Send a tweet to businessman and billionaire Elon Musk and maybe get a reply. In this case, a Twitter user commented that the SpaceX CEO could be smiling after NASA's budget was approved. Musk replied and he is, apparently, not happy with the approved amount.

The NASA 2018 budget from the signed bill is a little over $19 billion. The budget can allegedly support the agency's mission to Mars. However, Musk didn't think that it would suffice. Musk also believes that the budget won't do his company, SpaceX any good.

Kara Swisher from Recode commented on Twitter that Musk could be "smiling" somewhere after the budget was approved. Musk surprisingly responded to the Tweet.

"I am not," SpaceX CEO Elon Musk, said in a Tweet. "This bill changes almost nothing about what NASA is doing. Existing programs stay in place and there is no added funding for Mars.

Musk added that there could be an additional bill that will help propel the mission to Mars, but the current budget does not include enough funding to make it happen. President Trump already signed the S.442 bill and it's expected to facilitate NASA's deep space exploration programs, according to a report by CNBC.

Although the bill exclusively stated that it will help fund human explorations to Mars and beyond, commercial space flight company owner Elon Musk doubts that the existing budget will be sufficient to sustain the journey to Mars projects. Likewise, the bill won't do any good to help his dream of space tourism.

SpaceX is a NASA affiliate in transporting goods to the International Space Station (ISS) and in bringing scientific data from ISS back to Earth. But Musk's ultimate goal is to send humans to Mars.

Last year, Musk delivered his speech called "Making Humans a Multiplanetary Species" where he enumerated what SpaceX is doing to colonize Mars. It includes harnessing resources from the red planet and building a Mars transporter that can send humans to deep space.