ESA/MPG: LISA Pathfinder

[bystander]

LISA Pathfinder Set for Launch Site
ESA Space Science | LISA Pathfinder | 2015 Sep 01

[img3="LISA Pathfinder Exploded View - Credit: ESA/ATG Medialab"]http://www.esa.int/var/esa/storage/imag ... mage_2.jpg[/img3][hr][/hr]

LISA Pathfinder, ESA’s demonstrator for spaceborne observations of gravitational waves, is ready to leave for Europe’s Spaceport in Kourou, French Guiana.

Scheduled for launch on a Vega rocket later this year, the spacecraft was on display today at IABG’s test centre in Ottobrunn, near Munich, Germany, where final integration and extensive tests were performed over the past few months.

This was the last chance for scientists, engineers and members of the media to see LISA Pathfinder before it is packed for shipping.

“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, ESA’s project scientist.

Gravitational waves are ripples in the fabric of spacetime produced by accelerating massive bodies, such as a pair of orbiting black holes. Predicted by Albert Einstein’s general theory of relativity in 1915, they are expected to be ubiquitous in the Universe, but have not been directly detected to date.

While ground-based searches for these elusive messengers of gravity have been under way for the past few decades, a gravitational-wave observatory in space would open up new possibilities in this quest.

LISA Pathfinder will test the fundamental technologies and instrumentation needed for such an observatory, demonstrating them for the first time in space.

“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,” says Paul.

Among the anticipated sources of gravitational waves are supernova explosions and double black holes. These objects are thought to be associated with overwhelmingly powerful events. For example, the energy released in gravitational waves during the last few minutes of the merging of just one pair of supermassive black holes is comparable to the total energy emitted as light by all stars and galaxies across the cosmos over the same time.

Scientists are also looking forward to discovering even more, unexpected cosmic sources once they are able to ‘listen’ to the Universe on this new channel. ...

LISA Pathfinder on the Way to Launch
Max Planck Institute for Gravitational Physics | 2015 Sep 01

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Click to play embedded YouTube video.

Click to play embedded YouTube video.

[bystander]

Liftoff for LISA Pathfinder
Max Planck Institute for Gravitational Research
Albert Einstein Institute | 2015 Dec 03

Major step towards a gravitational wave observatory in space on 100th anniversary of Einstein's General Relativity

The LISA Pathfinder satellite mission lifted off earlier today on a Vega rocket from the European spaceport in Kourou, French Guiana, on its way to demonstrate technology for observing gravitational waves from space. “This mission is one large step towards a spaceborne gravitational wave detector. 96 percent of the Universe cannot be observed with existing astronomical methods. A future mission like eLISA will detect gravitational waves from space, for example from supermassive black hole binaries, and open a new window to the gravitational Universe,” says Prof. Dr. Karsten Danzmann, director at the Albert Einstein Institute and professor at Leibniz Universität Hannover. ...

LISA Pathfinder Carries Advanced NASA Thruster Tech
NASA | JPL-Caltech | 2015 Dec 03

The LISA Pathfinder spacecraft is on its way to space, having successfully launched from Kourou, French Guiana (Dec. 3 local time/Dec. 2 PST). On board is the state-of-the-art Disturbance Reduction System (DRS), a thruster technology developed at NASA's Jet Propulsion Laboratory, Pasadena, California.

LISA Pathfinder, led by the European Space Agency (ESA), is designed to test technologies that could one day detect gravitational waves. Gravitational waves, predicted by Einstein's theory of general relativity, are ripples in spacetime produced by any accelerating body. But the waves are so weak that Earth- or space-based observatories would likely only be able to directly detect such signals coming from massive astronomical systems, such as binary black holes or exploding stars. Detecting gravitational waves would be an important piece in the puzzle of how our universe began.

The incredible faintness of gravitational waves makes it critical to keep a spacecraft stable enough to detect them. But there are obstacles to staying completely still, even in seemingly empty space. Most notably, solar radiation pressure -- the force exerted by sunlight -- pushes on the spacecraft ever so delicately. In fact, the force of solar radiation pressure on LISA Pathfinder is analogous to the weight of a grain of sand on earth.

