How many SpaceX 2nd stages are in heliocentric orbits?

Question

I can think of one particularly famous SpaceX 2nd stage in heliocentric orbit that even has its own website: https://www.whereisroadster.com/ and I know one was used to send DSCOVR towards Sun-Earth L1, though I'm not sure how it got there:

• Did DSCOVR travel “along the stable manifold of it's future SE L1 Halo orbit” to get there?
• Can Lissajous orbits have stable/unstable manifolds?

But it's the SpaceNews.com article about an upcoming launch NASA awards DART launch contract to SpaceX got me thinking, how many Falcon 9 2nd stages are "out there" beyond Earth orbit?

Answer 1

7

According to this list on Wikipedia the only launches to heliocentric orbit were DSCOVR, Elon Musk's Tesla Roadster, TESS, and DART. No other SpaceX rocket went beyond a geostationary transfer orbit (GTO). In launches to GTO the second stage is typically left in a decaying elliptical low-Earth orbit, until it re-enters the atmosphere. (see e.g. here, here or here)

• DSCOVR was sent to the Sun-Earth Lagrange point L1. Without station keeping this Falcon 9 second stage will have left this point and is now somewhere on the edge between heliocentric orbit and Earth's hill sphere.

• Elon Musk's Tesla Roadster and the second stage that launched it are on an elliptical heliocentric orbit that crosses Mars' orbit.

• TESS was launched onto a lunar flyby trajectory, after which the Falcon 9 second stages was placed in a heliocentric orbit:

For the Falcon 9 second stage, the day was not done at TESS separation as SpaceX planned to dispose the upper stage into a heliocentric orbit by firing its engine a third time to escape Earth’s gravitational influence.

https://spaceflight101.com/tess/falcon-9-launches-tess-planet-hunter/

• DART was sent on a collision course with an asteroid, which of course orbits around the sun:

But because DART was launched as a dedicated Falcon 9 mission, the payload along with Falcon 9's second stage was placed directly on an Earth escape trajectory and into heliocentric orbit when the second stage reignited for a second engine startup or escape burn.

• The Korean Lunar orbiter Danuri used an ballistic lunar transfer to get into Moon orbit.

Because Danuri was launched as a dedicated Falcon 9 mission, the payload along with Falcon 9's second stage was placed directly on an Earth escape trajectory and into heliocentric orbit when the second stage reignited for a second engine startup or escape burn.

https://en.wikipedia.org/wiki/Danuri

• Hakuto-R/Emirates Lunar Mission/Lunar Flashlight was an internationally shared launch using an Ballistic lunar transfer.

At T+plus 40 minutes, with the rocket soaring over Africa, the upper stage reignited for a nearly minute-long firing to propel the payloads on a trajectory to escape the grip of Earth’s gravity and head into deep space. https://spaceflightnow.com/2022/12/11/falcon-9-ispace-mission-1-live-coverage/

• The Euclid telescope was launched to the Sun-Earth L2 point. So like DSCOVR, the upper stage will be between heliocentric orbit and Earth orbit.

Other planned SpaceX missions to heliocentric orbit are Psyche (with possibly Janus as secondary payload) and Europa Clipper.

Answer 2

I'll supplement @KarlKastor's "4" answer and highlight some future missions at the end that will up the total:

4

Past missions

1. According to Wikipedia, the Triana (also known as DSCOVR or GoreSat) was launched by the NOAA (National Oceanic and Atmospheric Administration) on February 11 of 2015. It's purpose was to measure the weather and climate in space. It also was used as an Earth observation satellite. It was sent to the Lagrange Point, L1. A Lagrange Point is a pint in space where the gravity of 2 bodies, in this case the Sun and the Earth balance each other out. The second stage is now somewhere between the Earth's and Sun's spheres of influence.
2. The TESS (Transiting Exoplanet Survey Satellite) was launched on April 18 of 2018. It's purpose was to discover new exoplanets around the brightest stars for a 2 years period. It would accomplish this by using the transit method. The transit method involves noticing the slight dimming of the host star when the planet passes around it, indicating its existence. While the mission itself was launched into lunar flyby, the second stage is in a heliocentric orbit.
3. The DART (Double Asteroid Redirection Test) was launched on November 24 of 2021 by NASA. It's purpose was to test a method of deflecting asteroids or other dangerous NEOs (Near Earth Objects). In approximately 4 months, the craft will intentionally crash into the asteroid Didymos to test this. Since the asteroid, of course orbits around the Sun, that is where it's second stage is.
4. An, of course, how could I forget about Elon Musk's Tesla Roadster. It was an electric car made by his company TESLA. It was launched as a dummy payload for the Falcon Heavy's maiden flight. It, and it's second stage, orbit around the Sun.

Future missions

Of course, there will more. For example, the Psyche mission is planned to explore the origins of planetary cores. JANUS may join it to explore asteroids with its dual spacecraft. Also, while the Europa Clipper was originally planned to be launched on the NASA SLS (Space Launch System) rocket, it has now been moved to a Falcon Heavy rocket. It going to be a Jupiter orbiter mission, which will flyby various of Jupiter's moons. Namely, it will fly by Europa no less than 44 times. So, if you count future missions, then 7.