OrbitalHub

Credits: ESA/NASA

The Carnival of Space is up(side down under) on Astroblog.

Ian Musgrave presents interesting stories from around the blogosphere this week in four categories: Down To Earth, Mars, Other bits of unimportant dust and gas, and Beyond the Solar System.

OrbitalHub made it in the third category with Columbus.

Credits: ESA/NASA

Columbus is an integral part of the International Space Station (ISS), and it is the first European laboratory dedicated to long-term experimentation in zero-g conditions. The projected lifetime of the laboratory is ten years.

The laboratory is named after the famous Italian navigator and explorer Christoforo Columbus, who discovered the Americas in 1492.

The Columbus Laboratory is a large, pressurized aluminum cylinder measuring 4.5 meters in diameter and 6.9 meters in length. Its side walls contain eight research racks, with another two in the ceiling. Each one of these racks contains its own power and cooling systems. Video and data links systems feed information back to researchers and control centers on the Earth.

Columbus is the smallest ISS laboratory, but it has the same scientific, power, and data handling capacity as the other laboratories owned by Russia, USA, and Japan.

Credits: ESA/NASA

Scientific experiments started immediately on the Columbus because the laboratory arrived at the station with four scientific facilities pre-installed.

Columbus is used to carry out experiments in many different disciplines, including biology, biotechnology, fluid and material science, medicine, and human physiology.

The key element in these experiments is the micro gravity. In micro gravity, with gravitational forces much weaker than on the ground, processes that are obscured by gravity become noticeable. The research racks onboard Columbus are designed to investigate how micro gravity affects materials, biological specimens, and people.

Columbus contains the European Physiology Module Facility, the Fluid Science Laboratory, the BioLab, the Material Science Laboratory, and the European Drawer Rack, which can house a variety of small experiments.

Credits: ESA/NASA

Problems that are investigated on Columbus include the loss of bone cells by astronauts, plant growth in micro gravity, fluids behavior, and combustion of materials.

Experiments are also conducted outside of Columbus. These experiments are used to study the Earth or to expose materials to the harsh radiation, temperature, and the vacuum of space.

The mission that delivered the Columbus Laboratory to the ISS was STS-122. On February 7, 2008, the Space Shuttle Atlantis lifted off from Cape Canaveral, with Columbus docked into its cargo bay.

A vital part of the ISS and a prerequisite for the STS-122 mission, the Italian-built Node2 module (a.k.a. Harmony) was delivered to the ISS by the STS-120 mission in October 2007. The node is used as a connecting component for the Columbus Laboratory and the Kibo Laboratory. Node2 is also a docking port for the Space Shuttle.

Credits: ESA/NASA

Prior to the STS-122 mission , there were two spacewalks performed by the ISS Expedition 16 crew to prepare Node2 in order to receive the Columbus Laboratory.

ESA astronauts Léopold Eyharts from France and Hans Schlegel from Germany were members of the STS-122 mission. With five other NASA astronauts, they were part of the Columbus assembly and commissioning mission.

Schlegel spent twelve days in space and undertook two spacewalks to install the laboratory. Eyharts oversaw the installation and the start-up of the laboratory during a longer mission spent onboard the ISS.

Columbus was attached to the Harmony module on February 11, 2008, during the first spacewalk of the STS-122 mission. During this spacewalk, NASA astronauts Stanley Love and Rex Walheim spent nearly eight hours outside the ISS. The ISS robotic arm, Canadarm2, was used to move the laboratory from the cargo bay of the Space Shuttle to the starboard side of the Harmony module.

Credits: ESA/NASA

The second spacewalk of the mission lasted six hours and forty-five minutes. Schlegel and Walheim performed a regular station maintenance operation: they replaced the nitrogen tank that is used to pressurize the ammonia cooling system that runs on the ISS.

ESA was quite inspired to name the laboratory Columbus because it will open the world of micro gravity to a multitude of discoveries, in the same way that Christoforo Columbus opened up the New World to European explorers.

Credits: NASA

The propulsion division of SpaceX has performed another important test. After the test of the Falcon 9’s first stage Merlin engines, the smallest engine of the SpaceX family, Draco, has been put to test.

During the test, the thruster fired for ten minutes, paused for ten minutes, and then was restarted for an additional minute.

The test was performed on a new vacuum test stand built by SpaceX, and put into operation in March 2008 at the SpaceX Test Facility outside McGregor, Texas.