The Disturbance Reduction System uses colloid micronewton thrusters, the first of their kind, to keep the spacecraft as still as possible and compensate for solar pressure. These thrusters electrically charge small liquid droplets and accelerate them through an electric field in order to generate thrust. Developed by Busek Co., Natick, Massachusetts, with technical support from JPL, the thrusters will deliver 5 to 30 micronewtons of thrust (about the weight of a mosquito) continuously, with exquisite precision, to counteract the force of sunlight.

The DRS microthrusters aim to control the spacecraft's position to within a millionth of a millimeter, using software provided by NASA's Goddard Spaceflight Center, Greenbelt, Maryland. ...

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[b][color=#0000FF][size=150]Mock LISA Daughter Challenge[/size][/color][/b]

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<<In so-called Mock LISA Data Challenges (MLDC) scientists already demonstrated the feasibility of eLISA data analysis. MLDCs are based on blind challenges of increasing complexity – from a few sources in the first challenge to the full combination of all likely sources in the data stream in the most recent fourth challenge. Scientific research groups from all over the world developed, tested and implemented a wide variety of techniques. As a result a proof-of-concept for eLISA data analysis is strongly tested and ready to go.

eLISA data will be publicly available after a short period (perhaps around 6 months) in the form of a catalogue that includes the identified sources and their parameters as well as the basic strain measurements and the software tools to analyse those data streams. During the time between data ingestion and catalogue production the quality of the data will be ensured and the parameters of sources will be extracted to a suitable precision.

In the meantime, the data will be accessible to the Science Team members; participation of independent scientists in the Science Team is foreseen. The catalogue will be updated during the course of the mission to incorporate the increasing precision of the parameters for continuous or quasi-continuous sources (compact binaries and extreme mass ratio inspirals). Transient events, such as massive black hole mergers, will be announced as soon as possible to allow the community to plan for electromagnetic co-observation of a merger event.>>

[saturno2]

Very interesting

[bystander]

First Locks Released from LISA Pathfinder's Cubes
ESA Science & Technology | LISA Pathfinder | 2016 Feb 03

[img3="LISA Pathfinder in space. Credit: ESA–C.Carreau"]http://sci.esa.int/science-e-media/img/ ... 4_625w.jpg[/img3][hr][/hr]

Today, the lock fingers that kept the two test masses on LISA Pathfinder secure during the launch and cruise phase were successfully unlocked. As planned, the two cubes are still attached to the spacecraft via an additional mechanism that will hold them in place until mid February, as the teams carry on with the spacecraft and payload commissioning.

Tests on LISA Pathfinder are proceeding on schedule. The spacecraft completed its six-week journey in space, reaching its operational location in orbit around the Lagrange point L1 on 22 January 2016. ...

[bystander]

LISA Pathfinder Test Masses Floating Freely
Max Planck Institute for Gravitational Research
Albert Einstein Institute | 2016 Feb 16

The LISA Pathfinder mission scientists have successfully released both of the cubic gold–platinum test masses inside the satellite. LISA Pathfinder will place these cubes in the most precise free fall ever obtained to demonstrate technologies for observing gravitational waves from space. ...

Test Cubes Floating Freely Inside LISA Pathfinder
ESA Science & Technology | LISA Pathfinder | 2016 Feb 16

[bystander]

Freefall Achieved on LISA Pathfinder
ESA | Space Science | Science & Technology | 2016 Feb 24

[img3="LISA Pathfinder Test Masses (Credit: ESA/ATG Medialab)"]http://sci.esa.int/science-e-media/img/ ... ng_625.jpg[/img3][hr][/hr]

On Monday, the two cubes housed in the core of ESA’s LISA Pathfinder were left to move under the effect of gravity alone – another milestone towards demonstrating technologies to observe gravitational waves from space.

