National Aeronautics and Space Administration

Glenn Research CenterGlenn Research Center

Proposal for a Balloon Assisted Launch System

Background

Very small satellites are increasing in popularity with universities, smaller companies and certain sectors of the government. Nanosatellites (<10 kg in mass) and picosatellites (<1 kg) provide simple platforms for zero-gravity experiments. Developments in the capabilities of constellations of satellites and improvements in the size, weight and cost of electronics make small satellites a viable and developing option for many space applications.

However, launching small satellites can be prohibitively expensive for an organization, at several times the cost of the satellite. They are often launched as secondary or tertiary payloads on large rockets, at a low launch priority on a long timescale. A proposed balloon-assisted launch for delivering small satellites into orbit will provide cost benefits and reduce barriers to launch.

A balloon or set of balloons would bring a platform housing a rocket with a small payload (~10 kg) to the upper edge of the atmosphere. The rocket would then launch from the platform at that height, eventually deploying the payload into low Earth orbit. Similar technology was tried during the 1950s with sounding rockets launched from high-altitude balloons, and is currently being researched—however, no end product is currently capable of orbit insertion using this method.

Motivation

In light of the above discussion, the 2008 NASA Glenn Academy asserts that a balloon-based launch system will lower the costs and time delays associated with current small satellite launch methods due to a dedicated use profile. A high-altitude launch will reduce the air drag acting on a launch vehicle, reducing propellant needs. A simple calculation using MATLAB that compared a launch from 120,000 ft with a ground launch suggested that a 25% decrease in required propellant mass was possible with a high-altitude launch system.

Developing a balloon-based launch system for small satellite orbit insertion offers the following:

• Facilitation of simple, rapid and low-cost expansion of space research and technology development.
• Spurring of public interest and funding with a more accessible space technology program.
• Increase of access to space.

Full-Scale Design

The Academy has begun a conceptual design for a balloon-assisted launch system. The payload specifications were based on the smallest satellite with demonstrated potential: three standardized picosatellites and a deployment housing (~5 kg) into a desired circular, low altitude (~200 km) orbit. A three-stage solid propellant launch vehicle will be sized for the small payload, perhaps modeled the Pegasus rocket’s upper stages. The launch platform, using a rotating disk, adjustable arms and electric motors, will be designed to house, orient, ignite and release the launch vehicle for successful launch. The design concentrates on minimizing complexity while achieving enough accuracy to acquire the desired orbit. Finally, an appropriate balloon system will be chosen to carry all of the preceding components to an altitude of 36 km, which lies above about 99% of the Earth’s atmosphere.

Unique design features we seek to implement include:

• The use of spin stabilization to control launch vehicle attitude fluctuations during launch, since fins become impractical at high altitudes where the air density is much lower
• A launch platform with completely adjustable azimuth and pitch angles at launch
• The design of the smallest rocket ever to provide orbital insertion

Division of Responsibilities

Analysis

  • Design
    • Ephraim Chen
    • Kristen Uhmeyer
  • Experimentation
    • Mehran Mohebbi
    • Tom Vo

Business

  • Marketing and Finances
    • Mary Beth Lewton
    • Kimberly Trent
  • Contacts
    • Sabrina Thompson

Concept Demonstration

Ideally, with more time and resources a complete demonstration of the full-scale design would be constructed. Alternatively, a small physical concept demonstration will be conducted that will help support promote research in balloon-assisted launch systems.

Concept Demonstration – Goals

1. Demonstrate a performance gain (i.e. higher acceleration and larger altitude change) with a high-altitude rocket launch relative to a ground rocket launch.
2. Foster broader public interest leading to more funding and continued research and development in this area.
Concept Demonstration – System Components

The main components of the system are the Rocket, Launch Pad, Balloon and Ground Monitoring.
To meet Goal 1, both the Rocket and Launch Pad will need an accurate altimeter functional at high altitudes. This will be required to measure the performance of the high altitude rocket launch for comparison against the ground launch test. An accelerometer could also be used for a performance comparison between the two launches.

Goal 2 may be satisfied with just sensor data, however, images or video of the rocket launching at the high altitude would foster more public interest.
Other supporting system components are a communication system to provide tracking of each component and relay any sensor data for real-time monitoring on the ground.

