The experiment will employ a trio of spacecraft flying in formation in the shape of an equilateral triangle that has sides one million kilometers long, wit

1. A. Voyager-2
2. B. New Horizons
3. C. LISA Pathfinder
4. D. Evolved LISA

Answer: D

Explanation

The experimental research on black holes using gravitational waves expanded following the second detection of gravitational waves by the LIGO detector. After the success of the LISA Pathfinder experiment, the evolved Laser Interferometer Space Antenna (eLISA) project is a plan of setting into space three spacecraft, a mother and two daughter spacecraft, which will fly in a triangular formation, trailing the earth in its orbit around the sun at a distance of over 50 million km. Each arm of the imaginary triangle, from the mother to each daughter spacecraft, will measure about a million km. Inside these spacecraft will float “freely falling” test masses – cubes with sides measuring abut 46 mm. Laser interferometers will accurately measure changes in the distance between these cubes. If they should be affected by a gravitational wave, the minute changes in this distance are measure by the interferometer. Hence option (d) is the correct answer.