It has been an intense couple of months for LISA Pathfinder. After launch on 3 December and six burns to raise the orbit, it finally reached its work site – 1.5 million km from Earth towards the Sun – in January, and the team of engineers and scientists started to switch on and test its systems. ...

After verifying that everything was working as planned, the intensity of the electrostatic forces was gradually reduced until none was being applied along the sensitive axes of the masses. This resulted in a brief test of drag-free motion, on 19 February.

Finally, on 22 February, the team tackled the greatest challenge: setting the two cubes completely free, letting them move under the effect of gravity alone and actively manoeuvring the spacecraft around them.

To do this, LISA Pathfinder measures the position and orientation of each cube, and corrects its movement by firing microthrusters to keep it centred on one cube. ...

[bystander]

LISA Pathfinder Begins Its Science Mission
Max Planck Institute for Gravitational Physics
Albert Einstein Institute | 2016 Mar 08

Perfectly still satellite laboratory to validate key technologies for gravitational-wave detection in space

After completing a long series of tests on the spacecraft and payload, the ESA mission LISA Pathfinder has started its science mission. Over the next six months it will conduct hundreds of experiments to pave the way for future space-borne gravitational-wave observatories like eLISA. Researchers from the Max Planck Institute for Gravitational Physics (Albert Einstein Institute) and the Institute for Gravitational Physics of Leibniz Universität Hannover are leading mission partners.

LISA Pathfinder is a technology demonstrator satellite mission, about 1.5 million kilometers from the Earth towards the Sun. There, mission scientists have now set up a space laboratory to study the perfect free fall of two cubic test masses. The team will use it to test technologies necessary for future space-borne gravitational-wave observatories. ...

A Perfectly Still Laboratory in Space
ESA | Space Science | Science & Technology | 2016 Mar 08

Following a long series of tests, ESA's LISA Pathfinder has started its science mission to prove key technologies and techniques needed to observe gravitational waves from space. ...

[bystander]

LISA Pathfinder Exceeds Expectations
ESA | Space Science | Science & Technology | LISA Pathfinder | 2016 Jun 07

ESA's LISA Pathfinder mission has demonstrated the technology needed to build a space-based gravitational wave observatory.

[c][attachment=0]LISA_Pathfinder_performance[1].jpg[/attachment][/c]

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Results from only two months of science operations show that the two cubes at the heart of the spacecraft are falling freely through space under the influence of gravity alone, unperturbed by other external forces, to a precision more than five times better than originally required.

In a paper published today in Physical Review Letters, the LISA Pathfinder team show that the test masses are almost motionless with respect to each other, with a relative acceleration lower than 1 part in ten millionths of a billionth of Earth’s gravity.

The demonstration of the mission’s key technologies opens the door to the development of a large space observatory capable of detecting gravitational waves emanating from a wide range of exotic objects in the Universe. ...

Click to play embedded YouTube video.

LISA Pathfinder Exceeds Expectations
Albert Einstein Institute | Leibniz University, Hannover
Max Planck Institute for Gravitational Physics | 2016 Jun 07

Paving the Way to Space-Based Gravitational-Wave Detectors
Physics | American Physical Society | 2016 Jun 07

LISA Pathfinder Paves the Way for Space-Based Gravitational Wave Observatory
News | American Physical Society | 2016 Jun 07

LISA Pathfinder Paves Way for Space-Based Detection of Gravitational Waves
NASA | Goddard Space Flight Center | 2016 Jun 07

Sub-Femto-g Free Fall for Space-Based Gravitational Wave Observatories: LISA Pathfinder Results - M. Armano et al

• Physical Review Letters 116(23):1101 (2016 Jun 10) DOI: 10.1103/PhysRevLett.116.231101

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[bystander]

LISA Pathfinder Completes First Operations Phase
ESA | Science & Technology | LISA Pathfinder | 2016 June 24

On Saturday 25 June, the LISA Technology Package (LTP) – a European payload on ESA's LISA Pathfinder – completes its nominal operations phase, passing the baton to the Disturbance Reduction System (DRS), an additional experiment provided by NASA. This won't be the last time the European experiment is run – the recently approved mission extension will see the LTP back in action for seven months starting in November this year. ...

