DE102023115899B3 - Deployable reflecting telescope, satellite with a deployable reflecting telescope and method for deploying a reflecting telescope - Google Patents

Abstract

The invention relates to a deployable mirror telescope (2), in particular for a satellite (1), preferably a small/micro satellite or CubeSat, comprising at least:
- a hinged segmented main mirror (3) which is formed by a number of separate flat mirror segments (3a) which are connected to a hinged support structure (5) via first joint devices (4);
- the foldable support structure (5) for receiving the mirror segments (3a) of the main mirror (3), which is formed by a plurality of first rod-shaped connecting elements (5a) which are connected to one another via second joint devices (5b); and
- a fold-out secondary mirror (6).

Description

The invention relates to a deployable mirror telescope. The invention also relates to a satellite, in particular a small/micro satellite or CubeSat with a deployable mirror telescope and a method for deploying a mirror telescope.

In recent years, visual earth observation has undergone major changes, moving from complex and expensive satellites in geostationary orbit (GEO) and LEO (Low Earth Orbit) (approx. 500 km - 1000 km) to small satellites or micro satellites, especially CubeSats, which are deployed in large numbers in lower earth orbits. These offer the advantage of enabling rapid revisits (repeated observation of the same point on earth) due to their large number, and thus observing each point below their trajectories more frequently. Constellations of optical CubeSats with more than 150 satellites are currently known. This allows up to twelve revisits of a specific point on the ground per day.

At present, the majority of CubeSat systems for earth observation are based on 3U format CubeSats (dimensions approx. 10 x 10 x 30 cm ³ , weight approx. 5 kg). However, these limit the available optical aperture to around 90 mm. This results in a ground resolution of around 3 m from an altitude of 400 km. However, the altitude and the low mass also mean a very limited lifespan of one to two years in orbit. In addition, the resolution of 3 m is still below the target value of better than 1 m. This resolution is achieved by satellites such as SkySat, which, however, are significantly larger and more expensive with dimensions of around 60 × 60 × 95 cm ³ and a weight of 120 kg. The optically clear aperture of such satellites is around 450 mm.

The next generation of CubeSats will therefore also use a larger base structure to increase the resolution, but at a cost that is significantly lower than that of SkySat class satellites. Such satellites achieve an aperture size of 180 mm in a CubeSat of size 12U (20 x 20 x 30 cm ³ ). However, these systems also only achieve the resolution of 1 m from very low orbits and thus have a very short lifetime.

One way to increase the optical aperture - and thus the resolution - of an optical Earth observation telescope without increasing the launch volume is to use unfoldable telescope mirrors, or telescope mirrors that are only brought into their final configuration in orbit. The most prominent example of this is currently NASA's James Webb Space Telescope (JWST).

For some time now, efforts have been made to develop foldable optical telescopes that allow a larger optical aperture than the dimensions of the satellite in launch configuration allow. These can be used in both CubeSats and larger satellites.

Reference is made to the following publications: “ “A Deployable Telescope for Sub-Meter Resolutions from MicroSatellite Platforms, Dennis Dolkens, Delft University of Technology, October 2014,” “Primary Mirror Fine Positioning Mechanism for a Deployable Space Telescope, SM Pepper, Delft University of Technology, November 27, 2018 " and “Design of deployment systems for high-resolution deployable telescope based on CubeSat, Daim Haobin et. al, Xi'an Institute of Optics and Precision Mechanics, November 24, 2021 “.

However, previous publications on foldable mirror telescopes only describe systems with simple folding mechanisms, where the walls on the sides are folded outwards, thus creating a larger optical diameter. Such telescopes are also called "pedal-style" telescopes.

