OrbitalHub

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.

Credits: NASA

One of the crucial requirements for a man-rated launch system is a reliable Launch Abort System (LAS). LAS is basically a top-mounted rocket connected to a crew module and it is used to separate the crew module from the rest of the launch vehicle in case of emergency.

An emergency can be anything from an explosion of the launch vehicle on the launch pad to a failed separation of the lower stage during flight.

In the case of the Orion Module, several designs were considered for the LAS: the Multiple External Service Module Abort Motor concept, the Crew Module Strap On Motors concept, and the In-Line Tandem Tractor (Tower) concept. The latter concept was incorporated in the Ares I/Orion design.

The Tandem Tractor (Tower) design of the LAS has three motors: an Attitude Control Motor (eight nozzles), a Jettison Motor (four aft nozzles), and the Abort Motor (four exposed flow nozzles). These motors will make possible the separation of the module and the control of the flight after the separation from the launch vehicle. An important component of the LAS is the Boost Protective Cover (BPC), which protects the crew module from the exhaust of the motors.

Credits: NASA

The LAS is designed to perform on the launch pad as well as during the first 300,000 feet after the launch. There are three possible scenarios for the abort procedure: on the launch pad, on the mid-altitude flight segment (up to an altitude of 150,000 feet), and on the high-altitude flight segment (from 150,000 feet to 300,000 feet, where the LAS is jettisoned on a nominal flight). Tests will have to be performed to cover these scenarios: on the launch pad as well in flight.

NASA has made available animations of the test flights planned for the LAS. One is the animation of the Orion Module LAS pad abort flight test. The second presents the Orion Module LAS ascent abort flight test.

Credits: NASA

Currently, the Launch Abort System of the Orion Module is under development.

The first full-scale test fire of the motor that powers the LAS was completed on November 20, 2008. This was the first time a LAS test has been conducted since the 1960s, when the LAS for the Apollo Program was tested.

Credits: JAXA

If measures are not taken to address the effects of the greenhouse gases produced by our civilization, extreme climate changes will occur: droughts, heat waves, and floods.

Understanding the behavior of greenhouse gases is critical for developing effective measures to fight climate change.

The Greenhouse Gases Observing Satellite (GOSAT) is the first satellite to observe greenhouse gases from space. The main contributors behind GOSAT are the Japan Aerospace Exploration Agency (JAXA), the National Institute for Environmental Studies (NIES), and the Ministry of Environment (MOE). The chosen nickname for GOSAT is IBUKI, which means breath or puff.

The data collected by the GOSAT satellite will help us make better estimates as to how different areas on Earth contribute to global warming through the emission of greenhouse gases. The data will also help us understand the behavior of the greenhouse gases by combining global observation data collected on orbit with data collected on the ground, and it will also help us improve simulation models.

Credits: JAXA

The observation instrument onboard GOSAT is called the Thermal And Near-infrared Sensor for carbon Observation (TANSO).

There are two sensors that collect data for the instrument: a Fourier Transform Spectrometer (FTS) and a Cloud Aerosol Imager (CAI).

The sensors will observe the infrared light from the Earth’s surface and will return measurements that can be used to calculate the abundance of carbon dioxide (CO₂) and methane (CH₄).

The operational orbit will allow GOSAT to circle the Earth in roughly 100 minutes and to return above the same Earth coordinates every three days. One thing to mention here is that the observations can be done only on cloud-free areas, meaning that on average only ten percent of the total number of measurements can be used for calculating the abundance of CO₂ and CH₄. However, the number of measurement points surpasses the current number of ground measuring points (under 200) and areas that have never been monitored will be covered by GOSAT observations.

Credits: JAXA / MHI

A Mitsubishi H-IIA launch vehicle will inject GOSAT into its predetermined orbit: a sun-synchronous sub-recurrent orbit at a perigee altitude of 667 km, apogee altitude of 683 km, and an inclination of 98 degrees. It will be the fifteenth flight of an H-IIA. The model used for this launch, H2A202, has two solid rocket boosters.

Besides GOSAT, which is the main payload, the payload includes several piggyback payloads. In the case of an excessive launch capability, it is common practice to include in the payload small satellites that are made by private companies or universities.

Seven micro-satellites, six selected through public tender and one JAXA satellite, will be launched by the H-IIA launch vehicle with Ibuki: KAGAYAKI / SORUN CORPORATION (debris detection and Aurora electric current observation mission), STARS / Kagawa University (tether space robot demonstration), KKS-1 / Tokyo Metropolitan College of Industrial Technology (demonstration of the micro cluster and three axis attitude control functions), PRISM / The University of Tokyo (earth image acquisition by using an expandable refracting telescope), SOHLA-1 / ASTRO TECHNOLOGY SOHLA (measurements of thunder and lightning), SPRITE-SAT / Tohoku University (observations of the sprite phenomenon and gamma radiation of the Earth’s origin), and Small Demonstration Satellite-1 (SDS-1) / JAXA (on-orbit verification of the space wire demonstration).

