[26.09.2018]

Immenstaad, 07 September 2018: The complex deployment work for ICARUS on ISS was conducted on August 15th. The Russian cosmonauts Oleg Artemyev and Sergey Prokopyev successfully installed the ICARUS antenna “demonstrator”- a large antenna assembly which consists of a transmit and multiple receive antennas. They were able to finish the deployment within 7 hours and 45 minutes.
ICARUS will enter a 2-3 months commissioning phase after health of the equipment on the ISS is verified.

[Source: Gerst/ESA]		[Source: Gerst/ESA]

When asking the two brave Russian cosmonauts, they would certainly confirm the complexity of the mission that required long time special trainings in addition to novel high-tech deployment equipment and techniques.

The innovation-driven region around Lake of Constance provides big players and mid-size space enterprises great conditions for these kinds of missions with all facilities for upfront tests and trainings.
Funded by DLR, the MPI for Ornithology selected SpaceTech, an innovative small space system integrator in Immenstaad, for the challenging development.
SpaceTech was responsible for the development and production of the entire space segment, consisting of inboard computer and outboard antenna assembly deployed on the ISS, as well as for the pre-development of the so-called tag – the tiny transmitter that rides on the bird’s or other animal’s back. SpaceTech subcontracted Von Hörner & Sulger, INRADIOS and STT-SystemTechnik as established German SMEs in space business for parts of the development and manufacturing.

The development activities of the demonstrator included as well, underwater training model, since water delivers conditions closest to working without gravity. On the other side of the lake, the ICARUS project crew found these underwater training conditions in the thermal bath and pool of Constance, where the model was tested in cooperation with the trainers of the cosmonauts before being shipped to the Gagarin Training Center in Moscow. The most challenging fact of this special deployment for the cosmonauts Oleg Artemyev and Sergey Prokopyev was the necessity of working with both hands in parallel, not able to hold on to anything. Engineering made it feasible with the solution of a strong bracket for their feet.

Another topic worth mentioning is the complexity of interaction of antennas up in space and the small tags moving on earth or in the air close to earth: SpaceTech’s high-tech system is able to pick up on the very weak signal that the tag is able to transmit due to its small size. This is a huge challenge, knowing that millions of other signals are sent everywhere all of the time. This ultra-sensitive hardware together with a unique software makes possible not only to hear the “soft” voices of the tags, but also to “understand” what they are saying.

Humankind may now ask, why we would need all that?
Because it can “make the world a little better”. Using the evolved senses of animals to forecast disasters like earth quakes or volcano eruptions or global change are only two of the world-changing applications possible.

[27.09.2018]

The German-French satellite MERLIN (Methane Remote Sensing LIDAR Mission) is a mission to observe the concentration of the greenhouse gas methane. In this cooperation between CNES and DLR, CNES signs responsible for the Satellite Bus, which is a Myriade Evolution, and DLR signs responsible for the Instrument. The instrument on MERLIN is a pulsed high power LIDAR (Light Detecting and Ranging) operating precisely at the methane absorption lines at 1645.55 nm wavelength. The instrument emits two different wavelengths called ‘online’ and ‘offline’: Online means located in the absorption feature and offline beside it for reference purposes.

To enable the required emission wavelengths around 1645.5-1645.7 nm, a frequency reference unit (FRU) is part of the instrument on the satellite. The frequency reference unit contains a methane gas cell, several diode lasers (1064 nm and 1645 nm emission wavelength), a wavemeter and the associated control electronics including an FPGA for stabilizing the diode laser emissions and the high power laser pulse frequency to the methane cell and the wavemeter. The FRU is delivering its optical signals to the high power laser and measures their wavelengths and the ones of the high power laser pulses to MHz accuracy. In addition it performs the wavelength stabilisation control loops for the internal diode laser and of the OPO of the high power laser.  

One and a half years after the start phase C/D, SpaceTech GmbH delivered the CDR data package for the frequency reference unit to Airbus and DLR. The co-location took place on the 25th and 26th of July 2018 at the SpaceTech premises in Immenstaad. All RIDs have been closed and no showstoppers for the CDR have been found. The engineering model has been built and  its final testing phase has started.

After the successful operation of the LRI on GRACE-FO in orbit, the development of the frequency reference unit is the next major C/D development activity for a laser-optical instrument at SpaceTech.

Key and driving requirements of the FRU are:

• 5 mW of optical output power at 1645 nm with a laser frequency accuracy and stability of  10 MHz
• 10 mW of optical output power at 1064 nm with less than 1 MHz linewidth
• Measurement of every single transmitted pulse with a systematic error of less than 8 MHz
• Controlling the cavity of the optical parametric oscillator in the main laser

Links:
DLR Site in MERLIN (http://www.dlr.de/rd/desktopdefault.aspx/tabid-2440/3586_read-31672/)
Animated in orbit maneuvers of the MERLIN satellite: https://www.youtube.com/watch?v=tmlSAB-ltek
Scientific publication: http://www.mdpi.com/2072-4292/9/10/1052

		MERLIN Satellite [CNES]
		Transparent model view of the FRU
		Picture of the engineering model of the FRU

Das diesem Bericht zugrundeliegende FE-Vorhaben wird im Auftrag des Bundesministeriums für Wirtschaft und Energie (BMWi) unter dem Förderkennzeichen 50EP1301 durchgeführt. Die Arbeiten sind Teil einer Kooperation zwischen DLR Raumfahrt-Management und CNES beim deutsch-französischen MERLIN-Satellitenprojekt. STI führt die Arbeiten im Unterauftrag der Firma Airbus DS GmbH, Ottobrunn durch. Die Verantwortung für den Inhalt dieser Veröffentlichung liegt beim Autor.

