Principal-Investigator-Led Missions in the Space Sciences (2006)

Each PI-led mission line in the space sciences serves a different community and targets an area of space science, as described in the announcements of opportunity (AOs).¹ (Program descriptions from recent AOs are summarized in Appendix C.) The missions that have been selected to date under the Explorer and Discovery programs and their status are summarized in Tables 2.1 and 2.2, which also include a brief description of the key science goals and accomplishments of each mission.

The Explorer Program is NASA’s oldest flight program dedicated to science investigations—Explorer 1 was launched January 31, 1958. Swift,² the most recent (it launched successfully on November 20, 2004), is the 84th Explorer and the third mission in the Medium-class Explorer (MIDEX) line.

The purpose of the Explorer Program is to provide frequent flight opportunities for spaceborne scientific investigations that meet the objectives of the Astronomy and Physics Division and the Heliophysics Division of NASA’s Science Mission Directorate. Initially an essentially core mission program with PI-provided instruments, the Explorer Program was active during the 1960s and 1970s but became relatively inactive during the early 1980s. Activity decreased when NASA anticipated that the space shuttle would be the preferred launch vehicle for most Explorer-class investigations. Following the loss of the shuttle Challenger, this strategy was reconsidered, and in 1988 the Explorer Program was reconstituted. At the same

time, NASA also transitioned from large facility-class Explorers, such as the Cosmic Background Explorer (COBE), the Advanced Composition Explorer (ACE), and the Rossi X-Ray Timing Explorer (RXTE), in which the implementing NASA center was assigned the primary technical management role, to smaller and competed PI-led Explorers, in line with the PI mode established for the Discovery Program. The introduction of cost caps on the RXTE and ACE missions was part of this transition. NASA Goddard Space Flight Center (GSFC) participated in the development of a series of Small-class Explorer (SMEX) missions that allowed for increased levels of PI leadership but maintained project management responsibility at GSFC—for example, Transition Region and Coronal Explorer (TRACE), Submillimeter Wave Astronomy Satellite (SWAS), and Wide-Field Infrared Explorer (WIRE). Once its development phase was complete, the Far Ultraviolet Spectroscopic Explorer (FUSE) became the first mission fully led by a PI and cost-capped. There are currently three categories of Explorer missions: University-class Explorers (UNEX),³ SMEX, and MIDEX.⁴

The UNEX, SMEX, and MIDEX mission lines presently have cost caps of $15 million, $120 million, and $180 million, respectively, adjusted for inflation at the discretion of NASA depending on the circumstances of selection timing or delays. The cost cap for each of these mission lines has been adjusted over time with each new AO. Each AO also solicits proposals for missions of opportunity (MoOs).⁵ Since 1988 there have been one UNEX AO, five SMEX AOs, and three MIDEX AOs. The selection of additional UNEX missions is on hold pending the availability of a suitable small (<$10 million) U.S. launch vehicle. The currently operational PI-led Explorers include FUSE, Cosmic Hot Interstellar Plasma Spectrometer (CHIPS), Galaxy Evolution Explorer (GALEX), Imager for Magnetopause-to-Aurora Global Exploration (IMAGE), Ramaty High Energy Solar Spectroscopic Imager (RHESSI), Swift, and Wilkinson Microwave Anisotropy Probe (WMAP), along with High-Energy Transient Explorer-2 (HETE-2), a mission of opportunity. Programs now in development include Time History of Events and Macroscale Interactions during Substorms (THEMIS), Wide-field Infrared Survey Explorer (WISE), Aeronomy of Ice in the Mesosphere (AIM), Interstellar Boundary Explorer (IBEX), and Nuclear Spectroscopic Telescope Array (NuSTAR), along with Coupled Ion Neutral Dynamics Investigation (CINDI), Two Wide-Angle Imaging Neutron-Atom Spectrometers (TWINS), and Astro-E2 as missions of opportunity. The Explorer Program has a strong association with the Explorer Program Office, which is located at GSFC (see Chapter 4).

