ScienceNot yet confirmed elsewhere1 publisher2 min readPublished Updated
L3Harris will build the last test telescope before NASA makes LISA flight hardware
L3Harris will build the Engineering Test Unit for NASA's all-glass LISA telescope, the agency's last pre-flight unit before flight hardware. NASA is supplying the telescopes and laser system for the ESA-led gravitational-wave observatory, due to launch in the mid-2030s.
The Scientist · Science desk
What happened
- L3Harris delivered a prototype telescope to NASA in 2024, and it served as the engineering development unit for the new test unit.
- In June the team handed over a structural model of the telescope, built in metal where the real one uses glass.
- Each of LISA's three satellites will carry two telescopes that send and receive infrared laser beams between neighbouring spacecraft at the same time.
- NASA's other contributions include devices that control electric charge on the proof masses and data analysis to identify and characterise gravitational-wave sources.
Why it matters
- constraint This is the last rehearsal unit. Any problem it exposes has to be designed out before NASA commits to six flight telescopes, two for each spacecraft.
- capability For the first time ESA gets NASA optics in hand, and mismatches between the US telescope and the European-led spacecraft can turn up on a test article before any flight unit exists.
- exposure Because NASA supplies the telescope in every laser link, a defect found in this unit would fall to the US side of the partnership to fix.
Ritva Keski-Kuha, who leads the LISA Telescope program at NASA's Goddard Space Flight Center, said: "This will be our last pre-flight unit and our first optical telescope delivery to ESA." [12] NASA's own phrase for the unit is a final step toward the future production of flight hardware [2]. That puts the US telescope work one step short of production.
The telescopes are part of the measurement. Through them the spacecraft track tiny changes in their separation [6], across arms 2.5 million km long [5]. "These changes are tiny, smaller than the width of a helium atom, but through them LISA will reveal a sea of low-frequency gravitational waves that we cannot currently detect through facilities on Earth," said Ira Thorpe, NASA's project scientist for the mission at Goddard [7]. Each telescope will be made entirely of Zerodur, a ceramic-glass composite used in high-precision work because it resists changing shape across a wide range of temperatures [9].
Ground-based observatories first detected gravitational waves in 2015 [17]. Thorpe said LISA "will be able to detect mergers of monster black holes billions of light-years away, map compact pairs of white dwarfs, neutron stars, and stellar-mass black holes in our own cosmic backyard, and perhaps provide new insights into gravity itself." [8]
On the prototype, Keski-Kuha said: "We've put the prototype through rigorous testing, and we're bringing everything we've learned into this new telescope." [11] NASA did not publish prototype results, the value of the L3Harris work or a delivery date for the test unit [1].
Another part of LISA's measurement already has a mission behind it. Each spacecraft flies around a free-floating gold-platinum cube so that the cube falls under gravity alone [16]. In 2016, ESA's LISA Pathfinder mission showed that non-gravitational forces on such proof masses could be reduced to the level gravitational-wave detection needs [15]. So far the telescope has been tested only on ground hardware that L3Harris and NASA built [10] [13].
What to watch
- Whether NASA or L3Harris discloses the contract value and a delivery date for the Engineering Test Unit.
- Results from ESA's tests of the glass unit, the first optical telescope it receives from NASA.
- A NASA announcement that production of the six flight telescopes has started.
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- [1]
L3Harris Technologies will design, assemble, and integrate a new telescope for NASA's LISA contribution, called the Engineering Test Unit.
- [2]
NASA describes the Engineering Test Unit as a final step toward the future production of flight hardware.
- [3]
The LISA mission is led by ESA and is slated for launch in the mid-2030s.
- [4]
As a collaborative partner, NASA is contributing the telescopes, other critical hardware, and engineering and scientific support to LISA.
- [5]
LISA will deploy three satellites into an Earth-following orbit, forming a triangular array 2.5 million kilometers (1.6 million miles) on each side.
- [6]
Each LISA satellite will include two telescopes that use infrared laser beams to simultaneously transmit and receive signals between adjacent spacecraft; through them the spacecraft measure minuscule changes in their relative distances, the signals of passing gravitational waves.
- [7]
"These changes are tiny, smaller than the width of a helium atom, but through them LISA will reveal a sea of low-frequency gravitational waves that we cannot currently detect through facilities on Earth," said Ira Thorpe, NASA project scientist for the mission at Goddard Space Flight Center.
ReportedSupportedSource: Ira Thorpe, NASA Goddard2 sources— create a free account to open themView cited source - [8]
"The LISA mission will be able to detect mergers of monster black holes billions of light-years away, map compact pairs of white dwarfs, neutron stars, and stellar-mass black holes in our own cosmic backyard, and perhaps provide new insights into gravity itself," said Ira Thorpe.
ReportedSupportedSource: Ira Thorpe, NASA Goddard2 sources— create a free account to open themView cited source - [9]
Each LISA telescope will be made entirely of Zerodur, an amber-colored ceramic-glass composite widely used in high-precision applications because it resists changes in shape across a wide range of temperatures.
- [10]
In 2024, L3Harris delivered a prototype telescope to NASA that served as an engineering development unit for the Engineering Test Unit.
- [11]
"We've put the prototype through rigorous testing, and we're bringing everything we've learned into this new telescope," said Ritva Keski-Kuha, lead for the LISA Telescope program at NASA Goddard.
ReportedSupportedSource: Ritva Keski-Kuha, NASA Goddard2 sources— create a free account to open themView cited source - [12]
"This will be our last pre-flight unit and our first optical telescope delivery to ESA," said Ritva Keski-Kuha.
ReportedSupportedSource: Ritva Keski-Kuha, NASA Goddard2 sources— create a free account to open themView cited source - [13]
In June, the team delivered a structural model of the telescope made from metal instead of glass.
- [14]
Additional NASA contributions to LISA include the laser system, devices to manage the buildup of electric charge on the proof masses, data analysis for identifying and characterizing individual gravitational-wave sources, and additional scientific and engineering expertise.
- [15]
In 2016, ESA's LISA Pathfinder mission showed it was possible to reduce non-gravitational forces on the proof masses to the level needed for gravitational-wave detection.
- [16]
Each of the three LISA spacecraft contains a free-floating gold-platinum cube called a proof mass; the spacecraft flies around the cube and manages its environment so it falls only under the influence of gravity.
- [17]
Gravitational waves were predicted by Einstein's 1916 general theory of relativity and first detected by ground-based observatories in 2015.
- [18]
LISA's constellation carries six telescopes in total, all supplied by NASA.
Sources
1 independent publisher whose own reporting we read for this story.
- nasa.govNASA Advances LISA Mission Contributions With New Test Telescope
1 article · October 8, 2026
- phys.orgNASA advances LISA mission contributions with new test telescope
1 article · October 9, 2026
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