Parker Solar Probe Makes History as Scientists Urge Future Investments in Heliophysics Research

NASA’s Parker Solar Probe survived its close encounter with the Sun this week, getting closer than any previous spacecraft.  The success comes at the same time a new Decadal Survey from the National Academies makes the case for future investments in heliophysics research, including the Geospace Dynamics Constellation that NASA is proposing to cancel because of budget cuts.

Launched in 2018 with its namesake, renowned space physicist Gene Parker on hand to watch, Parker Solar Probe came within 3.8 million miles of the surface of the Sun on December 24. That’s closer than any spacecraft. NASA describes it as “touching” the Sun.

Nicky Fox, currently the head of NASA’s Science Mission Directorate, was Parker Solar Probe’s project scientist when she was at the Johns Hopkins University Applied Physics Lab. JHUAPL designed, built and operates the spacecraft.  In a post on X, she explains — in less than 60 seconds! — why the mission is so important.

This Dec. 24, @NASASun’s Parker Solar Probe will fly closer to our star than ever before! ???? Watch #ScienceinSeconds, as I explain why this historic milestone matters — and how it’s helping us unlock the Sun’s secrets.

Learn more: https://t.co/4NgwhuEjsY pic.twitter.com/OELR0tQgBF

— Dr. Nicky Fox (@NASAScienceAA) December 23, 2024

She and the rest of the team were relieved when they received a beacon tone from the probe late on December 26, confirming it survived the encounter while traveling at 430,000 miles per hour. They must wait until January 1 for the spacecraft to be in position to send the data back to Earth, however.

Signal Received. ????

NASA’s #ParkerSolarProbe made history with its closest pass to the Sun—3.8M miles at 430,000 mph. A signal received at APL confirms the probe is healthy & operating normally. Telemetry data expected Jan. 1. https://t.co/x0RIfx4clc

@NASASun @NASASolarSystem

— Johns Hopkins APL (@JHUAPL) December 27, 2024

The probe made 21 passes of the Sun before this and will make more in the future. This one is historic because it’s the first to get so close.

Studies of the Sun are part of the scientific discipline of solar and space physics, also called heliophysics. The National Academies of Sciences, Engineering, and Medicine produce Decadal Surveys every 10 years — a decade — for each of NASA’s science disciplines where members of the science community volunteer their time to deliberate and determine the key science questions that need to be addressed in the next decade and recommend missions to answer them.  NASA and Congress rely heavily on Decadals because they represent a consensus of each community.

The Academies released its latest heliophysics Decadal Survey earlier this month. The 773-page report, “The Next Decade of Discovery in Solar and Space Physics: Exploring and Safeguarding Humanity’s Home in Space,” covers a lot of ground, but the Geospace Dynamics Constellation (GDC) is of particular interest.

It was a top priority in the last heliophysics Decadal, and still is. But Fox, a heliophysicist herself, had to make the difficult decision to recommend terminating GDC in the FY2025 budget request because of unanticipated budget cuts to NASA’s science programs due to the Fiscal Responsibility Act.

She “paused” the program in the FY2024 request hoping the budget situation would improve, but the reverse happened. Congress hasn’t completed action on the FY2025 request yet, but the Senate Appropriations Committee notes it is still waiting for a report from NASA requested in FY2024 for a plan on launching GDC by the end of the decade and would appropriate $15 million for GDC in FY2025.

NASA provides each Decadal committee with a “funding wedge” estimate of how much money might be available over the 10 years to pay for whatever they recommend. It is only an estimate, of course, and the Decadal committees are required to include “decision rules” to advise NASA on what to do if the actual funding is less (or more).

At a December 5 briefing, study co-chairs Stephen Fuselier of Southwest Research Institute and Robyn Millan of Dartmouth College made clear that the decision rules in this report are intended to preserve GDC. If cuts are needed, they should be taken from other heliophysics activities first, not GDC.

Millan said they hope this Decadal “kicks it off again” and they are “reaffirming” its importance along with another spacecraft, DYNAMIC, which will work in tandem with GDC. DYNAMIC also was recommended in the previous Decadal.

GDC and DYNAMIC (Dynamical Neutral Atmosphere–Ionosphere Coupling) are intended to be launched within three months of each other.  “These two upper-atmosphere missions form a coordinated constellation, where GDC observes Earth’s high-latitude energy and momentum input resulting from coupling with solar wind and magnetosphere and DYNAMIC measures momentum and energy forcing resulting from coupling with the lower atmosphere through waves.”

The “science that these missions represent has only been amplified over the years,” they write, offering four reasons why they should be completed in the next decade.

The report says NASA’s heliophysics division budget would have to increase by 17 percent from FY2025 to FY2026 to $1 billion to complete the program of record and launch those two missions in 2031. To accomplish all of the report’s recommended research strategy, it would have to increase by 8.25 percent each year to the end of the decade on top of that.

The decision rules in Chapter 6 provide a prioritized list of where to cut if funding is insufficient. Delaying GDC is last on the list. Delaying DYNAMIC is next to last.

Speaking to the Academies’ Space Studies Board on November 19, Fox said she was looking forward to seeing how the science that GDC would produce is prioritized this time and if there are “maybe creative ways” to do some of that science even if they can’t do the full mission.

The report appears to support GDC as it was formulated in the last Decadal Survey, not with alterations.

GDC and DYNAMIC are about completing what was in the last Decadal Survey. The report, prepared at the request of NASA, NOAA and the National Science Foundation (NSF), also has proposals for the future with a theme of capturing the “dual nature of the field” — discovering the secrets of the local cosmos and expanding and safeguarding humanity’s home in space.

A key recommendation is that advancing solar and space physics requires creating an Integrated HelioSystems Laboratory (HSL) that brings together the assets of NASA, NOAA and NSF, and investments from them as well as the Air Force Office of Scientific Research (AFOSR) and international partners.

At the December 5 briefing, Joe Westlake, head of NASA SMD’s heliophysics division, thanked the Academies for the “vivid vision” for the next 10 years. “This is an ambitious Decadal Survey and we’re excited about that.”