Sunday, April 17, 2016

Mission proposal essay

I haven't put up a post in a couple of days, due to finishing an online course.  The last assignment was a essay presenting a made-up space mission to a space agency.  I decided to publish it as a blog post.


Snow Area Measurement, Mapping, and analYsis (SAMMY)

This is a proposal for mission to launch a satellite which will gather valuable information relating to global snow condition.

Mission goals

This mission will launch a satellite to gather data about snow condition around the globe, providing important information about climate change’s effects.  

It will accurately map information about snow around the entire planet.  This will provide valuable data on snowmelt, snowpack, and the processes driving them.  With SAMMY, we can track snow area, depth, and quality, which is a highly important yardstick for global warming and extremely valuable for climate change tracking.  By gathering data on snow quality, we can learn more about climate change and the Earth’s weather patterns.  

SAMMY will use a near polar orbit to gather data over the entirety of Earth’s surface.  A polar orbit is just like an equatorial low Earth orbit, but it’s rotated 90 degrees, so every 90 minutes, when the satellite comes back to the same point on it’s orbit, the Earth has rotated below it to the south, so a new area is below the satellite. (King, 339)

Importance of this mission

Addressing climate change is a global imperative, and the measurement of snow quality is a very good way of learning about it and its effects.  

SAMMY will be able to collect data far more efficiently than local ground-based methods.  Due to its polar orbit, it can gather data about snow on a global scale, rather than in the very small, localized, areas where weather stations are.

Publishing this data will be valuable for many scientific, educational, and citizen-based entities around the world.  The data on the condition of snow will also create large benefits in areas such as: meteorology (improved weather models), snow-based recreation (increased safety), and better information for search and rescue (pinpointing where blizzards and avalanches have occurred).  

Technical challenges

The largest technical challenge will be the accuracy of the snow-monitoring measurements.  This should be surmountable by using such techniques as GPS location for the satellite, or other calibration techniques.  

Instrument technology also appears to be an issue with SAMMY.  Technology will soon be available that enable the creation of instruments that can measure snow condition from orbit.  However, this will require a relatively long development process.  To keep the budget low and time of development low, use of pre-fabricated or off-the-shelf components will be maximized.

Other options

There are other options for gathering the same data.  The most obvious one is a large array of ground based stations.  These stations could give more accurate measurement, but the largest problem with that is getting enough stations to even come close to the area SAMMY would cover.  

Another option is the use of snowfall measuring satellites.  While snowfall measuring satellites are good for meteorology, they cannot track general quality as well as SAMMY would.  

SAMMY will fill an important gap in Earth observation satellites.  

Systems engineering approach


The payload is the most important part of any space mission.  In this mission the payload will contain the space-hardened instruments used for the collection of the data.  Also required is a datahandling system, and a transmission system so the data can be used on Earth.
A Guidance, Navigation and Control (GN&C) system is absolutely required by the space environment for keeping the spacecraft on course.  An electrical subsystem is necessary for providing power to the components of the spacecraft.  Thermal control will prevent heat from building up during the daylit portion of the orbit, while heaters will prevent the spacecraft from freezing during the unlit portion of the orbit.  


The payload consists of the required instruments for gathering the location, depth, and quality of snow around the planet.  The selection of the instruments will be made in a further study.  The data on snow, accumulated by the instruments, will need processing for transmission by the datahandling system, which consists of a group of computers that turn raw data from the instruments into compressed and arranged data for transmission.  Then the processed data will be transmitted by the telecommunications system, which is primarily composed of the antenna.  The antenna will transmit in the 1-40 GHz range of all satellites.  

In a low polar orbit, atmospheric drag, gravitational forces, and debris in the form of old satellites, used upper stages, paint flecks, and many other sources create the need for a propulsion and attitude control system.  It will keep the satellite pointing in the right direction (attitude), in the correct orbit, and away from debris, which would damage or destroy the satellite.  The attitude control system will use reaction wheels, which work by speeding up or slowing down flywheels for high-accuracy, low-fuel use attitude control.

The attitude control system will be commanded by an inertial control system.  Inertial control systems work by the fact that a gyroscope will keep pointing in the same direction, regardless of location of rotation.  However, they will eventually become out of plane due to small forces applied to them over time.  A gimballed star tracker, which works by staying pointed at various reference stars will be required to correct the inertial control system (“Spacecraft Star Trackers”, 10).

The electrical subsystem will consist of a primary power source.  Solar panels will be used, and they will collect power during the sunlit portion of the orbit.  The surface area of the solar panels will be determined after the power requirements are determined.  Batteries will be used for a secondary power source during the portion of the orbit which is not sunlit.  The powerhandling system, which is a simple group of computers, will control charging of the batteries and providing conditioned power to the other systems.  

Thermal control will consist of radiators and heaters for individual instruments and systems.  The radiators are flat plates, sometimes with channels inside them for pumping fluid through them, that radiate heat away from the spacecraft in the form of infrared radiation.  The heaters keep the spacecraft warm during the extremely cold portion of the orbit with no sunlight.

Finally, the structure will consist of a either a pre-made bus, which is a pre-fabricated spacecraft platform, with everything a spacecraft needs except for the payload, or a custom structure.  The PROTEUS bus’ specifications appear to be very similar to the requirements (“PROTEUS Data Package”).

Ground segment

The ground segment will handle data collection, data processing, and spacecraft command.  
The existing network for spacecraft communication can handle data reception and spacecraft command.  The data can be processed after it’s been transmitted.  Then the data will be compiled into charts, maps, and graphs and then published.

The mission control segment of the ground segment will control all aspects of the spacecraft.  

Launch segment

There are many launch vehicles that would work for this mission.  The selection will be dictated by compatibility of the satellite with the launch vehicle’s adapter(s), capabilities of the launch vehicle, and cost.
Also to be considered is the environment inside the fairing, including the cleanliness level, noise level, axial and lateral g’s, temperature, and pressure.

Final note

The SAMMY spacecraft would provide a large benefit in many areas that are crucial to the world’s successful adaption to global temperature increase..  It would create a large return for a relatively small cost.

Thank you for reading.


Various, cited section by King, Michael Our Changing Planet. Page 339 Pub: 2007. Accessed April 

Spacecraft Star Trackers. NASA. page 10. Pub. July 1970. Accessed April 2016. URL:
Rapid III Spacecraft PROTEUS Data Package. Pub. ???? Accessed April 2016. URL:
Taylor, Travis. Introduction to Rocket Science and Engineering. CRC Press. Pub. 2009 Accessed April 2016.