Physical experiments in Earth-based laboratories are very often negatively influenced by gravity. Material physics studies, for example, various processes in metallic alloys on an atomic scale. The corresponding experiments require “weightlessness” for high quality results. MAPHEUS, a DLR research rocket program, provides this microgravity environment to DLR material physics payloads. On an annual basis, a MAPHEUS rocket is launched into space to approximately 150 km altitude. The payload then experiences 3.5 minutes of microgravity before it re-enters the Earth’s atmosphere.
MAPHEUS (Materialphysikalische Experimente unter Schwerelosigkeit) is carried out under the lead of the DLR Institute of Space Systems. The material physics experiments are selected, designed and built by the DLR Institute of Materials Physics in Space. The Mobile Rocket Base (MORABA) of DLR is, together with Esrange Space Center of SSC, responsible for launch operations and the provision of rocket systems, comprising a service-, rate control- and recovery system. The launches take place at Esranve Space Center in Kiruna, Sweden. Following the maiden flight of MAPHEUS-1 in May 2009, MAPHEUS-2 started successfully on 28 October 2010, and MAPHEUS-3 on 25 November 2012. MAPHEUS-4 is scheduled for May/June 2013.
With research rockets like MAPHEUS, space becomes a laboratory for physical phenomena that take place on an atomic scale. The investigated effects include atomic transport processes in liquid Al- and Ge-based alloys with the ultimate goal of determining diffusion coefficients (ATLAS-M experiment). The DEMIX-M experiment investigates the miscibility, miscibility gaps and demixing in Cu-based metallic alloys during controlled cooling. Finally, the behavior of magnetically-excited granular matter is studied with the MeGraMa-M experiment facility. MAPHEUS-3 further included a high temperature shear cell oven to be integrated into an X-ray radiography instrument on MAPHEUS-4. Experimental challenges on MAPHEUS include the high temperatures and therefore high power required for phase changes in metallic alloys.
Compared to other microgravity platforms such as the drop tower or parabolic flights, research rockets like MAPHEUS offer an attractive combination of long experiment times and high quality microgravity. The flights on a yearly basis and the ability to fly an experiment with different sample composition on more than one flight opportunity ensure a wealth of scientific results.
From its fourth flight onwards, MAPHEUS uses a single stage solid propellant rocket motor (S30) that launches the payload to more than 150 km. During the ascent, the vehicle is spin-stabilized, rotating around its own longitudinal axis. At an altitude of about 70 km, a so-called Yo-Yo system and a Rate-Control-System eliminate any, marking the start of the microgravity phase. After re-entry into the atmosphere, the scientific experiments land on a parachute.