In " High-resolution deployable CubeSat prototype, Noah Schwartz et. Al, UK Astronomy Technology Centre, December 13, 2020 “ also describes a foldable CubeSat mirror. This configuration shows a clear direction dependence of the resolution, since the diameter of the entrance aperture is not constant. In the areas of the unfolded mirrors, this diameter can be adjusted by the length of the mirror segments. This results in an “adjustable” resolution along these axes. In the areas between the mirrors, however, there is no free aperture. This creates an image with clear imaging artifacts. The configuration described is also not easily scalable or applicable to different configurations. Although the mirror segments can be extended or even a second folding can be provided which extends the segments further, all of this only contributes to the problem mentioned above that the resolution is not available in all spatial directions. In addition, the configuration does not use the available volume in the starting configuration efficiently. The space within the mirror segments is almost empty.

Other telescopes, primarily the JWST, have significantly reduced the problem of direction-dependent resolution by using hexagonal mirror segments. The deviation of the aperture from the ideal circular shape is significantly smaller.

However, folding like the JWST also requires a very limited packing density of the mirror segments in the launch configuration and is only suitable to a limited extent for use in CubeSats due to the massive mechanical basic structure. None of the concepts mentioned above have yet been realized in a "flightable" form. The implementations are limited to prototypes, some of which deviate quite far from the proposed designs and only achieve significantly smaller free apertures than intended.

A similar concept to the JWST was already used in the US 5,898,529 A and later in US 2005/0088734 A1 held.

A more complex but more compact folding was used in the US 8,179,598 B1 treated.

For “pedal-style” telescopes, the US 2013/0229709 A1 and the WO 2022/109747 A1 referred to.

The DE 20 2005 020 683 U1 describes a device for the space-saving deployment of a deployable optical system for space use.

The CN 1 15 980 962 A relates to a light condensing structure, apparatus and system, wherein the light condensing structure comprises a base, a primary mirror assembly and an adjustment assembly, wherein the light condensing apparatus comprises a light condensing structure, a secondary mirror assembly and a pivoting mirror assembly, and wherein the light condensing system comprises the light condensing apparatus and a satellite platform (namely, a satellite body).

The CN 1 13 568 134 A relates to the technical field of optical space remote sensing, in particular to a deployment mechanism of a space diffraction primary mirror with heat dissipation and low shock characteristics.

Proceeding from this, the present invention is based on the object of creating a deployable mirror telescope of the type mentioned at the outset, which avoids the disadvantages of the prior art, in particular requires little installation space when folded up and provides a large aperture when unfolded.

This object is achieved according to the invention by a deployable mirror telescope having the features mentioned in claim 1.

• - einen aufklappbaren segmentierten Hauptspiegel, welcher durch eine Anzahl von separaten flächigen Spiegelsegmenten gebildet ist, welche über erste Gelenkeinrichtungen mit einer auseinanderklappbaren Tragstruktur verbunden sind;
• - die auseinanderklappbare Tragstruktur zur Aufnahme der Spiegelsegmente des Hauptspiegels, welche durch mehrere erste stabförmige Verbindungselemente, die über zweite Gelenkeinrichtungen miteinander verbunden sind, gebildet ist; und
• - einen ausklappbaren Sekundärspiegel.

According to the invention, a deployable telescope or mirror telescope, in particular for a satellite, preferably a small / micro satellite or CubeSat, is proposed, which comprises at least:

• - a hinged segmented main mirror, which is formed by a number of separate flat mirror segments which are connected to a foldable support structure via first joint devices;
• - the foldable support structure for receiving the mirror segments of the main mirror, which is formed by a plurality of first rod-shaped connecting elements which are connected to one another via second joint devices; and
• - a fold-out secondary mirror.

The "foldable" telescope according to the invention is particularly suitable for use on small satellites or micro satellites (e.g. in 12U format), but can also be used on larger satellites with the necessary modifications. With a segmented main mirror and a foldable arm for the secondary mirror, the installation space required during launch can be significantly reduced, while in flight configuration a telescope with a large aperture is realized. The invention allows a combination of inexpensive individual mirror segments to form a mirror of high optical quality. The telescope according to the invention can take up a format of 12U when folded and, when unfolded, result in an aperture of approx. 600 mm, which corresponds to approximately twice the length of the longest edge of a 12U system. The mirror segments can have a diameter of 20 cm, for example. The invention also allows an increase in the packing density for optical telescopes during the launch phase and thus the use of inexpensive carrier systems for launch (especially for mirrors larger than 1 m in diameter in geostationary orbit).

