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11
The Role of Technology Development
in Planetary Exploration
The 50-year exploration of the solar system by robotic spacecraft not only has been one of the great adven-
tures in history, but also has transformed humankind’s understanding of the collection of objects orbiting the Sun.
Mission after mission, new, stunning discoveries have been made, each in its turn altering our view of the nature
of the solar system. The scientific harvest from these robotic missions has been sensational, but the extraordinary
breadth and depth of these discoveries would not have been possible without the parallel technology developments
that provided the necessary capabilities.
Table 11.1 summarizes the key findings and recommendations from Chapters 4 through 8 that are related to
technology development.
TECHNOLOGY: PORTAL INTO THE SOLAR SYSTEM
Ongoing missions underscore the value of past technology investments. For example, Dawn’s ion propulsion
engine is the essential enabling component of its unique mission to investigate two of the largest asteroids. After
a flight of nearly 4 years, Dawn will arrive at 4 Vesta to spend approximately a year, starting in the summer of
2011, making detailed observations of 4 Vesta, after which the spacecraft will cruise for another 3 years toward
its second asteroid destination, 1 Ceres. At 1 Ceres in 2015-2016, Dawn will conduct another complete scientific
investigation. Such a two-asteroid mission would not have been possible using classical chemical propulsion. Years
ago, analytic studies showed that continuous-thrust, high-specific-impulse propulsion opened up many different
mission opportunities, including missions with multiple targets. These studies triggered the technology develop-
ment program that resulted in the ion engines that are currently propelling Dawn toward 4 Vesta.
The Mars Exploration Rovers, now in their seventh year conducting scientific observations while roaming the
Red Planet, benefited immensely from significant precursor technological investments in both mobility systems and
the scientific payload. The story is essentially the same for all pioneering robotic planetary missions: they would
not have been possible, and would not have produced such extraordinary results, without the visionary technology
developments that enabled or enhanced their capabilities.
Continued success of the NASA planetary exploration program depends on two major elements. It is axiomatic
that the sequence of flight projects must be carefully selected so that the highest-priority questions in solar system
science are addressed. But it is equally important that there be an ongoing, robust, stable technology develop-
ment program that is aimed at the missions of the future, especially those missions that have great potential for
303
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304 VISION AND VOYAGES FOR PLANETARY SCIENCE
TABLE 11.1 Key Technology Findings and Recommendations from Chapters 4 Through 8
Chapter 4
The Primitive Chapter 5 Chapter 6 Chapter 7 Chapter 8
Bodies The Inner Planets Mars The Giant Planets Satellites
Technology Continue technology Continue current Key Continue Develop the
development developments initiatives. technologies developments in technology necessary
in several areas necessary to ASRGs, thermal to enable Jupiter
including ASRG and Possibly expand accomplish protection for Europa Orbiter.
thruster packaging incentives to Mars Sample atmospheric
and lifetime, include capabilities Return are Mars probes, Address technical
thermal protection for surface access ascent vehicle, aerocapture and/ readiness of orbital
systems, remote and survivability rendezvous or nuclear-electric and in situ elements
sampling and coring for challenging and capture of propulsion, and of Titan Saturn
devices, methods of environments such as orbiting sample robust deep-space System Mission
determining that a Venus’s surface and return container, communications including balloon
sample contains ices frigid polar craters and planetary capabilities. system, low-
and organic matter on the Moon. protection mass/low-power
and of preserving it technologies. instruments, and
at low temperatures, cryogenic surface
and electric sampling systems.
thrusters mated to
advanced power
systems.
Develop a program
to bridge the TRL
4-6 development
gap for flight
instruments.
discovery and are not within existing technology capabilities. Early investment in key technologies reduces the
cost risk of complex projects, allowing them to be initiated with reduced uncertainty regarding their eventual
total costs. Although the need for such a technology program seems obvious, in recent years investments in new
planetary exploration technology have been sharply curtailed and monies originally allocated to it have been used
to pay for flight project overruns. As already stressed in Chapter 9, it is vital to avoid such overruns, particularly
in flagship projects.
In the truest sense, reallocating technology money to cover short-term financial problems is myopic. The
long-term consequences of such a policy, if sustained, are almost certainly disastrous to future exploration. Meta-
phorically, reallocating technology money to cover tactical exigencies is tantamount to “eating the seed corn.”
