LISA Pathfinder - Vega (VV06) - Kourou ZLV - 03.12.2015

Автор Salo, 30.07.2015 08:14:45

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Цитировать ESA Operations‏Подлинная учетная запись @esaoperations 2 мин. назад

#LISAPathfinder's heart still beating! This signal will fall to nothing 10secs after PI Stefano Vitale sends last command at ~20:00cest

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Цитировать ESA - European Space Agency был(-а) в прямом эфире. · 32 мин ·

Live video from the Main Control Room at ESOC, ESA's mission control centre, Darmstadt, Germany, as we get ready to send the final command to LISA Pathfinder.

ZOOR

#83
Птичку жалко. Красивый эксперимент, красивый КА - и такая короткая миссия.
Неужели нельзя было придумать куда его в интересах науки двинуть? Из L большого импульса не надо.
Я зуб даю за то что в первом пуске Ангары с Восточного полетит ГВМ Пингвина. © Старый
Если болит сердце за народные деньги - можно пойти в депутаты. © Neru - Старому


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http://spaceflight101.com/lisa-pathfinder/lisa-pathfinder-spacecraft-ends-communications-with-earth/
ЦитироватьLISA Pathfinder Spacecraft ends Communications with Earth after superb Mission Success
July 18, 2017

ESA's LISA Pathfinder received its final commands fr om Earth on Tuesday, marking the end of a highly successful mission of one and a half years that demonstrated the working principle for a future gravitational waves observatory and completed a series of technical tests in its last weeks of operation to help inform the design of the future observatory mission – opening up an entirely new field of astronomy.

The primary objective of the LISA Pathfinder mission was the demonstration of a key technology needed for the measurement of gravitational waves – tiny ripples in the fabric of space predicted by Albert Einstein a century ago and measured for the first time by the ground-based LIGO observatory in 2015.
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Photo: ESA

While Earth-based instruments like LIGO are limited to frequencies above 100 cycles per second, a space-based observatory could measure waves with frequencies of a fraction of 1 Hertz by placing test masses into perfect drag-free flight, only influenced by gravity, and measuring their relative position to one another to detect a passing gravitational wave. However, detecting gravitational waves will require test masses to be kept motionless to unprecedented levels of accuracy since gravitational waves will only cause a displacement on a scale of a few millionths of a millionth of a meter over a cosmic distance of a million Kilometers.


Gravitational waves are created by the interaction of supermassive objects – Image: R. Hurt/Caltech

LISA Pathfinder was tasked with demonstrating whether drag-free flight would be possible and the small spacecraft also put to the test the laser-based measurement system that allows the test mass position to be measured with pico-meter accuracy – even over distances of one million Kilometers.

An operational LISA mission would consist of three spacecraft, deployed into a precise triangular formation 2.5 million Kilometers apart to detect passing gravitational waves that stem from super-massive phenomena in the Universe like two interacting black holes, supernova explosions or Neutron Star binaries. Retiring any technical risks prior to the tremendous financial investment in LISA was the primary goal of the $630 million pathfinder mission.


The LISA Technology Package with two gold test masses and a highly precise laser interferometer – Image: ESA/ATG Medialab

Launching in December 2015 and arriving at its remote operating location 1.5 million Kilometers from Earth in January 2016, the 480-Kilogram LISA Pathfinder began its mission by demonstrating drag-free flight using its test mass package and a Cold Gas Micropropulsion System to counter any internal and external influences arising from solar pressure or cosmic dust impacts to keep the masses in an environment only driven by gravity. Later in the mission, the cold gas thrusters were switched off and NASA's Disturbance Reduction System took over to demonstrate a second micropropulsion system which made use of Colloid Micro-Newton Thrusters.

According to ESA, the free-fall environment of the two test masses was better than originally required – only experiencing a relative acceleration of ten millionths of a billionth of Earth's gravity, around 10,000 times better than any previous drag-free mission – making LISA Pathfinder the most sensitive instrument for acceleration ever flown.


