New Horizons Outer Heliosphere Science & Instrument Shutdown Simulator

TARGET: New Horizons (NH)

HELIOCENTRIC RANGE: 59.2 AU

TERMINATION SHOCK DIST: ~84.0 AU

REGION: Outer Kuiper Belt

Sun

New Horizons Path

Voyager 1 & 2 Exits

Kuiper Belt Expanse

Termination Shock (~84 AU)

Heliocentric Distance (r):

40 AU (Pluto/Arrokoth) 50 AU 60 AU (Current Ops) 70 AU 80 AU (Shock Boundary)

59.2 AU

Solar Wind Density (n_sw)

0.0014 cm⁻³

1/r² Geometric Thinning

Solar Wind Speed (v_sw)

418 km/s

Mass-loading Deceleration

Pickup Ion Flux (H+/He+)

14.8 cm⁻² s⁻¹

Interstellar Neutral Influx

Daily Science Return

94.5%

Loss Rate: 5.5%

In-Situ Particle Spectrum vs Outer Heliosphere Gradient

PACKETS: 44.8 kbps

Mission Operating Profile

Full Science Baseline 100% Data

Simultaneous SWAP solar wind ion monitoring and PEPSSI energetic pickup ion spectrography through outer Kuiper Belt.

NASA Proposed Shutdown 0% Plasma

De-power both SWAP & PEPSSI to close agency budget shortfall; eliminates outer heliospheric particle physics.

Compromise Duty-Cycle 50% Sampling

Maintain core SWAP solar wind density readings; power down PEPSSI high-energy pickup ion tracking.

Instrument Power Bus

SWAP ONLINE

Solar Wind Around Pluto (0.025 - 7.5 keV ions). Tracks core solar wind speed falloff & density.

PEPSSI ONLINE

Pluto Energetic Particle Spectrometer (25 keV - 1 MeV). Resolves interstellar pickup ions & cosmic seeds.

Heliosphere Science Continuity 94.5%

Fiscal vs Scientific Trade-Off

NASA Annual Ops Cost: ~$9.5M / yr

SWAP/PEPSSI Share: $1.8M / yr (19%)

Cumulative Data Loss: 0.0 GB (0%)

Voyager In-Situ Redundancy: 0% (Different Vector)

Why 58–80 AU is Irreplaceable: The Pickup Ion Revolution

As the solar wind races outward at ~400 km/s, its density drops proportionally to 1/r². By 59 AU (New Horizons' current location), the solar wind has become so tenuous that neutral atoms streaming in from the Very Local Interstellar Medium (VLISM) undergo charge-exchange with solar wind protons, becoming ionized.

These newly born Interstellar Pickup Ions (PUIs) are instantly swept up and accelerated by the interplanetary magnetic field. While PUIs represent only ~0.1% of particles near Earth, at 60 AU they carry over 50% of the solar wind's total thermal pressure, slowing the solar wind before it hits the Termination Shock.

The Scientific Crisis: Voyager 1 had no functioning plasma detector, and Voyager 2's plasma instrument was damaged and could not resolve low-energy PUIs. New Horizons is the only operational spacecraft in history equipped with dedicated modern spectrometers (SWAP and PEPSSI) calibrated to measure this fundamental shock-precursor physics.

Trajectory Divergence: New Horizons vs. Voyagers

Voyager 1 crossed the termination shock at ~94 AU at high northern ecliptic latitude (+35°), while Voyager 2 crossed at ~84 AU in the southern hemisphere (-32°). Neither probe passed through the dense mid-plane of the Kuiper Belt.

New Horizons is traveling almost exactly along the ecliptic plane (~2° inclination). This allows it to study solar wind interaction with Kuiper Belt dust grains and localized neutral gas clouds that were completely invisible to the Voyager flyouts.

Powering down SWAP and PEPSSI terminates the human species' sole continuous in-situ dataset linking planetary orbits to interstellar space until proposed interstellar probes launch in the late 2030s or 2040s.

Why 58–80 AU is Irreplaceable: The Pickup Ion Revolution

Trajectory Divergence: New Horizons vs. Voyagers

Heliospheric Science Impact Dossier