponding need to safeguard the purity of the procurement process. The combined protections of International Traffic in Arms Regulations, brown-outs and black-outs associated with government procurements, firewalls to separate programs and people, and competitive pressures combine to create a significant obstacle to the sharing of sensor information, and they stifle the collaboration of industry, government, academia, and nations in climate observations. Creating mechanisms for collaboration and partnership could greatly benefit climate science. For example, one of this report’s reviewers noted the progress made within the IOCCG, OSTST, and GHRSST-PP in both operational system development and reanalysis.
Minimal Insight into Algorithm Development
Algorithms and science applications represent the intellectual core of the process that turns sensor observations (inputs) into climate, weather, and other environmental products and services (outputs)—and ultimately socioeconomic benefits. Developing improved algorithms that go beyond today’s state of practice requires individuals with a deep intellectual background in specific science disciplines. For example, every improvement in spectroradiometric quality (e.g., an increase in the “bit depth” of an observation from 8, to 10, to 12, to 14 bits), while providing new abilities to resolve phenomena of interest, also creates the need for improved algorithms that untangle the desired signal from the environmental “noise.”
Many participants stated that it is critical that communities of interest, often government-academic-contractor teams with careers spent in the field, be at the center of the algorithm development process. When systems are procured in a turn-key fashion, decisions are often dominated by the highest-cost and highest-schedule-risk items (e.g., spacecraft, launch, sensor, computing system). As a consequence, a less-than-optimal algorithm development solution may be selected without community input or oversight. When algorithm development becomes decoupled from the communities of interest and practice, higher-cost, higher-risk, and lower-performing solutions can be unintended but unavoidable consequences. While recognizing that algorithms must be reliably implemented and maintained as operational code, ensuring maximum insight, oversight, participation, and leadership of the most relevant science communities could greatly benefit climate science.