Longer Translunar Flight Times

[Big RI Joe]

                During the space race it was3 days from the pad to the moon. Why are the current lunar transit times much loner?

[Jim]

                During the space race it was3 days from the pad to the moon. Why are the current lunar transit times much loner?

They are using trajectories that require less performance allowing for co-manfesting with non lunar payloads

[laszlo]

And they can get away with those slower trajectories because they're not launching humans during a solar maximum the way they were during Apollo.

[daedalus1]

Lower energy  = less fuel  = more payload.

[pathfinder_01]

In addition to what has been said, what the payload is matters as well.

Humans need fast trips and they also want trips where a free return is possible. Cargo does not.  For humans slow trips means the need to carry more supplies and be exposed to more radiation which in turn means more mass.  For Cargo like an unmanned lander this does not matter as much. The slowest trip to the moon was done by the probe Smart-1 in 2003, it took a year and used Solar Electric Propulsion.

[Big RI Joe]

In addition to what has been said, what the payload is matters as well.

Humans need fast trips and they also want trips where a free return is possible. Cargo does not.  For humans slow trips means the need to carry more supplies and be exposed to more radiation which in turn means more mass.  For Cargo like an unmanned lander this does not matter as much. The slowest trip to the moon was done by the probe Smart-1 in 2003, it took a year and used Solar Electric Propulsion.

During the "space race" unmanned lunar probes normally had a 72 hour transit time

[pathfinder_01]

They were likely smaller and they likely didn't trust the probe to last very long. There are slow low energy trajectories that can increase payload to up to 30% at the expense of time.

[Big RI Joe]

Surveyor spacecrafts ,launched by Atlas Centaurs weighed approximately a ton and surveyed for several lunar days returning data

[Jim]

Surveyor spacecrafts ,launched by Atlas Centaurs weighed approximately a ton and surveyed for several lunar days returning data

Pathfinder was referring to early probes.

The US gov't paid for everything and could afford the launch vehicle/spacecraft.

Current spacecraft are commercial, and costs matter.

[Big RI Joe]

1) Surveyor was launched between 1966 and 1968.

[Jim]

1) Surveyor was launched between 1966 and 1968.

and your point is?