Shensuo(spacecraft)

IHP-1

Mission type	Heliosphere science, planetary flyby
Operator	Chinese National Space Administration
Mission duration	25 years (planned)
Start of mission
Launch date	Proposed: May 2024
Flyby ofEarth(gravity assist)
Closest approach	October 2025
Flyby of Earth(gravity assist)
Closest approach	December 2027
Flyby ofJupiter
Closest approach	March 2029
Flyby of50000 Quaoar
Closest approach	2040 (tenative)
Distance	TBD

IHP-2

Mission type	Heliosphere science, planetary flyby
Operator	Chinese National Space Administration
Mission duration	25 years (planned)
Start of mission
Launch date	Proposed: May 2024–2026
Flyby ofEarth(gravity assist)
Closest approach	May 2027
Flyby of Earth(gravity assist)
Closest approach	March 2032
Flyby ofJupiter
Closest approach	May 2033
Flyby ofNeptune
Closest approach	January 2038
Distance	1,000 km
Flyby ofTriton
Closest approach	January 2038
Distance	TBD
Flyby of Kuiper belt object(TBD)
Closest approach	TBD
Distance	TBD

Shensuo(Chinese:Thần thoi), formerlyInterstellar Express,is a proposedChinese National Space Administrationprogram designed to explore theheliosphereandinterstellar space.The program will feature two or threespace probesthat will purportedly be launched in 2024 and follow differing trajectories to encounterJupiterto assist them out of the Solar System. The first probe,IHP-1,will travel toward the nose of the heliosphere, while the second probe,IHP-2,will fly near to the tail, skimming byNeptuneandTritonin January 2038.There may be another probe—tentativelyIHP-3—which would launch in 2030 to explore to the northern half of the heliosphere.IHP-1andIHP-2would be the sixth and seventh spacecraft toleave the Solar System,as well as first non-NASAprobes to achieve this status.

History

The heliosphere and the interstellar medium have so far been explored by only three NASA probes:Voyager 1,Voyager 2,andNew Horizons.BothVoyagersused gravity assists to take them out of the plane of the ecliptic:Voyager 1to the north withSaturnin 1980, andVoyager 2to the south withNeptunein 1989.New Horizonswas designed to stay within the plane to allow for exploration of otherKuiper belt objects.However, none of these probes are exploring the tail of the heliosphere;Pioneer 10,which was headed toward the tail after its Jupiter flyby in 1973, lost contact with Earth in 2003. Later spacecraft which would remain within theSolar System,such asCassini–Huygens,have gathered valuable data on the heliosphere and how it interacts with the interstellar medium, suggesting that the heliosphere is not shaped like a comet but is rather spherical.

Overview

Each probe is to weigh about 200 kilograms, to useradioisotope thermoelectric generatorsfor power, and to carry 50 kilograms or more of scientific instruments such as optical cameras, magnetometers, dust detectors, and neutral atom and particle payloads.They will also study anomalouscosmic rays,interplanetary dust, and the interstellar medium.Depending on whether monopropellant or ion propulsion is used, the probes would be launched using eitherLong March 3BorLong March 5rockets.WhileIHP-1andIHP-2will use RTGs for power,IHP-3,if approved, would use a nuclear reactor.

Thedwarf planetQuaoarand its moonWeywotare currently being considered as potential flyby targets forIHP-1.Centaurexploration has also been considered for both probes.

While a 2024 launch date was targeted, theCOVID-19 pandemichas caused some delays, which may render it to launch at a later date. Future dates of May 2025 and 2026 launches have already been considered forIHP-2,and it is possible thatIHP-1could be moved to those as well.

