Solar and Space Physics Get a Detailed 10-Year Plan

An array of large, medium, and small spacecraft, including the canceled solar probe flight into the Sun’s atmosphere, should be launched over the next 10 years as part of a “time ordered” mix of projects to better understand the Sun and the Sun–Earth environment, according to a National Research Council report. Put together over 18 months by a 15-member solar and space physics survey committee, the report lays out a literal flow chart of NASA, NSF, and National Oceanic and Atmospheric Administration (NOAA) projects based on “scientific importance, technological readiness, and synergy among different programs,” said committee member James Burch of the Southwest Research Institute in San Antonio, Texas.

The report, released in early August, contains recommendations for programs separated into three basic categories: moderate programs (mostly space missions costing between $250 and $400 million); small programs (costing less than $250 million); and “vitality” programs that are not missions per se, but recommendations to improve solar theory, modeling, information, and education programs to reenergize the field.

The report also calls for NASA to restore the $650 million solar probe mission, which was canceled last year. That mission was designed to put a spacecraft within four solar radii of the Sun’s surface, and is viewed as having “especially high scientific value,” said committee chairman Louis Lanzerotti, a physicist with Bell Laboratories, Lucent Technologies, in Murray Hill, New Jersey.

Although the solar probe mission is important, the committee realized that there is no money for the project in NASA’s budget, Lanzerotti said, so the committee took two approaches to recommending the flight. “The solar probe is the highest priority as a major mission, but you can’t do the solar probe at the same time you do all of the other missions unless you have an add-on of funding,” he said. Without extra money, the committee concluded, the solar probe would have to move from the front to the end of the line of committee-endorsed projects. For all of the recommended projects, the committee provided alternative flow charts based on whether the solar probe mission gets new funding and goes early or moves to the back of the queue.

The report, titled The Sun to the Earth, and Beyond: A Decadal Research Strategy in Solar and Space Physics , was inspired by the well-known astronomy and astrophysics decadal report. “I’m the chair of the solar and space physics committee of the [National Academy of Sciences] space studies board,” Burch said, “and my committee felt that the astronomy and astrophysics report [most recently published in 2001] was a very powerful report and had it right. Their recommendations usually get done because both the [federal] agencies and Congress feel the recommendations are from the academy and ought to guide the programs. In solar and space physics, it hadn’t been happening that way. We felt like a study needed to be done that was national in scope.”

After discussions among several scientists in the solar and space physics community and NASA officials, Ed Weiler, NASA’s associate administrator for space science, wrote a letter to the NAS, asking that the study be done. The NAS then appointed five independent panels to make recommendations on heliospheric physics; solar wind and magnetosphere interactions; atmosphere-ionosphere-magnetosphere interactions; solar theory, modeling, and data exploration; and education and society. After reviewing the panel recommendations, the survey committee set the priorities for the final report.

Fundamental questions

The report said that there are longstanding and fundamental scientific questions about the physics of the Sun, the interplanetary medium, and the space environments of Earth and the planets. To answer those questions, the committee delineated five challenges that should be at the center of solar and space physics research for the next decade:

To help meet those challenges, the committee looked at all of the federal support for solar and space physics research and then brought the programs together into a coordinated planning strategy. “The existence of ongoing NSF programs and facilities in solar and space physics, of two complementary mission lines in the NASA Sun–Earth Connection program (Living with a Star, and Solar Terrestrial Probes), and of … activities in NOAA and the Department of Defense helps facilitate such an approach,” the report said.

This integrated systems approach creates a tapestry of interwoven projects that will, if done in the appropriate order, augment each other, Lanzerotti said. Although the report gives priority rankings to missions and facilities, he said, it doesn’t mean that the lower-ranked items are less important. “It is a time-oriented ranking.”

The interconnectedness of the rankings is apparent in the report’s overview of some of the recommended projects: “As a key first element … the committee endorsed three approved NASA missions, Solar-B, STEREO, and [the] Solar Dynamics Observatory [SDO]. Together with ongoing NSF-supported solar physics programs and facilities as well as the start of the Advanced Technology Solar Telescope [ATST], these missions constitute a synergistic approach to the study of the inner heliosphere that will involve coordinated observations of the solar interior and atmosphere and the formation, release, evolution and propagation of coronal mass ejections toward Earth.”

Later in the decade, overlap from the SDO, ATST, Magnetospheric Multiscale project (a cluster of four spacecraft), Frequency Agile Solar Radio telescope, and NSF’s Relocatable Atmospheric Observatory “will form the intellectual basis for a comprehensive investigation of magnetic reconnection in the dense plasma of the solar atmosphere and the tenuous plasmas of geospace.”

NOAA’s role should grow

The committee also recommended that NOAA be responsible for operating the next satellite that collects solar wind data at the L1 Lagrangian point. NASA’s ACE spacecraft currently has that task. The L1 recommendation is one in a series of recommendations that would increase NOAA’s role in developing better monitoring and predictive abilities related to space weather. The National Space Weather program was established in the mid-1990s to study the Sun–Earth interaction and environment, but given the vulnerability of the US electrical power system and other systems to disruption by solar activity, more needs to be done, the report says.

NASA, NSF, and the other agencies affected by the report were expected to be briefed in September and hadn’t yet reacted to the recommendations, Lanzerotti said. Burch noted that science missions in the report “may not be exactly what [the federal agencies] want to do or the sequence they want to do them in, but I think overall it’s going to be very helpful.”

In addition to the projects, the committee recommended programs to improve technology so “future science objectives” in solar and space physics can be met. NASA is urged to “assign high priority to the development of advanced propulsion and power technologies required for the exploration of the outer planets, inner and outer heliosphere, and local interstellar medium.” Finally, the report does something few other science overview reports have done—it gives specific cost estimates for each of the projects recommended. The committee allowed $650 million for the solar probe mission, and the Geospace Network project is estimated at $400 million. The price for the multi-spacecraft Solar Wind Sentinels mission is set at $300 million, while the Small Instrument Distributed Ground Network, an NSF program to provide ionospheric and upper atmospheric measurements, should cost about $5 million per year

“We felt it was mandatory to make reasonable costing estimates,” Lanzerotti said. “There is no question we could fall on our face on some of these costs, but we’ve also said if something really gets outrageous [in cost], then we’ll have to rethink where it fits in the queue of projects.”