[bystander]

Next Step Toward a Gravitational-Wave Observatory in Space
European Space Administration | Science and Technology | 2016 Oct 25

Today, ESA has invited European scientists to propose concepts for the third large mission in its science programme, to study the gravitational Universe.

A spaceborne observatory of gravitational waves – ripples in the fabric of spacetime created by accelerating massive objects – was identified in 2013 as the goal for the third large mission (L3) in ESA's Cosmic Vision plan.

A Gravitational Observatory Advisory Team was appointed in 2014, composed of independent experts. The team completed its final report earlier this year, further recommending ESA to pursue the mission having verified the feasibility of a multisatellite design with free-falling test masses linked over millions of kilometres by lasers.

Now, following the first detection of the elusive waves with ground-based experiments and the successful performance of ESA's LISA Pathfinder mission, which demonstrated some of the key technologies needed to detect gravitational waves from space, the agency is inviting the scientific community to submit proposals for the first space mission to observe gravitational waves. ...

[bystander]

NASA Team Explores Using LISA Pathfinder as 'Comet Crumb' Detector
NASA | GSFC | 2017 Apr 17

Click to play embedded YouTube video.

LISA Pathfinder, a mission led by the European Space Agency (ESA) with contributions from NASA, has successfully demonstrated critical technologies needed to build a space-based observatory for detecting ripples in space-time called gravitational waves. Now a team of NASA scientists hopes to take advantage of the spacecraft's record-breaking sensitivity to map out the distribution of tiny dust particles shed by asteroids and comets far from Earth.

Most of these particles have masses measured in micrograms, similar to a small grain of sand. But with speeds greater than 22,000 mph (36,000 km/h), even micrometeoroids pack a punch. The new measurements could help refine dust models used by researchers in a variety of studies, from understanding the physics of planet formation to estimating impact risks for current and future spacecraft. ...

The mission's primary goal was to test how well the spacecraft could fly in formation with an identical pair of 1.8-inch (46 millimeter) gold-platinum cubes floating inside it. The cubes are test masses intended to be in free fall and responding only to gravity.

The spacecraft serves as a shield to protect the test masses from external forces. When LISA Pathfinder responds to pressure from sunlight and microscopic dust impacts, the spacecraft automatically compensates by firing tiny bursts from its micronewton thrusters to prevent the test masses from being disturbed. ...

In response to an impact, LISA Pathfinder fires its thrusters to counteract both the minute "push" from the strike and any change in the spacecraft's spin. Together, these quantities allow the researchers to determine the impact's location on the spacecraft and reconstruct the micrometeoroid's original trajectory. This may allow the team to identify individual debris streams and perhaps relate them to known asteroids and comets. ...

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<<Zodiacal light is a faint, roughly triangular, diffuse white glow seen in the night sky that appears to extend up from the vicinity of the Sun along the ecliptic or zodiac. It is caused by sunlight scattered by space dust in the zodiacal cloud. It is best seen just after sunset in spring, and just before sunrise in autumn when the zodiac is at a steep angle to the horizon, but is so faint that either moonlight or light pollution renders it invisible.

The zodiacal light decreases in intensity with distance from the Sun, but on very dark nights it has been observed in a band completely around the ecliptic. In fact, the zodiacal light covers the entire sky and is responsible in large part for the total skylight on a moonless night. Another phenomenon—a faint, but slightly increased, oval glow directly opposite the Sun—is called the gegenschein.

The dust forms a thick pancake-shaped cloud in the Solar System collectively known as the zodiacal cloud, which occupies the same plane as the ecliptic. The dust particles are between 10 and 300 micrometres in diameter, most with a mass around 150 micrograms [i.e., approximately a billionth the LISA Pathfinder mass of 125 kg such that a 30 km/s impact imparts a 30 micron/sec push].

