LISA Pathfinder

spacecraft with Earth in the background — An artist's concept of the European Space Agency's LISA Pathfinder spacecraft, designed to pave the way for a mission detecting gravitational waves. NASA's Jet Propulsion Laboratory (JPL) developed a thruster system on board. Credit: ESA

LISA Pathfinder’s goal was to stay as steady as possible while in orbit to test technology for future missions to detect gravitational waves with a space-based observatory.

The mission exceeded ESA’s expectations, paving the way for gravitational wave observatories in space.
ESA plans a follow-up mission, the Laser Interferometer Space Antenna (LISA), in 2034.

Launch Date	Dec. 3, 2015
Launch Site	Kourou / ELV
Launch Vehicle	Vega
Destination	L1 Lagrange Point
Type	Orbiter
Status	Powered down; in parking orbit
Agency	European Space Agency
Alternate Names	Small Missions for Advanced Research in Technology-2 (SMART-2)

Firsts

First demonstration of key technology that paved the way for a space-based observatory to measure gravitational waves.

Key Dates

Launch: Dec. 3, 2015

Arrived at L1 Lagrange Point: Jan. 22, 2016

ESA announced mission success: April 2016

Mission extended: Nov. 1, 2016

Mission completed: June 30, 2017

Spacecraft powered down: July 18, 2017

In Depth

Objective: Lagrange Point L1

Spacecraft Mass: 4,211 pounds (1,910 kilograms)

Mission Design and Management: ESA

Scientific Instruments:

1. LISA Technology Package (LTP)

2. Disturbance Reduction System (DRS)

LISA Pathfinder was launched to Lagrange Point L1, a location in space that’s about 930,000 miles (1.5 million kilometers) from Earth in the direction of the Sun. L1 is like a parking spot in space -- a place where a spacecraft can orbit and maintain a nearly constant distance to Earth.

The spacecraft’s main goal was to hold still, in fact to be as motionless as possible. This allowed scientists to test technology that will be used on a future mission that will carry gravitational wave detectors – ESA’s Laser Interferometer Space Antenna (LISA), tentatively planned for launch in 2034.

A gravitational wave is a ripple in space-time caused by large objects moving at a very high speed. Events that can cause gravitational waves include merging black holes, supernova explosions and large stars spiraling around each other.

The spacecraft had a main science spacecraft and a propulsion module. The propulsion module was used to boost LISA Pathfinder’s orbit and to send it to Lagrange Point L1.

The key technology test on the mission was the LISA Technology Packager (LTP). It had two gold-platinum cubes that were about two inches (46 milimeters) in diameter, each weighing about 4.5 pounds (2 kilograms).

The cubes were released to free-fall inside the spacecraft, each suspended inside its own special canister and isolated from all forces except gravity. The spacecraft used special thrusters to keep it centered around the cubes while a laser interferometer kept track of the distance between them, about 15 inches (38 centimeters).

The second test package, the Disturbance Reduction System (DRS), was a NASA-built system made up of special micro-thrusters and a computer.