ASIM: Climate and giant lightning discharges to be studied from the International Space Station

Mounted on the ISS external facilities on the Columbus module, the Atmosphere-Space Interactions Monitor (ASIM) will study giant electrical discharges (lightning) in the high-altitude atmosphere above thunderstorms.

DTU Space provides the scientific management on this project and delivers a package of instruments (2 cameras, 3 photometers and one X- and gamma-ray detector) which is to be placed on the International Space Station.

ASIM is a number of specially designed cameras for the International Space Station that will observe the Earth's atmosphere. ASIM will give new insights into climate processes that can help improve climate models.


Introduction

Research

Technology

Mission 

Partners



Introduction

The Atmosphere-Space Interactions Monitor (ASIM) will study the Earth's atmosphere as one system, from the surface of the Earth to the edge of space. The atmosphere is the thin layer that covers the planet and protects life on our journey through space.

ASIM will observe extreme thunderstorms, water vapor, clouds, aerosols and their interplay in the atmosphere.

The mission is realized through the European Space Agency (ESA). The National Space Institute - Danish Technical University provides the scientific leadership, and the Danish company Terma the technical leadership. Other major partners include the University of Valencia in Spain and the University of Bergen in Norway, who are involved in the development of the instruments.

DTU Space provides the scientific management on this project and delivers a package of instruments (2 cameras, 3 photometers and one X- and gamma-ray detector) which is to be placed on the International Space Station,

ASIM is a number of specially designed cameras for the International Space Station that will observe the Earth's atmosphere. ASIM will give new insights into climate processes that can help improve climate models.


Research

ASIM research has three themes: Climate processes, the interplay of the atmosphere with the Earth's surface and changes to the atmosphere from space processes.

Click to read more about each theme:

Climate processes 

  • Thunderstorms
  • Electrical discharges in the stratosphere and mesosphere
  • X- and gamma-radiation from thunderstorms
  • Water vapor transport
  • Cloud nucleation
  • Gravity waves
  • Noctilucent clouds
  • The dynamics of the upper atmosphere

Earth's surface and the atmosphere 
  • Hurricanes
  • Dust storms
  • Volcanoes
  • Forest fires

Interactions of space processes with the atmosphere  
  • Comets and meteors
  • NO from solar radiation
  • Thunderstorm interactions with the ionosphere and magnetosphere
  • Aurora

Measurements from other satellites and instrumentation on the ground and on aircraft or balloons will also be used. 

 

Technology

 

The International Space Station

The International Space Station (ISS) orbits the earth at an altitude of about 400 km. It continues to be expanded with additional modules and facilities, the latest being the Columbus module delivered by the European Space Agency (ESA), to be launched in January 2008. Denmark has delivered hardware and software to the ISS and has conducted physiological tests on astronauts to understand the functioning of the human blood pressure under weightless conditions.  Denmark has selected three candidates to ESA’s corps of astronauts, to which admission will be opened in 2009.

The ISS is in the lowest permanently available orbit. Altitude is maintained by the spaceships docking at the station. They give the ISS a boost with their engines, lifting the altitude. If this is not done, the ISS will loose altitude because of air drag and burn up within 2 years.

The orbital plane is 51.6 degrees relative to the equatorial plane. This allows for observations over the main thunderstorm regions of the earth. At the same time, the ISS reaches sufficiently high latitudes to study energetic particle precipitation and aurora powered by violent storms on the sun. 

Columbus

ASIM scientific instruments include 2 cameras, 3 photometers and one X- and gamma-ray detector. The 4 cameras with 4 companion photometers are directed forward towards the horizon (ram, limb). Two cameras, two photometers and the X- and gamma-ray detectors are directed downwards (nadir). The cameras and the photometers constitute the Modular Multispectral Imaging Array (MMIA). Each module includes two cameras and two photometers, such that there are 3 MMIA modules in all, two pointing forward and one downward. The MMIA instruments observe in different optical spectral bands. The two MMIA modules which are directed forward towards the horizon observe thunderstorms from the side, where it is possible directly to identify the effects on the atmosphere as a function of altitude.

The X- and gamma-ray detector is called the Modular X- and Gamma-Ray Sensor (MXGS). X- and gamma-rays are strongly absorbed in the atmosphere. This is why the detector points directly downwards, such that a minimum of atmosphere is between the detector and the thunderstorms within its field of view.  Most of the atmosphere is below the altitude where giant lightning and terrestrial gamma-ray flashes are generated. Therefore, space is particularly well suited to observe these phenomena in the band reaching from gamma-rays to UV, which is difficult to observe from the ground. ASIM is measuring in these bands (colors).