“Draco performed perfectly during the entire test, with expected temperatures and excellent performance,” said David Giger, Propulsion Manager, SpaceX. “We also broke the SpaceX record for longest continuous burn previously held by Kestrel, the Falcon 1 second stage engine.”

The Dragon spacecraft uses eighteen Draco thrusters for orbital maneuvering, attitude control, and to initiate the atmospheric re-entry. Each Draco thruster can deliver up to 400N of force. The thruster is powered by a combination of mono methyl hydrazine (MMH) and nitrogen tetroxide (NTO), which is the same bipropellant used by the orbital maneuvering system (OMS) of the Space Shuttle.

Credits: NASA

MMH and NTO are used as propellants because they have long on-orbit lifetimes. This will allow the Dragon spacecraft to perform longer missions to the International Space Station (ISS). The goal is to use the spacecraft as an emergency escape capsule for the crew working on the ISS.

SpaceX has released a video of the Draco thruster vacuum firing.

Credits: NASA

The Carnival of Space #82 is up on Space Disco. This edition is a videotastic edition of the carnival. Dave Mosher presents the wooden plank on Mars, the biggest star in the Universe, the Venus, Jupiter, and Moon conjunction, and many other stories.

OrbitalHub presents the James Webb Space Telescope in this edition of the Carnival of Space.

Credits: NASA

The James Webb Space Telescope (JWST) is the successor of the Hubble Space Telescope (HST). While Hubble looks at the sky in the visible and ultraviolet light, JWST will operate in the infrared.

JWST is a joint mission of NASA, ESA, and the Canadian Space Agency.

The project started in 1996 and was initially known as the Next Generation Space Telescope (NGST). In 2002, the project was renamed the James Webb Space Telescope in honor of NASA administrator James E. Webb, who led the agency from February 1961 to October 1968.

The JWST will use a large deployable sunshade to keep the temperature of the telescope to about 35K. Operating at this temperature gives the telescope exceptional performance in near-infrared and mid-infrared wavebands. The JWST observatory will have a five to ten year lifetime and it will not be serviceable by astronauts.

JWST will be able to see the first galaxies that formed in the early Universe, and how the young stars formed planetary systems.

Credits: NASA

The JWST observatory includes the Integrated Science Instrument Module (ISIM), the Optical Telescope Element (OTE), and the Spacecraft Element containing a spacecraft bus (which offers the support functions for the observatory) and the sunshield.

I will say a few words about each one of them.

The Optical Telescope Element (OTE) collects the light coming from space. Thanks to a 6.5 meter primary mirror, JWST will be able to see the galaxies from the beginning of the Universe. The OTE is also composed of the Fine Steering Mirror (FSM), the secondary mirror support structure (SMSS), and the primary mirror backplane assembly (PMBA). Other subsystems of the OTE are the tertiary mirror and the fine steering mirror. The PMBA contains the Integrated Instrument Module (IIM).

Because the primary mirror is too large to fit inside any available payload fairing, it had to be made out of eighteen hexagonal segments. Some of the elements will be folded before the launch and unfolded during the commissioning phase at the L2 point. NASA made available some neat animations showing how the observatory will be folded in order to fit into the launcher payload, and how the sun shields and the primary mirror will unfold before the observatory becomes operational.

Credits: NASA

The sunshield will keep the scientific payload of the observatory away from any light from the Sun, the Earth, or the Moon. Because JWST will observe primarily the infrared light from very distant objects, the temperature of the scientific payload must be maintained at very low values (under 50K). This requirement is so important that even a part of the observatory (the spacecraft bus) had to be placed on the warm side of the sunshield.

The sunshield not only protects the scientific instruments from the heat of the Sun, the Earth, the Moon, and the warm spacecraft bus electronics, but it also provides a stable thermal environment. This is necessary in order to maintain the alignment of the eighteen hexagonal components of the mirror while the observatory changes its orientation relative to the Sun.

The primary mirror is the essential component of a telescope. The design of the primary mirror was driven by a number of important requirements: the size, the mass, and the temperature at which the mirror will operate.

Credits: NASA

In order to be able to see galaxies from thirteen billion light-years away, scientists determined that the mirror must have a diameter of at least 6.5 meters.

The weight of the primary mirror has only one tenth of the mass of Hubble’s mirror per unit area. Considering the size of the mirror, this made the task of launching the telescope into space achievable.

Due to the fact that the telescope will observe the light in the infrared spectrum, the temperature of the mirror has to be as low as –220 degrees Celsius. If operating at the same temperature as the ground telescopes do, the infrared glow of the mirror would interfere with the light received from distant galaxies. Basically, these distant galaxies would disappear in the noise generated by the telescope.

