  Current research focuses on designing fast trajectories to the
trans-Neptunian object (TNO) (90377) Sedna to study the surface and composition
from a close range. Studying Sedna from a close distance can provide unique
data about the Solar System evolution process including protoplanetary disc and
related mechanisms. The trajectories to Sedna are determined considering flight
time and the total characteristic velocity (${\Delta}V$) constraints. The time
of flight for the analysis was limited to 20 years. The direct flight, the use
of gravity assist manoeuvres near Venus, the Earth and the giant planets
Jupiter and Neptune, and the flight with the Oberth manoeuvre near the Sun are
considered. It is demonstrated that the use of flight scheme with
${\Delta}VEGA$ (${\Delta}V$ and Earth Gravity Assist manoeuvre) and
Jupiter-Neptune gravity assist leads to the lowest cost of ${\Delta}V$=6.13
km/s for launch in 2041. The maximum payload for schemes with ${\Delta}$VEGA
manoeuvre is 500 kg using Soyuz 2.1.b, 2,000 kg using Proton-M and Delta IV
Heavy and exceeds $12,000$ kg using SLS. For schemes with only Jupiter gravity
assist, payload mass is twice less than for ones with ${\Delta}$VEGA manoeuvre.
As a possible expansion of the mission to Sedna, it is proposed to send a small
spacecraft to another TNO during the primary flight to Sedna. Five TNOs
suitable for this scenario are found, three extreme TNOs 2012 VP113, (541132)
Lele\=ak\=uhonua (former 2015 TG387), 2013 SY99) and two classical Kuiper Belt
objects: (90482) Orcus, (20000) Varuna.