[15.08.2018]

Today, starting 18:00 CEST/German time, the ICARUS antenna will be installed outside the service Module Zvezda by the russian Cosmonauts Oleg Artemyev and Sergey Prokopyev. The Extra-Vehicular Activity wll be coverd live by NASA TV under:

https://www.nasa.gov/multimedia/nasatv/index.html#public (starting 17:00 CEST/German time)

With 5-7 hours, this is one of the longest EVAs ever performed by russia. After the final system level tests, the payload is planned to be fully operational at the beginning of Autumn.

ICARUS payload is designed to receive science information from miniaturized devices attached to animals, known as tags, and send reconfiguration commands if needed. The hardware on the ISS is designed to communicate with more than 100 tags simultaneously, providing the capability of daily communication with thousands of devices around the Globe.

SpaceTech GmbH has developed, manufactured and tested the ICARUS payload over the last 4 years as leader of a team of German SMEs. The project was commissioned by the Max Planck Institute for Ornithology and is funded by the German Space Agency DLR in cooperation with Roscosmos.

[04.07.2018]

We are proud to announce that with the activation of the Laser ranging interferometer (LRI) on GRACE Follow-On on June 13th 2018, the first optical instrument flight hardware of SpaceTech is fully operational in orbit! This is a major milestone for our activities in the field of laser-optical intrumentation and proof of STIs capabilities to provide top notch optical instrument equipment.

The LRI measures the changes of the inter-satellite distance of the two GRACE FO satellites flying in approx. 220 km distance to each with unprecedented accuracy down to several ten nanometers (about 1/1000th of the thickness of a human hair).

Under contract to the Geoforschungszentrum Potsdam (GFZ) (and under the scientific lead of Albert Einstein Institute Hannover - AEI) SpaceTech signed responsible for the development of the optical bench, the retroflector, and the instrument baffles of the LRI, starting from prototypes to EM, QM and FMs for both satellites. On the German side, the photoreceivers of the optical bench were provided by DLR Institute for optical systems in Berlin, while STI subcontracted Airbus DS and Hensoldt Optronics for the steering mirror on the optical bench and the manufacturing and assembly of the Zerodur parts of the retroreflector . On the US side we had a close cooperation with JPL who where responsible for the mission and provided the US part of the LRI (the laser, the cavity & the phasemeter).

The optical bench (shown above), consisting of an titanium optical bench with integrated and attached high performance laser optics, receives the laser signal via an optical fiber interface, launches the beam out of the fiber into free space, shapes it and directs it to µrad accuracy to the second spacecraft by means of a fine steering mirror. In addition it receives the laser signal from the second spacecraft and superimposes it with the local signal onto quadrant photoreceivers to aqcuire the DWS and heterodynes signal for the ranging measurement.  Main challenges in the development were the high wavefront planarity requirement of lambda/12 (pv), the beam alignment error of less than 10 µrad and the ranging noise contribution of less than 5 nm/sqrt(Hz). To achieve this a low thermal noise, low mechanical stress, highly stable optical bench design was developed, including a newly designed ultra-stable monolithic beam collimator, which is now available for further applications.

The retroreflector (shown above) , consisting of an ultra-stable carbon-fiber structure with attached zerodur optics, routes the laser beam around the center of mass of the respective spacecraft, essential to achieve Nanometer accuracy to the ranging measurement. Main challenges of this development were the limited available space in the satellite in conjuction with the demanding mirror alignment error of less than 40 µrad, less than 400 nm/K vertex stability and less than lambda/15 wavefront planarity(pv). 

A first evaluation of the measurement of the laser ranging interferometer is shown in the picture below

graphic: B. Knispel/G.Heinzel/Max Planck Institute for Gravitational Physics; GRACE FO data: NASA, GFZ, JPL; map data: SRTM

In addition the the contribution to the LRI equipment, STI has been  responsible for:

• the LRI instrument integration @ STI facitlities in cooperation with JPL, DLR Bremen, Airbus DS and AEI
• the spacecraft primary structures (structural analysis and procurement)
• the ASTSS tertiary structure (manufactured by CST)
• the deployable S-Band boom
• the Coarse Earth-Sun-Sensors (CESS)
• the satellite MGSE & transport containers

We did this in contract to the Geoforschungszentrum Potsdam (GFZ) for the LRI  (and under the scientific lead of Albert Einstein Institute Hannover - AEI) and in subcontract to Airbus DS for the other contributions and in close cooperation with our collegues at JPL, the DLR Institutes in Bremen and Berlin Adlershof as well as Hensoldt Optronics.

STI is proud to be part of this mission and thankful for the great cooperation of all project partners!

Much more information on GRACE Follow-On can be found here:

• https://gracefo.jpl.nasa.gov
• http://www.aei.mpg.de/2277280/first-light-for-grace-follow-on-laser-interferometer
• https://www.gfz-potsdam.de/sektion/globales-geomonitoring-und-schwerefeld/projekte/gravity-recovery-and-climate-experiment-follow-on-grace-fo-mission/