LISA Pathfinder exceeds Expectations – Image: ESA


Image: ESA–C.Carreau

LISA exceeded expectations by orders of magnitude. In fact, the instrument achieved its mission requirements within the first day of operations and further tweaking showed LISA Pathfinder's precision for frequencies between 60 milli-Hertz and 1 Hz surpassed the requirement for an operational LISA mission by a factor of over 100. At lower frequencies down to 1 mHz, scientists found, LISA would be limited by gas molecules bouncing off the test masses and causing disturbance while the spacecraft was still outgassing.

Having tested out both the Cold Gas and the Colloid Thrusters over a six-month primary mission, LISA Pathfinder entered a six-month extended mission in December, continuing in orbit around the Sun-Earth Lagrange Point 1 that offered a stable gravitational and thermal environment for the test mission.


Image: ESA–C.Carreau

In January, engineers switched off all but the most essential heaters on the spacecraft to cool the vehicle from a steady temperature of 22°C to 11°C to slow down the outgassing the reduce the mean particle speed in order to see whether that would affect the measurement efficiency at the lower frequencies. By February, the team determined that the signal-to-noise ratio for the 1 – 60 mHz range had reached acceptable levels for a future gravitational waves observatory.

In addition to its technology demonstration mission, LISA Pathfinder also produced auxiliary data found valuable in a number of scientific fields. The mission achieved the most sensitive measurement of the perturbation of the free-fall motion caused by cosmic rays; LISA Pathfinder data will also be re-purposed to assess the distribution and influx of cosmic dust particles and the mission delivered data useful for quantum physicists.


LISA Pathfinder Star Tracker Exposure for NEO Hunt – Image: ESA

Since January, LISA Pathfinder's redundant Star Tracker had been updated with a software patch to collect one ten-minute long-exposure image per hour for the remainder of the mission to support ESA's Near-Earth Object office in their search for asteroids. Several asteroids have been identified in the images and additional work is underway to analyze the data and fit trajectories for all NEOs discovered by the mission. The test was primarily used to evaluate this imaging technique for potential future space-based NEO observatories that could patch up a blind corner as incoming asteroids can not be seen from Earth when approaching from the sun's direction.

Heading into the last four weeks of mission operations, engineers started pushing the spacecraft's various systems to the lim it to gather valuable data on their performance and help with the design of the operational LISA mission. Teams looked at the properties of the vacuum enclosures holding the test masses, the charging properties of the gold test masses themselves and tried out the test mass grabbing & release mechanisms in different operational conditions.

The scientific part of the mission ended on June 30 and engineers were handed full control over the mission for some hardware tests that could not be safely performed during the science mission. First up were a series of thermal tests with the spacecraft in different orientations relative to the sun to assess thermal effects on various subsystem components including the performance of the micropropulsion system. Other tests looked at potential magnetic interference from the pressure regulation valves in the propulsion system on the craft's magnetic momentum and test masses.


LISA Pathfinder Cold Gas Nozzles – Photo: ESA

Engineering limits on the micropropulsion system were tested out by reducing the tank pressure to under one bar and a range of other tests involving the thrusters were conducted over a period of around one week including a full thrust test and firings at different temperatures to fully understand the system's capabilities to improve the performance of future spacecraft. Also, engineers measured the output of the solar array to asses degradation after an extended stint in the challenging space environment.

Intentional power fluctuations were introduced into the Laser Interferometer that measures the distance between the test masses with pico-meter accuracy to demonstrate its operational envelope and potential influence on the masses. More capture & release tests with the masses were on tap on July 13 using the electrostatic control system within the test mass enclosure to zero-in on its limitations.

On July 14, the Mission Team reacted on short notice and postponed a spin-up maneuvering test and put the craft back into science mode to measure the charge build up on the test masses under high solar activity as there had just been an Earth-directed solar flare. Teams also completed another low-pressure test on the thrusters going to a tank pressure of only 0.2 bar.


