Mars rover Perseverance refines course toward Red Planet

Course correction to Mars, I like that :) Last night and early this morning I enjoyed using my 90-mm refractor telescope and viewed Mars at 179x. Very distinct surface features visible now and south polar cap with the planet distinct gibbous shape (not fully illuminated yet). At my location tonight, Mars is up now in Pisces. Weather looks good tonight too so later near 0100 or so, I plan to do some more Mars observing using my telescope, this time 200x views.
 
  • Like
Reactions: Lovethrust
Apr 7, 2020
162
29
1,610
Course correction to Mars, I like that :) Last night and early this morning I enjoyed using my 90-mm refractor telescope and viewed Mars at 179x. Very distinct surface features visible now and south polar cap with the planet distinct gibbous shape (not fully illuminated yet). At my location tonight, Mars is up now in Pisces. Weather looks good tonight too so later near 0100 or so, I plan to do some more Mars observing using my telescope, this time 200x views.
Me too! I used my 100mm reflector at x160 (As high as I can get unfortunately), the polar cap absolutely glowed! I could also make out intermittently details in the southern highlands. Jupited was beautiful as well, I could just make out the GRS. Of course Saturn was gorgeous, couldn’t make out the Cassini division as the atmosphere was boiling here but could make out a cloud smudge.
Overall a great night!!!
 
  • Like
Reactions: rod
Wolf, I am no rocket expert but as I recall, even Apollo missions need some tweaking on their journey to the Moon so space probes to Mars, likely need some course corrections too. Mars and the space probes are moving :)
 
  • Like
Reactions: Torbjorn Larsson
Wolfshadow said, "I was thinking about this earlier and I guess I assumed that there are some variables that need to be taken into account from time to time over the course of the trip from Earth to Mars. Is this not correct?"

Wolfshadow, I went back and looked at my stargazing log of Mars. Stellarium and Starry Night Pro Plus 8 show the distance between you and Mars when observing, as well as other position information. This is very dynamic, especially as Mars approaches opposition this year in October and goes retrograde on 10-Sep. This morning when I viewed Mars using my telescope, it was about 0.556 AU from Earth. My log shows Mars when I observed on 31-May, was 1.014 AU from Earth. I can only imagine what would happen if I programmed Perseverance journey to Mars and when the probe arrives at Mars, Mars had moved a bit farther, perhaps a few kilometres. Oops :)
 

Wolfshadw

Moderator
Apr 1, 2020
644
557
2,760
@rod
I get that when trying to land, you don't want to be off by a few kilometers, but if 50 years ago, we could plot a course to rendezvous with all of the outer planets, I would think, 50 years later, that we'd be able to completely and accurately plot a course to intercept with Mars without the need for course corrections.

I mean Voyager getting a gravity boost from Jupiter, on it's way to Saturn. If you're off by even a fraction of a degree, you could miss Saturn altogether, so the math had to be pretty darned accurate and that was 50 years ago!

-Wolf sends
 
  • Like
Reactions: rod
@rod
I get that when trying to land, you don't want to be off by a few kilometers, but if 50 years ago, we could plot a course to rendezvous with all of the outer planets, I would think, 50 years later, that we'd be able to completely and accurately plot a course to intercept with Mars without the need for course corrections.

I mean Voyager getting a gravity boost from Jupiter, on it's way to Saturn. If you're off by even a fraction of a degree, you could miss Saturn altogether, so the math had to be pretty darned accurate and that was 50 years ago!

-Wolf sends
FYI, concerning Voyager I and II missions, you appear to assume that zero course corrections took place during their voyages. Do you have references to support this view?
 
  • Like
Reactions: Torbjorn Larsson
Wolfshadow et al. The space.com report does state "Four more such maneuvers are scheduled before the rover's February 2021 landing."

There have been numerous missions to Mars by NASA over the years and other groups. Did past missions to Mars also need course corrections? My guess, this is not a first here reporting course corrections used to reach the planet.
 

Wolfshadw

Moderator
Apr 1, 2020
644
557
2,760
FYI, concerning Voyager I and II missions, you appear to assume that zero course corrections took place during their voyages. Do you have references to support this view?
No. I realize that course corrections were necessary. I just mistook your initial comment as sarcasm:

Course correction to Mars, I like that
My mistake and apologies.

-Wolf sends
 
Apr 7, 2020
162
29
1,610
The Voyager grand tour must be the most incredible navigation feat ever followed closely by New Horizons which was like hitting a hole in one from 600 yards!
On Earth it might be Captain Bligh’s amazing feat of navigating the long boat of the Bounty to safety.
 
Jan 4, 2020
217
95
1,660
I get that when trying to land, you don't want to be off by a few kilometers, but if 50 years ago, we could plot a course to rendezvous with all of the outer planets, I would think, 50 years later, that we'd be able to completely and accurately plot a course to intercept with Mars without the need for course corrections.
The classical newtonian gravity and mechanics hasn't changed even though the software and location equipment has. Since the need for precision is higher than the launch craft can provide, they always have and always will have routine timing for course corrections (if they are needed, sometimes they are still near enough spot on).

I suspect that when they can start to move to "interplanetary GPS" by way of using pulsars for location, which recently was shown to be feasible, they will start to hand off guidance for larger missions to the crafts themselves. Almost certainly if they are manned and want independent navigation backup abilities throughout the missions.
 
  • Like
Reactions: rod

ASK THE COMMUNITY