  This paper on ASTROD I is based on our 2010 proposal submitted for the ESA
call for class-M mission proposals, and is a sequel and an update to our
previous paper [Experimental Astronomy 23 (2009) 491-527; designated as Paper
I] which was based on our last proposal submitted for the 2007 ESA call. In
this paper, we present our orbit selection with one Venus swing-by together
with orbit simulation. In Paper I, our orbit choice is with two Venus
swing-bys. The present choice takes shorter time (about 250 days) to reach the
opposite side of the Sun. We also present a preliminary design of the optical
bench, and elaborate on the solar physics goals with the radiation monitor
payload. We discuss telescope size, trade-offs of drag-free sensitivities,
thermal issues and present an outlook. ASTROD I is a planned interplanetary
space mission with multiple goals. The primary aims are: to test General
Relativity with an improvement in sensitivity of over 3 orders of magnitude,
improving our understanding of gravity and aiding the development of a new
quantum gravity theory; to measure key solar system parameters with increased
accuracy, advancing solar physics and our knowledge of the solar system; and to
measure the time rate of change of the gravitational constant with an order of
magnitude improvement and the anomalous Pioneer acceleration, thereby probing
dark matter and dark energy gravitationally. It is envisaged as the first in a
series of ASTROD missions. ASTROD I will consist of one spacecraft carrying a
telescope, four lasers, two event timers and a clock. Two-way, two-wavelength
laser pulse ranging will be used between the spacecraft in a solar orbit and
deep space laser stations on Earth, to achieve the ASTROD I goals.