ESA Mission Control before Sending LPF's final Command – Photo: ESA

Starting on Monday, teams at the European Space Operations Center began the process of passivation – placing LISA Pathfinder in a fully safe state for the end of its mission with all tanks vented down, batteries discharged and transmitters disabled for all eternity. Data was dumped from the spacecraft memory and the LISA Technology Package was powered off, marking the end of test mass operations after over 16 months. Commands were also uplinked to disable the redundant spacecraft computer and put the vehicle into safe mode.

On Tuesday, LISA Pathfinder checked in for one last four-hour communications pass, receiving commands to fully power off the A-chain on onboard systems. At 18 UTC, teams at ESOC sent the final command to the faraway spacecraft, being transmitted by the Cebreros ground station in Spain and reaching the spacecraft some five seconds later after traversing 1.5 million Kilometers, instructing the spacecraft to power off the transmitter and shut down all remaining onboard systems. The carrier signal from LISA Pathfinder faded ten seconds after the command was sent as the craft went silent for the rest of time.


LISA Mission Concept – Image: ESA[/COLOR][/SIZE]

To comply with debris safety regulations, LISA Pathfinder completed a five-day "de-orbit" maneuver in April – firing its thrusters to depart the L1 location and enter a stable orbit around the sun inside that of Earth. Trajectory assessments showed a chance of under 0.2% for the spacecraft intersecting Earth or the Moon in the next 100 years.

""Before LISA Pathfinder, gravitational wave astronomy from space was a theoretical possibility, with its future implementation hidden behind a thick, dark wall," said ESA Head of Mission Operations Paolo Ferri. "This mission has opened a 'door' in this wall. The road to achieving a future mission that will detect gravitational waves is still very long, but we can see it and we can now start planning our long journey to reach it."


Image: ESA

ESA's Science Program Committee officially cleared the way for the LISA mission to move forward on June 20, allowing it to enter a detailed phase of study to work out the spacecraft design and precise scientific scope of the mission which – if passing final selection – would be looking at a launch date in 2034.

LISA, going by the full name of Laser Interferometer Space Antenna, would have a launch mass of 6,000 Kilograms, requiring an Ariane 6 launch vehicle to send the three craft on a 1.5-year drift into their independent heliocentric orbit for a primary mission of at least four years. NASA is expected to be involved as a partner, covering around 20% of the cost through instruments and other technologies.
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ЦитироватьZOOR пишет:
Неужели нельзя было придумать куда его в интересах науки двинуть?
А смысл? Его научная аппаратура свое отработала, более ни на что аппарат не рассчитан.

tnt22


tnt22

https://spaceflightnow.com/2017/07/19/pathfinder-probe-for-gravitational-wave-observatory-ends-mission/
ЦитироватьPioneering probe for gravitational wave observatory ends mission   
July 19, 2017 Stephen Clark

The European Space Agency's LISA Pathfinder spacecraft, now sailing around the sun on a trajectory away from Earth, was deactivated Tuesday after a nearly 18-month mission testing previously-untried lasers, vacuum enclosures, exotic gold-platinum cubes and micro-thrusters needed for a trio of gravitational wave observatories set for launch in the 2030s.

Stefano Vitale, principal investigator of the LISA Pathfinder mission's core instruments, sent the long-planned command to "passivate" the probe at 1800 GMT (2 p.m. EDT) Tuesday from the European Space Operations Center in Darmstadt, Germany.

The end of LISA Pathfinder's mission Tuesday marked another turning point in gravitational wave research, a field of astrophysics reinvigorated in the last two years by two major advances, according to Paul McNamara, the mission's project scientist at ESA.
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Artist's illustration of the LISA Pathfinder spacecraft. Credit: ESA

First came the launch of LISA Pathfinder on Dec. 3, 2015. Three months later, scientists announced the first confirmed detection of gravitational waves, ripples in the fabric of spacetime produced by the movement of massive objects in space, such as immense supermassive black holes at the centers of galaxies.

The gravitational waves, first predicted more than a century ago by Albert Einstein, were discovered by scientists crunching data gathered in September 2015 from a ground-based observatory called LIGO, which has antennas positioned 1,800 miles (3,000 kilometers) apart in Hanford, Washington, and Livingston, Louisiana.