The committee unequivocally recommends that a substantial program of planetary exploration technology
development should be reconstituted and carefully protected against all incursions that would deplete its
resources. This program should be consistently funded at approximately 6 to 8 percent of the total NASA
Planetary Science Division budget. The technology program should be targeted toward the planetary missions that
NASA intends to fly, and should be competed whenever possible. This reconstituted technology element should
aggregate related but currently uncoordinated NASA technology activities that support planetary exploration, and
their tasks should be reprioritized and rebalanced to ensure that they contribute to the mission and science goals
expressed in this report. The remainder of this chapter discusses the specific items that should be addressed by
this reconstituted technology program.
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THE ROLE OF TECHNOLOGY DEVELOPMENT IN PLANETARY EXPLORATION
From Laboratory to Spaceflight
Given an appropriate technology program budget, the way in which the monies are allocated to the different
phases of technology development should be informed both by the lessons of past efforts at technology infusion,
and by the guideline that any technology to be used on a flight mission should be at technology readiness level 6
prior to the project’s preliminary design review. The technology readiness level (TRL) is a widely used reference
system for measuring the development maturity of a particular technology item. In general, a low TRL refers to
technologies just beginning to be developed (TRL 1-3), and a mid-TRL covers the phases (TRL 4-6) that take an
identified technology to a maturity at which it is ready to be applied to a flight project (Figure 11.1).
A primary deficiency in past NASA planetary exploration technology programs has been an overemphasis on
TRLs 1-3 at the expense of the more costly but vital mid-level efforts necessary to bring the technology to flight
readiness. Many important technological developments, therefore, have been abandoned, either permanently or
temporarily, after they have reached TRL 3 or 4. This failure to continue to mature the technologies has resulted
in a widespread “mid-TRL crisis” that has, in turn, created its own unique set of problems for flight projects. A
new flight project that desires to use a specific technology must either complete the development itself, with the
concomitant cost and schedule risk, or forgo the capability altogether. To properly complement the flight mission
program, therefore, the committee recommends that the Planetary Science Division’s technology program
should accept the responsibility, and assign the required funds, to continue the development of the most
important technology items through TRL 6. Otherwise it will remain difficult, if not impossible, for flight
projects to infuse these technologies without untoward cost and/or schedule risk.
System Test, Launch
TRL 9
& Operations
TRL 8
System/Subsystem
Development
TRL 7
Technology
Demonstration TRL 6
TRL 5
Technology
Development
TRL 4
Research to Prove
Feasibility TRL 3
TRL 2
Basic Technology
Research
TRL 1
FIGURE 11.1 Technology readiness levels for space missions. SOURCE: NASA.
Figure 3.1.1.eps
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306 VISION AND VOYAGES FOR PLANETARY SCIENCE
Technology Infusion Initiatives
In recent competed mission solicitations, NASA provided incentives for infusion of new technological capabili-
ties in the form of increases to the proposal cost cap. Specific technologies included as incentives were the following:
• Advanced solar-electric propulsion, NASA’s Evolutionary Xenon Thruster (NEXT),
• Advanced bipropellant engines, the Advanced Material Bipropellant Rocket (AMBR),
• Aerocapture for orbiters and landers, and
• A new radioisotope power system, the Advanced Stirling Radioisotope Generator (ASRG).
These technologies continue to be of high value to a wide variety of solar system missions. The committee
recommends that NASA should continue to provide incentives for the technologies listed above until they
are demonstrated in flight. Moreover, this incentive paradigm should be expanded to include advanced solar
power (especially lightweight solar arrays) and optical communications, both of which would be of major
benefit for planetary exploration.
The Need for Innovation
A significant concern with the current planetary exploration technology program is the apparent lack of inno-
vation at the front end of the development pipeline. Truly innovative, breakthrough technologies appear to stand
little chance of success in the competition for development money inside NASA, because, by their very nature,
they are directed toward far-future objectives rather than specific near-term missions.
