How many spacecraft have been sent in a heliocentric orbit in all history?
By this, I mean spacecraft sent to stay in heliocentric orbit.
The satellites orbiting planets or moons don't count.
Related question
Is there a database for space junk beyond Earth orbit, and is Roadster in it?
Here is a start List of artificial objects in heliocentric orbit. Noting the discussion in comments around the OP, this link purports to be just a list of what "is" in solar orbit as opposed to "was" at sometime".
Note from this second link that a) things put into solar orbit don't necessarily stay there and b) these objects are largely untracked.
Actually everything below is a direct quote of the wiki page without any checking of correctness. I put it all into one block quote though it has come out as if it is several different quotes (and all non-block-quote text beyond this point is also from the first link given):
United States
The United States has placed in heliocentric orbit:
Pioneer 4 – Moon (1959)
Ranger 3 – Moon (1961)
Ranger 5 – Moon (1963)
Mariner 2 – Venus (1962)
Mariner 3 – Intended for Mars, communication lost when launch shroud failed to separate (1964)
Mariner 4 – Mars (1964-1967)
Mariner 5 – Venus (1967)
Pioneer 5, Pioneer 6, Pioneer 7, Pioneer 8, and Pioneer 9 – Sun (1966-1969)
S-IVB for Apollo 8 (1968)
S-IVB for Apollo 9 (1969)
S-IVB and LM Snoopy (ascent stage) for Apollo 10 (1969)
S-IVB for Apollo 11 (1969)
Mariner 6 and Mariner 7 – Mars (1969)
S-IVB for Apollo 12 (1969) – temporarily recaptured in Earth orbit 2002, escaped again 2003
ICE – Comets Giocabinni-Zinner and Halley (1974-1987)
Mariner 10 – Venus and Mercury (1974-1975)
Mars Observer (1992) – Intended for Mars, failed prior to orbital insertion (1993)
Protective cover of Cassini CDA instrument (1997)[1]
Stardust – Comet Wild 2 (1999-2006)
Genesis – Solar wind sample mission (2001-2004)
CONTOUR – Intended to flyby several comets, failed after launch (2002), seen as three separate fragments
Spitzer Space Telescope (2003-2020)
Deep Impact – Comet Tempel 1
STEREO-A and STEREO-B (2006-2016)
Kepler Mission (2009-2018)
TAGSAM head cover – jettisoned from OSIRIS-REx (2018)[2]
MarCO-A and MarCO-B – CubeSat relays for InSight (2018-2019)
Parker Solar Probe (2018-present)
On Apollos 8 and 10–17, each S-IVB upper stage jettisoned four sections of a truncated conical adapter that supported the Apollo service module and (except for Apollo 8) enclosed the Apollo Lunar Module. These panels are in heliocentric orbit, including those from Apollos 13–17 whose S-IVBs impacted the Moon, as the S-IVBs jettisoned them before maneuvering themselves into lunar impact trajectories. The panels continued on lunar flyby trajectories into heliocentric orbit. (The adapter panels on Apollo 9 were jettisoned in Earth orbit before the S-IVB burned into an Earth escape trajectory. They eventually decayed.)
U.S.-based commercial spaceflight companies have placed in heliocentric orbit:
Elon Musk's Tesla Roadster with Falcon Heavy second stage (2018)
Soviet Union/Russian Federation
The Soviet Union or the Russian Federation has placed in heliocentric orbit:
Luna 1 – Intended to crash on Moon (1959)
Venera 1 – Intended for Venus, communication lost en route (1961)
Mars 1 – Intended for Mars, communication lost en route (1962)
Zond 2 – Intended for Mars, communication lost en route (1964)
Zond 3 – Moon (far side) and interplanetary space (1965)
Venera 2 – Venus (1966)
Mars 4 – Intended to orbit Mars, but retrorocket failed, mission partial success (1974)
Mars 6 coast stage – Mars (1974)
Mars 7 coast stage – Mars (1974)
Mars 7 lander – Intended to land on Mars, but missed planet (1974)
Venera 11 cruise stage – Venus (1978)[citation needed]
Venera 12 cruise stage – Venus (1978)[citation needed]
Venera 13 cruise stage – Venus (1982)
Venera 14 cruise stage – Venus (1982)
Vega 1 – Venus and Halley's Comet (1984-1986)[citation needed]
Vega 2 – Venus and Halley's Comet (1984-1986)
Phobos 1 – Intended for Mars and moon Phobos, communication lost en route (1988)
European Space Agency (ESA)
The European Space Agency has placed in heliocentric orbit:
Helios 1 (joint U.S./Germany) – Sun (1975-1985)
Helios 2 (joint U.S./Germany) – Sun (1976-1979)
Giotto mission – Halley's Comet (1985-1992)
Ulysses (joint U.S./ESA) – Jupiter and Sun's north and south poles (1990-2009)
Japan
Japan has placed in heliocentric orbit:
Sakigake – Halley's Comet (1985-1999)
Suisei – Halley's Comet (1985-1991)
Nozomi – Intended for Mars, but retrorocket failed (1998-2003)
MINERVA mini-lander – Intended for asteroid Itokawa but missed (2005)
IKAROS – Venus flyby (active)[3]
DCAM1 & DCAM2 – Ejected from IKAROS (2010)
SHIN-EN – failed mission to Venus
SHIN-EN 2 – amateur radio satellite, material demonstration (possibly active)[4]
ARTSAT2:DESPATCH – Deep space artwork (2014)
China
China has placed in heliocentric orbit:
Chang'e 2 – asteroid 4179 Toutatis flyby
+1 (related Is there a database for space junk beyond Earth orbit, and is Roadster in it?)
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