The Young Engineers' Satellite 2 (YES2) is a 36 kg student-built
tether satellite that is part of
ESA's
Foton-M3
Foton (or Photon) is the project name of two series of Russian science satellite and reentry vehicle programs. Although uncrewed, the design was adapted from the crewed Vostok spacecraft capsule. The primary focus of the Foton project is materi ...
microgravity
The term micro-g environment (also μg, often referred to by the term microgravity) is more or less synonymous with the terms ''weightlessness'' and ''zero-g'', but emphasising that g-forces are never exactly zero—just very small (on the I ...
mission. The launch of the Russian Foton-M3 occurred on September 14, 2007, at 13:00 (CEST) by a
Soyuz-U launcher. The project was carried out by Delta-Utec SRC and supervised by the ESA Education Office and was nearly entirely designed and build by students and young engineers.
The YES2 deployment took place Sept. 25, 2007. The mission objective was to deploy a 30 km long and 0.5 mm thin tether (made of
Dyneema) in two controlled stages, in order to release a small, spherical, lightweight
reentry capsule
A reentry capsule is the portion of a space capsule which returns to Earth following a spaceflight. The shape is determined partly by aerodynamics; a capsule is aerodynamically stable falling blunt end first, which allows only the blunt end to re ...
called Fotino into a predetermined trajectory to a landing area in Kazakhstan. The scientific objectives of the mission have been achieved. The YES2 featured the first multi-stage tether deployment. It could be reconstructed within about 20 m accuracy for the first stage (3400 m) and 100–150 m for the 31.7 km deployment as a whole. The first stage was deployed accurately (about 10–20 m error), the second stage overdeployed by 1.7 km. Fotino released as planned during a swing of the tethered system through the vertical (as seen from Foton). The tether properties, deployment dynamics and tether deployer system performance could be evaluated. The tether deployer performed nominally. However, due to an electrical fault, the on-board computer failed to register the final length correctly and only a partial deployment was initially reported based on telemetry available in real-time. Initial deployment friction was found to exceed the nominal range, revealed by post-mission testing to be most likely due to a thermomechanical settling of the tether spool
[ES]
YES
page Some weeks after mission completion, analysis of the full data set confirmed that the tether deployed to its full length of 31.7 km. No signal was ever received from the "Fotino" re-entry capsule after separation, and it was lost.
YES2 established a new world record as the longest artificial structure in space and was later included in the Guinness Book of Records Edition 2009.
The YES2 project
Most of the work done in this ambitious project (like design, manufacturing and integration) was done by students and young engineers. In total some 450 students participated.
Soon after the beginning of the project, four "Centres of Expertise" were created. These were universities which were responsible for parts of the satellite or subsystems. The centres were:
Samara
Samara ( rus, Сама́ра, p=sɐˈmarə), known from 1935 to 1991 as Kuybyshev (; ), is the largest city and administrative centre of Samara Oblast. The city is located at the confluence of the Volga and the Samara (Volga), Samara rivers, with ...
State Aerospace University, Russia (mission analysis, GPS);
University of Modena
The University of Modena and Reggio Emilia ( it, Università degli Studi di Modena e Reggio Emilia), located in Modena and Reggio Emilia, Emilia-Romagna, Italy, is one of the oldest universities in Italy, founded in 1175, with a population of 2 ...
and Reggio Emilia, Italy (re-entry capsule);
Hochschule Niederrhein in
Krefeld, Germany (tether);
University of Patras, Greece (mechanical and thermal). Coordination and system engineering was carried out by prime contractor Delta-Utec SRC from the Netherlands.
Towards the end of the project, in the manufacturing and integration phase, the work concentrated on the Delta-Utec office in
Leiden and ESA's ESTEC in
Noordwijk, where the satellite was built and tested.