The Optical Cameras

Field-og-view

Forward: 20x20 degrees; Downward: 56 degrees

Pixels 1024x1024
Spatial resolution Forward: 300-600 m; Downward: 300-400 m
Bits/pixel 12
Time resolution 80 ms
Spectral bands

Forward: 337nm; 391.4nm; 650-800nm;762nm

Downward: 337nm; 650-777nm

The cameras are light sensitive without the use of intensifiers. This is made possible by a new CCD, with on-chip amplification. Thismeans that the CCD will not be damaged if the cameras view the sun or the moon by mistake. Because the cameras are light sensitive, they can only observe during the night or at sunrise and sunset seen from the space station.  

 

The Optical Photometers

Photometers are used to measure rapid time variations, which cannot be done by imaging cameras. They view the exact same region but measure only the total photon flux from the region - but with high time resolution. 

Field-of-view

Forward: 20x20 degrees; Downward: 80x80 degrees

Time resolution 10 microseconds
Spectral bands

Downward: 180-300nm, 337nm, 777nm

 

The X- and gamma-ray detector

The detector plane is made of semiconductor crystals that are sensitive to photons hitting the crystals. The detector measures each photon and determines its energy and time of arrival. This detector principle is relatively new and allows for a simpler design than used in the past.

Energy range

7-500 keV

Energy resolution <10%
Detector area.

1032 cm2


The Mission

The Launch

ASIM is expected to be launched to the International Space Station (ISS) in 2015, from where it will observe the atmosphere for 2 years. ASIM will be carried by the HTV (Heavy Transfer Vehicle), which is a cargo vessel able to carry up to 6 tons of supplies for the space station. The HTV is launched by a rocket, but has its own propulsion system allowing it to maneuver to the space station.

Operations

When ASIM is mounted on the external pallets of Columbus, the instruments will be turned on by commands sent from the control center outside Odense, Denmark. The first operational period is used to check if the instruments have survived the violent vibrations experienced during launch. This phase is called the 'commissioning phase'.

If the instruments work properly, the real scientific observational phase can begin. The X- and Gamma-ray sensor is on continuously, except during passage of the South Atlantic Anomaly (SAA), where  the earth's magnetic field is weak, allowing considerable fluxes of energetic particles to reach the space station. The optical instruments are on during the night time and sunrise/sunset seen from the space station. The instruments capture automatically flashes of activity. Certain observations, such as those taken over the Mediterranean region, are executed as time-tagged commands sent in advance to ASIM.

Partners

The Technical Consortium

Design and development of the ASIM payload is done by an international consortium:

Terma – Space, Herlev, Denmark

  • Project management 
  • Lead on development of the optical cameras (MMIA) 
  • Software

Damec, Odense, Denmark 

  • ASIM main computer
  • Mechanical structure for instruments 
  • Ground communication center (in Odense)

National Space Institute -DTU, Copenhagen, Denmark

  • Lead on development of the X- and gamma-ray sensor (MXGS)
  • Lead on payload mechanical design
  • Computer and software for the optical instruments (MMIA)

COM – DTU, Lyngby, Denmark

  • Image compression

FORCE, Technology, Brøndby, Denmark

  • Calibration of  MXGS

Universidad de Valencia, Valencia, Spanien

  • MXGS mechanical structure
  • MXGS computer

Universitetet i Bergen, Norge

  • MXGS detector plane

The Scientific Team 

The ASIM project is advised by an 'ASIM Facility Science Team' who include:

  • Torsten Neubert, National Space Institute - DTU (chairman)
  • Victor Reglero, Universidad de Valencia, Spain
  • Nikolai Østgaard, Universitetet i Bergen, Norway
  • Elisabeth Blanc, Commisariat à l’Énergie Atomique, France

Further consultations involve the 'ASIM International Science Team'. To date, the science team includes 80 research groups from 29 countries. In Denmark the following are members:

  • National Space Institute - Danish Technical University
  • Danish Meteorological Institute
  • Niels Bohr Institute, University of Copenhagen
  • Aalborg University

Contact

Torsten Neubert
DTU Space
+45 45 25 97 31

Contact

Olivier Arnaud Chanrion
DTU Space
+45 45 25 97 81