List of artificial objects leaving the Solar System

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Spacecraft that have left or are about to leave the Solar System are depicted as square boxes 2023 interstellar probes NASA-JPL eyes.png
Spacecraft that have left or are about to leave the Solar System are depicted as square boxes
Trajectories of distant spacecraft from launch to 2030
Trajectories of distant spacecrafts.svg
Trajectories of distant spacecrafts - equatorial view.svg
Top: Polar view; Bottom: Equatorial view
Plot of Voyager 2's heliocentric velocity against its distance from the Sun, illustrating the use of gravity assist to accelerate the spacecraft by Jupiter, Saturn and Uranus, and finally its encounter with Neptune's Triton. Very massive planets attract spacecraft towards them, through the gravitational force; this force accelerates the spacecraft. If the spacecraft is not on a collision trajectory with the planet, and the spacecraft is travelling faster than the escape velocity of the planet, the spacecraft will travel past the planet gaining speed from the gravitational acceleration; this is called a gravity assist (or "gravitational slingshot"). Voyager 2 velocity vs distance from sun.svg
Plot of Voyager 2′s heliocentric velocity against its distance from the Sun, illustrating the use of gravity assist to accelerate the spacecraft by Jupiter, Saturn and Uranus, and finally its encounter with Neptune's Triton. Very massive planets attract spacecraft towards them, through the gravitational force; this force accelerates the spacecraft. If the spacecraft is not on a collision trajectory with the planet, and the spacecraft is travelling faster than the escape velocity of the planet, the spacecraft will travel past the planet gaining speed from the gravitational acceleration; this is called a gravity assist (or “gravitational slingshot”).

Several space probes and the upper stages of their launch vehicles are leaving the Solar System, all of which were launched by NASA. Three of the probes, Voyager 1 , Voyager 2 , and New Horizons are still functioning and are regularly contacted by radio communication, while Pioneer 10 and Pioneer 11 are now derelict. In addition to these spacecraft, some upper stages and de-spin weights are leaving the Solar System, assuming they continue on their trajectories.

Contents

These objects are leaving the Solar System because their velocity and direction are taking them away from the Sun, and at their distance from the Sun, its gravitational pull is not sufficient to pull these objects back or into orbit. They are not impervious to the gravitational pull of the Sun and are being slowed, but are still traveling in excess of escape velocity to leave the Solar System and coast into interstellar space.

Planetary exploration probes

Although other probes were launched first, Voyager 1 has achieved a higher speed and overtaken all others. Voyager 1 overtook Voyager 2 a few months after launch, on December 19, 1977. [12] It overtook Pioneer 11 in 1981, [13] and then Pioneer 10—becoming the probe farthest from the Sun—on February 17, 1998. [14] Voyager 2 is moving faster than all other probes launched before it; it overtook Pioneer 11 in the late 1980s and then Pioneer 10 — becoming the second-farthest spacecraft from the Sun — on July 18, 2023. [15] [16]

Depending on how the "Pioneer anomaly" affects it, New Horizons will also probably pass the Pioneer probes, but will need many years to do so. It will overtake Pioneer 11 in 2143, and will overtake Pioneer 10 in 2314, but will never overtake the Voyagers. [13]

Speed and distance from the Sun

To put the distances in the table in context, Pluto's average distance (semi-major axis) is about 40 AU.

NameLaunchedDistance from the Sun (AU)
(as of 2024) [17] [18] 		Speed (km/s) [17] [18]
Voyager 1 1977163.90317.0
Voyager 2 1977136.88715.4
Pioneer 10 1972136.31511.9
Pioneer 11 1973114.09011.2
New Horizons 200659.19913.7

Note: Data above as of June 24, 2024. Source: JPL, [17] NASA SSD Simulator, [18] and for New Horizons. [19]

Solar escape velocity is a function of distance (r) from the Sun's center, given by

where the product G Msun is the heliocentric gravitational parameter. The initial speed required to escape the Sun from its surface is 618 km/s (1,380,000 mph), [20] and drops down to 42.1 km/s (94,000 mph) at Earth's distance from the Sun (1 AU), and 4.21 km/s (9,400 mph) at a distance of 100 AU. [21] [22]

In order to leave the Solar System, the probe needs to reach the local escape velocity. Escape velocity from the sun without the influence of Earth is 42.1 km/s. In order to reach this speed, it is highly advantageous to use as a boost the orbital speed of the Earth around the Sun, which is 29.78 km/s. By later passing near a planet, a probe can gain extra speed from a gravity assist.

