Spaceflight Insider

LISA Pathfinder launched on gravitational experiment

Vega VV06 launch of Lisa PathFinder

Liftoff of Vega VV06 carrying LISA Pathfinder on Dec. 3, 2015, from Europe’s Spaceport in French Guiana. Photo Credit: Stephane Corvaja / ESA

After a one-day delay, the LISA Pathfinder mission was successfully launched on board a Vega rocket. The mission took to the skies early Thursday morning at 1:04 a.m. local time (04:04 GMT) on Dec. 3, 2015, from Europe’s spaceport in Kourou, French Guiana. The spaceport is most noted for Ariane rocket launches for the European Space Agency (ESA).

The launch was delayed from Dec. 2 due to technical concerns regarding the thermal readiness of the upper stage engine. The engine had to start two times to place the spacecraft into the correct orbit, so it was crucial to make sure the engine would re-ignite in the temperature extremes it would endure. After an extra day of analysis, it was decided to proceed with the launch.

LISA Pathfinder in space

An artist’s impression of LISA Pathfinder in space. Image Credit: ESA/ATG medialab

The objective of the LISA Pathfinder is to test the technology needed to look for gravitational waves. These ripples in spacetime were predicted by Albert Einstein when he published his General Theory of Relativity over 100 years ago on Dec. 2, 1915. While the theory of the gravity waves has been around for some time, the technology to test these infinitesimally small waves is only now being developed. Einstein’s theory predicts that these waves or fluctuations in spacetime should be universal.

“This is an extremely challenging mission that will pave the way for future space-based projects to observe gravitational waves, opening a new window to explore the cosmos,” said Paul McNamara, LISA Pathfinder’s project scientist. “Gravitational waves are an entirely fresh and different way to study the universe, providing an important complement to the well-established approach of astronomy, based on observing the light emitted by celestial bodies.”

The core of the LISA Pathfinder is a pair of identical gold-platinum cubes. The two 1.81-inch (46 millimeters) cubes are spaced exactly 1.4961 inches (38.000 millimeters) apart. Additionally, the complicated equipment on the spacecraft is designed to cancel out the effects of external forces, except gravity. These cubes will experience the purest free-fall ever produced. The laser interferometer on board will measure the movements of these cubes to within 0.01 nanometers as they float free from other forces. Scientist hope that this level of sensitivity will tease out the elusive gravity waves.

Constructed by Airbus Defense and Space, the spacecraft has an operational mass of 1,060 pounds (480 kilograms). The mission is expected to last 1 year, but LISA Pathfinder is equipped with enough Cold Gas propellant for an extended mission.

LISA Pathfinder is a precursor to the Evolved Laser Interferometer Space Antenna (eLISA) mission – a network of three satellites that will be positioned more than 620,000 miles (1 million kilometers) apart. Using an 8 inch (20 centimeter) wide laser interferometer, eLISA will be one of the largest and most sensitive instruments ever created. It will measure the stretching and squeezing of spacetime by the gravity waves. Scientists hope to measure the frequency, phase, and polarization of these waves.

The Vega rocket is the newest launcher for ESA, first launched in 2012. With a height of 98 feet (30 meters) and a diameter of 9.8 feet (3 meters), the vehicle is designed for launching smaller up to between 3,150 pounds (1,430 kilograms) to 4,328 pounds (1,963 kilograms), depending on the desired orbit. LISA Pathfinder was the sixth successful flight of the design, designated VV06. To date, all launches of the Vega rocket have been successful. There are currently seven more launches planned with this design.

The spacecraft separated from the upper stage booster 1 hour and 45 minutes after liftoff. Controllers plan to raise the spacecraft to its operational orbit in six critical engine burns. In a little over two weeks, LISA Pathfinder will be propelled to its final destination, orbiting the stable Lagrange Point L1 over 932,000 miles (1.5 million kilometers) away.

Video courtesy of Arianespace


Joe Latrell is a life-long avid space enthusiast having created his own rocket company in Roswell, NM in addition to other consumer space endeavors. He continues to design, build and launch his own rockets and has a passion to see the next generation excited about the opportunities of space exploration. Joe lends his experiences from the corporate and small business arenas to organizations such as Teachers In Space, Inc. He is also actively engaged in his church investing his many skills to assist this and other non-profit endeavors.

Reader Comments

Actually it turns out there is a problem in the elementary geometry underlying the general theory of relativity. Einstein said that “in the presence of a gravitational field, the geometry is not Euclidean.” At that time Euclidean geometry and non-Euclidean were seen as both logically consistent (just not logically consistent with each other). When Hilbert added the coordinate line to geometry, virtually everyone in the twentieth century took Hilbert’s system as a correct foundation, including Einstein.Yet there was a flaw that resulted from adding a coordinate system. The non-Euclidean geometry then becomes self-contradicting!

When Hilbert added the features to comprise the real number line and coordinates, the very earliest axioms required subtle modifications. From Euclid’s to draw a line from one point to any other, and extend it in a straight line, Hilbert first produced, two points determine a line and determine it completely. But this eventually became every pair of points is in some line (Axiom I. 1) and two different lines cannot contain the same pair of points (Axiom I. 2) (paraphrased). This ‘line’ is what became a coordinate line.  Yet Axiom I. 2 is incompatible with one of the two types of non-Euclidean geometry (geometry with no parallels), and this is not the only problem. Then there was a problem with the remaining type. Apparently virtually no one had thoroughly and correctly reexamined the implications indicated by the subtle modifications of those elementary axioms.  

Math with coordinates or angles, was based on Hilbert’s Theorem 8 [5 in earlier editions of his book] about a line dividing a plane in two, and on the SAS triangle congruency theorem (12). Hilbert said that based on Theorem 8, Theorem 10, which expanded the structure to three dimensions, expressed “the most important facts about the ordering of the elements of space.”

Hilbert proved Theorem 8 based on his Axiom I. 2, one of the modified axioms, and on Pasch’s triangle axiom, which Hilbert believed was an independent foundational axiom, common to Euclidean and non-Euclidean geometry, including that remaining type. Theorem 12 (SAS) presupposed Theorem 8. However, contrary to what Hilbert believed, the triangle axiom was not an independent foundational axiom. It was a proposition that combined a more elementary triangle axiom and Hilbert’s Axiom of Parallels which Hilbert called “Euclid’s Axiom.” This Axiom of Parallels, “Euclid’s Axiom,” was a logical equivalent of the original Playfair’s axiom, which was the logical substitute for Euclid’s famous fifth postulate added by Playfair to Euclid’s geometry in 1795.

Why the non-Euclidean geometry is self-contradicting is explained in short order in a brief Facebook Note, that explains how general relativity lost its coordinate system. Part II of the Note explains how this was overlooked throughout the twentieth century:

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