The Augmented Satellite Launch Vehicle took the SLV-3 design and strapped two extra solid boosters to its sides, making a 24-metre, five-stage, all-solid rocket able to put 150 kg satellites into a 400 km orbit. Its first two flights failed, its last two succeeded, and the technologies it tested, from strap-on boosters to improved guidance and control, went straight into PSLV.
ASLV flew four times, every flight carrying a SROSS science satellite. All four are here.
4 milestones from 1987 to 1994: 2 successes, 2 failures, 0 partial successes and 0 other milestones.
ASLV was a low-cost test-bed: a way to try out the technologies a much bigger rocket would need while still launching small scientific satellites of the Stretched Rohini Satellite Series (SROSS).
24 Mar 1987 · ASLV · Failure
The first ASLV carried SROSS-1 with scientific instruments. According to published accounts, the two strap-on boosters burned normally but the core first stage did not ignite as they finished, and the rocket fell into the sea.
13 Jul 1988 · ASLV · Failure
The second flight, carrying SROSS-2, passed the point where D1 had failed but lost control shortly afterwards and broke up. Two failures in a row led to a long review of the rocket's control and guidance before it flew again.
20 May 1992 · ASLV · Success · First ASLV success
ASLV-D3 placed the 106 kg SROSS-C in an orbit of about 255 × 430 km. The orbit was low, and the satellite re-entered on 15 July 1992 after a two-month mission — but the rocket had worked.
Comeback from ASLV-D2.
What went wrong: D1's core stage never ignited after the boosters burned out; D2 lost control and broke up.
Why: Gaps in stage-ignition reliability and in the vehicle's control at booster separation, according to published accounts.
What fixed it: ISRO overhauled the ignition, control and guidance systems over four years; D3 reached orbit.
4 May 1994 · ASLV · Success
The last ASLV placed SROSS-C2 in orbit, carrying scientific instruments for space research. Five months later, PSLV succeeded for the first time — and ASLV, its job as a test-bed done, was retired.
Augmented Satellite Launch Vehicle. It "augmented" the SLV-3 design with two strap-on solid boosters to lift heavier satellites — about 150 kg instead of 40 kg.
Four times, between 1987 and 1994. The first two flights failed and the last two placed SROSS-C and SROSS-C2 satellites in orbit.
ASLV was always meant as a low-cost technology demonstrator. Once PSLV, which could carry far heavier satellites, succeeded in October 1994, there was no need to keep flying the smaller rocket.
Related: All ISRO Rockets, SLV-3, PSLV, ISRO Missions Timeline.