Propulsion stages

A Star-48 rocket motor like the one used to launch the New Horizons probe PAM-D rocket stage.jpg
A Star-48 rocket motor like the one used to launch the New Horizons probe

Every planetary probe was placed into its escape trajectory by a multistage rocket, the last stage of which ends up on nearly the same trajectory as the probe it launched. Because these stages cannot be actively guided, their trajectories are now different from the probes they launched (the probes having been guided with small thrusters that allowed course changes). However, in cases where the spacecraft acquired escape velocity because of a gravity assist, the stages may not have a similar course and there is the extremely remote possibility that they collided with something. The stages on an escape trajectory are:

In addition, two small yo-yo de-spin weights on wires were used to reduce the spin of the New Horizons probe prior to its release from the third-stage rocket. Once the spin rate was lowered, these masses and the wires were released, and so are also on an escape trajectory out of the Solar System. [28] [29]

None of the above objects are trackable – they have no power or radio antennas, spin uncontrollably, and are too small to be detected. Their exact positions are unknowable beyond their projected Solar System escape trajectories.

The third stage of Pioneer 11 is thought to be in solar orbit because its encounter with Jupiter would not have resulted in escape from the Solar System. [24] [ better source needed ]Pioneer 11 gained the required velocity to escape the Solar System in its subsequent encounter with Saturn.[ dubious – discuss ]

On January 19, 2006, the New Horizons spacecraft to Pluto was launched directly into a solar-escape trajectory at 16.26 kilometers per second (58,536 km/h; 36,373 mph) from Cape Canaveral using an Atlas V and the Common Core Booster, Centaur upper stage, and Star 48B third stage. [30] New Horizons passed the Moon's orbit in just nine hours. [31] [32] The subsequent encounter with Jupiter only increased its velocity, and enabled the probe to arrive at Pluto three years earlier than without this encounter.

Thus the only objects to date to be launched directly into a solar escape trajectory were the New Horizons spacecraft, its third stage, and the two de-spin masses. The New Horizons Centaur (second) stage is not escaping; it is in a 2.83-year heliocentric (solar) orbit. [25]

The Pioneer 10 and 11, and Voyager 1 and 2 Centaur (second) stages are also in heliocentric orbits. [29] [33]

Future

Voyager 1 and close encounters of the Sun with other stars in the next 100,000 years. NearSunStarsSimple.jpg
Voyager 1 and close encounters of the Sun with other stars in the next 100,000 years.

Given the huge emptiness of interstellar space, all the objects listed here are likely to continue into deep space in timelines that, barring the exceptionally unlikely chance of their colliding with (or being collected by) another object, could outlast even the Main Sequence existence of the Sun's life, billions of years hence. [34] One estimated timescale as to the likelihood of the Pioneer or Voyager spacecraft colliding with a star (or stellar remnant) is 1020 (100 quintillion) years. [35] [36] They are very unlikely, however, to gain enough velocity to escape the Milky Way galaxy [35] (or its future merger with the Andromeda galaxy) into intergalactic space.

Ulysses

In 1990, the solar probe Ulysses was launched towards Jupiter in order to reach a high-inclination heliocentric orbit over the Sun's poles; the spacecraft was shut down in 2008. Ulysses is currently in a 79° inclination orbit around the Sun with its apoapsis crossing the orbit of Jupiter. In November 2098, it will have another close fly-by with Jupiter, crossing between the orbits of Europa and Ganymede. After this slingshot maneuver, it will possibly enter a hyperbolic trajectory around the Sun and eventually leave the Solar System. [37]

Ulysses is now switched off as its RTG power supply has run down, and so is uncontactable and cannot be tracked or guided in any way since 2009. Its exact trajectory is therefore unknowable as factors such as solar radiation pressure could significantly alter its encounter path.

See also

Related Research Articles

<i>Pioneer 11</i> First spacecraft to visit Saturn (1973–1995)

Pioneer 11 is a NASA robotic space probe launched on April 5, 1973, to study the asteroid belt, the environment around Jupiter and Saturn, the solar wind, and cosmic rays. It was the first probe to encounter Saturn, the second to fly through the asteroid belt, and the second to fly by Jupiter. Later, Pioneer 11 became the second of five artificial objects to achieve an escape velocity allowing it to leave the Solar System. Due to power constraints and the vast distance to the probe, the last routine contact with the spacecraft was on September 30, 1995, and the last good engineering data was received on November 24, 1995.