The test program included:
*
electromagnetic compatibility
Electromagnetic compatibility (EMC) is the ability of electrical equipment and systems to function acceptably in their electromagnetic environment, by limiting the unintentional generation, propagation and reception of electromagnetic energy whic ...
testing in the "Maxwell" EMC test chamber
* simulation of space environment in a
thermal vacuum chamber
*
vibration testing
Vibration is a mechanical phenomenon whereby oscillations occur about an equilibrium point. The word comes from Latin ''vibrationem'' ("shaking, brandishing"). The oscillations may be periodic function, periodic, such as the motion of a pendulum ...
on a shake table
*
functional tests of all components and sub-systems
The satellite was handed over to ESA at the beginning of May 2007 and was shipped to Samara (Russia) soon after, where YES2 was mated to Foton-M3 for the first time for test purposes. Afterwards YES2 and Foton were separated again and brought to Baikonur (Kazakhstan) by train where the whole satellite was completely integrated and mated with the launcher, a
Soyuz-U rocket. Foton-M3 and YES2 finally launched on 14 September 2007 at 13:00 (CEST) from the Gagarin launch pad at
Baikonur Cosmodrome
The Baikonur Cosmodrome ( kk, Байқоңыр ғарыш айлағы, translit=Baiqoñyr ğaryş ailağy, ; russian: Космодром Байконур, translit=Kosmodrom Baykonur, ) is a spaceport in an area of southern Kazakhstan leased to R ...
.
The main contribution of the project has been the demonstration of a complex controlled deployment in two stages. Post-flight, several independent sources of deployment data were collected, including deployment length and rate measurements from YES2 itself as well as highly precise triaxial
accelerometer data from a separate experiment on the Foton carrier spacecraft. These data confirmed that the deployment did progress mostly successfully, in particular the critical first stage and stage transition and the tether deployer performed nominally. The data that has been recovered has helped to understand the deployer performance and tether dynamics in yet unseen detail, including explicit signatures of sound waves, transverse waves and spring-mass motion. The small
reentry capsule
A reentry capsule is the portion of a space capsule which returns to Earth following a spaceflight. The shape is determined partly by aerodynamics; a capsule is aerodynamically stable falling blunt end first, which allows only the blunt end to re ...
Fotino, intended to demonstrate the SpaceMail concept, was not successfully recovered. Calculations based on YES2 sensor data indicate that the landing site should be in or near the
Aral Sea
The Aral Sea ( ; kk, Арал теңізі, Aral teñızı; uz, Орол денгизи, Orol dengizi; kaa, Арал теңизи, Aral teńizi; russian: Аральское море, Aral'skoye more) was an endorheic basin, endorheic lake lyi ...
. Alternatively, the capsule, experimental in itself, may have burnt up or crashlanded.
Design of the satellite
There are three main components of the experiment:
*FLOYD – the YES2 deployment mechanism located on the Foton spacecraft;
*MASS – the Mechanical data Acquisition and Support System;
*FOTINO – a small spherical capsule, with a diameter of 40 cm and a mass of 6 kg.
YES2 mission design
During the flight, the FLOYD mechanism ejected the other two components. There was then to be a controlled deployment of a 30 km long tether. Orbital dynamics caused the Fotino capsule to be positioned in front of the mother spacecraft. By bringing the deployment to a halt, a pendulum-like swing was induced. When the capsule and tether swung through the local vertical, the tether was cut. Since the capsule was then going too slowly to stay in orbit, it has entered a trajectory to re-enter the atmosphere from an altitude of about 250 km, protected by a heat shield made of novel materials. Once it reached an altitude of 5 km, a parachute was intended to deploy to ensure a soft landing on the steppes of Kazakhstan.
Since data from the Fotino was not downlinked and the Fotino capsule itself was not recovered, it is not known how well the capsule has survived the entry.
See also
*
Space tether
Space tethers are long cables which can be used for propulsion, momentum exchange, stabilization and attitude control, or maintaining the relative positions of the components of a large dispersed satellite/spacecraft sensor system. Depending on t ...
References
External links
HomepageESA project homepageYES2 Tether and Re-entry Capsule Fotino Mission AnimationTethers in Space: A propellantless propulsion in-orbit demonstration- TU Delft Institutional Repository
{{European Space Agency
European Space Agency satellites
Spacecraft launched in 2007
Technology demonstrations
Spacecraft launched by Soyuz-U rockets