The Discovery Program was created in the early 1990s era of faster-better-cheaper. Its goals, as stated in 1992, were to “increase flight rates and launch schedule certainty, complement large missions to keep a steady rate of incoming planetary data, broaden university and industry participation in solar system exploration missions, and increase public awareness of solar system exploration missions.”⁶ Discovery Program rules are very similar to those of the Explorer Program but have additional constraints—namely, predefined budgetary profiles and launch within a defined time frame. The cost cap for the Discovery Program remained fairly constant at approximately $330 million but then increased to $360 million for the 2004 AO and to $425 million in 2006 in real-year dollars.⁷ In 1999, NASA Headquarters created a

Discovery Program Office staffed by civil servants and located at the Jet Propulsion Laboratory (JPL) and then, in 2004, moved it to the Marshall Space Flight Center (MSFC) (see Chapter 4).⁸

To date, 10 Discovery missions have been selected for flight. The first two Discovery-class missions, Near Earth Asteroid Rendezvous (NEAR) and Mars Pathfinder, were carried out as predefined facility-class style missions and managed by NASA Headquarters. These two missions had scientific leadership by PIs but do not fit the definition of PI-led missions used for the present analysis. The remaining eight Discovery-class missions were competed PI-class missions. The currently active Discovery missions include Stardust,

Messenger, and Deep Impact. The first two of these missions have been launched but their prime data sets have yet to be returned. Deep Impact reached its cometary target and its results are under analysis. Two missions now in development include Dawn and Kepler. (See Table 2.2 for a list of all Discovery flight projects.)

The New Frontiers Program was introduced in 2002 to further enable PI-led missions to explore the solar system and/or return samples for study. A recent decadal survey of the NRC⁹ recommended five Medium-class mission investigations as an initial target set for New Frontiers missions: Comet Surface Sample Return, South Pole Aitken Basin Sample Return, Venus In Situ Explorer, Jupiter Polar Orbiter with Probes, and a Pluto/Kuiper Belt mission, now awaiting launch at Kennedy Space Center. The first New Frontiers competition led to New Horizons, a Pluto/Kuiper Belt mission. The other four investigations comprised the possible set of solar system targets for the 2003 New Frontiers AO. NASA recently selected Juno, a Jupiter Polar Orbiter with Probes, as the second New Frontiers mission. The NASA Science Mission Directorate budget through mission completion for each of these missions can be up to $700 million, in FY 2003 dollars, the largest cost cap for any PI-class mission. These missions may employ radioactive power sources and evolved expendable launch vehicles, such as the Atlas V or Delta IV. The New Frontiers rules are very similar to those of the Discovery Program except for the larger cost cap and the constraint that missions should launch within 4 years of NASA approval of the concept and preliminary mission design studies.¹⁰

Program management for New Frontiers resides within the joint Discovery/New Frontiers Program Office at MSFC.

The Mars Scout Program, which had its start following the post-Mars mission loss program reevaluation,¹¹ has as its primary goal the launching of scientifically focused missions to Mars. Mars Scout missions are intended to augment or complement, but not duplicate, major missions being planned as part of NASA’s Mars Exploration Program or those currently under development by foreign space agencies. The first Mars Scout mission opportunity requires a launch before December 31, 2007, and has a cost cap of $325 million (FY 2003 dollars). NASA selected the Phoenix Lander, which will search for water and complex organic molecules in the northern polar regions of Mars,¹² to be the first Scout mission for the 2007 opportunity. The Scout mission after that is planned to launch in 2011, though no AO has been issued. Future Mars Scout opportunities are also planned to occur quadrennially—that is, at every other favorable Mars launch opportunity.¹³

The Mars Scout Program follows many of the rules established for the Discovery Program, except that it is restricted to Mars science. NASA’s Jet Propulsion Laboratory manages the Mars Scout Program within the Mars Exploration Program for the NASA Science Mission Directorate.

In the early years of the Explorer and Discovery programs, there were facility-class or hybrid missions in which the spacecraft and mission operations were provided by the Explorer Program itself.¹⁴ Solar Anomalous and Magnetospheric Particle Explorer (SAMPEX), Fast Auroral Snapshot Explorer (FAST), WIRE, SWAS, COBE, RXTE, and ACE (see Figure 1.1) are examples of facility or hybrid missions developed under the Explorer Program. NEAR and Mars Pathfinder are examples of facility or hybrid missions from Discovery. During the development of these missions, the competitively selected PIs were responsible for one or more instruments, the science operations, and the data analysis. The PIs set the requirements for the spacecraft and worked closely with the program office to ensure that the spacecraft and mission operations met the scientific requirements. PI costs were capped and the PIs were responsible for devising the best organizational approach to accomplishing their responsibilities; in many ways these missions resemble the PI-led missions discussed in this report. Although missions of this type are not the present concern of the committee, this study has benefited from some of the lessons learned from such missions.¹⁵

