Psyche launch — to a metal world
NASA's Psyche spacecraft left on 13 October 2023 for the metal-rich asteroid 16 Psyche, to find out whether it is the exposed core of a shattered early planet.
Available views: Orbit ✓ · Sky — (not visible in the sky)
The story
On 13 October 2023 NASA's Psyche spacecraft lifted off on a Falcon Heavy rocket, headed for the asteroid 16 Psyche. The asteroid lies in the main belt between Mars and Jupiter and is about 220 km across on average, roughly one and a half times the distance a fast train covers in an hour. Observations suggest it contains a lot of metal, such as iron and nickel.
That is why scientists think 16 Psyche might be the core of a small planet that began to form early in the solar system's history and was later broken apart. Earth also has a metal core, but it lies thousands of kilometres underground where no one can see it. If the idea is right, Psyche offers a chance to look at the inside of a planet from the outside. It is still only an idea, and testing it is the purpose of the mission.
The spacecraft flies on Hall-effect thrusters, a kind of electric engine. Electricity is used to push xenon gas out of the back at very high speed. The push is very gentle, about the weight of a few coins resting on your hand. But if it is left running for months and years, the speed builds up a great deal while using far less fuel than an ordinary rocket. Psyche is the first mission to use this type of thruster to travel between planets.
On 15 May 2026 the spacecraft flew about 4,600 km above Mars, using the planet's gravity to change its speed and direction. It is now heading out to the asteroid belt and is due to reach 16 Psyche in August 2029. The orbit view shows the probe passing Mars and then catching up with the asteroid for their meeting.
Mission goals
The cores of Earth, Mars and Venus all lie deep underground, and so far they have been studied only by watching how earthquake waves travel through them. If 16 Psyche really is a piece of a core, its surface could show directly how a planet separates, with heavy metal sinking to the middle and lighter rock staying outside.
There is a puzzle, though. Psyche's density is about 4 grams per cubic centimetre. That is heavier than ordinary rock but much lighter than solid iron. So it may be a mixture of metal and rock, or a lump of metal full of empty gaps. Working out which is the first question to answer after arrival.
The spacecraft also carries a laser communication experiment called DSOC. In November 2023 it sent its first laser signal from about 16 million km away. In April 2024, from 226 million km, about one and a half times the distance between Earth and the Sun, it sent data at 25 megabits per second. Laser links can carry much more data than radio, which could matter for future crewed missions to Mars.
Mission chronology and background
16 Psyche was discovered in 1852 by the Italian astronomer Annibale de Gasparis. It was the sixteenth asteroid ever found, hence the number, and it is named after Psyche from Greek myth. Later radar observations found patches on its surface that reflect radio waves strongly, a hint of metal. The mission was selected in 2017 as part of NASA's Discovery programme.
Launch was first planned for August 2022, but testing of the flight software ran late and it slipped by a year. That pushed arrival back from 2026 to 2029. In April 2025 the pressure in the propellant feed dropped unexpectedly, so the thrusters were paused; the team switched to a backup line and started them again.
After arrival the spacecraft will orbit the asteroid for about 26 months. It begins about 700 km up to map the whole surface, then steps down in four stages to 75 km while measuring gravity, composition and magnetism. If the magnetometer finds a leftover magnetic field, that would be evidence of a metal core that was once molten.
Other milestones of this mission
- Psyche arrives at the metal asteroid(planned)
Where to see it — sky and simulator
The spacecraft is far too small and distant to see. Select it in the orbit view to see where it is now, the path it has flown and its 2029 arrival point. Switch on asteroids and the orbit of 16 Psyche, which takes about five years to go around the Sun, is drawn as well.
The asteroid itself can be seen through a telescope. It shines at between magnitude 9.5 and 12.5, dozens of times fainter than the faintest stars visible to the naked eye, so a small telescope shows it only as a tiny point like a star. It is brightest around opposition, when it is closest to Earth. The sky view shows which constellation it is in now.
See this for yourself — replay the moment in the orbit view
FAQ
Is 16 Psyche really made of metal?
It is metal-rich, but its density falls between rock and iron, so it may be a metal-rock mix or a lump of metal with many gaps. That is the first question to settle on arrival.
When does it arrive?
It flew past Mars in May 2026 to adjust its path and is due to arrive in August 2029.
Why does laser communication matter?
It can send far more data than radio. That is what crewed missions to faraway places such as Mars will need for high-quality video.
How weak is the electric thrust?
About the weight of a few coins on your hand. But left running for years, it builds up a large change in speed for very little fuel.
Related
- Psyche arrives at 16 Psyche
- DART — humanity moves an asteroid
- Lucy at Eurybates
- Psyche — object index
- Mars — object index
Times and figures are approximate — verify with official sources when planning travel. Simulation uses J2000 mean elements.