In today’s Bulldog wrapup of space, science and technology news:

  • Elon Musk posts video of ‘electric sled’ for tunnel travel
  • NASA nixes crew for test flight of new megarocket in 2019
  • Astronauts ace station’s 200th spacewalk
  • Congo announces 9 suspected Ebola cases, including 3 deaths

The details:

  • Elon Musk posts video of ‘electric sled’ for tunnel travel

Billionaire entrepreneur Elon Musk on Friday posted video on social media of what he describes as an electric sled speeding through a tunnel, a test of a system he envisions for 3-D networks of underground passages for speeding traffic under Los Angeles’ congested roads.

[VIDEO: Watch a recap at https://www.youtube.com/watch?v=Jhx-sCYVgeI ]

He posted on Twitter and Instagram that such sleds could transport cars at 125 mph (200 kmh), with automatic switching from one tunnel to the next.

The video shows the sled, apparently riding a monorail, zipping through alternately dark and lighted sections of the tunnel. Musk warned that watching it may cause motion sickness or seizures.

The founder of the SpaceX rocket and the Tesla electric car companies told a recent TED Talk his ideas for improving the speed and cost-effectiveness of tunnel boring.

  • NASA nixes crew for test flight of new megarocket in 2019

NASA’s new megarocket will launch without astronauts on its test flight, now delayed until 2019 because of technical challenges, the space agency’s top leaders said Friday.

In February at the request of the White House, NASA began studying the possibility of putting a crew on the first flight. After reviewing the costs and risks, the space agency decided against it. The White House took part in the decision, said NASA’s Acting Administrator Robert Lightfoot.

Still in development, the super-sized Space Launch System rocket is meant to eventually send astronauts to Mars. The first launch had been targeted for next year, but now won’t happen until 2019 when NASA will send an unoccupied Orion capsule to the vicinity of the moon for a three-week trial run.

The second flight will have astronauts on board. It is scheduled for 2021, but will almost certainly be later because of all the delays with the first flight.

It would have cost a lot more money and time to add life-support systems and other human-required equipment for the test flight, said Bill Gerstenmaier, head of NASA’s human explorations and operations.

“The best plan we have is actually the plan we’re on right now,” he said.

The test flight can be more dynamic, as NASA calls it, without a crew, and the lessons learned can help advance the next mission when people finally are on board.

  • Astronauts ace station’s 200th spacewalk

An equipment water leak shortened Friday’s spacewalk by two U.S. astronauts at the International Space Station, but they still managed to replace a faulty electronics box.

Despite the initial trouble, it was a milestone moment as Peggy Whitson and Jack Fischer floated outside on the station’s 200th spacewalk.

The astronauts wasted no time removing the old electronics box, their No. 1 chore, and plugging in a new unit. The device — a bit unwieldy at more than 5 feet long — supplies electricity and data to science experiments on the outside of the station. The pair also whipped through other tasks, leaving only two undone.

During earlier preparations, a small amount of water leaked from the connection point between an umbilical hose and Fischer’s suit. The hose is one of two that provide water, oxygen, power, cooling and communications for astronauts before they float outside.

The leaky hose had to be disconnected before the spacewalk could begin. The astronauts ended up sharing Whitson’s hose while they waited, which reduced their suit battery power. As a result, Mission Control cut the spacewalk from the intended 6 ½ hours to four hours even before it began.

  • Congo announces 9 suspected Ebola cases, including 3 deaths

One person has been confirmed dead from Ebola in an outbreak in a remote corner of northern Congo as health authorities look into a total of nine suspected cases, including two other deaths, the country’s health minister and the World Health Organization said Friday.

One case of the hemorrhagic fever was confirmed out of the five tested since the outbreak emerged April 22 in Bas-Uele province, Health Minister Oly Ilunga Kalenga said. He said the confirmed case was of the Zaire strain of the virus.

The outbreak could test a recently developed experimental Ebola vaccine that WHO says could be used in emergencies. The global vaccine alliance GAVI said 300,000 doses are available “if needed to stop this outbreak becoming a pandemic.”

This vast, impoverished Central African nation has had seven known Ebola outbreaks in the past, including one in 2014 with several dozen cases. That outbreak was not connected to the massive epidemic in Guinea, Liberia and Sierra Leone that left thousands dead.

So far all the cases have been tied to a remote village, and it’s a strain of Ebola that’s been seen in the country before.