The committee hopes that the new NASA Office of the Chief Technologist formed in 2010 will reconstitute
an activity similar to the previous NASA Institute for Advanced Concepts (NIAC) that will elicit an outpouring
of innovative technological ideas, and that those concepts will be carefully examined so that the most promising
can receive continued support. However, it is not yet clear exactly how future technological responsibilities will
be split between the new NASA technology office and the individual mission directorates. Given the unique needs
of planetary science, it is therefore essential that the Planetary Science Division develop its own balanced
technology program, including plans both to encourage innovation and to resolve the existing mid-TRL crisis.
These plans should be carefully coordinated with the NASA technology office to optimize their management and
implementation.
TECHNOLOGY NEEDS
Core Multi-Mission Technologies
Although the ingenuity of the nation’s scientists and engineers has made it appear almost routine, solar system
exploration still represents one of the most audacious undertakings in human history. Any planetary spacecraft,
regardless of its specific destination, must cope with the fundamental challenges of traveling long distances from
Earth and the Sun, surviving and operating over the resulting long mission duration, and operating without real-
time control from Earth and with limited data streams. These vehicles must be equipped to make a wide range of
measurements while simultaneously dealing with the challenges of alien and frequently harsh environments. As
future mission objectives evolve, meeting these challenges will require continued advances in several technology
categories, including the following areas:
• Reduced mass and power requirements for spacecraft and their subsystems;
• Improved communications capabilities yielding higher data rates;
• Increased spacecraft autonomy;
• More efficient power and propulsion for all phases of the missions;
• More robust spacecraft for survival in extreme environments;
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THE ROLE OF TECHNOLOGY DEVELOPMENT IN PLANETARY EXPLORATION
• New and improved sensors, instruments, and sampling and sample preservation systems; and
• Mission and trajectory design and optimization.
The Requirement for Power
Of all the multi-mission technologies that support future missions, none are more critical than high-efficiency
power systems for use throughout the solar system. In particular, the committee notes the special significance of the
new highly efficient ASRG, which enables up to a 75 percent reduction in the use of plutonium-238 compared to
systems based on thermoelectric conversion. As discussed in Chapter 9, plutonium-238 is a limited and expensive
resource, production of which is currently at a standstill, and future production plans are uncertain. Since more
efficient use of the limited plutonium supply will help to ensure a robust and ongoing planetary program, the
committee’s highest priority for near-term multi-mission technology investment is for the completion and
validation of the Advanced Stirling Radioisotope Generator.
Progress in these core technology areas will benefit virtually all planetary missions, regardless of their spe-
cific mission profile or destination. The robust Discovery and New Frontiers programs envisioned by this report
would be substantially enhanced by such a commitment to multi-mission technologies. For the coming decade,
it is imperative that NASA expand its investment program in these fundamental technology areas, with
the twin goals of reducing the cost of planetary missions and improving their scientific capability and reli-
ability. Furthermore, while the requirements will vary from mission to mission, the scope of these challenges
requires careful planning so that research and development can establish the proper technological foundation. To
accomplish this goal, the committee recommends that NASA expand its program of regular future mission
studies to identify as early as possible the technology drivers and common needs for likely future missions.
Capability-Driven Technology Investments
In structuring its multi-mission technology investment programs, it is important that NASA preserve its focus
on fundamental system capabilities rather than concentrating solely on individual technology tasks. An example
of such an integrated approach, which NASA is already pursuing, is the advancement of solar electric propulsion
systems to enable a wide variety of new missions throughout the solar system. This integrated approach consists
of linked investments in new thrusters, specifically the NEXT xenon thruster (Figure 11.2), plus new power pro-
cessing, propellant feed system technology, and the systems engineering expertise that enables these elements to
work together.
The committee recommends that NASA consider making equivalent systems investments in the advanced
Ultraflex solar array technology that will provide higher power at greater efficiency, and an aerocapture to
enable efficient orbit insertion around bodies with atmospheres.
Investing in these system capabilities will yield a quantum leap in the ability to explore the planets and
especially the outer solar system and small bodies. Perhaps more importantly, the availability of these systems
is imperative in order for NASA to meet its solar system exploration objectives within reasonable budgetary
constraints.
Planning for Competed Missions in the Next Decade
Solar system exploration in the coming decade will include many missions selected through open competition.