• - ein Rotationslager, dessen Welle mit einem der Spiegelsegmente verbunden ist und welches eine Drehung des verbundenen Spiegelsegments von einer Startposition in eine aufgeklappte Endposition zulässt; und/oder
• - einen Federmechanismus, welcher dazu ausgelegt ist, eine Drehung des verbundenen Spiegelsegments von der Startposition in die aufgeklappte Endposition zu bewirken und welcher vorzugsweise mittels einer lösbaren Arretierung, beispielsweise eines entfernbaren Stifts, durchschmelzbarer Nylonschnüre oder dergleichen aktivierbar ist; und/oder
• - wenigstens eine Dämpfungseinrichtung, welche dazu ausgelegt ist, die durch den Federmechanismus bewirkte Drehbewegung zu dämpfen; und/oder
• - wenigstens zwei, vorzugsweise drei V-Kugellager, welche in der aufgeklappten Endposition des verbundenen Spiegelsegments durch V-förmige Nuten und darin aufgenommene, an die V-förmigen Nuten angepasste, Kugeln gebildet sind; und/oder
• - eine oder mehrere Verstelleinrichtungen bzw. Aktoren, vorzugsweise Piezoaktoren, welche dazu ausgelegt sind, eine Feinjustierung der Ausrichtung des verbundenen Spiegelsegments, insbesondere um zwei Kippachsen und in der Fokuslage zu ermöglichen und vorzugsweise unterhalb der Kugeln der V-Kugellager angeordnet sind.

A first articulation device may comprise at least:

• - a rotary bearing, the shaft of which is connected to one of the mirror segments and which allows rotation of the connected mirror segment from a starting position to an unfolded end position; and/or
• - a spring mechanism which is designed to cause a rotation of the connected mirror segment from the starting position to the unfolded end position and which is preferably actuated by means of a releasable locking device, for example a removable pin, meltable nylon cords or the like; and/or
• - at least one damping device which is designed to dampen the rotational movement caused by the spring mechanism; and/or
• - at least two, preferably three V-ball bearings, which in the unfolded end position of the connected mirror segment are formed by V-shaped grooves and balls accommodated therein and adapted to the V-shaped grooves; and/or
• - one or more adjustment devices or actuators, preferably piezo actuators, which are designed to enable fine adjustment of the alignment of the connected mirror segment, in particular about two tilt axes and in the focus position and are preferably arranged below the balls of the V-ball bearings.

The position of the individual mirror segments and their supporting structures can be determined with high precision (e.g. in the µm range) and without play using three V-ball bearings in the first joint devices. This enables defined and stable positioning to be achieved. The special feature here is that the segments are not referenced to a higher-level mechanical structure, but are positioned relative to one another. The V-ball bearings and their arrangement enable static determination in six degrees of freedom and thus a clear, reproducible position to be created.

Piezo fine adjusters or piezo actuators on the V-ball bearings, especially underneath the balls, enable adjustment of the individual mirror segments in tilt around two axes, as well as in the focus position. Appropriate solid-state joints can also be used for this purpose.

The spring mechanism can be activated, for example, by means of a removable pin or pin. The at least one damping device can, for example, have a hose filled with silicone oil or the like.

The second joint devices can also be provided with damping devices to avoid high rotational speeds.

In a very advantageous embodiment of the invention, the mirror segments can be hexagonal.

By using hexagonal segments, a high filling factor of the entrance pupil and an almost homogeneous resolution in all spatial directions are achieved.

The mirror segments can have a curved surface, in particular an off-axis hyperbolic or parabolic one. The unfoldable mirror telescope according to the invention can preferably be a Ritchey-Chrétien-Cassegrain telescope.

The mirror segments can be arranged in a ring shape when unfolded.