The engineering challenge that scientists faced was to build a lightweight mirror that would preserve its optical and geometric properties when cooled to –220 degrees Celsius. Using beryllium was the solution. Beryllium is lightweight (it is widely used in the aerospace industry) and it is very good at holding its shape across a range of temperatures.

As we mentioned above, the PMBA contains the Integrated Instrument Module (IIM), which is the scientific payload onboard the observatory. The scientific payload includes the following scientific instruments: the Mid-Infrared Instrument (MIRI), the Near-Infrared Spectrograph (NIRSpec), the Near-Infrared Camera (NIRCam), and the Fine Guidance Sensor (FGS).

The MIRI is an imager/spectrograph that covers the wavelength range from 5 to 27 micrometers. The nominal operating temperature for the MIRI is 7K. The NIRSpec covers two wavelength ranges: from 1 to 5 micrometers (medium-resolution spectroscopy) and from 0.6 to 5 micrometers (lower-resolution spectroscopy). The NIRCam was provided by the University of Arizona. NIRCam covers the spectrum from 0.6 to 5 micrometers. The FGS is a broadband guide camera that is used for guide star acquisition and fine pointing.

Credits: ESA

The spacecraft bus is composed of every subsystem of the observatory minus the sunshield and the scientific payload, and it provides the necessary support functions for the operations of the observatory. The spacecraft bus contains the Electrical Power Subsystem (EPS), the Attitude Control Subsystem (ACS), the Communication Subsystem (CS), the Command and Data Handling Subsystem (C&DHS), the Propulsion Subsystem (PS), and the Thermal Control Subsystem (TCS).

One interesting thing I would like to mention here is that the C&DH subsystem is using a solid-state recorder as memory/data storage for the observatory. I cannot envision a hard disk drive taking all of the vibrations during the launch and running for ten years without any flaws, so the choice of using radiation hardened solid-state memory units on long-term space mission spacecrafts seems to be the optimal choice.

The launch vehicle chosen for this mission is the European Ariane 5. The Ariane 5, carrying the James Webb Space Telescope, will liftoff from Guiana sometime in 2013. The space telescope will operate from the L2 point of the Sun-Earth system.

All three agencies that are part of the project, ESA, NASA, and CSA, have web pages dedicated to the JWST observatory.

Credits: NASA

Last week we presented GOSAT a.k.a. Ibuki, a mission that has as its objective the mapping of carbon dioxide and methane in the Earth’s atmosphere. A similar mission is getting ready to launch on the other side of the Pacific: the Orbiting Carbon Observatory (OCO). OCO is a NASA Earth System Science Pathfinder (ESSP) Program mission.

The mission team includes the Orbital Sciences Corporation, the Jet Propulsion Laboratory, and Hamilton Sundstrand Sensor Systems.

The atmospheric carbon dioxide (CO₂) is an important greenhouse gas. CO₂ absorbs and traps infrared radiation emitted by the Earth’s surface, preventing it from escaping to space. OCO will provide global CO₂ measurements from space. The data collected during the mission will help scientists understand the global carbon cycle. This understanding is essential to improve the predictions of future atmospheric CO₂ increases and its impact on the climate.

The OCO has a mass of 407 kg. The two GaAs solar arrays will provide 324 W orbit average for the scientific payload onboard. The satellite will use hydrazine thrusters for stabilization while on orbit. The estimated life span for the mission is 24 months.

The scientific payload includes three spectrometers. The spectrometers can detect what gases are in the Earth’s atmosphere and determine their amounts. The measurements will translate into monthly estimates of atmospheric CO₂ over 621-square-mile regions of the Earth’s surface. From its sun-synchronous orbit, OCO will map the globe once every sixteen days. These maps will help locate CO₂ sources and sinks.

Credits: NASA / Orbital

OCO will be placed on orbit by a Taurus XL launch vehicle. Taurus XL is a solid fuel launch vehicle built by the Orbital Sciences Corporation. According to the Taurus fact sheet, it provides launch capability for satellites weighing up to 1,590 kg. The range of launch missions supported by Taurus include low inclination low Earth orbit (LEO), polar LEO, sun-synchronous LEO, geo-transfer orbit, and interplanetary trajectory.

Depending on the configuration, Taurus can have a mass from 69,000 to 77,000 kg and can have a length from 27 to 32 m.

The mission launch is scheduled for early 2009. The Taurus XL launch vehicle will lift off from Vandenberg Air Force Base, California.