Discovery and New Frontiers missions would benefit substantially from enhanced technology investments in the
multi-mission technology areas described above; however, two issues have yet to be overcome:
• The nature of the peer review and selection process effectively precludes reliance on new and “unproven”
technology, since it increases the perceived risk and cost of new missions; and
• It is difficult to ensure that proposers have the intimate knowledge of new technologies required to effec-
tively incorporate them into their proposals.
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FIGURE 11.2 NEXT xenon thruster. SOURCE: NASA.
Left unchecked, these two issues will ultimately limit the scope and ingenuity of competed missions.
While expanding its investments in generic multi-mission technologies, NASA should encourage the intel-
ligent use of new technologies in its competed missions. NASA should also put mechanisms in place to ensure
that new capabilities are properly transferred to the scientific community for application to competed mis-
sions. One example of such a transfer mechanism is the development of a freely available technology database,
customized with the information required by new proposals and populated by technologies that have been pre-
screened by NASA to ensure that they can be infused at a manageable risk. This database should be accompanied
by publication of the results of technology development tasks in free and open media; plans for such publication
should be made a prerequisite to the award of technology funding. In this manner NASA can ensure that its tech-
nology resources are used to the benefit of the entire community of potential mission proposers.
Technology for Flagship Missions in the Next Decade
NASA’s comprehensive and costly flagship missions are strategic in nature and have historically been assigned
to NASA centers rather than competed. They can benefit from, and in fact are enabled by, strategic technology
investments. The following sections provide a brief summary of the technological needs for the five flagship mis-
sion candidates discussed in Chapter 9.
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THE ROLE OF TECHNOLOGY DEVELOPMENT IN PLANETARY EXPLORATION
Mars Astrobiology Explorer-Cacher
MAX-C is the first component of the Mars Sample Return campaign. For the MAX-C sample caching rover,
the most challenging technology is sample acquisition, processing, and encapsulation on Mars. For the later
elements in the Mars Sample Return campaign, the two greatest technological challenges are the Mars Ascent
Vehicle (MAV), which will carry the samples from the martian surface to Mars orbit, and the end-to-end plan-
etary protection and sample containment system. These three high-priority technologies will each require major
long lead investments if the overall Mars Sample Return campaign is to have an acceptably high probability of
success. The estimated required investment to bring the MAV up to TRL 6, for example, is around $250 million.
Additional technology developments may be required to enable precision landing by the Mars Sample Return
lander, and autonomous rendezvous and guidance for the Mars Sample Return orbiter. During the decade of
2013-2022, NASA should establish an aggressive, focused technology development and validation initiative
to provide the capabilities required to complete the challenging Mars Sample Return campaign. Along with
other required developments of infrastructure capabilities, such as sample handling facilities and Mars telecom-
munications, these developments will enable an intensive Mars exploration program leading to return of samples
from the planet’s surface.
Jupiter Europa Orbiter
The Jupiter Europa Orbiter (JEO) mission will have to contend with the challenge of Jupiter’s harsh radiation
environment and the need to operate far from the Sun. Fortunately, because significant development has already
been accomplished in many key technical areas, the JEO mission currently envisioned requires no fundamentally
new technology in order to accomplish its objectives. However, the capability to design and package the science
instruments, especially the detectors, so that they are able to acquire sufficiently meaningful data in the jovian
radiation environment, has not yet been completely demonstrated. A supporting instrument technology program
aimed specifically at the issue of acquiring meaningful scientific data in a high-radiation environment would
be extremely valuable, both for JEO and for any other missions that will explore Jupiter and its moons in
the future. Planetary protection requirements will provide additional challenges for both the JEO spacecraft and
its instruments.
Uranus Orbiter and Probe
The major technological challenges of this mission are as follows:
• Long-lived, flight-qualified ASRGs, with lifetimes in excess of 15 years;
• Lightweight materials for the orbiter structure and subsystems; and
• Thermal protection systems for the probe.
Although the Uranus mission can be accomplished using chemical propulsion, the availability of a flight-
tested, comparatively inexpensive solar-electric propulsion module would result in both a wider range of launch
dates and more mass in orbit around Uranus. Aerocapture capability would enhance a Uranus orbiter mission. For
a Neptune orbiter, the advantages of aerocapture are enormous.