To date, the PI-led missions listed in Tables 2.1 and 2.2 have involved PIs from academia, industry, nonprofit organizations, and NASA centers. The PIs have had a range of experience in the technical/engineering and management areas. As mentioned above, some PIs run their projects in a hands-on mode and are as much technical managers as they are project scientists, interacting on a daily, if not hourly, basis with the hardware development effort. These PIs have typically gained experience by playing key roles in major instrument investigations on core missions or by leading major suborbital projects. They are often located at laboratories that specialize in flight hardware design and provision. Other PIs have significant technical management experience from high-level home institution and/or interinstitutional teaming activities that involve various types of scientific and technical organizations. These PIs often have access to local infrastructure geared toward supporting large projects. Others are traditional space scientists—physicists, astronomers, planetary geologists, or astrobiologists—who reside in college and university environments where they teach, advise graduate students, and carry out research. Even if their own research has emphasized experimental technology, these PIs rely heavily on technical expertise available at other institutions in putting together their PI-led mission team. Of course most PIs overlap all three of these categories to some extent.

Project managers (PMs) are the PI-appointed (or agreed-on) technical leads for mission implementation. A PM may be at the same institution as the PI or may be part of the teaming agreement with a NASA center or other institution. The PM is not always named or even known at the time the mission is selected by NASA for development. (Explorers do not require a PM to be named in the proposal; Discovery and

New Frontiers mission lines do require naming a PM in the concept proposal). The backgrounds of PMs, like those of PIs, are diverse. Some PMs segue into projects from other but similar mission roles, some come from other flight projects or large technical projects, and some are new to such tasks. To a large extent, the appropriateness of a PM’s preparation lies in his or her institutional affiliation. Much of the experience necessary for fulfilling project management responsibilities is available and can be obtained at a NASA center that routinely provides PMs for PI-led missions, an aerospace company that builds space hardware, or a government or academic laboratory with a history of delivering major instruments for missions. The supply of experienced PMs is, however, limited, and PIs must compete for a good PM (see the section “Proposing Team Experience and Leadership,” in Chapter 7). A NASA center, or any other institution, will provide a PM only if that is the agreed-on role of that organization on the PI’s team. A PI who intends to use a NASA center PM must arrange to do so as early as possible.

NASA centers play the third key leadership role in the PI-led mission organization. Each PI-led mission line—Explorer, Discovery, Mars Scout, and New Frontiers—encourages the involvement of NASA centers. PI programs deal with unique challenges related to the high-level partnering between a PI and the NASA center and the associated divisions of responsibility for the technical management of the mission. The Explorer Program Office has been located at GSFC for nearly the entire history of the program. Explorer PIs can consult or engage GSFC in their project management and technical support functions, although other institutions or centers can be contracted to manage a project or to provide the spacecraft. The Applied Physics Laboratory (APL) and JPL were originally designated as participating centers for the Discovery Program. Such restrictions have recently been relaxed. Although Discovery, Mars Scout, and New Frontiers PIs may now propose with any NASA center, company, or academic institution in a lead role, they often partner with JPL (a federally funded research and development center) or APL (a not-for-profit organization) because the capabilities available at those institutions make them strategic, attractive, and convenient partners. The combined Discovery/New Frontiers Program Office was recently relocated from JPL to MSFC, in part because some PIs competing on those programs are located at JPL. The Mars Scout Program Office is currently located at JPL, which is also the home of NASA’s Mars Exploration Program Office. (Chapter 4 describes program offices in detail.) Because of the high demand for and limited resources available to support PI-led proposals, some organizations limit the number of proposals they participate in. Various internal selection practices are used for this purpose, depending in large part on the special interests or expertise of the NASA center or the company in the topic or concept being proposed. Thus there is likely to be an element of preselection associated with the role of a NASA center or a company in PI-led missions.

Regardless of the institutional choices and arrangements for PI-led missions, the PI, the PMs, and the lead center must work closely to organize all aspects of the project, from proposal to launch. From the beginning they must have a total understanding of the mission and of their own responsibilities and authority. When a partnering NASA center or company is asked by the PI to provide a PM, it is often the case that one individual acts as PM during the proposing phase and another takes over after selection. In such cases the second PM inherits the cost cap, basic implementation scheme, and partners engaged by the proposing team. His/her agreement with the original plans is not guaranteed, so that working relationships and strategies must often be adjusted during the postselection phases of the mission.