HALO on the tarmac (Photo: ©DLR)
HALO ("High Altitude and Long Range Research Aircraft") was handed over to DLR in January 2009. Since then it has been the newest member of the DLR aircraft fleet and one of the most advanced research aircraft in the world.
HALO is based on a Gulfstream G550 business jet. Its combination of long range, maximum flight altitude (up to 15 km), payload and flexibility makes HALO to a worldwide unique research aircraft. With its operating range of more than 8000 km HALO is capable of performing missions on a global scale. Any region from the poles to the tropics and remote areas of the Pacific Ocean can be reached with HALO. Outside the tropics measurements can be performed in the transition region between stratosphere and troposphere.
The scientific payload of HALO is up to 3000 kg. Due to numerous modifications HALO is a real flying laboratory. There are more than 20 apertures in the fuselage for mounting of inlets. Openings with a diameter of about 50 cm are designed for optical windows. Hard points below the wings and the lower fuselage can carry scientific instruments outside the cabin, e.g. particle measuring probes.
In cooperation with partners from universities, the Helmholtz-Association, the Max-Planck-Society and the Leibniz Association, the Institute of Atmospheric Physics investigates important scientific questions.
In autumn 2010 HALO performed its maiden scientific flight during the so-called Techno-Mission. Since then, some 20 missions have been carried out with HALO. The long range of HALO allows missions in many regions of the world, whether over the Polar Regions, the Brazilian rainforest, over Africa or over the China Sea.
The scientific issues are as diverse as the deployment regions of the missions: Megacities as sources of pollutants, large-scale transport of trace species through the Asian monsoon, gravity waves at high northern and southern latitudes, the interaction of clouds, convection and climate, distribution of greenhouse gases, exchange processes at the tropopause, investigation of high ice clouds, to name but a few.
HALO during the ML-CIRRUS mission in spring 2014, equipped with air intakes and particle measurement systems under the probes (Photo: ©DLR).
The Institute of Atmospheric Physics is one of the most important scientific users of HALO. Here numerous instruments for the in-situ measurement of trace gas concentrations, aerosol and cloud properties have been developed for the operation on board of HALO. Remote sensing instruments like lidar can determine the concentrations of traces gases, water vapour and aerosol particles below and above the aircraft, respectively.
Colleagues from the institute were involved in most of the missions with measurements and planning. Several missions were and are also organized and coordinated from within the Institute. The Institute also maintains the database where the data of most HALO missions are archived.