The Space We Need

May 31, 2017

Our Kickstarter campaign is finally live, and we have received many questions about the technological contribution of D-Sat to the space industry.


We have already gone through the various applications of satellite technology to life on Earth. A new breed of space companies is about to launch the next generation of space infrastructures using hundreds smaller, high performance satellites, as opposed as a few very large satellites. These kinds of infrastructures will enable services we only dream about, like global Internet wireless coverage, monitoring of a wide variety of phenomenon, affordable real-time imaging of any location on Earth, and much more.


This trend will create an exponential increase in orbital traffic that will require a new approach to fleet management that ensures that spent spacecraft don’t endanger the operations of operational satellites.


There are three basic approaches to get rid of older spacecraft: doing nothing, indirect decommissioning, and direct and controlled decommissioning.


Mega-constellation will use hundreds of satellites to provide the next generation of advanced global services. This exponential increase in space traffic requires a new approach to fleet management.


Doing Nothing


The first approach to deal with the end of life of a spacecraft is to simply pull the plug. Left on its own, the spacecraft will continue orbiting around the Earth. Its orbit will slowly decay over time, until it will be low enough to trigger an uncontrolled re-entry. The time of decay depends on the initial altitude of the spacecraft, and it can go from ten years for lower orbits, to hundreds or even thousands of years for higher orbits.


The re-entry is uncontrolled, so it is not possible to guarantee that it won’t happen over populated areas. Up to a few years ago this was the only way to conclude a space mission. Nowadays, this approach is forbidden by international debris regulations, which demands to perform an indirect decommissioning maneuver that will reduce the time to re-entry down to 25 years or less. In a scenario where the space traffic is going to increase exponentially, the number of re-entering satellites is also going to follow the same increase rate, and this is why this approach cannot be tolerated anymore.


Indirect Decommissioning


With indirect decommissioning, the operator performs a maneuver that lowers the perigee of the orbit down to an altitude where it will touch the higher layers of the atmosphere several times a day. Over time, the atmospheric drag will lower the apogee of the orbit, until the moment it will be low enough to trigger an uncontrolled re-entry.


This approach can reduce the time to re-entry from a hundred years down to 25 years or less. It is a significant improvement, but the spacecraft remains in an orbit that can cross the path of active satellites. Ground controllers need to monitor these dead spacecraft, and perform expensive collision-avoidance maneuvers whenever necessary. With the projected increase in the number of satellites in orbit this is definitely bad news for satellite operators.


However, if a spacecraft fails before the end of its planned mission, there will be no way to perform a decommissioning maneuver. In a constellation of a thousand satellites that requires a resupply of a hundred of new satellites every year, it is possible that the percentage of failed satellites stuck in the operational orbit is large enough to disrupt the operations.


Moreover, the re-entry will still be uncontrolled, with possible implication on safety on the ground. 




Direct and Controlled Decommissioning


In a direct and controlled decommissioning, a satellite is put it into an immediate re-entry path that causes re-entry in about half an hour. The trajectory of the satellite crosses the atmosphere at an angle that causes its immediate destruction. Operators are in control of the trajectory, so they can make sure that re-entry will happen over the ocean, away from populated areas.


This approach solves the two biggest issues of the previous approaches: it removes the spacecraft immediately, and ensures a controlled and safe re-entry. However, it presents an issue of its own.


Satellites are equipped with thrusters that are designed for low-thrust station-keeping maneuvers. Performing a direct re-entry with this kind of engines is tricky and consumes a lot of fuel, significantly reducing the life of the satellite. Besides the usual risk of major malfunction of the spacecraft, that will leave the satellite where it is, the maneuver can fail, leaving the satellite in a lower orbit that will decay over time.


There must be a better way!





The D-Sat Way


D-Sat will be the first satellite in history that will perform a direct and controlled re-entry at end its mission thanks to a dedicated device.


D-Sat is equipped with an independent propulsive device specialized in executing direct and controlled decommissioning maneuvers in the most effective way, using the least amount of mass necessary, leaving spacecraft operators free to use the internal propellant until the last drop.


This propulsive device is independent from the main spacecraft, so it is possible to activate it and control it from the ground even in case of major failure of the spacecraft, guaranteeing proper decommissioning even in the worst-case scenario.


We want to bring this approach to the next generation of satellites, to enable the projected exponential increase in space traffic that does not endanger the operations of other spacecraft, and you can help us achieve this vision by joining our Kickstarter campaign. Remember: even a small contribution can go a long way in creating the safer space we need for the next generation of satellite applications.



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