ESA Juice Completes Earth Gravity Assist: Key Facts and Exam Context
ESA's Jupiter Icy Moons Explorer (Juice) flew past Earth on 28 September 2026 at about 8,640 km over the Indian Ocean. The flyby bent its path by 20° and added 3.5 km/s. This post covers what is done, what is still pending, and the exam context.
On this page
ESA's Jupiter Icy Moons Explorer (Juice) completed an Earth flyby on 28 September 2026. It used Earth's gravity to change course towards Jupiter while spending very little fuel. Closest approach was at 13:45 CEST (11:45 UTC, which is 17:15 IST), when the spacecraft was about 8,640 km above the Indian Ocean. ESA reports that the flyby deflected Juice by 20° and increased its velocity by 3.5 km/s.
What happened and when
The event date is 28 September 2026, and ESA's report is dated the same day. GKToday's summary is dated 5 October 2026, so it is a later write-up of an event that was already complete.
- Event: Earth gravity-assist flyby by ESA's Juice spacecraft.
- Altitude: about 8,640 km above the Indian Ocean at closest approach.
- Effect: a 20° deflection from the pre-flyby path and a 3.5 km/s velocity increase.
- Navigation: in the four weeks before the flyby, operators used only one small trajectory correction out of six opportunities set aside.
Why the flyby matters
Saving fuel for Jupiter
A gravity assist (often called a slingshot) uses a planet's gravity and motion to change a spacecraft's speed and direction without burning much propellant. ESA's Spacecraft Operations Manager Angela Dietz said only a small amount of the propellant reserved for this flyby was used. This leaves more for observations of Jupiter's icy moons.
A test run for the instruments
ESA says the flyby was also a chance to test Juice's science instruments. Juice carries 10 science instruments. Earlier chances came during the 2024 lunar-Earth gravity assist and the 2025 observations of Comet 3I/ATLAS. ESA also says Juice spent several days in Earth's magnetotail, which gave it a chance to measure magnetic fields and charged particles far from Earth. ESA says these data can be combined with observations from the European-Chinese Smile mission.
Status as of 5 October 2026
| Item | Status | Basis |
|---|---|---|
| Earth flyby, 28 September 2026 | Completed | ESA and GKToday |
| Extra spacecraft tracking (since 17 August) | Ongoing until 10 October | ESA |
| Release of images and spectra from some instruments | ESA said on 28 September that it expected to publish them "in the coming weeks"; the supplied evidence does not confirm which have been released | ESA |
| Another Earth flyby, January 2029 | Scheduled | ESA |
| Jupiter arrival, 2031 | Planned | ESA and GKToday |
| Ganymede orbit, 2034 | Planned | GKToday only; ESA's text in the evidence gives no date |
Mission background for revision
- Full name: Jupiter Icy Moons Explorer.
- Agency: European Space Agency, with contributions from NASA, JAXA and the Israel Space Agency. It is the first Large-class mission in ESA's Cosmic Vision programme.
- Launch: April 2023 on an Ariane 5 from Europe's Spaceport in Kourou.
- Targets: Jupiter and its ocean-bearing moons Ganymede, Callisto and Europa.
- Plan: an eight-year cruise with Earth and Venus flybys, then 35 flybys of the three large moons while orbiting Jupiter, before a change of orbit to Ganymede.
Exam-relevant context
This topic fits Science and Technology and space current affairs. Questions on such events often test the mission name, the agency, the technique and the basic facts. The evidence does not show that any exam has asked about this flyby, so treat these points as revision material rather than a prediction.
- Gravity assist is a slingshot manoeuvre that saves propellant on long missions.
- GKToday notes that NASA's Juno used an Earth gravity assist on 9 October 2013 before reaching Jupiter. This point comes from GKToday only.
- GKToday lists Ganymede as the largest moon in the Solar System and Jupiter as the fifth planet from the Sun.
Evidence limits to remember
Is this the "third Earth" flyby?
GKToday calls this Juice's third Earth gravity assist. ESA's related story is titled "Juice to fly past Earth for third gravity assist". ESA's text separately describes the January 2029 encounter as a third flyby of Earth, and it refers to the 2024 lunar-Earth gravity assist. The sources count these flybys in different ways. For an exam, remember the date, the 20° deflection and the 3.5 km/s gain rather than relying on the ordinal number.
Other gaps
ESA's page lists the moons as "Ganymede, Europa and Ganymede" in one sentence, but its mission summary names Ganymede, Callisto and Europa, so the latter is used here. GKToday gives the speed gain as about 12,606 km/h. This is simply the same 3.5 km/s expressed in km/h, and ESA reports it in km/s.
FAQ
When did Juice make its Earth flyby?
On 28 September 2026, with closest approach at 11:45 UTC.
How close did Juice get to Earth?
ESA reports about 8,640 km above the Indian Ocean.
When does Juice reach Jupiter?
ESA and GKToday both give 2031 as the planned arrival, with another Earth flyby planned for January 2029 on the way.
Sources & Further Reading
| Document / Website | Link |
|---|---|
| ESA JUICE Completes Earth Gravity Assist – GKToday | Open ESA JUICE Completes Earth Gravity Assist – GKToday ↗www.gktoday.in |
| ESA - Successful Earth flyby improves Juice’s course to Jupiter | Open ESA - Successful Earth flyby improves Juice’s course to Jupiter ↗www.esa.int |
| ESA - Juice to fly past Earth for third gravity assist | Open ESA - Juice to fly past Earth for third gravity assist ↗www.esa.int |