<span class="mw-page-title-main">Pioneer program</span> Series of United States uncrewed lunar and planetary space probes (1958-60; 1965-92)

The Pioneer programs were two series of United States lunar and planetary space probes exploration. The first program, which ran from 1958 to 1960, unsuccessfully attempted to send spacecraft to orbit the Moon, successfully sent one spacecraft to fly by the Moon, and successfully sent one spacecraft to investigate interplanetary space between the orbits of Earth and Venus. The second program, which ran from 1965 to 1992, sent four spacecraft to measure interplanetary space weather, two to explore Jupiter and Saturn, and two to explore Venus. The two outer planet probes, Pioneer 10 and Pioneer 11, became the first two of five artificial objects to achieve the escape velocity that will allow them to leave the Solar System, and carried a golden plaque each depicting a man and a woman and information about the origin and the creators of the probes, in case any extraterrestrials find them someday.

<i>Voyager 1</i> NASA space probe launched in 1977

Voyager 1 is a space probe launched by NASA on September 5, 1977, as part of the Voyager program to study the outer Solar System and the interstellar space beyond the Sun's heliosphere. It was launched 16 days after its twin, Voyager 2. It communicates through the NASA Deep Space Network (DSN) to receive routine commands and to transmit data to Earth. Real-time distance and velocity data are provided by NASA and JPL. At a distance of 165.2 AU from Earth as of October 2024, it is the most distant human-made object from Earth. The probe made flybys of Jupiter, Saturn, and Saturn's largest moon, Titan. NASA had a choice of either doing a Pluto or Titan flyby; exploration of the moon took priority because it was known to have a substantial atmosphere. Voyager 1 studied the weather, magnetic fields, and rings of the two gas giants and was the first probe to provide detailed images of their moons.

<i>Voyager 2</i> First spacecraft to visit Uranus and Neptune (launched in 1977 by NASA)

Voyager 2 is a space probe launched by NASA on August 20, 1977, as a part of the Voyager program. It was launched on a trajectory towards the gas giants Jupiter and Saturn and enabled further encounters with the ice giants Uranus and Neptune. It remains the only spacecraft to have visited either of the ice giant planets, and was the third of five spacecraft to achieve Solar escape velocity, which allowed it to leave the Solar System. Launched 16 days before its twin Voyager 1, the primary mission of the spacecraft was to study the outer planets and its extended mission is to study interstellar space beyond the Sun's heliosphere.

<i>Pioneer 10</i> First spacecraft to visit Jupiter and the outer Solar System (1972–2003)

Pioneer 10 is a NASA space probe launched in 1972 that completed the first mission to the planet Jupiter. Pioneer 10 became the first of five planetary probes and 11 artificial objects to achieve the escape velocity needed to leave the Solar System. This space exploration project was conducted by the NASA Ames Research Center in California. The space probe was manufactured by TRW Inc.

<span class="mw-page-title-main">Voyager program</span> Ongoing NASA interstellar program

The Voyager program is an American scientific program that employs two interstellar probes, Voyager 1 and Voyager 2. They were launched in 1977 to take advantage of a favorable planetary alignment to explore the two gas giants Jupiter and Saturn and potentially also the ice giants, Uranus and Neptune - to fly near them while collecting data for transmission back to Earth. After Voyager 1 successfully completed its flyby of Saturn and its moon Titan, it was decided to send Voyager 2 on flybys of Uranus and Neptune.

<span class="mw-page-title-main">Gravity assist</span> Space navigation technique

A gravity assist, gravity assist maneuver, swing-by, or generally a gravitational slingshot in orbital mechanics, is a type of spaceflight flyby which makes use of the relative movement and gravity of a planet or other astronomical object to alter the path and speed of a spacecraft, typically to save propellant and reduce expense.

<i>New Horizons</i> NASA spacecraft launched in 2006

New Horizons is an interplanetary space probe launched as a part of NASA's New Frontiers program. Engineered by the Johns Hopkins University Applied Physics Laboratory (APL) and the Southwest Research Institute (SwRI), with a team led by Alan Stern, the spacecraft was launched in 2006 with the primary mission to perform a flyby study of the Pluto system in 2015, and a secondary mission to fly by and study one or more other Kuiper belt objects (KBOs) in the decade to follow, which became a mission to 486958 Arrokoth. It is the fifth space probe to achieve the escape velocity needed to leave the Solar System.

<span class="mw-page-title-main">Heliosphere</span> Region of space dominated by the Sun

The heliosphere is the magnetosphere, astrosphere, and outermost atmospheric layer of the Sun. It takes the shape of a vast, tailed bubble-like region of space. In plasma physics terms, it is the cavity formed by the Sun in the surrounding interstellar medium. The "bubble" of the heliosphere is continuously "inflated" by plasma originating from the Sun, known as the solar wind. Outside the heliosphere, this solar plasma gives way to the interstellar plasma permeating the Milky Way. As part of the interplanetary magnetic field, the heliosphere shields the Solar System from significant amounts of cosmic ionizing radiation; uncharged gamma rays are, however, not affected. Its name was likely coined by Alexander J. Dessler, who is credited with the first use of the word in the scientific literature in 1967. The scientific study of the heliosphere is heliophysics, which includes space weather and space climate.

