Open Access

Jan Thimo Grundmann, Jens Biele, Bernd Dachwald, Christian D. Grimm, Caroline Lange, Stephan Ulamec, Christian Ziach, Tom Spröwitz, Michael Ruffer, Patric Seefeldt, Peter Spietz, Norbert Toth, Yuya Mimasu, Andreas Rittweger, Jean-Pierre Bibring, Andy Braukhane, Ralf Christian Boden, Etienne Dumont, Stephan Siegfried Jahnke, Michael Jetzschmann, Hans Krüger, Michael Lange, Antonio Martelo Gomez, Didier Massonett, Tatsuaki Okada, Marco Sagliano, Kaname Sasaki, Silvio Schröder, Martin Sippel, Thomas Skoczylas, Elisabet Wejmo

• Following the successful PHILAE landing with ESA's ROSETTA probe and the launch of the MINERVA rovers and the Mobile Asteroid Surface Scout, MASCOT, aboard the JAXA space probe, HAYABUSA2, to asteroid (162173) Ryugu, small landers have found increasing interest. Integrated at the instrument level in their mothership they support small solar system body studies. With efficient capabilities, resource-friendly design and inherent robustness they are an attractive exploration mission element. We discuss advantages and constraints of small sub-spacecraft, focusing on emerging areas of activity such as asteroid diversity studies, planetary defence, and asteroid mining, on the background of our projects PHILAE, MASCOT, MASCOT2, the JAXA-DLR Solar Power Sail Lander Design Study, and others. The GOSSAMER-1 solar sail deployment concept also involves independent separable sub-spacecraft operating synchronized to deploy the sail. Small spacecraft require big changes in the way we do things and occasionally a little more effort than would be anticipated based on a traditional large spacecraft approach. In a Constraints-Driven Engineering environment we apply Concurrent Design and Engineering (CD/CE), Concurrent Assembly, Integration and Verification (CAIV) and Model-Based Systems Engineering (MBSE). Near-term solar sails will likely be small spacecraft which we expect to harmonize well with nano-scale separable instrument payload packages.