Gravitational wave research requires huge detectors spread of thousands or millions of miles because the ripples are observed at very low frequencies as they travel through the universe at the speed of light. Astronomers say the waves, which can be triggered by violent phenomena such as black hole mergers, reveal a new way of studying the cosmos impossible with conventional optical telescopes.

The back-to-back breakthroughs catapulted gravitational waves to the forefront of astronomical journals and space mission planning.

"Was it a big step forward? Absolutely, because up to this point there were two doubts," McNamara said in an interview this week with Spaceflight Now. "One doubt was gravitational waves don't exist, and then LIGO comes along and detects them.

"Then we launched LISA Pathfinder, and we demonstrated the hardware in space," he said. "So the two big questions — do they exist and can we detect them? — both were answered within three months of each other."

LISA Pathfinder was named for a follow-on mission dubbed the Laser Interferometer Space Antenna, which was formally sel ected by ESA's science planning board June 20 to move into the next phase of mission planning after decades of starts and stops.

"With the astonishing success of LISA Pathfinder, we now know how to build a mission like LISA," said Vitale, a researcher at the University of Trento and the National Institute for Nuclear Physics in Italy.

Launched from French Guiana aboard a Vega rocket, the hexagonal space probe is about the size of a small car. LISA Pathfinder reached an operating point at the L1 Lagrange point nearly a million miles (1.5 million kilometers) from Earth in January 2016, lurking near a gravitational balance point between in a direction toward the sun.

In March 2016, on the first day LISA Pathfinder was in full science mode, ground controllers confirmed the mission had already met its minimum success requirements.

Two gold-platinum test cubes launched inside the LISA Pathfinder spacecraft were released from their launch restraints, a complicated procedure involving needle-like appendages that carefully pulled away from the cubes — each 1.8 inches (46 millimeters) on a side and with a mass of 4.4 pounds (2 kilograms) — to avoid disturbing them with electrostatic forces.


At the core of LISA Pathfinder are the two test masses: a pair of identical 46-millimeter gold–platinum cubes, floating freely, several millimeters from the walls of their housings. The cubes are separated by 38 centimeters and linked only by laser beams to measure their position continuously. Credit: ESA/ATG medialab

The crux of the mission was to prove the test cubes could be kept in a constant state of nearly perfect free fall during LISA Pathfinder's mission.

Two sets of low-impulse thrusters essentially steered the spacecraft around the free-floating test masses suspended inside two vacuum enclosures placed 15 inches (38 centimeters) apart on the satellite.

Accelerometers aboard LISA Pathfinder precisely tracked its movements, and a control computer sent signals to the low-thrust rocket packs outside the probe to continuously correct to keep the test cubes from contacting the walls of their chambers.

A high-precision laser interferometer constantly measured the range between the two test cubes, and that device also exceeded requirements, measuring the relative motion of the test masses with a precision of a femtometer, or one quadrillionth of a meter.

LISA Pathfinder is 10,000 times more stable than any satellite flown on a previous science mission, officials said, demonstrating that it was possible for the test masses to remain virtually motionless with respect to each other.

ESA said the test masses had a relative acceleration of only ten billionths of a billionth of Earth's gravity, an achievement made possible by a tedious accounting of every component of the spacecraft that could influence the floating metallic cubes.

Many of the lessons learned from LISA Pathfinder were not in how to build a space-rated gravitational wave detector, but how to operate it, McNamara said. Even the switch-on of a transponder or star tracker added noise to the instrument beyond acceptable limits.

"This is such a sensitive instrument that it responds to anything changing whatseover," NcNamara said. "We've learned that, for LISA, we have to assume if you make any changes on-board its going to take you time to recover back into equilibirium. If you turn any unit on, you turn any heater on, or do anything on the spacecraft to put it in a slightly different orientation, it'll take you a week to get back to operational status."