<span class="mw-page-title-main">Interstellar probe</span> Space probe that can travel out of the Solar System

An interstellar probe is a space probe that has left—or is expected to leave—the Solar System and enter interstellar space, which is typically defined as the region beyond the heliopause. It also refers to probes capable of reaching other star systems.

<span class="mw-page-title-main">Outline of space exploration</span> Overview of and topical guide to space exploration

The following outline is provided as an overview of and topical guide to space exploration.

<span class="mw-page-title-main">Star 48</span> American solid rocket motor developed by Thiokol

The Star 48 is the largest of a family of solid rocket motors used by many space propulsion and launch vehicle stages, almost exclusively as an upper stage. It was developed primarily by Thiokol Propulsion and after several mergers, is manufactured by Northrop Grumman’s Space Systems division. A Star 48B stage is also one of the few man-made items sent on escape trajectories out of the Solar System, although it is derelict since its use. The Star 48B variant was the PAM-D upper stage used on the retired Delta II rocket.

<span class="mw-page-title-main">Exploration of Jupiter</span> Overview of the exploration of Jupiter the planet and its moons

The exploration of Jupiter has been conducted via close observations by automated spacecraft. It began with the arrival of Pioneer 10 into the Jovian system in 1973, and, as of 2024, has continued with eight further spacecraft missions in the vicinity of Jupiter and two more en route. All but one of these missions were undertaken by the National Aeronautics and Space Administration (NASA), and all but four were flybys taking detailed observations without landing or entering orbit. These probes make Jupiter the most visited of the Solar System's outer planets as all missions to the outer Solar System have used Jupiter flybys. On 5 July 2016, spacecraft Juno arrived and entered the planet's orbit—the second craft ever to do so. Sending a craft to Jupiter is difficult, mostly due to large fuel requirements and the effects of the planet's harsh radiation environment.

<span class="mw-page-title-main">TAU (spacecraft)</span> Cancelled NASA space probe to travel 1000 AU from the Sun

TAU was a proposed uncrewed interstellar probe that would go to a distance of one thousand astronomical units from the Earth and Sun by the NASA Jet Propulsion Laboratory in 1987 using tested technology. One scientific purpose would be to measure the distance to other stars via stellar parallax. Studies continued into 1990, working with a launch in the 2005–2010 timeframe.

<span class="mw-page-title-main">Exploration of Neptune</span> Overview of the exploration of Neptune

Neptune has been directly explored by one space probe, Voyager 2, in 1989. As of 2024, there are no confirmed future missions to visit the Neptunian system, although a tentative Chinese mission has been planned for launch in 2024. NASA, ESA, and independent academic groups have proposed future scientific missions to visit Neptune. Some mission plans are still active, while others have been abandoned or put on hold.

Shensuo, formerly Interstellar Express, is a proposed Chinese National Space Administration program designed to explore the heliosphere and interstellar space. The program will feature two or three space probes that will purportedly be launched in 2024 and follow differing trajectories to encounter Jupiter to 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 by Neptune and Triton in January 2038. There may be another probe—tentatively IHP-3—which would launch in 2030 to explore to the northern half of the heliosphere. IHP-1 and IHP-2 would be the sixth and seventh spacecraft to leave the Solar System, as well as first non-NASA probes to achieve this status.

<i>Interstellar Probe</i> (spacecraft) Proposed NASA space probe to travel 1000 AU from the Sun

Interstellar Probe (ISP) is a proposed NASA space probe designed to explore and characterize the heliosphere and interstellar space. The study was originally proposed in 2018 by NASA for the Applied Physics Laboratory. It would have a baseline launch between 2036 and 2041. The probe would launch on a direct hyperbolic trajectory to encounter Jupiter after six to seven months, after which the probe would travel at a speed of about 6–7 astronomical units (900,000,000–1.05×109 kilometres) per year, leaving the heliosphere after only 16 years.

<span class="mw-page-title-main">Timeline of New Horizons</span>

Timeline for the New Horizons interplanetary space probe lists the significant events of the launch, transition phases as well as subsequent significant operational mission events; by date and brief description.

