Mars madness! China, UAE to reach the Red Planet this week ahead of epic NASA rover landing

[Admin]

Mars missions from China and the UAE arrive in orbit around the Red Planet this week, followed by the landing of NASA's Mars rover Perseverance next week.

Mars madness! China, UAE to reach the Red Planet this week ahead of epic NASA rover landing : Read more

 

[newtons_laws]

The article says "At that time, Hope will burn its engines for 27 minutes to reduce its speed from over 75,000 mph (121,000 kph) to about 11,200 mph (18,000 kph), slow enough for Mars to gravitationally capture Hope. " It would be useful when quoting spacecraft velocities to make absolutely clear what it is being measured relative to. For example it could be measured relative to the Earth from where it was launched, relative to the Sun, or relative to Mars which it has to achieve orbit around. My guess would be you are quoting velocities relative to the Sun, but I could be mistaken.

 

[Geomartian]

Delta-V change is the usual measurement. Unless you do a Wile E Coyote into the bottom of the canyon.

What did the sign say that the Hope probe was holding up?

 

[newtons_laws]

Delta-V change is the usual measurement. Unless you do a Wile E Coyote into the bottom of the canyon.

What did the sign say that the Hope probe was holding up?

Delta-V change is the usual measurement when doing a velocity change (e.g by firing the engine), but quoting a value for the actual velocity as the article did requires a frame of reference against which the velocity is being measured. Elsewhere I saw in a BBC article that they were explicitly quoting the velocity relative to the Sun, as I expected. Quote "Hope had been approaching Mars at over 120,000km/h (relative to the Sun)" https://www.bbc.co.uk/news/science-environment-55998848