Such precision is needed because gravitational waves have an amplitude of a few millionths of a millionth of a meter over a distance of a million kilometers (621,000 miles). Any larger movement of the test masses would mask the gravitational wave.

The LISA Pathfinder mission cost around $630 million, a figure that includes contributions from ESA, NASA and other institutions scattered across Europe.

LISA Pathfinder was conceived to prove a gravitational wave mission was technically feasible.

"People just didn't think it was possible," McNamara said. "That's why LISA Pathfinder came into being. It was just to see could we build an instrument which was quiet enough."


Artist's impression of a Laser Interferometer Space Antenna (LISA) mission concept spacecraft. Credit: AEI/Milde Marketing/Exozet

The concept for the LISA mission sel ected by ESA last month calls for three spacecraft similar to LISA Pathfinder to launch in 2034 into an orbit around the sun that trails the Earth.

The LISA spacecraft will fly in a triangular formation more than 1.5 million miles (2.5 million kilometers) apart, linked by lasers to track the exact distances between the nodes, which will each contain two free-floating test masses. Sensors will watch for tiny variations in the range between the craft as gravitational waves pass through the solar system.

"With gravitational waves, it's a completely new endeavor we're taking on," McNamara told Spaceflight Now. "This idea of flying three spacecraft separated by millions of kilometers, and you have to be able to measure the distance to a hundredth the size of an atom."

"We have exceeded not only the requirements set for LISA Pathfinder, but also the accuracy required for LISA at all frequencies: we are definitely ready to take the next step," said Karsten Danzmann, a LISA Pathfinder co-investigator, the lead proposer of the LISA mission, and director at the Max Planck Institute for Gravitational Physics in Germany.

ESA expects the LISA mission to cost up to $1.2 billion (more than a billion euros), not including support from NASA.

Paul Hertz, director of NASA's astrophysics division, said Wednesday that the U.S. space agency wants to contribute technology and hardware to the LISA mission roughly equivalent to around 20 percent of the mission's total cost.

NASA and ESA originally planned a larger, more ambitious LISA mission, but NASA dropped out of the partnership in 2011 due to budget constraints. ESA pressed on with a scaled-back gravitational wave observatory, which received prioritization from the agency in 2013 ahead of the LISA concept's selection last month.

European officials want ESA to lead the LISA mission to avoid falling victim to another failed partnership, but NASA will still be a significant contributor. After discussions in the last few years for NASA to be a 10 percent partner, the U.S. stake in the LISA mission is now likely to be closer to 20 percent.

"We are talking about a more substantial contribution than a 10 percent share," Hertz said. "ESA has welcomed us as a very major partner."

NASA might develop lasers and telescopes for the LISA observatory, or the mission's charge management system. Another potential U.S. addition to the mission could be the micro-thrusters needed to deftly control each of the LISA spacecraft, which will be assembled in Europe.

LISA is third in ESA's "Cosmic Vision" line of large-class billion-euro space science missions.

A robotic spacecraft that will orbit Jupiter, and then circle Jupiter's largest moon Ganymede, is on schedule for launch aboard an Ariane 5 rocket in 2022, followed by liftoff of the Athena X-ray astronomy observatory in 2028.

Then it will be LISA's turn.

Before shutting down LISA Pathfinder, controllers fired its thrusters to nudge it out of its post at the L1 Lagrange point in April to head into a heliocentric orbit around the sun. The maneuver minimized the chance the spacecraft will return to Earth's vicinity.

LISA Pathfinder's science mission officially ended June 30, and engineers spent the final weeks practicing procedures to recapture the test masses inside their housings, which might be necessary if problems develop on the LISA mission. Other final tasks included monitoring the instrument's behavior when the spacecraft's thrusters were turned off, and tracking the test masses' response to a coronal mass ejection fr om the sun.

Scientists were eager to see how the spacecraft responded when it was zapped by ionizing energy fr om a solar eruption last week. In particular, mission officials wanted to know whether the instrument would still provide useful science data when the test masses were hit by charged particles. Reviews of that data are still ongoing, McNamara said.

