The VentureStar SSTO qualifies. It was intentionally set up to develop risky new technologies such as composite liquid hydrogen propellant tanks and aerospike engines, and get them flying in an operational vehicle. The composite tanks of the 1/3-scale suborbital X-33 technology demonstrator failed in testing, and ended up heavier than an aluminum equivalent ...
Because there's no indication of the oxygen isotopes indicitive of biological activity.
free Oxygen is biologically derived.
Also the isotope ratios of volitile compounds to produce organic molecules differ in soil and atmosphere, Mars it's identical indicating no recent history of biological augmentation of the atmosphere.
The real short version is that Horizons is maintained by a single person who has other assignments at NASA, and only adds missions as they are requested by the public, or newly launched. Older missions that were still active ~20 years ago. There are archives where this older data can be pulled, just not web based.
There are some other reasons for this. One ...
I'm not aware of any structured courses for a 10 year old, but that doesn't mean they don't exist.
In the meantime I would recommend your son watch good quality documentaries, such as those produced by:
Anything presented by Neil deGrasse Tyson, such as the 2014
continuation of Cosmos
Anything presented by Brian Cox
Beside the good answers (I like this) you already have, there is still an important fact left uncovered:
All the answers I read are just about launch costs, but there is also the factor price of the payload.
When taking a payload to space with the space shuttle, the payload has to be certified for human space flight having effects on every nut and bolt and ...
SLS major work locations:
Alabama- Testing & upper stage, engineering design
Utah- Solid rocket motor
Florida- Launch pad updates
Louisiana- Core booster, Orion
California- Main engines
Colorado- Engineering for upper stage, Orion
So far as I can tell, it seems like these are where the major contracts are, although I don't doubt ...
“Are we there yet?” (45th Space Wing's goal of being able to support 48 launches per year from Cape Canaveral)
We won't know for certain this year about the 48 launches, but since they are "on pace for 39" this year and could support three launches in three days, it seems likely that this is imminent.
Space News' 45th Space Wing to attempt three ...