Designing a space debris removal mission targeting a Cosmos 3M rocket body in leo using a chemical engine and an elechtrodynamic tether to perform the de-orbiting

Starting Literature:

[2] D.J. Kessler & B.G. Cour-Palais; Collision Frequency of Artificial Satellites: The Creation of a Debris Belt, Journal of Geophysical Research, Vol 83, June 1978, Pages 2637- 2646

[3] Trushlyakov V.,Jakovlev M., Shatrov J, Shalay V.V, DeLuca L.T, Galfetti L., Active de-orbiting system of SLC upper stages and spacecraft based on hybrid gas rocket engines, Book of 3-th European Conference on Space Science, Versailles, France, 6-9 July, 2009

[4] Trushlyakov V, Shalay V., Shatrov J., Jakovlev M., Kostantino A., Аctive de-orbiting onboard system from LEO of upper stages of launchers, Proc. “5th European Conference on Space Debris”, Darmstadt, Germany, 30 March – 2 April 2009, (ESA SP-672, July 2009)

[5] Claudio Bombardelli, Javier Herrera-Montojo, Ander Iturri-Torrea and Jesus Peláez Electrodynamic tethers for space debris removal, 2010,Technical University of Madrid, Spain

Aim & Steps

• 
  Investigation on objects that can be tracked and disposed of (size, mass, altitude).
  
• 
  Modeling the satellite and space debris.
  
• 
  Mission phases: far approach(1), close approach(2), de-orbiting(3).
  

1. 
   Composition of the system proposed (far approach): satellite (+ tether system + micro tug).
   
2. 
   Composition of system proposed (close approach): satellite + tether system (20 km) + micro tug.
   
3. 
   Composition of system proposed (de-orbiting): satellite + tether system (20 km) + micro tug + space debris.
   

• 
  How to perform de-orbiting after grabbing?
  

• 
  Chemical engine: one or more burns to reduce altitude and provide de-orbiting of the whole system.
  
• 
  Elechtrodynamic tether: using the interaction of the magnetic field with a current that flows in the tether, to generate a force to pull down the whole system through the atmosphere to the ground.
  

• 
  Compare the result.
  

Accomplished Milestones

• 
  Investigation on object that can be tracked and dispose (size, mass, altitude).
  
• 
  Modeling the satellite and space debris
  
• 
  Investigation on object that can be tracked and dispose (size, mass, altitude).
  
• 
  Definition of launcher and launch site
  
• 
  Initial simulation of the launch
  

Definition of the orbit

The identification of the orbital region where the space debris situation is more critical is the starting point of this research.

LEO or GEO?

89%of the ~950 operational satellites are either in a low earth orbit (LEO, 300-2000 km altitude) or a geosynchronous orbit (GEO, ~36000 km altitude). Hence, these two regions form the first focus of our selection.



Figure : Distribution of space debris in different orbits

Both have specific characteristics regarding the presence and evolution of space activities, but in the LEO region, satellites and debris elements are quite widely scattered in terms of altitude, inclination and ascending node. This, in combination with the fact that orbital speeds are considerably higher than in GEO, makes both the amount of crossings and the relative velocities of the bodies during these crossings very high. The wide and random distribution of objects also implies that a system of graveyard orbits (as in the GEO case) is not practical. Another critical issue is that manned space-missions are performed at (low) LEO altitudes, making it essential that the risk of collision is minimized to the greatest possible extent. So, as described in [5], the combination of a higher debris concentration, a large number of crossings and high relative velocities in the LEO region may lead to an exponential growth of debris objects by a future cascade of collisions.

Orbital parameters

Once the LEO region is defined as a primary target of our investigation, the most critical orbital parameters must be identified to choose a proper target for the mission.

Studies were performed for predicting the probability of collision in the next centuries using NASA’s LEGEND model, based on the past and current debris environment. These studies form the basis of further orbital selection [1][4]. The collision probability in the next 50 years is higher at the altitude bands containing the highest fragments concentration caused by the catastrophic events of Fengyun 1c at ~850km and Iridium-Cosmos at ~800km. The critical altitude band is extended to 800-1000 km.

Figure - Normalized distribution of predicted catastrophic collisions as a function of altitude and spatial density (1). (Distributions, for objects 10 cm and larger, at the end of 2005 and 2205)

Higher inclinations (60°-110°) are much more crowded as a direct result of the high number of past and present satellites which use these zones to fulfill their mission goals. The peak between 90° and 100° is due once again to the high amount of fragments of Fengyun 1c. Thus, efforts for actively remove debris should focus on objects in those orbits.

Figure - Amount of detected LEO objects per inclination band for 800-1000km altitudes. Results are based on SSN data of October 2010 (using (2) and (3)) and inclination distribution for objects involved in future LEO collisions (4).

Unlike the semi-major axis and inclination, no particular trend can be seen in the right ascension of the ascending node (RAAN) of the current debris environment and future collisions. This is due to the oblateness of the Earth, which makes space debris RAAN a permanently evolving parameter.

Figure 2: Evolution of debris cloud from Iridium 33 and Cosmos 2251 satellite collision in 2009 (5). Image (a) shows the situation at the time of the collision, (b) depicts the orbits of the various debris objects 6 months later.

Figure - Amount of detected LEO objects a function of eccentricity. Results are based on SSN data of October 2010 (2) (3).