How far is Mars from Earth, and how long would a trip with people take?

"Mars has an orbit with a semimajor axis of 1.524 astronomical units (228 million km) (12.673 light minutes)"

"However, crewed missions to Mars using chemical propulsion take around 7-10 months at a minimum, posing significant challenges for crew health and mission reliability."

"The distance at close approach varies between about 54 and 103 million km (34 and 64 million mi) due to the planets' elliptical orbits, which causes comparable variation in angular size ."

"56 million km is the closest distance between Mars and Earth"

"These results show that NTP can feasibly reduce travel times to 70-90 days during the optimal launch window while achieving a hyperbolic excess velocity, or V-infinity of 10 km/s."

"At their furthest Mars and Earth can be as far as 401 million km (249 million mi) apart."

"in 2003 the minimum distance was 55.76 million km, nearer than any such encounter in almost 60,000 years (57,617 BC)"

"NTP offers a significant reduction in transit time when compared to chemical propulsion but remains consistent with current reactor technology and demonstrated technological advancements."

"Mars comes into opposition from Earth every 2.1 years."

"Oppositions range from about 0.68 AU when Mars is near aphelion to only about 0.37 AU when Mars is near perihelion."

"The average time between the successive oppositions of Mars, its synodic period, is 780 days; but the number of days between successive oppositions can range from 764 to 812."

"during that 780-day synodic period"

"The gravitational potential difference and thus the delta-v needed to transfer between Mars and Earth is the second lowest for Earth."

"For a mission between Earth and Mars , for example, these launch windows occur every 26 months."

"The lowest energy transfer to Mars is a Hohmann transfer orbit , a conjunction class mission which would involve a roughly 9-month travel time from Earth to Mars"

"for example, in the case of Mars, the period is 780 days (2.1 years)."

"A Hohmann transfer orbit also determines a fixed time required to travel between the starting and destination points; for an Earth-Mars journey this travel time is about 9 months."

"This would be a 34-month trip."

"a few weeks every 26 months (e.g. Mars launch periods )"

"They are also often used for these situations, but low-energy transfers which take into account the thrust limitations of real engines, and take advantage of the gravity wells of both planets can be more fuel efficient."

"Shorter Mars mission plans have round-trip flight times of 400 to 450 days"

"A fast Mars mission of 245 days (8.0 months) round trip could be possible with on-orbit staging."

"NASA has pushed towards higher delta-V “opposition” class missions, which consist of a short 30-day Martian stay and an overall length of two years."

"In the reference mission, the transit time to Mars is 270 days, with 240 days of EP burn time."

"The 1,100 days total trip time allows the hybrid propulsion stage to deliver cargo to Mars every other Earth-Mars transit opportunity."

"For the first two Mars surface mission in the Evolvable Mars Campaign, the short trip time allows the hybrid propulsion stage to be reused for three round-trip journeys to Mars, which matches the hybrid propulsion stage's designed lifetime for three round-trip crew missions to the Martian sphere of influence."

"Based on the relative orbits of Mars and Earth, the distance between Earth and Mars ranges from 55 to 400 million km over a synodic period of approximately 26 months."

"On a mission to Mars, there will be as long as 22-min one-way communication delays between the ground and the crew, causing major changes to current communication infrastructures."

"Launch (or Earth departure) requirements vary significantly over this cycle."

"For a human Mars exploration mission, it is required to minimize the time-of-flight of the interplanetary trajectories to mitigate the adverse effects of the radiation environment and prolonged weightlessness conditions on the health of the crew."

"The astronauts may spend as many as 500 days on the planet’s surface before returning to Earth."

"For crewed conjunction-class missions, trip times are typically 180 to 210 days each way, stay times on Mars are typically 500 days or more, and total mission time is around 900 days."