For more details on the additional payload for the GOSAT/Ibuki mission, you can check out the piggyback payload web page on the JAXA web site. Some of the links on the page require knowledge of Japanese or hands-on experience with the Google translation tool.

The launch date for GOSAT/Ibuki has been set. The H-IIA Launch Vehicle No.15 will liftoff sometime between 12:54 and 1:16 PM on January 21, 2009.

Check out the GOSAT / IBUKI program page on the JAXA web site for more information.

Credits: ESA

The European presence in space has become more prominent over the years. The development of the Columbus Laboratory and the introduction of the Automated Transport Vehicle (ATV) are two major milestones that have opened a new era for Europe’s presence in space.

Europe now aspires to consolidate its independence with the Large Cargo Return (LCR) and the Crew Transport Vehicle (CTV).

The LCR and the CTV are the new versions of the ATV that are now being considered by ESA’s Human Spaceflight Directorate. These versions of the ATV reuse the service module of the ATV configuration. A capsule with re-entry capability will replace the integrated cargo carrier. In the first phase, the capsule will bring cargo from the ISS down to Earth. The ultimate goal is to be able to carry a full crew up to the ISS and bring the crew back to Earth.

Credits: ESA

Atmospheric re-entry is not a new challenge for ESA engineers.

Past programs – like the Atmospheric Re-entry Demonstrator – and future programs – like the Intermediate Experimental Vehicle (IXV) – will help validate models used for the simulation of the re-entry phase and also provide a solid base in designing materials for the thermal protection system.

However, one challenge that needs to be addressed is the ejection system for the CTV/Ariane V configuration. The safety of the crew has to be ensured in the case of an anomaly on the launch pad or during the ascent phase of the flight. ESA will have to develop new technologies to satisfy this crucial requirement.

Credits: ESA

ESA has already proposed the LCR and the CTV versions of the ATV as the next step in the evolution of the ATV. However, the decision to go forward lies with the Council of the European Space Ministers. If ESA proposals are approved, the first flight of the LCR is expected in 2015, and the CTV could be docking to the ISS by 2020.

Check out ESA’s podcast about the new proposed programs that are based on the ATV.

Credits: NASA

The Multi-Purpose Logistics Module (MPLM) is a pressurized module that is used on Space Shuttle missions to transfer cargo to and from the International Space Station (ISS).

A typical MPLM mission starts in the cargo bay of a Space Shuttle. The MPLM is carried to the ISS and berthed to one of the docking modules by the Canadian robotic arm. The supplies are offloaded and then finished experiments and waste are loaded on to the module. At the end of the mission, the MPLM is moved to the Space Shuttle cargo bay and returned to Earth.

The Italian Space Agency (ASI) provides the modules to NASA. Three MPLMs have been built and delivered to NASA thus far. NASA owns the MPLMs and ASI receives research time on ISS in exchange. The MPLMs were named after great figures in Italian history: Leonardo, Raffaello, and Donatello. However, some of the mission badges display the ninja turtles instead.

The construction of the first MPLM – Leonardo – began in April 1996. Leonardo was delivered to NASA in August 1998. Raffaello and Donatello followed in August 1999 and February 2001, respectively. Each MPLM can make 25 return trips to space.

Credits: NASA

The MPLM is 6.4 meters long and 4.6 meters in diameter. The module weighs 4.5 tons and it can deliver up to 10 tons to the ISS. The design of the module resembles the payload module that is part of the ATV. In addition, ATV has a service module that offers autonomy. Obviously, ATV was the direct beneficiary of the knowledge gained during the design and operational phases of the MPLM.

There is room for sixteen standard payload racks (International Standard Payload Racks – ISPR) in the MPLM. Even if it is not used to carry a human crew, MPLM has its own life-support system. Furthermore, it has a 3 KW internal power supply.

Credits: NASA

The current Space Shuttle mission – STS 126 – has delivered the MPLM Leonardo to the ISS. Leonardo is on its fifth spaceflight and hauled over 14,000 pounds of supplies and equipment to ISS.

Part (a small part) of the payload was turkey, candied yams, stuffing, and dessert for a Thanksgiving meal at the station.

A special piece of equipment, the GLACIER, was also delivered to the station. GLACIER stands for General Laboratory Active Cryogenic ISS Experiment Refrigerator. GLACIER is a double locker cryogenic freezer that will be used for transporting and preserving science experiments. The payload also included a galley for the Destiny laboratory, an advanced Resistive Exercise Device (aRED), and two new crew quarter racks for the expanded station crew.

Credits: NASA

There are two more MPLM missions scheduled before the Space Shuttle retires. STS-128 will carry Leonardo in July 2009, and Raffaello will be docked to ISS during the STS-131 mission in February 2010.