When the mirror telescope is folded, the mirror segments can be braced against each other and secured by launch locks. Furthermore, when the mirror telescope is folded, the support structure can form a magazine in which the mirror segments are arranged one behind the other.

In the launch configuration, the segments can be braced against each other and secured by launch locks. In addition, the individual mirror segments can be arranged one behind the other in a magazine in the launch configuration. These measures increase the natural frequencies of the arrangement and reduce unwanted movements under launch load (of 20 g, for example). The launch locks can, for example, include nylon cords that are melted before unfolding using appropriately designed and arranged electrical resistors. The resistors are energized accordingly.

The secondary mirror can be folded out by a plurality of second rod-shaped connecting elements which are connected to one another via third joint devices and can be connected to the fold-out support structure or a reference structure of the satellite.

The segmented main mirror can be formed by six mirror segments. In addition, six first joint devices and/or six second joint devices can be present.

Claim 9 specifies a satellite, in particular a small/micro satellite or CubeSat with a deployable mirror telescope according to the invention.

• - in einem ersten Schritt mehrere oder alle, insbesondere sechs zweite Gelenkeinrichtungen zum Auseinanderklappen der Tragstruktur jeweils eine Drehung, insbesondere um etwa 120° ausführen, wonach
• - in einem zweiten Schritt mittels der ersten Gelenkeinrichtungen eine Drehung der Spiegelsegmente von der Startposition in die aufgeklappte Endposition erfolgt, und wonach
• - in einem dritten Schritt eine oder mehrere, insbesondere drei zweite Gelenkeinrichtungen jeweils eine weitere Drehung, insbesondere um etwa 120° ausführen, um die klappbare Tragstruktur wenigstens annähernd vollständig oder ganz zu schließen und den segmentierten Hauptspiegel auszubilden.

Claim 10 relates to a method for deploying a mirror telescope according to the invention which is arranged on a satellite, wherein:

• - in a first step, several or all, in particular six second joint devices for unfolding the support structure perform a rotation, in particular by about 120°, after which
• - in a second step, the mirror segments are rotated from the starting position to the unfolded end position by means of the first joint devices, and then
• - in a third step, one or more, in particular three second articulation devices each carry out a further rotation, in particular by approximately 120°, in order to close the foldable support structure at least approximately completely or entirely and to form the segmented main mirror.

After completion of the second step, the rotation bearings of the first joint devices can be decoupled to prevent the formation of a statically overdetermined system.

Before the first step, the secondary mirror can be unfolded.

In the third step, every second of the second articulation devices can carry out the further rotation, in particular by approximately 120°, in order to close the foldable support structure at least approximately completely or entirely and to form the segmented main mirror.

In the third step, the components arranged at both ends of the support structure facing away from one another (i.e. rod-shaped connecting elements or second joint devices) can be connected to one another, in particular firmly, in order to at least approximately or completely close the foldable support structure. In the third step, the rearmost of the first rod-shaped connecting elements can thus preferably be firmly connected to the frontmost second joint device in order to at least approximately completely or completely close the foldable support structure. This measure can create a rigid and reproducible arrangement.

The process of unfolding a mirror telescope can be started after reaching the orbit by releasing the tension of the mirror segments and the launch locks.

After the third step, a fine adjustment of the alignment of the mirror segments around two tilt axes and in the focus position can be carried out by means of actuators, preferably piezo actuators.

In the process of unfolding a mirror telescope, the mirror segments can be positioned relative to each other.

Advantageous embodiments and further developments of the invention emerge from the subclaims.

In the following, embodiments of the invention are described in principle with reference to the drawing.

