ACE
ACE (Advanced Composition Explorer) — a NASA observatory at the Sun–Earth L1 point, about 1.5 million km sunward of Earth (launched 25 August 1997). It samples particles from the Sun, from interstellar space and from the rest of the galaxy, and its real-time solar-wind readings give advance warning of geomagnetic storms.
Key facts
Mission & specifications
Mission
- Operator
- NASA
- Launched
- August 25, 1997
- Status
- Active
Trajectory
- Speed rel. Earth
- 385 m/s
- Computed from the cached state vector, relative to Earth
- Distance from the Sun
- 0.987 AU
- Computed from the cached position
- Distance from Earth
- 2,094,537 km
- Computed from cached positions
- Distance from Venus
- 0.267 AU
- Computed from cached positions
Mission
ACE, the Advanced Composition Explorer, was launched by NASA on a Delta II on 25 August 1997. A month later, at the top of a long orbit reaching 1.37 million km from Earth, it was steered toward the Sun–Earth L1 point, and on 12 December 1997 it settled into a Lissajous orbit around it, about 1.5 million km sunward of Earth. It was declared operational on 21 January 1998. From there it samples matter from the Sun, from interstellar space and from the rest of the galaxy — solar-wind ions, energetic particles from solar flares and galactic cosmic rays — with six high-resolution spectrometers and three monitoring instruments. Its Real-Time Solar Wind system sends a constant stream of readings to Earth, giving advance warning of geomagnetic storms. ACE was built for a mission of at least five years and is still working almost three decades later. Its position here is JPL Horizons'; JPL holds its trajectory from July 2006 onward.
- 1997ACE launches on a Delta II rocketLaunch
Into a long orbit reaching 1.37 million km from Earth.
- 1997Arrives at the L1 pointArrival
Settles into a Lissajous orbit about 1.5 million km sunward of Earth.
- 1998Declared operationalMilestone
Its real-time solar-wind readings begin warning of geomagnetic storms.
Images
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