In 2007, Brian May, lead guitarist with the band Queen, completed his PhD thesis A Survey of Radial Velocities in the Zodiacal Dust Cloud 36 years after having started and abandoning it to pursue a career in music. He was able to submit it only because of the minimal amount of research on the topic undertaken during the intervening years. May describes the subject as being one that became "trendy" again in the 2000s.>>

. https://apod.nasa.gov/apod/ap140114.html
. https://apod.nasa.gov/apod/ap120405.html

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<<Nicolas Fatio de Duillier (26 February 1664 – 12 May 1753) was a Swiss mathematician known for his work on the zodiacal light problem, for his role in the Newton v. Leibniz calculus controversy, and for originating the "push" or "shadow" theory of gravitation. (Fatio assumed that the universe is filled with minute particles, which are moving indiscriminately with very high speed and rectilinearly in all directions except when shadowed by a nearby planet to which it is thereby attracted.)

Fatio was born in Basel, Switzerland, in 1664, the seventh of fourteen children of Jean-Baptiste and Cathérine Fatio. The family moved in 1672 to Duillier. Before he was eighteen, Fatio wrote to the astronomer Giovanni Domenico Cassini, suggesting a new method of determining the Sun's distance from the Earth and an explanation of the form of Saturn's ring. Encouraged by Cassini's reply, he went to Paris in the spring of 1682, and was kindly received. Fatio began astronomical studies under Cassini at the Parisian observatory. In 1683, Cassini presented his theory of the zodiacal light. Fatio followed his observations, repeated them at Geneva in 1684, and gave in 1685 new and important developments of this theory. They were published in his Lettre à M. Cassini … touchant une lumière extraordinaire qui paroît dans le ciel depuis quelques années.

In London in 1687, Fatio made the acquaintance of John Wallis and Edward Bernard (1638-1697) and worked out a solution of the inverse tangent problem. In 1690, he wrote a letter to Huygens, in which he outlined his own gravitational theory, which later became known as Le Sage's theory of gravitation. Soon after that, he read its content before the Royal Society. This theory, on which he worked until his death, is based on minute particles which push gross matter to each other.

Fatio alleged that he had convinced Newton of certain mistakes in the latter's monumental work Philosophiæ Naturalis Principia Mathematica. He put himself on a par with Newton, and in a letter to Huygens, dated 1691, wrote that it was really unnecessary to ask Newton to prepare a new edition. "However," he adds, "I may possibly undertake it myself, as I know no one who so well and thoroughly understands a good part of this book as I do." Huygens wrote on the margin of this letter ‘"appy Newton".

When Leibniz sent a set of problems for solution to England, he mentioned Newton and failed to mention Fatio among those probably capable of solving them. Fatio retorted by sneering at Leibniz as the "second inventor" of the calculus. In replying to Fatio, Leibniz appealed to Newton himself as having admitted the independent discovery. Fatio stirred up the whole Royal Society to take a part in the dispute.

Fatio retired to Worcester, where he formed some congenial friendships and busied himself with scientific pursuits, alchemy, and the mysteries of the cabbala. In 1732, through the influence of John Conduitt, Newton's nephew-in-law, he endeavoured without success to obtain some reward for having saved the life of the Prince of Orange. He assisted Conduitt in planning the design and writing the inscription for Newton's monument in Westminster Abbey.>>

[bystander]

Good Night, LISA Pathfinder!
Albert Einstein Institute | Max Planck Institute for Gravitational Physics | 2017 Jul 19

LISA Pathfinder has been switched off as planned on the evening of 18th of July, ending its successful mission which surpassed all expectations

After 16 months of science measurements an international team deactivated the LISA Pathfinder satellite on the evening of the 18th of July 2017. The gravitational-wave laboratory in space powered down after receiving the last commands in the evening and circles the Sun on a safe parking orbit. LISA Pathfinder has tested key technologies for LISA, the future gravitational-wave observatory in space, and has demonstrated their operative readiness. LISA is scheduled to launch into space in 2034 as an ESA mission and will “listen” to the entire Universe by measuring low-frequency gravitational waves. ...

