Ed Lu

Finding a million asteroids!

[Ed Lu @astroEdLu]

@JeffBezos Yes, but everyone should have some stake in the efficient use of our taxes. So everyone should pay something (even if small) so they have an incentive to vote for improving our system.

[Ed Lu @astroEdLu]

Our new ephemeris propagation service is now available at https://t.co/XOKGms4LT1

[Ed Lu @astroEdLu]

If you need to propagate many state vectors and predict the sky position, magnitude, rates etc for an object in space, the @b612foundation can help you.

[Ed Lu @astroEdLu]

@DJSnM Sounds like a business opportunity to me! Perhaps an Android Auto or Apple Car Play app from the phone?

[Ed Lu @astroEdLu]

This incident is the reason for the rule that in NASA T-38s we were not allowed to do circle to land approaches in actual instrument conditions. We could practice them in good weather, but they are challenging because they are flown substantially lower than the usual traffic pattern altitude, and because of the high speeds (240 knots for gear and flaps, roughly 165 knots on final)

[Ed Lu @astroEdLu]

@DJSnM Yes"fun" in the "not fun" sense of the word!

[Ed Lu @astroEdLu]

The Shuttle simulator had no way to simulate the g forces, but the Russians had a simulator in a huge centrifuge. So if you screwed up and did a 9 g reentry, you actually had the pleasure of feeling that in the centrifuge. Good times!

[Ed Lu @astroEdLu]

Parachute opening is a wild ride!

[Ed Lu @astroEdLu]

If you weren't careful about how steep your skip was, you could pay a big penalty in terms of g forces.

[Ed Lu @astroEdLu]

Skipping off the atmosphere can cause your next entry into the atmosphere quite steep, which means very high g forces.

[Ed Lu @astroEdLu]

If you come in too steep and have your lift vector pointed up, you can "skip" off the atmosphere and climb back upwards into very thin atmosphere which if you are not careful can put you into thin enough air so you have very little steering ability.

[Ed Lu @astroEdLu]

Of course the Shuttle had much more lift to drag ratio and so could steer much further cross range if needed.

[Ed Lu @astroEdLu]

We used to train to fly reentry manually in the Soyuz as well as Shuttle. The same principle of rolling to control drag and cross range to end up at the target landing spot was used.

[Ed Lu @astroEdLu]

Like all capsules, there is a small amount of lift vector which is used to steer both cross range as well as the angle at which they dig into the atmosphere. Both are controlled by rolling the vehicle left or right.

[Ed Lu @astroEdLu]

@DJSnM Inertial frame of reference and Earth centered frame of reference

[Ed Lu @astroEdLu]

I never got tired of watching the Earth from space!

[Andrew McCarthy @AJamesMcCarthy]

They had to cover the window on the Earth facing-side on Orion so I guess this already happened lol

[Ed Lu @astroEdLu]

@DJSnM The real party is aboard the capsule! Tickets are limited though.

[LeoLabs @LeoLabs_Space]

LeoLabs detected a fragment creation event involving SpaceX Starlink 34343 on 29 March 2026.

Learn more. ⤵️

[Ed Lu @astroEdLu]

@Stuck4ger @DJSnM Maybe they didn't make it look like a figure 8 because it would look too much like the Apollo 8 patch?