• 1 eine vereinfachte perspektivische Ansicht eines erfindungsgemäßen entfaltbaren Spiegelteleskops;
• 2 eine vereinfachte perspektivische Ansicht eines erfindungsgemäßen entfaltbaren Spiegelteleskops, welches auf einem Satelliten angeordnet ist;
• 3 eine vereinfachte perspektivische Ansicht einer ersten Gelenkeinrichtung des erfindungsgemäßen Spiegelteleskops in einer Startposition;
• 4 eine vereinfachte perspektivische Ansicht einer ersten Gelenkeinrichtung des erfindungsgemäßen Spiegelteleskops in einer Endposition;
• 5 eine vereinfachte perspektivische Ansicht des erfindungsgemäßen Spiegelteleskops im gefalteten Zustand;
• 6 eine erste vereinfachte perspektivische Darstellung des Hauptspiegels des erfindungsgemäßen Spiegelteleskops beim Ausklappen;
• 7 eine zweite vereinfachte perspektivische Darstellung des Hauptspiegels des erfindungsgemäßen Spiegelteleskops beim Ausklappen; und
• 8 eine vereinfachte perspektivische Ansicht des entfalteten bzw. ausgeklappten Hauptspiegels des erfindungsgemäßen Spiegelteleskops.

They show:

• 1 a simplified perspective view of a deployable mirror telescope according to the invention;
• 2 a simplified perspective view of a deployable mirror telescope according to the invention, which is arranged on a satellite;
• 3 a simplified perspective view of a first joint device of the mirror telescope according to the invention in a starting position;
• 4 a simplified perspective view of a first joint device of the mirror telescope according to the invention in an end position;
• 5 a simplified perspective view of the mirror telescope according to the invention in the folded state;
• 6 a first simplified perspective view of the main mirror of the mirror telescope according to the invention when unfolded;
• 7 a second simplified perspective view of the main mirror of the mirror telescope according to the invention when unfolded; and
• 8 a simplified perspective view of the unfolded or unfolded primary mirror of the mirror telescope according to the invention.

Functionally identical elements are provided with the same reference symbols in the figures.

• - einen aufklappbaren segmentierten Hauptspiegel 3, welcher durch eine Anzahl von separaten flächigen Spiegelsegmenten 3a gebildet ist, welche über erste Gelenkeinrichtungen 4 mit einer auseinanderklappbaren Tragstruktur 5 verbunden sind;
• - die auseinanderklappbare Tragstruktur 5 zur Aufnahme der Spiegelsegmente 3a des Hauptspiegels 3, welche durch mehrere erste stabförmige Verbindungselemente 5a, die über zweite Gelenkeinrichtungen 5b miteinander verbunden sind, gebildet ist; und
• - einen ausklappbaren Sekundärspiegel 6.

1 shows a deployable telescope or mirror telescope 2 according to the invention, in particular for a satellite 1 (see 2 ), preferably small / micro satellites or CubeSat, which comprises at least:

• - a hinged segmented main mirror 3, which is formed by a number of separate flat mirror segments 3a, which are connected to a foldable support structure 5 via first joint devices 4;
• - the foldable support structure 5 for receiving the mirror segments 3a of the main mirror 3, which are connected by several first rod-shaped shaped connecting elements 5a, which are connected to each other via second joint devices 5b; and
• - a fold-out secondary mirror 6.

As from 1 As can be seen further, the secondary mirror 6 can be folded out by a plurality of second rod-shaped connecting elements 6a, which are connected to one another via third joint devices 6b, and can be connected to the foldable support structure 5 or a reference structure of the satellite 1 (not shown in more detail). The folding out of the secondary mirror 6 can be carried out, for example, via spring mechanisms (not shown in more detail).

In 2 The satellite 1, in particular a small / micro satellite or CubeSat with the inventive unfoldable mirror telescope 2 is shown in simplified form. As can be seen from 2 As can be seen, the satellite 1 further comprises at least one camera or an optical or electronic or optoelectronic sensor 1a, which is preceded by the mirror telescope 2, in particular also by further optical elements not shown, and at least one data communication device 1b. Of course, the satellite 1 can also comprise further optical or electronic components not shown, as well as a housing.

The mirror segments 3a can have a, in particular off-axis, hyperbolic or parabolic curved surface. The unfoldable mirror telescope 2 according to the invention can preferably be a Ritchey-Chrétien-Cassegrain telescope. As can be seen, the mirror segments 3a can be hexagonal. Furthermore, the mirror segments 3a can be arranged in a ring-like manner when unfolded.

