ChargerSat-2

The UAHuntsville ChargerSat-2 project is a student satellite development project to design, build, test, and operate an orbital CubeSat system that will conduct relevant microgravity science on boiling properties in extreme microgravity.


  • Primary Mission
  • Secondary Mission
  • Program Goals
  • Microgravity Testing

Primary Mission Details

The UAHuntsville ChargerSat-2 program's primary focus is to investigate the heat transfer properties of nucleate boiling in extreme microgravity. More specifically, the ChargerSat-2 spacecraft will investigate 2 key aspects of nucleate boiling in microgravity, the effects of surface roughness and the effects of convection, caused by tiny accelerations on the order of 10-4m/s2 to 10-5m/s2. The ChargerSat-2 mission exploits three student designed technologies being developed at UAHuntsville, the boiling instrument and an "aerodynamically" stabilized drag device.

Initial CAD models of a Boiling Chamber and the Initial Concept models of the ChargerSat-2 System

The Science

The science collected by the ChargerSat-2 satellite will contribute to the understanding of the effects of micro-gravity on nucleate boiling. This boiling regime is not a popular mode of heat transfer in space applications due to limited experimental data supporting the theory of its principles. This data should help unlock the regime for use in all technologies needing fluid based heat transfer in space. An example could be a spacecraft thermal management system or an experiment needing to host higher temperature fluid tests.

Surface Roughness

The driving factor of nucleate boiling in microgravity has been associated with the surface roughness of the heated element. This property is driven by conduction through the bubble cell walls as they collect on a heated surface. The bubble cell walls can be increased by creating more nucleation points. The ChargerSat-2 Boiling Instrument will not only measure the heat transfer characteristics of each sample but also be collecting images of the boiling at the surface of the samples. This will allow the team to also look at bubble size, quantity, and contact angle.

Local Acceleration

The ChargerSat-2 Spacecraft will not only have the ability to change its local acceleration but it will also be able to measure tiny disturbances, on the order of 10-4m/s2 to 10-5m/s2. The ability to change and measure the spacecraft's local acceleration allows the ChargerSat-2 team to investigate the effects of convection on the heat transfer during boiling. The data collected by the ChargerSat-2 Spacecraft will allow the team to look into the relationship between the boiling properties measured and the small amount of acceleration on the system in orbit. The ChargerSat-2 is able to change its acceleration by deploying or retracting its "aerodynamically" stabilized drag device.

The Boiling Instrument

Initial CAD models of the Boiling Instrument

Key Design Features of the Boiling Instrument:

  • The Boiling Instrument consists of 2 boiling chambers with support electronics.
  • Each boiling chamber can test up to 6 surface roughness samples.
  • The supporting electronics is capable of not only measuring the thermal properties of the samples but can also take pictures of the boiling at the surface of a sample.

For more information on the Boiling Instrument:

The Drag Device

CAD Model of the Drag Device Deployment System

Key Design Features of the Drag Device:

  • When deployed, the drag device is able to increase the surface area of the spacecraft by nearly an order of magnitude. This allows ChargerSat-2 to drastically change the amount of drag on the satellite.
  • The tapered design allows the drag device to stabilize the spacecraft in its orbital plane. This makes the drag forces on the satellite predictable.
  • The ChargerSat-2 Drag Device will be able to retract. The ability to retract the drag device when not performing a boiling experiment allows us to greatly extend the orbital lifetime of the ChargerSat-2 mission. Starting at a 350km orbit, ChargerSat-2 would burn up in less than a week if it left its drag device deployed. By only having the drag device deployed when conducting a boiling experiment, ChargerSat-2 could last over a month in the same 350km starting orbit.

For more information on the Drag Device:

  • Josh Thibaudeau, 2013, AIAA Region II Student Conference
    Deployable Stable Particle Deflector for Nano Satellites
    Manuscript

Secondary Mission Details

CAD Model of the Drag Device Deployment System

Many CubeSat investigations around the world are developing end-of-mission devices that will speed up the de-orbit process after the mission is over. A standard 1U CubeSat in an 800km orbit will not de-orbit for over 25 years, even though the typical proposed mission lifetime of a CubeSat is often less than a year. The ability to de-orbit quickly after end-of-mission reduces the chance of a CubeSat becoming just another piece of space debris. The secondary mission of ChargerSat-2 is to demonstrate a predictable de-orbit device. This de-orbit device will allow us to responsibly plan future ChargerSat mission and free up orbits when we are done using them. The de-orbit orbit device developed for ChargerSat-2 will help us prevent any future ChargerSat spacecraft from becoming dangerous space debris.

ChargerSat-2 will use it's drag device, which is required for our primary mission, as a end-of-mission de-orbit device. The Drag Device increase the surface area of the satellite by nearly an order of magnitude, greatly increasing the drag forces.

Initial Orbital Lifetime Study with Different Sized Drag Devices

For more information on the Drag Device:

  • Josh Thibaudeau, Deployable Stable Particle Deflector for Nano Satellites Manuscript

Program Goals

  • Design, fabricate, and operate a satellite system using the capacities of a multi-disciplinary team of engineering and scientific disciplines to develop an orbital system capable of conducting scientific investigations.
  • Develop a reusable ChargerSat Bus design, based on technologies developed for ChargerSat-1.
  • Inspire and engage the public in our missions and technical concepts

Microgravity Testing

Background

In 2012 the ChargerSat-2 team applied for a microgravity flight through NASA's NSPIRE Program, which is a research opportunity to fly payloads to be tested in microgravity on board an aircraft. This proposal was accepted and the ChargerSat-2 team will be ready for this flight by January 1st 2014.

Test Setup in the Parabolic Aircraft

There are three mission objectives for this experiment:

  • To verify proper functionality of the deployable drag device in micro-gravity
  • To capture 3-D maps of the deployable drag device through multiple articulations
  • To validate the performance of the microgravity boiling instrument before orbital flight

The ChargerSat-2 Parabolic Flight Testing can be broken down into 2 sets of experiments. The first experiment involves the drag device deployments and mapping. The second being the verification and characterization of the microgravity boiling instrument. Together in orbit, these technologies will support an improved understanding of the science mission.

Microgravity Boiling Instrument Verification and Characterization

Boiling Instrument Prototype Fall 2012

There are two main objectives to flying the boiling instrument on the parabolic flight campaign:

  • Raise the TRL of the boiling instrument to >TRL4 before orbital operations.
  • Investigate the effects of convection, caused by accelerations on the order of 10-2m/s2 and 10-3m/s2. This data, coupled with the data the ChargerSat-2 spacecraft will collect on orbit, will allow us to even better characterize the effects of each mode of heat transfer in microgravity.

Drag Device Deployment Experiment

The drag device supporting the ChargerSat-2 mission is an added capability to impart a deceleration on the satellite due to aerodynamics. This device not only features an aerodynamically stable design, but also supports an articulation feature which will effectively turn off the drag between science measurements. Additionally, the technology can be used as a de-orbit device, a needed feature of satellites at the end of a mission.