References

  1. ↑ "Pioneer 10 Live Position and Data". TheSkyLive.com. Retrieved August 11, 2019.
  2. ↑ "Pioneer 11 Live Position and Data". TheSkyLive.com. Retrieved August 11, 2019.
  3. ↑ "The Pioneer Missions". NASA. March 3, 2015.
  4. ↑ Gill, Victoria (December 10, 2018). "Nasa's Voyager 2 probe 'leaves the Solar System'". BBC News . Retrieved December 10, 2018.
  5. 1 2 3 "Voyager – Mission – Interstellar Mission". NASA. June 22, 2007. Retrieved August 14, 2013.
  6. ↑ Bailer-Jones, C. A. L. (August 2022). "Stars That Approach within One Parsec of the Sun: New and More Accurate Encounters Identified in Gaia Data Release 3". The Astrophysical Journal Letters. 935 (1). id. L9. arXiv: 2207.06258 . Bibcode:2022ApJ...935L...9B. doi: 10.3847/2041-8213/ac816a .
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  10. ↑ Brown, Dwayne (July 1, 2016). "New Horizons Receives Mission Extension to Kuiper Belt, Dawn to Remain at Ceres" (Press release). Washington, DC. NASA. Archived from the original on August 20, 2016. Retrieved October 6, 2016.
  11. ↑ "NASA's New Horizons Reaches a Rare Space Milestone". NASA . April 15, 2021. Retrieved June 6, 2024.
  12. ↑ Gebhardt, Chris; Goldader, Jeff (August 20, 2011). "Thirty-four years after launch, Voyager 2 continues to explore". nasaspaceflight.com. Retrieved July 15, 2015.
  13. 1 2 Cranor, David (December 4, 2017). "When the Voyagers passed the Pioneers". Nothing More Powerful. Retrieved December 4, 2017.
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  15. ↑ "Distance between the Sun and Voyager 2".
  16. ↑ "Distance between the Sun and Pioneer 10".
  17. 1 2 3 "Voyager – Mission Status". Jet Propulsion Laboratory . NASA . Retrieved November 4, 2019.
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  20. ↑ "What is escape velocity?". www.qrg.northwestern.edu. Retrieved October 25, 2018.
  21. ↑ "solar escape velocity at 100 AU - Wolfram|Alpha". www.wolframalpha.com.
  22. ↑ "WikiHow: How to Calculate Escape Velocity" . Retrieved December 17, 2018.
  23. ↑ "NASA - NASA Glenn Pioneer Launch History". NASA. Archived from the original on July 13, 2017. Retrieved April 1, 2015.
  24. 1 2 3 "rockets - Where are the upper stages for the Voyager/Pioneer stages? - Space Exploration Stack Exchange". stackexchange.com.
  25. 1 2 Stern, Alan; Guo, Yanping (October 28, 2010). "Where Is the New Horizons Centaur Stage?". Johns Hopkins University Applied Physics Laboratory.
  26. ↑ "Star 48b Third-stage Motor - Unmanned Spaceflight.com". unmannedspaceflight.com.
  27. ↑ Malik, Tariq (January 26, 2006). "Derelict Booster to Beat Pluto Probe to Jupiter". Space.com. Retrieved January 2, 2019.
  28. ↑ Pierre Bauduin. "New Horizons". weebau.com.
  29. 1 2 "Deep space probes and other manmade objects beyond near Earth space". johnstonsarchive.net.
  30. ↑ Scharf, Caleb A. (February 25, 2013). "The Fastest Spacecraft Ever?". Scientific American. Retrieved July 12, 2017.
  31. ↑ Neufeld, Michael (July 10, 2015). "First Mission to Pluto: The Difficult Birth of New Horizons". Smithsonian. Retrieved April 21, 2018.
  32. ↑ "New Horizons: Mission Overview" (PDF). International Launch Services. January 2006. Archived from the original (PDF) on September 9, 2016. Retrieved April 21, 2018.
  33. ↑ https://usspaceobjectsregistry.state.gov/Lists/SpaceObjects/DispFormaspx?ID=3348.html%5B%5D
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  35. 1 2 Bailer-Jones, Coryn A. L.; Farnocchia, Davide (April 3, 2019). "Future stellar flybys of the Voyager and Pioneer spacecraft". Research Notes of the American Astronomical Society. 3 (59): 59. arXiv: 1912.03503 . Bibcode:2019RNAAS...3...59B. doi: 10.3847/2515-5172/ab158e . S2CID   134524048.
  36. ↑ "Calculating the time it will take spacecraft to find their way to other star systems". Phys.org. December 2019.
  37. ↑ "Solar orbiter Ulysses ends mission after 18 years". Reuters. July 2009.
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