Hubble Servicing Mission 4 Blog

Q & A with ESA HST Drive Electronics Expert

by colleen on May.19, 2009, under SM4

ESA HST team member Udo Rapp at Kennedy Space Center

ESA HST team member Udo Rapp at Kennedy Space Center

Name: Udo Rapp

Title: Engineering Support for the Solar Array Drive Electronics (SADE).

What is your area of expertise?

My expertise is the Solar Array Drive Electronics (SADE) that controls all rotations of the solar arrays.

What made you choose this field?

I have been leading projects designing drive electronics for all kind of mechanisms on satellites for many years. I feel this is a quite interesting job as you are always working on projects where you can directly see the effects and the operation of the electronics; if the mechanism performs its tasks and movements as intended and with the required accuracy, you did a good job!

What are the challenges for the Drive Electronics for the Solar Arrays?

Well, the SADE (Solar Array Drive Electronics) for the Hubble Space Telescope has to perform suitably to specific requirements. It receives rotation commands from the spacecraft whenever a re-positioning of the solar arrays to point to the Sun is requested. The major requirement is then to calculate an extremely smooth velocity profile (plan for movement) and to control the solar arrays’ rotation accurately according to this profile. It has to be noted that the SADE was designed and built around the year 1980, where much effort had to be spent to build up all of the functions without the benefit of advanced processors and software that we know today.

How have the solar arrays and the drive mechanisms and electronics performed? We are closely watching all solar array positions and telemetry during the mission to ensure that no excessive slippage occurs which potentially might disturb the astronauts during their EVA work. From time to time the solar arrays have to be re-positioned, for example, to point the solar arrays to the Sun for battery charging or to provide the astronauts access to other locations on the telescope. All of this is operating perfectly.

How do you feel about supporting what many call the most powerful astronomical tool of our time?

It feels very special looking at the history of this project as it is very unique - the only space telescope that can be serviced by astronauts. It was launched in 1990 and has been operating well since that time. It’s been serviced and maintained several times in-orbit and it continues to deliver great pictures and science data from our distant past. Hubble is very special and unique for me.

Do you have a favourite HST image?

Not really. They all present colourful, sometimes very surprising views of the Universe, so it is hard for me to choose one favourite from so many great images.

Have you worked all of the servicing missions?

No. I started working on this project shortly after its launch in 1990 and I was involved in all serving mission preparations since then. However, this is the first time that I have had the opportunity to support a servicing mission at the operation control centre in GSFC (Goddard Space Flight Center) directly.

What has been the most exciting part of SM4 for you so far?

For me, the first egress of the astronauts during their first EVA (spacewalk) day was very exciting! To see them beginning their work and knowing that they were going to start all the work that’s been planned for months and years in painstaking detail felt very special.

What has been the most stressful part of SM4 for you so far?

We are crossing fingers. As I said before, everything is operating very well and there has been no stressful part at all. However, as we are working on 12-hours shifts throughout the mission, it still turns out to be a strenuous job.

What is next for you?

Continuing to monitor all solar array telemetry during Sm4 and, after the mission, I am responsible for several drive electronics projects in our company which will keep me busy for the next several months.

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That’s a lot of icing!

by colleen on May.19, 2009, under SM4

Hubble team members got to taste their success, courtesy of a beautifully decorated SM4 cake!

The HST SM4 logo

The HST SM4 logo served as inspiration for the celebratory cake.

Hubble team members celebrated the success of SM4 with a cake that was out of this world.

Hubble team members celebrated the success of SM4 with a cake that was out of this world.

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Celebration!

by colleen on May.19, 2009, under SM4

ESA HST Project Manager for the Science and Robotic Exploration Directorate Michael Eiden shares a handshake with Goddard Mission Operations Manager (MOM) Keith Walyus.

ESA HST Project Manager for the Science and Robotic Exploration Directorate Michael Eiden shares a handshake with Goddard Mission Operations Manager (MOM) Keith Walyus.

After Hubble was safely released from Atlantis, the team at Goddard Space Flight Center finally got the chance to take a well-deserved break and celebrate this historic mission. Goddard’s Mission Operations Manager (MOM) Keith Walyus thanked the ESA HST team for their hard work and support during SM4. In turn, ESA HST Project Manager for the Science and Robotic Exploration Directorate Michael Eiden shared warm congratulations on behalf of his team and the entire ESA organization.

The ESA HST team with Mission Operations Manager (MOM) Keith Walyus

The ESA HST team with Mission Operations Manager (MOM) Keith Walyus

Mission Operations Manager Keith Walyus toasts the Hubble team.