Enceladus Orbiter
The Enceladus Orbiter’s key scientific instruments are a mass spectrometer, a thermal mapping radiometer, a
dust analyzer, an imaging camera, and a magnetometer. Other than improvements in the sensitivity and accuracy of
the mass spectrometer and thermal mapping radiometer in particular, which would enhance the scientific mission,
the major technological challenge is ensuring the reliability and lifetime of the ASRGs. The mission requires three
ASRGs to deliver power throughout the Enceladus orbit phase, which lasts for at least a year beginning 12 years
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310 VISION AND VOYAGES FOR PLANETARY SCIENCE
after launch. Because of the potential habitability of Enceladus, planetary protection is an additional technological
challenge for an orbiter mission.
Venus Climate Mission
The Venus Climate Mission (VCM) includes four distinct flight elements: the carrier spacecraft that becomes
a Venus orbiter, a gondola and balloon system, a mini-probe, and dropsondes. The packaging of the mini-probe
and the dropsondes, especially integration of a sophisticated neutral mass spectrometer in the mini-probe, is the
key technological challenge of VCM. Although each of the components of the entry flight system, which contains
the gondola and the balloon, is close to TRL 6, indicating technological maturity, the entry flight system itself still
presents a significant design and development challenge. The management of the power, mass, and volume of this
“Russian doll” vehicle throughout its design cycle could be viewed as a technology development in its own right.
Future Mission Capabilities: 2023-2032
During the decade 2013-2022, the missions recommended by this decadal survey will address the most com-
pelling science objectives within the limited resources available to NASA. It is essential that the Planetary Science
Division also invest in the technological capabilities that will enable missions in the decade beyond 2022. During
the course of this decadal survey, a number of mission concepts have been studied to assess their cost, feasibility,
and scientific value, and these studies provide the foundation for important technology investments. Table 11.2
summarizes these missions and their key technology drivers. The committee strongly recommends that NASA
strive to achieve balance in its technology investment programs by addressing the near-term missions cited
specifically in this report, as well as the longer-term missions that will be studied and prioritized in the future.
RECOMMENDED TECHNOLOGY INVESTMENTS
Science Instruments
The instruments carried by planetary missions provide the data to address key science questions and test sci-
entific hypotheses. Among the wide variety of missions are flybys, orbiters, atmospheric probes, landers, rovers,
and sample returns. As would be expected, the range of science instruments that support these mission sets is also
broad. At present there are significant technological needs across the entire range of instruments, including the
improvement and/or adaptation of existing instruments and the development of completely new concepts.
Virtually all instruments can be improved by technological developments that reduce their mass and/or power
and/or data transmission requirements. Increased instrument sensitivities and measurement accuracies dramatically
expand the range of scientific hypotheses that can be addressed by a mission. Mass spectrometers are just one
example of a family of instruments that would benefit significantly from a science instrument technology program
aimed at improving basic instrument performance characteristics.
But improving and adapting existing instruments will not meet all the goals of future solar system missions.
New concepts must also be supported and developed. Astrobiological exploration in particular is severely limited
by a lack of flight-ready instruments that can address key questions regarding past or present life elsewhere in
the solar system. The committee recommends that a broad-based, sustained program of science instrument
technology development be undertaken, and that this development include new instrument concepts as well
as improvements in existing instruments. This instrument technology program should include the funding
of development through TRL 6 for those instruments with the highest potential for making new discoveries.