1. Rocket
The model selected will be large enough to contain the required electronics while simultaneously being capable of largest maximum altitude achievable. Other data would be desirable, such as acceleration, but room and weight issues will determine the possibility of additional devices.

Necessary Components

i. Pressure based Altimeter
ii. GPS Receiver & Antenna
iii. Communication- 900 MHz Transceiver & Antenna
iv. Microcontroller, PIC Processors
v. Power, Li-Ion Battery

Desired Additional Components

i. Video or Still Camera
ii. Temperature sensor
iii. Accelerometer

2. Launch Pad Interface (Balloon’s Payload)

The electronics required would be similar to the rocket system. The components that differ are the camera, the rocket ignition system, and rocket storage/ launch frame. The goal for the camera is to obtain images of the rocket launch at the high altitude. Some consideration will be needed for proper placement of the camera to obtain the best pictures of the rocket launching. The ignition system will either ignite off of altitude information or from a signal off the ground. The igniter used will be the “electric matches” that are used for current model rockets. A test in a cold environment similar to the expected temperatures at higher altitudes will be conducted to ensure proper functionality. Lastly, the rocket storage/ launch frame will consist of a long cylinder hollow tube housing the rocket. It will hang vertically with a slight angle to avoid hitting the balloon upon launch. The ground facing end of the cylinder tube will have a mechanical stop that will allow exhaust from the rocket to pass through. The other end of the tube will be left open to allow the rocket to escape.

Necessary Components

i. Pressure based Altimeter
ii. GPS Receiver & Antenna
iii. Communication- 900 MHz Transceiver & Antenna
iv. Microcontroller, PIC Processors
v. Onboard Video or Still Camera
vi. Rocket Ignition System
vii. Rocket Storage/Launch Frame
viii. Power, Li-Ion Battery

Desired Additional Components

i. Temperature sensor

3. Balloon

The balloon lift system will be selected when the overall system weight is known. This lift system configuration will be selected to get the rocket to the highest altitude possible before launching in a reasonable amount of time.

4. Ground Monitoring System

Real-time tracking and data monitoring capability for the rocket and platform would be required for system component recovery and logging measurements.

Rocket
• Location Tracking
• Sensor Data Monitoring
Platform
• Location Tracking
• Sensor Data Monitoring

Concept Demonstration – Pre-Balloon Launch Tasks

a. Conduct ground launch of rocket
b. Test ignition in simulated high altitude conditions (temperature) to address concerns
c. Test electronics in cold environment to verify proper operation.

Schedule

  • Week 2, June 2 – June 6:
    • Made initial presentation, assigned group roles
    • Developed a list of contacts and began reaching out
  • Week 3, June 9 – June 13:
    • Trade analysis and determine requirements
    • Look at cost issues
    • Made contacts to obtain hardware/funding
  • Week 4, June 15- June 20:
    • Choose an architecture for balloon design, begin conceptual design
    • Continue working/finding contacts to obtain hardware/funding
  • Week 5, June 23 – June 27:
    • Identify cost budgets (mass, cost, power)
    • Look at launch constraints
    • Prepare and give midterm presentation
    • Begin implementation plan
  • Week 6, June 30 – July 4:
    • Order or obtain critical components
    • Set a target launch date for the summer
    • Continue obtaining components and materials
  • Week 7, July 7 – July 11:
    • Begin building systems
    • Continue characterizing subsystems
  • Week 8, July 14 – July 18:
    • Finish building systems for experimental launch
    • Obtain launch clearances
  • Week 9, July 21 – July 25:
    • Troubleshoot implementation plan and technical designs
    • Carry out ground launch comparison test
  • Week 10, July 28 – August 1:
    • Launch date goal
    • Analysis of launch
    • Prepare and give Final Presentation

Conclusion

A complete analytical design of a balloon-assisted launch system required to get a small payload into low earth orbit is being done by Glenn Academy 2008. Since there is not enough time and resources required to build the analytical design, a Concept Demonstration will be conducted to draw attention to this research and to demonstrate the benefits of a high-altitude launch versus a ground-based launch.