Ashish Goel

Ashish_Goel.jpg

Contact

ashish09 AT stanford DOT edu

Education history

B. Tech, Engineering Physics, Indian Institute of Technology - Bombay, 2009

M.S, Aeronautics and Astronautics, Stanford University, 2011

Current/Recent projects

In Situ Measurements of Meteoroids and Dust Particles
I led the design of two space missions: MORGANA and ERDOS for carrying out measurements of the meteoroid environment around the Earth and the dust environment around Europa. Both these missions are CubeSat-based concepts that use the undersides of the deployed solar panels as impact surfaces and have sensors mounted on the outside walls of the CubeSat.

Transient Plasma Analyzer (TPA)
The space environment can have adverse effects on satellites operating in space. A satellite black-box can go a long way in diagnosing the various anomalies reported on satellites in space. One of the key elements of such a black box would be a plasma sensor capable of measuring the properties of ionospheric plasma, plasma associated with electrostatic discharge and plasma generated from a hypervelocity impact. We have designed and fabricated a plasma sensor that can measure the density, energy distribution and hence the temperature of plasma generated from a hypervelocity impact. While the lab has expertise in building such sensors for ground based hypervelocity impact tests, the TPA has been designed in a configuration suitable for deployment in space on a CubeSat platform.

Hypervelocity Impact Tests
I have been a member of the hypervelocity impact team that has carried out experiments at the Max Planck Institute for Nuclear Physics in Heidelberg, Germany; at the Colorado Center for Lunar Dust Acceleration Studies in Boulder, Colorado and at the NASA Ames Vertical Gun Range in Mountain View, California. In these experiments, we deployed optical, plasma and RF sensors for carrying out mesurements of the impact flash and the impact plasma. 

Hypervelocity Impact Flash
Ground based hypervelocity impact tests are an excellent way to understand the hypervelocity impact phenomenon in a controlled setting. A hypervelocity impact leads to the emission of an optical flash, followed by outward expansion of plasma and emission of electromagnetic radiation. The impact flash can give us vital information about the temperature of the target immediately after the impact, which is an important source term in any physics-based model of the impact phenomenon. The rise time of the optical signal can also serve as a proxy for the velocity of the incoming projectile. Optical sensors can hence be used on spacecraft to determine the mass and velocity of meteoroids and orbital debris that impact them on a regular basis. To meet this goal, I have developed a machine learning algorithm for estimating the impact speed from measurements of the impact flash.

Spacecraft Failure Analysis
It is known that anomalies occur in space systems on a regular basis. While efforts are made to diagnose the cause of these anomalies, many of them go unaccounted for. The limited health monitoring data collected is often not sufficient enough to nail down the cause of the anomaly. In order to assess the role played by different aspects of the space environment, we have carried out a statistical analysis of spacecraft anomalies by using data from multiple anomaly databases. My analysis shows that the failures have no correlation with the flux of shower meteoroids but there is a weak, yet statistically significant correlation with the flux of the sporadic meteoroids.

Research interests

Space Systems Design
Space Environment

Selected Publications

[1] “Estimation of Hypervelocity Impact Parameters from Measurements of Optical Flash”, Goel, A., Lee, N., Close, S., Int. J. Impact Eng., vol. 84, pp. 54-63, 10, 2015.
[2] “Design and Testing of Miniaturized Plasma Sensor for Measuring Hypervelocity Impact Plasmas”, Goel, A., Tarantino, P. M., Lauben, D. S., Close, S., Rev. Sci. Instrum. 86(4), pp. 043304. 2015.
[3] “Vault-1 – A Mission Architecture for Human Exploration of Near-Earth Objects”, Rabinovitch, J., Goel, A., Niedzielska, U., Ganesan, S., Forman, R., AIAA Space, 6.2012-5113, 2012
[4] “Design of a Flight Demonstration Experiment for Radioisotope Thermophotovoltaic Power Source”, Goel, A., Franz, B., Schillo, K., Reddy, S., Howe, S., NETS Proceedings, 2015
[5] “Electrical Anomalies on Spacecraft due to Hyervelocity Impacts”, Goel, A., Close, S., Aerospace Conference, IEEE, 2.1104, 2015.
[6] “Measurement of Total Electron Count of the Ionosphere and the Social Goal of Pratham, Indian Institute of Technology Bombay's First Student Satellite”, Saptarshi, B., Jha, J., Goel, A., Thakur, D., Neema, K., Rachh, M., Reddy, N., Meesla, S., Das, S., IAC Proceedings, IAC-10.B4.2.4, 2010
[7] “The Hemispheric Asymmetry of Solar Activity During the Last Century and the Solar Dynamo”, Goel, A., & Choudhuri, A.R., RAA, 9, 115, 2009

Other Interests

Anything outdoors (mountaineering, skiing, hiking, biking, swimming, climbing, running, tennis), birdwatching, trivia