Planetary exploration is the foundational interest of The Planetary Society. While there are both human and robotic aspects to planetary exploration, the robotic side has seen a far more expansive and extensive program over the history of space exploration. Our focus for human planetary exploration is considered within the Artemis program. Here we will consider robotic, science-driven exploration.
NASA's Planetary Science Division (PSD) is responsible for all robotic missions to destinations in our solar system except for the Sun and Earth. It funds the development and operations of planetary spacecraft, supports the national infrastructure for Plutonium-238 power systems, and is the primary source of research funding for the nation's professional planetary science community. Historically, it has received less than 10% of NASA's total budget.
Though it faced significant budget cuts in the early 2010s, the Planetary Science Division — in part due to the ongoing work by The Planetary Society and its members — has seen its fortunes improve in the past five years. The latest budget proposal from the Biden administration had the division growing to above $3.3 billion:
NASA's planetary science budget, with Biden's FY 2024 proposal. Data adjusted for inflation and normalized to maintain consistent accounting of launch costs and to remove Deep Space Network infrastructure costs between 2002 and 2007. Inflation-adjustment to 2022 dollars made using NASA's New Start Index. Source: Planetary Science Budget Dataset, compiled by Casey Dreier for The Planetary Society (accessible on Google Sheets or downloadable as an Excel file).
But all is not well with PSD. Recent congressional activity by the U.S. Senate would cut $522 million from 2023 levels, and threatens to cancel Mars Sample Return unless NASA can commit a $5.3 billion total mission cost.
At the time of writing (July 21st) the House had not released details of its NASA Budget.
|2023 Enacted||2024 PBR||Senate CJS||House CJS||Final|
|Mars Sample Return||$822.3||$949||$300||-||-|
|Lunar Discovery and Exploration||$486.3||$458.3||$458.3||-||-|
|Mars Sample Return||$822||$949||$300||-||-|
|Mars Exploration Program||$248.1||$268.6||-||-||-|
|Planetary Science Research||$290.6||$307.4||-||-||-|
All values are in millions of dollars. Entries in bold are major programs. Dashes in the Senate and House entries mean that the respective legislation did not specify funding for that program. Not all missions are listed here. For a more detailed listing, consult the FY2024 entry in the Planetary Exploration Budget Dataset.
There are nine major program areas within the Planetary Science Division:
Competitively selected, small-scale (~$500M each) spaceflight program with a goal of launching a new mission every 2 - 3 years. Current development projects include Psyche, DAVINCI, and VERITAS.
- New Frontiers
Competitively selected, mid-scale (~$1 billion each) spaceflight program with a goal of launching once per decade. Current development project is Dragonfly.
- Mars Exploration Program
This manages all existing Mars spacecraft and funds Mars-related technology and scientific research efforts. There are no projects in active development.
- Mars Sample Return
Due to the prominence of MSR, this project was elevated to its own high-level program that reports directly to upper-level NASA management. At the conclusion of the MSR project, this program will end. This is the highest planetary science priority for The Planetary Society right now.
- Lunar Discovery and Exploration
The scientific part of the Artemis effort. Includes the Commercial Lunar Payload Services program and upcoming VIPER mission.
- Outer Planets and Ocean Worlds
Currently developing the Europa Clipper spacecraft and related technology development for exploring the ice-moons of the outer solar system.
- Planetary Defense
Funds ground-based NEO observations and is developing the NEO Surveyor asteroid-hunting spacecraft. See our deep prep page on Planetary Defense for more information.
- Radioisotope Power
Funds the production of Plutonium-238 and related components, a critical power source for deep solar system and Mars surface exploration spacecraft (or any destination that can't use solar power).
- Planetary Science Research
Funds nearly all research by professional planetary scientists in the U.S.
The Decadal Survey
The scientific priorities of the Planetary Science Division are guided by the Decadal Survey, a once-per-decade report published by the National Academies of Sciences, Engineering, and Medicine. The survey is a product of a community-wide effort to define the highest-priority scientific questions facing the field and then identify the missions that could address them in a 10-year period.
The current decadal survey was released in 2022 and covers the years between 2023 and 2023.
Our top priority: Mars Sample Return
Mars Sample Return (MSR) is a complex, multi-mission, multi-agency effort to return samples of the Martian surface to Earth. It was identified as the highest-priority effort in the past decadal survey, and NASA has stated its intent to follow through on those recommendations in the coming decade.
Securing funding for Mars Sample Return is our top priority for robotic planetary exploration.
Both the Trump and Biden White Houses blessed the program with strong budget requests. Congress has provided full funding for the effort in 2021, 2022, and 2023. 2024 is proving to be more difficult.
The project is currently undergoing an unprecedented second independent review process to help control costs and complexity. We anticipate this review to be public prior to the Day of Action in 2023.
Goals for the reader
To understand the scope, major program elements, and upcoming projects within NASA's robotic planetary exploration efforts
To be able to convey the importance of funding Mars Sample Return in a timely manner, and to connect it with near-term legislative action
To understand how programmatic priorities are determined in planetary science