Mission Operations Manager Keith Walyus toasts the Hubble team.

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Pics from STOCC

by colleen on May.19, 2009, under SM4

The Space Telescope Operations Control Center (STOCC) at Goddard Space Flight Center just moments before HST release.

The Space Telescope Operations Control Center (STOCC) at Goddard Space Flight Center just moments before HST release.

Engineers in the Space Telescope Operations Center (STOCC) count down to Hubble's release.

Engineers in the Space Telescope Operations Center (STOCC) count down to Hubble's release.

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Shuttle released!

by colleen on May.19, 2009, under SM4

Hubble was released at 14:57 CEST (8:57 am EDT).  Atlantis commander Scott Altman and pilot Gregory C. Johnson are now manoeuvring the Shuttle away from the telescope.

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Shuttle crew preparing to release Hubble

by colleen on May.19, 2009, under SM4

After five incredibly successful spacewalks, the STS-125 crew is preparing to release Hubble. NASA’s associate administrator of the Science Missions Directorate Ed Weiler described this final mission to Hubble as “bittersweet” and, no doubt, the astronauts are feeling privileged to be the last humans to interact with the iconic instrument.

Later today, in preparation for their return to Earth, astronauts will checkout Atlantis’ thermal protection system.

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Q & A with Manfred Schmid - Mechanisms Expert

by colleen on May.19, 2009, under SM4

ESA HST team member Manfred Schmid is a mechanisms expert.

ESA HST team member Manfred Schmid is a mechanisms expert.

Name: Manfred Schmid

Title: Mechanisms Expert for ESA HST team

What is your area of expertise?

My experience in space systems started more than 30 years ago with the development of lightweight structures on the German Spacelab (flown on the Shuttle) and turned then over to the development of mechanical subsystems. Over the years I have been responsible for the conceptual design, development, system engineering or project management of many different space mechanisms flown on satellites or on the Shuttle. Typical examples for my field of experience are related to: scanning mechanisms, pointing mechanisms, solar array drives, hold-down and release mechanisms and large deployable antennas, among others.

Due to the movable components in every mechanism, such equipment is generally extremely mission-critical. Therefore in-depth knowledge and experience related to friction and wear, actuator design, bearing and gear design, and other factors is mandatory.

What made you choose this field?

I am not sure, but what I can say is that my grandfather owned a sawmill and when I was a child I watched the big frame saws working. Historical sawmills have a turbine, belt transmissions, a creek, a little lake to store the water and a lock to control the water flow. After studying all this during my first years and having trapped my first trout in the creek by hand, I developed a strong interest for engineering aspects and for nature and I recognized many analogies between these two fields.

This could have prompted me to join the merchant navy, to become a pilot or to study engineering. I chose the latter, probably because I wanted to be on the creative development side rather than to be on the application one.

How have the solar arrays and the drive mechanisms and electronics performed?

The equipment has performed perfectly over all the years. I am very satisfied that the Solar Array Drive Mechanism (SADM) which was designed more than 20 years ago in our mechanisms department (to which I am still assigned and which forms now part of Astrium GmbH) is working perfectly. This proves the soundness of the design concept which was developed and realised that time in close cooperation with ESA. Due to the continuity of our team over all the years (despite running through several company reorganization loops), we are today able to provide engineering support to missions such as SM4.

How do you feel about supporting what many call the most powerful astronomical tool of our time?

My working life has been closely aligned with the Shuttle’s life. We flew several scientific payloads on the Shuttle in the 1980s and in the beginning of the 1990s until the International Space Station was prioritized; but to have the chance to support a free-flying telescope such as Hubble for so long now has a different quality.

Do you have a favourite HST image?

There are two of them: One is a picture of the Hubble Spacecraft together with the earth in the background, taken from the Shuttle.

The other is a picture taken by Hubble and shows the Planet Uranus with its moon Ariel and the Ariel shadow on Uranus as well.

Have you worked all of the servicing missions?

No, my former (now retired) colleague Raimund Hostenkamp who was the Project and Engineering Manager during the Solar Array Drive Mechanism (SADM) and Solar Array Drive Electronics (SADE) development phases staffed the previous servicing missions. I was heavily involved in the project prior to SM 3 when the new solar array drives were built and tested.

What has been the most exciting part of SM4 for you so far?

A Shuttle launch is always very exciting since it is a manned mission. If such a mission is going to maintain and improve the hardware of an extremely important and complex system like Hubble, it gets even more exciting.

What has been the most stressful part of SM4 for you so far?

