Sojourner 1 is the spacecraft built at the Jamestown lunar colony and launched by NASA in 1994, with the capacity to land a manned mission on Mars in competition with Russia's Mars-94 spacecraft, and Helios' spacecraft Phoenix. The mission is commanded by Danielle Poole.
Sojourner-1 lands and takes off using thrusters mounted on the belly next to the landing gear, but accelerates towards the destination with horizontal thrusters on the back. The main K-32 NERVA (or some later variant of them) use nuclear fission for power, but the craft also employs the use of a large solar sails that allows for constant acceleration. The sail was constructed in secret ('Project Jolly Roger') and was used to push the Sojourner ahead into first place, when it otherwise appeared it would be reaching Mars last. With use of the sail, the Sojourner was scheduled to reach the red planet weeks before the other two competitors.
When the engines of the Mars-94 craft malfunctioned, the craft was forced to detour in order to rescue the cosmonauts in spite of this preventing them from reaching Mars, and in spite of Phoenix being better equipped for a rescue mission. The craft connected to the Soviet craft via a tether, which the cosmonauts would cross by hand. However, one of the Mars-94's liquid hydrogen tanks exploded, causing the ship to roll onto the Sojourner, damaging it greatly and killing two of its crew, and one of the cosmonauts attempting to escape the Mars-94 craft.
The craft survived however, and was able to refuel using Mars-94. The remaining astronauts and cosmonauts continued towards Mars on the damaged craft. Due to dust storms on the surface, the Helios crew were unable to attempt landing until the Sojourner was in orbit. A landing attempt was made using the Helios MSAM, but it was aborted by Ed Baldwin due to danger. Subsequently, Sojourner-1 became the first manned spacecraft to reach the Martian surface, although the engines became too damaged for the craft to ever leave. Commander Danielle Poole and the Cosmonaut commander were in brief conflict over who ultimately became the first human to step foot on the Martian surface, with both leaving together during the fight, making it a joint American and Soviet achievement.