As can also be seen, the segmented main mirror 3 can be formed by six mirror segments 3a. Furthermore, six first joint devices 4 can be present. In addition, six second joint devices 5b can be present.

In 3 a first joint device 4 of the mirror telescope 2 according to the invention is shown in a starting position. 4 shows the first joint device 4 of the mirror telescope 2 according to the invention in an end position.

• - ein Rotationslager 4a, dessen Welle mit einem der Spiegelsegmente 3a verbunden ist (nicht näher dargestellt) und welches eine Drehung des verbundenen Spiegelsegments 3a von der Startposition in die aufgeklappte Endposition zulässt (siehe auch 6 und 7); und/oder
• - einen nicht näher dargestellten Federmechanismus, welcher dazu ausgelegt ist, eine Drehung des verbundenen Spiegelsegments 3a von der Startposition in die aufgeklappte Endposition zu bewirken und welcher vorzugsweise mittels einer lösbaren Arretierung 4f, beispielsweise eines entfernbaren Stifts, durchschmelzbarer Nylonschnüre oder dergleichen aktivierbar ist; und/oder
• - wenigstens eine Dämpfungseinrichtung 4b, welche dazu ausgelegt ist, die durch den Federmechanismus bewirkte Drehbewegung zu dämpfen; und/oder
• - wenigstens zwei, vorzugsweise drei V-Kugellager 4c, welche in der aufgeklappten Endposition des verbundenen Spiegelsegments 3a durch V-förmige Nuten 4d und darin aufgenommene, an die V-förmigen Nuten 4d angepasste, Kugeln 4e gebildet sind; und/oder
• - eine oder mehrere nicht dargestellte Aktoren, vorzugsweise Piezoaktoren, welche dazu ausgelegt sind, eine Feinjustierung der Ausrichtung des verbundenen Spiegelsegments 3a, insbesondere um zwei Kippachsen und in der Fokuslage zu ermöglichen und vorzugsweise unterhalb der Kugeln 4e der V-Kugellager 4c angeordnet sind.

As can be seen from the 3 and 4 As can be seen, the first joint device 4 may comprise at least:

• - a rotary bearing 4a, the shaft of which is connected to one of the mirror segments 3a (not shown in detail) and which allows rotation of the connected mirror segment 3a from the starting position to the unfolded end position (see also 6 and 7 ); and/or
• - a spring mechanism (not shown in detail) which is designed to cause a rotation of the connected mirror segment 3a from the starting position to the unfolded end position and which can preferably be activated by means of a releasable locking device 4f, for example a removable pin, meltable nylon cords or the like; and/or
• - at least one damping device 4b, which is designed to dampen the rotational movement caused by the spring mechanism; and/or
• - at least two, preferably three V-ball bearings 4c, which in the unfolded end position of the connected mirror segment 3a are formed by V-shaped grooves 4d and balls 4e accommodated therein and adapted to the V-shaped grooves 4d; and/or
• - one or more actuators (not shown), preferably piezo actuators, which are designed to enable fine adjustment of the alignment of the connected mirror segment 3a, in particular about two tilt axes and in the focus position and are preferably arranged below the balls 4e of the V-ball bearings 4c.

Furthermore, the first joint device 4 has clamping devices 4g and a mechanism 4h for disengaging the rotary bearing 4a.

5 shows the main mirror 3 or its mirror segments 3a and the secondary mirror 6 in the folded state of the mirror telescope 2. The mirror segments 3a can be braced against each other and secured by launch locks (not shown in detail). The support structure 5 can form a magazine 7 in which the mirror segments 3a are arranged one behind the other.