[MargaritaMc]

This ESA notice from 20 June 2017 has details of what the mission has accomplished.
http://sci.esa.int/lisa-pathfinder/5923 ... g-mission/

LISA PATHFINDER TO CONCLUDE TRAILBLAZING MISSION

20 June 2017
After sixteen months of science operations, LISA Pathfinder will complete its mission on 30 June, having successfully demonstrated the technology to build ESA's future space observatory of gravitational waves.

It links to this announcement

http://sci.esa.int/cosmic-vision/59243- ... s-forward/
GRAVITATIONAL WAVE MISSION SELECTED, PLANET-HUNTING MISSION MOVES FORWARD

20 June 2017
The LISA trio of satellites to detect gravitational waves from space has been selected as the third large-class mission in ESA's Science programme.
[...] LISA Pathfinder will conclude its pioneering mission at the end of this month, and LISA, the Laser Interferometer Space Antenna, also an international collaboration, will now enter a more detailed phase of study. Three craft, separated by 2.5 million km in a triangular formation, will follow Earth in its orbit around the Sun.
Following selection, the mission design and costing can be completed. Then it will be proposed for 'adoption' before construction begins. Launch is expected in 2034

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Click to play embedded YouTube video.

http://sci.esa.int/cosmic-vision/59243- ... s-forward/
GRAVITATIONAL WAVE MISSION SELECTED, PLANET-HUNTING MISSION MOVES FORWARD

The LISA trio of satellites to detect gravitational waves from space has been selected as the third large-class mission in ESA's Science programme.

Three craft, separated by 2.5 million km in a triangular formation, will follow Earth in its orbit around the Sun.

[bystander]

A Final Farewell to LISA Pathfinder
NASA | JPL-Caltech | 2017 Jul 24

With the push of a button, final commands for the European Space Agency's LISA Pathfinder mission were beamed to space on July 18, a final goodbye before the spacecraft was powered down.

LISA Pathfinder had been directed into a parking orbit in April, keeping it out of Earth's way. The final action this week switches it off completely after a successful 16 months of science measurements.

While some spacecraft are flashy, never sitting still as they zip across the solar system, LISA Pathfinder was as steady as they come -- literally.

It housed a space-age motion detector so sensitive that it had to be protected against the force of photons from the Sun. That was made possible thanks to a system of thrusters that applied tiny reactive forces to the spacecraft, cancelling out the force of the Sun and allowing the spacecraft to stay within 10 nanometers of an ideal gravitational orbit.

These requirements for Pathfinder were so challenging and unique that LISA Pathfinder flew two independent systems based on different designs - one provided by NASA and one by ESA - and ran tests with both during its 16-month mission. ...

[bystander]

LISA mission passes review successfully and begins next stage of development
LISA | Albert Einstein Institute | 2018 Jan 22

[img3="The proposed LISA mission will detect gravitational waves in space using a trio of satellites, separated by millions of kilometers. Lasers will be employed to measure the minute changes in their relative distance induced by impinging gravitational wave. Credit: AEI/MM/exozet; GW simulation: NASA/C. Henze"]http://www.aei.mpg.de/800957/eLISA_2arm ... 932911.jpg[/img3][hr][/hr]

Before an ESA mission reaches the launch pad, it has to go through a number of approval procedures that ensure the mission´s readiness. The future space-based gravitational wave observatory, the Laser Interferometer Space Antenna (LISA), has recently passed its Mission Definition Review (MDR) with flying colours.

The MDR's goal is to review and confirm that

• LISA's present mission design is feasible and suitable,
• the mission requirements meet LISA´s science requirements,
• the requirements are mature and adequate to the current phase,
• the technology developments are adequate to the current phase, and
• the interfaces between spacecraft, payload ground segment and launcher are well defined.

LISA is scheduled for launch into space in 2034 as a mission of the European Space Agency (ESA). ...

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Click to play embedded YouTube video.