There is no real stress, but a constant tension that something could go wrong during the mission. Questions related to the solar array which have to be analyzed and resolved can come up at any time and the EVA (spacewalk) activities add additional tension as we have seen with the stubborn bolt during the STIS repair which did not want to come out - things like this can spoil a whole mission.

What is next for you?

I am responsible for several different projects in Europe and they are all in the critical test phase, therefore I am not sure whether I will have much time to relax from the night shift during this SM4 mission. What helps me a lot to manage the upcoming tasks is the support I get from my wife and the extremely good working atmosphere and cooperativeness I experience from all my colleagues.

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Final spacewalk completed

by colleen on May.18, 2009, under SM4

In seven hours, 2 minutes, astronauts John Grunsfeld and Drew Feustel completed all tasks for the fifth and final spacewalk of SM4. They installed batteries, removed and replaced a Fine Guidance Sensor (FGS) that helps point the telescope and they added three NOBL (New Outer Blanket Layers) for thermal protection.

Upon heading for Atlantis’ airlock, Grunsfeld wished Hubble a “good voyage.”

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ESA HST team SM4 mission status report: what happens during a “planning shift”

by colleen on May.18, 2009, under SM4

HST SM4 Status Report 4:

HST SM 4: Planning Shift - Flight Day 5, 6

A servicing mission calls for 24-hour support and the ESA Hubble team has been diligent since flight day 1. Splitting into two 12-hour shifts, the ESA team members work either on the “orbit shift” (03:00 - 15:30) or the “planning shift” (15:00 - 03:30). So whether they are morning people or a night people, it matters little since they get some of both during their shifts.

The ESA HST team during shift handover. Michael Eiden (far left) and Udo Rapp (far right) work the orbit shift, while Lothar Gerlach (second from left) and Manfred Schmid (second from right) work the planning shift.

The ESA HST team during shift handover. Michael Eiden (far left) and Udo Rapp (far right) work the orbit shift, while Lothar Gerlach (second from left) and Manfred Schmid (middle) work the planning shift.

During the planning shift, the astronauts are in their sleep period and functional verification testing is being carried out from ground on HST’s newly installed/repaired instruments and spacecraft subsystems. The point of the functional tests is to validate the correct performance of the HST hardware after repair. When anomalies have occurred during the orbit shift, their impact is being assessed and where necessary, a planning update for the next day’s orbit shift with corrective actions is being defined. Whenever ESA hardware is involved, the team provides engineering support for the re-planning.

Apart from the direct monitoring of the mission progress, potential upcoming issues are discussed online with our NASA interface colleagues in order to assure that no activities will be carried out during the mission that could jeopardize the ESA provided hardware or that might pose any risk to the hardware itself and subsequently to the mission.

During the planning shift on 15 May, the following activities were performed:

The HST ESA Planning Shift Team followed all activities linked to EVA-2 (spacewalk 2) operation, planning, handling and slewing of the solar array and monitored available Solar Array Drive and Electronics (SADE) housekeeping data. Between 20:00 and 23:00 GMT, two solar array slews (turns) were performed from 0 to 90 degrees and back to 0 degrees to charge the new set of batteries and to check their correct function.

A typical example for an activity checked closely during the planning shift was the investigation of a potential inadvertent solar array angular slippage during airlock depressurisation activities prior to EVA activities due to the associated airflow acting on the solar array. Flight rules require that during airlock depressurisation activities, the solar array is monitored by a camera to allow for quick intervention in case of excessive inadvertent solar array rotation.

Another typical planning investigation performed was based on a NASA request to monitor and document micrometeorite damages on the solar array wings. The solar arrays, being external to the spacecraft, are subjected to the severe environment of space, including: radiation, thermal cycling (as Hubble moves from Sun exposure to Earth shadow) and other space hazards such as debris and micrometeorites. Solar array slewing outside its typical operational range had been suggested for adequate view by the on-board camera. Together with the NASA computer aided design (CAD) team, a configuration was found which allows monitoring of the relevant wing impact area by two cameras and remaining within the mission typical solar array slew angle.

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Astronauts take a pic

by colleen on May.18, 2009, under SM4

Astronauts John Grunsfeld and Drew Feustel take a picture as they drift over Houston, Texas, home of the Johnson Space Center.

Astronauts John Grunsfeld and Drew Feustel take a picture as they drift over Houston, Texas, home of the Johnson Space Center.

While working on the removal and replacement of one of the Fine Guidance Sensors (FGS), astronauts John Grunsfeld and Drew Feustel take a moment to snap a photo.

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