The final commands uplinked to LISA Pathfinder turned off the craft's transponder and corrupted the memory files of the probe's primary and redundant computers by filling the processors with the names of scientists and engineers who worked on the mission.

"This is a celebration, and it's certainly not a sad moment," Vitale said moments before sending the order that silenced the spacecraft.

"LISA Pathfinder has done everything and more that we could have asked of it," McNamara said. "And it's allowed LISA to go ahead, so yes, we're sad that's going away and it's ending, but we're very happy LISA is taking off.

"It's another 17 years to go before that one launches, so we'll exercise our patience."
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tnt22

ЦитироватьHow LISA Pathfinder Detected Dozens of 'Comet Crumbs'

 NASA Goddard

18 нояб. 2019 г.

LISA Pathfinder, a mission led by ESA (the European Space Agency) that included NASA contributions, successfully demonstrated technologies needed to build a future space-based gravitational wave observatory, a tool for detecting ripples in space-time produced by, among other things, merging black holes. A team of NASA scientists leveraged LISA Pathfinder's record-setting sensitivity for a different purpose much closer to home — mapping microscopic dust shed by comets and asteroids.
Most of these particles, known as micrometeroids, have masses measured in micrograms, similar to a small grain of sand. But at speeds reaching 40,000 mph (64,000 kph), even micrometeoroids pack a punch.

The NASA team, led by Ira Thorpe at NASA's Goddard Space Flight Center in Greenbelt, Maryland, detected 54 impacts during the mission, which lasted from 2015 to 2017. Modeling the strikes allowed the researchers to determine what kinds of objects shed the dust. The findings are broadly consistent with existing ideas of what generates micrometeroids found near Earth. The dusty culprits are mostly short-period comets  whose orbits are determined by Jupiter. Comets with longer periods, like Halley's comet, also contributed dust that LISA Pathfinder sensed.

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.
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https://www.youtube.com/watch?v=CQeVHg4aA0shttps://www.youtube.com/embed/CQeVHg4aA0s (2:59)

Водитель

Одобрили

ЦитироватьESA одобрило постройку космической гравитационно-волновой обсерватории LISA 


Европейское космическое агентство (ESA) одобрило старт постройки трех аппаратов для будущей космической гравитационно-волновой обсерватории LISA. Она должна полететь в космос в 2035 году, сообщается на сайте агентства. 


LISA (Laser Interferometer Space Antenna) разрабатывается ESA совместно с NASA. Это космический лазерный интерферометр, который будет состоять из трех аппаратов, формирующих равносторонний треугольник со стороной в 1,5 миллиона километров. Принцип работы LISA аналогичен наземным обсерваториям LIGO и Virgo, однако она будет чувствительна к волнам гораздо меньшей частоты — рабочий диапазон составит от 0,1 миллигерца до 1 герца. Кроме того, треугольная схема вместо L-образной, которая используется на Земле, позволяет исследовать больше свойств гравитационных волн. В качестве пробных тел в LISA будут использоваться два двухкилограммовых кубика из золота и платины, эксперименты с ними проводились ранее на прототипе обсерватории LISA Pathfinder и оказались успешны. 


25 января 2024 года Комитет научной программы ESA завершил анализ проекта, признал, что он пригоден для постройки, и разрешил приступать к созданию научных приборов и космических аппаратов. До 2025 года будут выбраны подрядчики в Европе, а NASA предоставит лазеры, телескопы для приема лазерных лучей и источники ультрафиолетового света. 


Ожидается, что в космос три аппарата будут запущены при помощи тяжелой ракеты «Ариан-6» в 2035 году. Целями для LISA помимо событий слияний сверхмассивных черных дыр станут сверхкомпактные двойные системы в нашей галактике, содержащие нейтронные звезды и белые карлики, а также события слияний компактных объектов разных типов или разных масс.

https://nplus1.ru/news/2024/01/26/lisa-go
https://www.esa.int/Science_Exploration/Space_Science/Capturing_the_ripples_of_spacetime_LISA_gets_go-ahead