Scientific payload

The probes are proposed to carry the following suite of instruments:

Instrument	Dimension, range, resolution
Vector AtomicMagnetometer	Electromagnetic radiation: 8–70 000 nT; sensitive to 0.001–0.05 nT/Hz1/2,accurate to 0.005–3 nT
Plasma Analyzer	Plasma wave observations: 0.005–30 keV, resolution 8%
Pick-up Ion Analyzer	Ion counter: 0.002–40 keV/e, energy resolution 5%; mass resolution of H+, He+, He2+, N+, O+, Ne+
High Energy Particle Analyzer	Ionization analysis: Protons, 7–300 MeV Electrons, 200 keV – 10 MeV Heavy ions, 10 – 300 MeV/n
Energetic Particle Analyzer	Ionization analysis: Protons, 20 keV – 7 MeV Electrons, 20 keV – 400 keV Heavy ions, 0.5 – 20 MeV/n
Energetic Neutral Atom Analyzer	Images emission of energetic neutral atoms; ~1–100 keV H
Dust Particle Analyzer	Dust analysis: 400 cm2area, 10−17–10−9kg range, 1 –103km/simpact, 10−16–10−13charge
Camera	Narrow-angle: 1200mm focal length, 150mm aperture; 0.78°×1.05° FOV, 40–1000 nm wavelength, 6–8 spectra channels. Mid-angle: 150mm focal length, 37.5mm aperture, 6.28°x8.34° FOV, 460–1000 nm wavelength, 6–8 spectra channels. Wide-angle (4x); 38mm focal length, 20mm aperture, 30°×23.4° FOV, 600–1000 nm wavelength.
UV photometer	Ultraviolet mapping: 121.6 nm, 58.4 nm wavelength, 4°x4° FOV.
Infrared spectrometer	Infrared mapping:1–16 μm spectrum range, 9 cm−1spectrum resolution, 0.5° FOV

Trajectory

The goal of the spacecraft is to have travelled a total of 100 astronomical units by 2049, which is the centennial celebration of thePeople's Republic of China's founding.

IHP-1will launch in May 2024. In October 2025 it will return to Earth for agravity assist,then loop back in December 2027 for yet another gravity assist. In March 2029 the probe will fly by Jupiter to send it on a trajectory toward the nose of the heliosphere and potentially make observations ofcentaursor Kuiper belt objects, including the flyby of Quaoar, along the way.By 2049 the probe will be 85 AU away from the Sun.

IHP-2will launch between May 2024 and May 2026, but it will likewise receive two gravity assists from Earth in May 2027 and March 2032 respectively. The flyby of Jupiter in May 2033 will send it on a path to fly by Neptune in January 2038 at only 1,000 kilometers above its cloud tops. The probe may also release an atmospheric impactor prior to the flyby.After the flybys, the probe will visit a Kuiper belt object, and by 2049 the probe will have traveled 83 AU away from the Sun, heading toward the yet-unexplored tail of the heliosphere.

If launched withTianwen-4,there may be very well a chance for comparative planetology in some form. AfterIHP-2's flyby of Neptune and Triton is performed in 2038,Tianwen-4's Uranus flyby and probe would occur in 2039, andIHP-1's Quaoar flyby would occur in 2040, allowing for comparisons of similar planetary cohorts within a short span of only a few years.

Flyby targets

IHP-1

• 
  Earth (2x gravity assist)
• 
  Jupiter (flyby)
• 
  Quaoar and Weywot (flyby)

IHP-2

• 
  Earth (2x gravity assist)
• 
  Jupiter (flyby)
• 
  Neptune (flyby)
• 
  Triton (flyby)

See also

• Tianwen-4,a Chinese Jupiter orbiter to launch in 2029 that will include a component to fly byUranus.
• Interstellar Probe,a concept byNASAto explore the heliosphere to be launched sometime in the 2030s.
• Voyager 1and2,probes by NASA designed to explore the outer planets that have since passed the boundary between the heliosphere and interstellar space.
• Trident,a concept by NASA to explore Neptune andTriton,which would have been launched in 2025 on a trajectory to reach Triton in mid-2038.
• Neptune Odyssey,a concept by NASA designed to orbit Neptune and Triton that may carry an atmospheric probe as part of its cargo.