• - in einem ersten Schritt mehrere oder alle, insbesondere sechs zweite Gelenkeinrichtungen 5b zum Auseinanderklappen der Tragstruktur 5 jeweils eine Drehung, insbesondere um etwa 120° ausführen (siehe 6), wonach
• - in einem zweiten Schritt mittels der ersten Gelenkeinrichtungen 4 eine Drehung der Spiegelsegmente 3a von der Startposition in die aufgeklappte Endposition erfolgt (siehe 7), und wonach
• - in einem dritten Schritt eine oder mehrere, insbesondere drei zweite Gelenkeinrichtungen 5b jeweils eine weitere Drehung, insbesondere um etwa 120° ausführen, um die klappbare Tragstruktur 5 wenigstens annähernd vollständig zu schließen und den segmentierten Hauptspiegel 3 auszubilden.

Furthermore, a method for unfolding the mirror telescope 2 arranged on the satellite 1 is proposed, wherein:

• - in a first step, several or all, in particular six second joint devices 5b for unfolding the support structure 5 each carry out a rotation, in particular by approximately 120° (see 6 ), after which
• - in a second step, the mirror segments 3a are rotated from the starting position to the unfolded end position by means of the first joint devices 4 (see 7 ), and what
• - in a third step, one or more, in particular three second articulation devices 5b each carry out a further rotation, in particular by approximately 120°, in order to at least approximately completely close the foldable support structure 5 and form the segmented main mirror 3.

Before the first step, the secondary mirror 6 can be unfolded (not shown).

The second joint devices 5b can - analogously to the first joint devices 4 - also be provided with damping devices (not shown) which dampen the rotational movements. The rotational movements of the second joint devices 5b can also be brought about by spring mechanisms or the like which are not shown in detail.

In the third step, every second of the second joint devices 5b can carry out the further rotation, in particular by approximately 120°, in order to at least approximately completely close the foldable support structure 5 and form the segmented main mirror 3.

In the third step, the components 5a', 5b' arranged at both ends of the support structure 5 facing away from one another can be connected to one another, in particular firmly, in order to at least approximately or completely close the foldable support structure 5. In the third step, the rearmost of the first rod-shaped connecting elements 5a' can thus be connected, preferably firmly, to the frontmost second joint device 5b', in order to at least approximately or completely close the foldable support structure 5. The relevant second joint devices 5b' can be adapted accordingly for this purpose (see 6 and 7 ).

The process for unfolding the mirror telescope 2 can be started after reaching the orbit, whereby the tension of the mirror segments 3a and the launch locks are released.

After the third step, a fine adjustment of the alignment of the mirror segments 3a around two tilt axes and in the focus position can be carried out by means of the actuators, in particular piezo actuators.

In the method for unfolding the mirror telescope 2, the mirror segments 3a can thus be positioned relative to each other.

8 shows the fully unfolded or unfolded main mirror 3 of the mirror telescope 2 according to the invention with the support structure 5 but without the secondary mirror 6.

list of reference symbols

1

satellite

1a

optical sensor

1b

data communication device

2

reflecting telescope

3

primary mirror

3a

mirror segments

4

First joint devices

4a

rotary bearings

4b

damping device

4c

V-ball bearings

4d

V-shaped groove

4e

balls

4f

removable locking mechanism

4g

clamping device

4 hours

mechanism for disengaging the rotary bearing

5

supporting structure

5a,5a'

First rod-shaped connecting elements

5b,5b'

Second joint devices

6

secondary mirror

6a

Second rod-shaped connecting elements

6b

Third joint devices

7

magazine

Claims (16)