Survival in Extreme Environments
One of the biggest challenges of solar system exploration is the tremendous variety of environments that
spacecraft encounter. Exploring the surface of Venus for any period longer than a few hours requires engineering
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THE ROLE OF TECHNOLOGY DEVELOPMENT IN PLANETARY EXPLORATION
TABLE 11.2 Summary of Types of Missions That May Be Flown in the Years 2023-2033 and Their Potential
Technology Requirements
Objective: 2023-2032 Mission Architecture Key Capabilities
Inner Planets
Venus climate history Atmospheric platform High-temperature survival
Sample return Atmospheric mobility
Advanced chemical propulsion
Sample handling
Venus/Mercury interior Seismic networks Advanced chemical propulsion
Long-duration high-temperature subsystems
Lunar volatile inventory Dark crater rover Autonomy and mobility
Cryogenic sampling and instruments
Mars
Habitability, geochemistry, and geologic Sample return Ascent propulsion
evolution Autonomy, precision landing
In situ instruments
Planetary protection
Giant Planets and Their Satellites
Titan chemistry and evolution Coordinated platforms: Atmospheric mobility
orbiter, surface and/or lake Remote sensing instruments
landers, balloon In situ instruments-cryogenic
Aerocapture
Uranus and Neptune/Triton Orbiter, probe Aerocapture
Advanced power/propulsion
High-performance telecommuications
Thermal protection/entry
Primitive Bodies
Trojan and Kuiper belt object composition Rendezvous Advanced power/propulsion
Comet/asteroid origin and evolution Sample return Advanced thermal protection
Cryogenic sample return Sampling systems
Verification of samples—ices, organics
Cryogenic sample preservation
Thermal control during entry, descent, and landing
systems and science instruments that can withstand intense heat and pressure. A spacecraft that dwells in the equa-
torial plane of Jupiter, or that orbits any of the inner Galilean satellites, must be designed to handle an extremely
harsh radiation environment.
Systems or instruments designed for one planetary mission are rarely able to function properly in a different
environment. Yet technological developments often are considered completed as soon as the specified technology
demonstrates its functionality in a single environment. The committee recommends that, as part of a balanced
portfolio, a significant percentage of the Planetary Science Division’s technology funding be set aside for
expanding the environmental adaptability of existing engineering and science instrument capabilities.
In Situ Exploration
Future missions will emphasize in situ exploration in a variety of environments. These will include such
extremes as the atmospheres of the giant planets; the surfaces and atmospheres of Venus, Mars, and planetary
satellites; and the surfaces and subsurfaces of small bodies. Exploration of such diverse environments requires
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312 VISION AND VOYAGES FOR PLANETARY SCIENCE
a focused technology program element to prepare the required capabilities. Development of new and improved
capabilities for entry and landing, mobility, sample acquisition and return, and planetary protection will help ensure
progress toward the key objectives of the next and following decades.
Solar System Access and Other Core Technologies
The core multi-mission technologies described above provide the foundation for many of the missions that
comprise the majority of planetary flight opportunities. It is essential that the Planetary Science Division continue
to advance the state of the art in these technologies to benefit both the competed and the flagship mission programs.
In addition, flexibility to respond to new discoveries should be a hallmark of technology programs for the next
decade. The allocation of technology monies for discovery-driven elements will ensure the ability to react quickly
to the new needs and opportunities that are certain to emerge.
Research and development in the fields of celestial mechanics, trajectory optimization, and mission design have
paid substantial dividends in the recent past, identifying new and higher-performance opportunities for planetary
missions. A future sustained effort in this technology area is essential, both to exploit fully the expanding range of
possible mission modes (electric propulsion, aerocapture, etc.) and to continue to develop the automated software
tools for searching rapidly for the “best” mission opportunities.
Summary
The future of solar system exploration depends on a well-conceived, robust, stable technology investment
program. As recommended above, NASA’s Planetary Science Division should strive to set aside 6 to 8 percent
of its mission budget for technology investments. It should also make certain that its technology program has a
balanced portfolio, with significant investments in each of the key technology components. Table 11.3 presents
an example of a technology investment profile that would have the appropriate balance.
TABLE 11.3 An Example of a Possible Technology Investment Profile That Would Be Appropriately Balanced
for the Future Requirements for Solar System Exploration
Technology Element Percentage Allocation Key Capabilities
Science instruments 35 Environmental adaptation
Radiation tolerance
In situ sample analysis and age dating
Planetary protection
Extreme environments 15 Survivability under high temperature and pressure
Radiation tolerance (subsystems)
Survival and mobility in cryogenic conditions
In situ exploration 25 Sample acquisition and handling
Descent and ascent propulsion systems
Thermal protection for entry and descent
Impactor and penetrator systems
Precision landing
Mobility on surfaces and in atmospheres
Planetary protection
Solar system access and core 25 Reduced spacecraft mass and power
technologies Improved interplanetary propulsion
Low-power, high-rate communications
Enhanced autonomy and computing
Aerocapture
Improved power sources
Innovative mission and trajectory design