Deployable mirror telescope (2), in particular for a satellite (1), preferably a small/micro satellite or CubeSat, comprising at least: - a foldable segmented main mirror (3), which is formed by a number of separate flat mirror segments (3a), which are connected to a foldable support structure (5) via first joint devices (4); - the foldable support structure (5) for receiving the mirror segments (3a) of the main mirror (3), which is formed by a plurality of first rod-shaped connecting elements (5a), which are connected to one another via second joint devices (5b); and - a foldable secondary mirror (6). Reflector telescope (2) after claim 1 , wherein a first joint device (4) comprises at least: - a rotary bearing (4a), the shaft of which is connected to one of the mirror segments (3a) and which allows rotation of the connected mirror segment (3a) from a starting position to an unfolded end position; and/or - a spring mechanism which is designed to cause rotation of the connected mirror segment (3a) from the starting position to the unfolded end position and which can preferably be activated by means of a releasable lock (4f); and/or - at least one damping device (4b) which is designed to dampen the rotational movement caused by the spring mechanism; and/or - at least two, preferably three V-ball bearings (4c), which in the unfolded end position of the connected mirror segment (3a) are formed by V-shaped grooves (4d) and balls (4e) received therein and adapted to the V-shaped grooves (4d); and/or - one or more actuators, preferably piezo actuators, which are designed to enable fine adjustment of the alignment of the connected mirror segment (3a) about two tilt axes and in the focus position and are preferably arranged below the balls (4e) of the V-ball bearings (4c). Reflector telescope (2) after claim 1 or 2 , wherein the mirror segments (3a) are hexagonal. Reflector telescope (2) after claim 1 , 2 or 3 , wherein the mirror segments (3a) have a, in particular off-axis, hyperbolic or parabolic curved surface. Reflecting telescope (2) according to one of the Claims 1 until 4 , wherein the mirror segments (3a) are arranged in a ring-like manner in the unfolded state. Reflecting telescope (2) according to one of the Claims 1 until 5 , wherein in the folded state of the mirror telescope (2): - the mirror segments (3a) are braced against each other and secured by launch locks; and/or - the support structure (5) forms a magazine (7) in which the mirror segments (3a) are arranged one behind the other. Reflecting telescope (2) according to one of the Claims 1 until 6 , wherein the secondary mirror (6) can be folded out by a plurality of second rod-shaped connecting elements (6a), which are connected to one another via third joint devices (6b), and is connected to the fold-out support structure (5) or a reference structure of the satellite (1). Reflecting telescope (2) according to one of the Claims 1 until 7 , wherein the segmented main mirror (3) is formed by six mirror segments (3a), and/or wherein six first joint devices (4) are present, and/or wherein six second joint devices (5b) are present. Satellite (1), in particular small / micro satellite or CubeSat, with a deployable mirror telescope (2) according to one of the Claims 1 until 8 , at least one electronic or optoelectronic sensor (1a), upstream of which the mirror telescope (2) is connected, and at least one data communication device (1b). Method for unfolding a mirror telescope (2) according to one of the Claims 1 until 8 , which is on a satellite (1) to claim 9 is arranged, wherein: - in a first step, several or all, in particular six second joint devices (5b) for unfolding the support structure (5) each carry out a rotation, in particular by approximately 120°, after which - in a second step, the mirror segments (3a) are rotated from the start position into the unfolded end position by means of the first joint devices (4), and after which - in a third step, one or more, in particular three second joint devices (5b) each carry out a further rotation, in particular by approximately 120°, in order to at least approximately completely close the foldable support structure (5) and form the segmented main mirror (3). Method for unfolding a mirror telescope (2) according to claim 10 , whereby the secondary mirror (6) is unfolded before the first step. Method for unfolding a mirror telescope (2) according to claim 10 or 11 , wherein in the third step every second of the second articulation devices (5b) carries out the further rotation, in particular by approximately 120°, in order to at least approximately completely close the foldable support structure (5) and form the segmented main mirror (3). Method for unfolding a mirror telescope (2) according to claim 10 , 11 or 12 , wherein in the third step for at least approximately closing the foldable support structure (5), the rearmost of the first rod-shaped connecting elements (5a') is preferably firmly connected to the frontmost second joint device (5b'). Method for unfolding a mirror telescope (2) according to one of the Claims 10 until 13 , which is launched after reaching the orbit, whereby the bracing of the mirror segments (3a) and the launch locks are released. Method for unfolding a mirror telescope (2) according to one of the Claims 10 until 14 , wherein after the third step a fine adjustment of the alignment of the mirror segments (3a) about two tilt axes and in the focus position is carried out by means of the actuators. Method for unfolding a mirror telescope (2) according to one of the Claims 10 until 15 , wherein the mirror segments (3a) are positioned relative to each other.

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